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b87c355772
Summary: If the internal iterator is not valid, `SeekToLast` with iter_start_ts should have `valid_` is false without assertion failure. Test plan make check Pull Request resolved: https://github.com/facebook/rocksdb/pull/10279 Reviewed By: ltamasi Differential Revision: D37539393 Pulled By: riversand963 fbshipit-source-id: 8e94057838f8a05144fad5768f4d62f1893ec315
1684 lines
56 KiB
C++
1684 lines
56 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "db/db_iter.h"
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#include <iostream>
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#include <limits>
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#include <string>
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#include "db/dbformat.h"
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#include "db/merge_context.h"
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#include "db/merge_helper.h"
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#include "db/pinned_iterators_manager.h"
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#include "file/filename.h"
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#include "logging/logging.h"
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#include "memory/arena.h"
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#include "monitoring/perf_context_imp.h"
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#include "rocksdb/env.h"
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#include "rocksdb/iterator.h"
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#include "rocksdb/merge_operator.h"
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#include "rocksdb/options.h"
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#include "rocksdb/system_clock.h"
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#include "table/internal_iterator.h"
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#include "table/iterator_wrapper.h"
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#include "trace_replay/trace_replay.h"
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#include "util/mutexlock.h"
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#include "util/string_util.h"
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#include "util/user_comparator_wrapper.h"
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namespace ROCKSDB_NAMESPACE {
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DBIter::DBIter(Env* _env, const ReadOptions& read_options,
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const ImmutableOptions& ioptions,
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const MutableCFOptions& mutable_cf_options,
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const Comparator* cmp, InternalIterator* iter,
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const Version* version, SequenceNumber s, bool arena_mode,
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uint64_t max_sequential_skip_in_iterations,
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ReadCallback* read_callback, DBImpl* db_impl,
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ColumnFamilyData* cfd, bool expose_blob_index)
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: prefix_extractor_(mutable_cf_options.prefix_extractor.get()),
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env_(_env),
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clock_(ioptions.clock),
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logger_(ioptions.logger),
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user_comparator_(cmp),
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merge_operator_(ioptions.merge_operator.get()),
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iter_(iter),
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version_(version),
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read_callback_(read_callback),
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sequence_(s),
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statistics_(ioptions.stats),
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max_skip_(max_sequential_skip_in_iterations),
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max_skippable_internal_keys_(read_options.max_skippable_internal_keys),
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num_internal_keys_skipped_(0),
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iterate_lower_bound_(read_options.iterate_lower_bound),
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iterate_upper_bound_(read_options.iterate_upper_bound),
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direction_(kForward),
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valid_(false),
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current_entry_is_merged_(false),
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is_key_seqnum_zero_(false),
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prefix_same_as_start_(mutable_cf_options.prefix_extractor
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? read_options.prefix_same_as_start
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: false),
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pin_thru_lifetime_(read_options.pin_data),
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expect_total_order_inner_iter_(prefix_extractor_ == nullptr ||
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read_options.total_order_seek ||
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read_options.auto_prefix_mode),
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read_tier_(read_options.read_tier),
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verify_checksums_(read_options.verify_checksums),
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expose_blob_index_(expose_blob_index),
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is_blob_(false),
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arena_mode_(arena_mode),
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range_del_agg_(&ioptions.internal_comparator, s),
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db_impl_(db_impl),
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cfd_(cfd),
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timestamp_ub_(read_options.timestamp),
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timestamp_lb_(read_options.iter_start_ts),
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timestamp_size_(timestamp_ub_ ? timestamp_ub_->size() : 0) {
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RecordTick(statistics_, NO_ITERATOR_CREATED);
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if (pin_thru_lifetime_) {
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pinned_iters_mgr_.StartPinning();
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}
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if (iter_.iter()) {
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iter_.iter()->SetPinnedItersMgr(&pinned_iters_mgr_);
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}
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assert(timestamp_size_ == user_comparator_.timestamp_size());
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}
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Status DBIter::GetProperty(std::string prop_name, std::string* prop) {
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if (prop == nullptr) {
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return Status::InvalidArgument("prop is nullptr");
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}
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if (prop_name == "rocksdb.iterator.super-version-number") {
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// First try to pass the value returned from inner iterator.
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return iter_.iter()->GetProperty(prop_name, prop);
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} else if (prop_name == "rocksdb.iterator.is-key-pinned") {
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if (valid_) {
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*prop = (pin_thru_lifetime_ && saved_key_.IsKeyPinned()) ? "1" : "0";
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} else {
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*prop = "Iterator is not valid.";
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}
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return Status::OK();
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} else if (prop_name == "rocksdb.iterator.internal-key") {
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*prop = saved_key_.GetUserKey().ToString();
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return Status::OK();
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}
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return Status::InvalidArgument("Unidentified property.");
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}
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bool DBIter::ParseKey(ParsedInternalKey* ikey) {
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Status s = ParseInternalKey(iter_.key(), ikey, false /* log_err_key */);
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if (!s.ok()) {
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status_ = Status::Corruption("In DBIter: ", s.getState());
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valid_ = false;
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ROCKS_LOG_ERROR(logger_, "In DBIter: %s", status_.getState());
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return false;
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} else {
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return true;
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}
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}
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void DBIter::Next() {
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assert(valid_);
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assert(status_.ok());
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PERF_CPU_TIMER_GUARD(iter_next_cpu_nanos, clock_);
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// Release temporarily pinned blocks from last operation
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ReleaseTempPinnedData();
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local_stats_.skip_count_ += num_internal_keys_skipped_;
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local_stats_.skip_count_--;
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num_internal_keys_skipped_ = 0;
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bool ok = true;
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if (direction_ == kReverse) {
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is_key_seqnum_zero_ = false;
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if (!ReverseToForward()) {
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ok = false;
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}
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} else if (!current_entry_is_merged_) {
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// If the current value is not a merge, the iter position is the
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// current key, which is already returned. We can safely issue a
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// Next() without checking the current key.
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// If the current key is a merge, very likely iter already points
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// to the next internal position.
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assert(iter_.Valid());
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iter_.Next();
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PERF_COUNTER_ADD(internal_key_skipped_count, 1);
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}
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local_stats_.next_count_++;
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if (ok && iter_.Valid()) {
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if (prefix_same_as_start_) {
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assert(prefix_extractor_ != nullptr);
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const Slice prefix = prefix_.GetUserKey();
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FindNextUserEntry(true /* skipping the current user key */, &prefix);
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} else {
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FindNextUserEntry(true /* skipping the current user key */, nullptr);
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}
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} else {
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is_key_seqnum_zero_ = false;
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valid_ = false;
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}
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if (statistics_ != nullptr && valid_) {
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local_stats_.next_found_count_++;
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local_stats_.bytes_read_ += (key().size() + value().size());
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}
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}
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bool DBIter::SetBlobValueIfNeeded(const Slice& user_key,
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const Slice& blob_index) {
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assert(!is_blob_);
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if (expose_blob_index_) { // Stacked BlobDB implementation
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is_blob_ = true;
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return true;
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}
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if (!version_) {
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status_ = Status::Corruption("Encountered unexpected blob index.");
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valid_ = false;
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return false;
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}
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// TODO: consider moving ReadOptions from ArenaWrappedDBIter to DBIter to
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// avoid having to copy options back and forth.
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ReadOptions read_options;
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read_options.read_tier = read_tier_;
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read_options.verify_checksums = verify_checksums_;
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constexpr FilePrefetchBuffer* prefetch_buffer = nullptr;
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constexpr uint64_t* bytes_read = nullptr;
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const Status s = version_->GetBlob(read_options, user_key, blob_index,
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prefetch_buffer, &blob_value_, bytes_read);
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if (!s.ok()) {
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status_ = s;
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valid_ = false;
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return false;
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}
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is_blob_ = true;
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return true;
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}
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bool DBIter::SetWideColumnValueIfNeeded(const Slice& /* wide_columns_slice */) {
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assert(!is_blob_);
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// TODO: support wide-column entities
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status_ = Status::NotSupported("Encountered unexpected wide-column entity");
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valid_ = false;
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return false;
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}
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// PRE: saved_key_ has the current user key if skipping_saved_key
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// POST: saved_key_ should have the next user key if valid_,
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// if the current entry is a result of merge
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// current_entry_is_merged_ => true
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// saved_value_ => the merged value
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//
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// NOTE: In between, saved_key_ can point to a user key that has
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// a delete marker or a sequence number higher than sequence_
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// saved_key_ MUST have a proper user_key before calling this function
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//
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// The prefix parameter, if not null, indicates that we need to iterate
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// within the prefix, and the iterator needs to be made invalid, if no
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// more entry for the prefix can be found.
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bool DBIter::FindNextUserEntry(bool skipping_saved_key, const Slice* prefix) {
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PERF_TIMER_GUARD(find_next_user_entry_time);
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return FindNextUserEntryInternal(skipping_saved_key, prefix);
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}
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// Actual implementation of DBIter::FindNextUserEntry()
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bool DBIter::FindNextUserEntryInternal(bool skipping_saved_key,
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const Slice* prefix) {
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// Loop until we hit an acceptable entry to yield
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assert(iter_.Valid());
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assert(status_.ok());
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assert(direction_ == kForward);
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current_entry_is_merged_ = false;
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// How many times in a row we have skipped an entry with user key less than
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// or equal to saved_key_. We could skip these entries either because
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// sequence numbers were too high or because skipping_saved_key = true.
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// What saved_key_ contains throughout this method:
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// - if skipping_saved_key : saved_key_ contains the key that we need
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// to skip, and we haven't seen any keys greater
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// than that,
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// - if num_skipped > 0 : saved_key_ contains the key that we have skipped
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// num_skipped times, and we haven't seen any keys
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// greater than that,
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// - none of the above : saved_key_ can contain anything, it doesn't
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// matter.
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uint64_t num_skipped = 0;
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// For write unprepared, the target sequence number in reseek could be larger
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// than the snapshot, and thus needs to be skipped again. This could result in
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// an infinite loop of reseeks. To avoid that, we limit the number of reseeks
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// to one.
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bool reseek_done = false;
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is_blob_ = false;
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do {
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// Will update is_key_seqnum_zero_ as soon as we parsed the current key
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// but we need to save the previous value to be used in the loop.
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bool is_prev_key_seqnum_zero = is_key_seqnum_zero_;
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if (!ParseKey(&ikey_)) {
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is_key_seqnum_zero_ = false;
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return false;
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}
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Slice user_key_without_ts =
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StripTimestampFromUserKey(ikey_.user_key, timestamp_size_);
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is_key_seqnum_zero_ = (ikey_.sequence == 0);
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assert(iterate_upper_bound_ == nullptr ||
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iter_.UpperBoundCheckResult() != IterBoundCheck::kInbound ||
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user_comparator_.CompareWithoutTimestamp(
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user_key_without_ts, /*a_has_ts=*/false, *iterate_upper_bound_,
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/*b_has_ts=*/false) < 0);
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if (iterate_upper_bound_ != nullptr &&
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iter_.UpperBoundCheckResult() != IterBoundCheck::kInbound &&
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user_comparator_.CompareWithoutTimestamp(
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user_key_without_ts, /*a_has_ts=*/false, *iterate_upper_bound_,
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/*b_has_ts=*/false) >= 0) {
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break;
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}
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assert(prefix == nullptr || prefix_extractor_ != nullptr);
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if (prefix != nullptr &&
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prefix_extractor_->Transform(user_key_without_ts).compare(*prefix) !=
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0) {
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assert(prefix_same_as_start_);
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break;
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}
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if (TooManyInternalKeysSkipped()) {
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return false;
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}
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assert(ikey_.user_key.size() >= timestamp_size_);
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Slice ts = timestamp_size_ > 0 ? ExtractTimestampFromUserKey(
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ikey_.user_key, timestamp_size_)
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: Slice();
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bool more_recent = false;
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if (IsVisible(ikey_.sequence, ts, &more_recent)) {
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// If the previous entry is of seqnum 0, the current entry will not
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// possibly be skipped. This condition can potentially be relaxed to
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// prev_key.seq <= ikey_.sequence. We are cautious because it will be more
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// prone to bugs causing the same user key with the same sequence number.
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// Note that with current timestamp implementation, the same user key can
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// have different timestamps and zero sequence number on the bottommost
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// level. This may change in the future.
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if ((!is_prev_key_seqnum_zero || timestamp_size_ > 0) &&
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skipping_saved_key &&
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CompareKeyForSkip(ikey_.user_key, saved_key_.GetUserKey()) <= 0) {
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num_skipped++; // skip this entry
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PERF_COUNTER_ADD(internal_key_skipped_count, 1);
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} else {
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assert(!skipping_saved_key ||
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CompareKeyForSkip(ikey_.user_key, saved_key_.GetUserKey()) > 0);
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if (!iter_.PrepareValue()) {
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assert(!iter_.status().ok());
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valid_ = false;
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return false;
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}
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num_skipped = 0;
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reseek_done = false;
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switch (ikey_.type) {
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case kTypeDeletion:
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case kTypeDeletionWithTimestamp:
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case kTypeSingleDeletion:
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// Arrange to skip all upcoming entries for this key since
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// they are hidden by this deletion.
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if (timestamp_lb_) {
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saved_key_.SetInternalKey(ikey_);
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valid_ = true;
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return true;
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} else {
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saved_key_.SetUserKey(
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ikey_.user_key, !pin_thru_lifetime_ ||
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!iter_.iter()->IsKeyPinned() /* copy */);
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skipping_saved_key = true;
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PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
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}
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break;
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case kTypeValue:
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case kTypeBlobIndex:
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case kTypeWideColumnEntity:
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if (timestamp_lb_) {
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saved_key_.SetInternalKey(ikey_);
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if (ikey_.type == kTypeBlobIndex) {
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if (!SetBlobValueIfNeeded(ikey_.user_key, iter_.value())) {
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return false;
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}
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} else if (ikey_.type == kTypeWideColumnEntity) {
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if (!SetWideColumnValueIfNeeded(iter_.value())) {
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return false;
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}
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}
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valid_ = true;
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return true;
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} else {
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saved_key_.SetUserKey(
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ikey_.user_key, !pin_thru_lifetime_ ||
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!iter_.iter()->IsKeyPinned() /* copy */);
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if (range_del_agg_.ShouldDelete(
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ikey_, RangeDelPositioningMode::kForwardTraversal)) {
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// Arrange to skip all upcoming entries for this key since
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// they are hidden by this deletion.
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skipping_saved_key = true;
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num_skipped = 0;
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reseek_done = false;
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PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
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} else {
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if (ikey_.type == kTypeBlobIndex) {
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if (!SetBlobValueIfNeeded(ikey_.user_key, iter_.value())) {
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return false;
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}
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} else if (ikey_.type == kTypeWideColumnEntity) {
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if (!SetWideColumnValueIfNeeded(iter_.value())) {
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return false;
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}
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}
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valid_ = true;
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return true;
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}
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}
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break;
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case kTypeMerge:
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saved_key_.SetUserKey(
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ikey_.user_key,
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!pin_thru_lifetime_ || !iter_.iter()->IsKeyPinned() /* copy */);
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if (range_del_agg_.ShouldDelete(
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ikey_, RangeDelPositioningMode::kForwardTraversal)) {
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// Arrange to skip all upcoming entries for this key since
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// they are hidden by this deletion.
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skipping_saved_key = true;
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num_skipped = 0;
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reseek_done = false;
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PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
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} else {
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// By now, we are sure the current ikey is going to yield a
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// value
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current_entry_is_merged_ = true;
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valid_ = true;
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return MergeValuesNewToOld(); // Go to a different state machine
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}
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break;
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default:
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valid_ = false;
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status_ = Status::Corruption(
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"Unknown value type: " +
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std::to_string(static_cast<unsigned int>(ikey_.type)));
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return false;
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}
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}
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} else {
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if (more_recent) {
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PERF_COUNTER_ADD(internal_recent_skipped_count, 1);
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}
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// This key was inserted after our snapshot was taken or skipped by
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// timestamp range. If this happens too many times in a row for the same
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// user key, we want to seek to the target sequence number.
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int cmp = user_comparator_.CompareWithoutTimestamp(
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ikey_.user_key, saved_key_.GetUserKey());
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if (cmp == 0 || (skipping_saved_key && cmp < 0)) {
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num_skipped++;
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} else {
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saved_key_.SetUserKey(
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ikey_.user_key,
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!iter_.iter()->IsKeyPinned() || !pin_thru_lifetime_ /* copy */);
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skipping_saved_key = false;
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num_skipped = 0;
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reseek_done = false;
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}
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}
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// If we have sequentially iterated via numerous equal keys, then it's
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// better to seek so that we can avoid too many key comparisons.
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//
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// To avoid infinite loops, do not reseek if we have already attempted to
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// reseek previously.
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//
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// TODO(lth): If we reseek to sequence number greater than ikey_.sequence,
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// then it does not make sense to reseek as we would actually land further
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// away from the desired key. There is opportunity for optimization here.
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if (num_skipped > max_skip_ && !reseek_done) {
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is_key_seqnum_zero_ = false;
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num_skipped = 0;
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reseek_done = true;
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std::string last_key;
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if (skipping_saved_key) {
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// We're looking for the next user-key but all we see are the same
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// user-key with decreasing sequence numbers. Fast forward to
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// sequence number 0 and type deletion (the smallest type).
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if (timestamp_size_ == 0) {
|
|
AppendInternalKey(
|
|
&last_key,
|
|
ParsedInternalKey(saved_key_.GetUserKey(), 0, kTypeDeletion));
|
|
} else {
|
|
const std::string kTsMin(timestamp_size_, '\0');
|
|
AppendInternalKeyWithDifferentTimestamp(
|
|
&last_key,
|
|
ParsedInternalKey(saved_key_.GetUserKey(), 0, kTypeDeletion),
|
|
kTsMin);
|
|
}
|
|
// Don't set skipping_saved_key = false because we may still see more
|
|
// user-keys equal to saved_key_.
|
|
} else {
|
|
// We saw multiple entries with this user key and sequence numbers
|
|
// higher than sequence_. Fast forward to sequence_.
|
|
// Note that this only covers a case when a higher key was overwritten
|
|
// many times since our snapshot was taken, not the case when a lot of
|
|
// different keys were inserted after our snapshot was taken.
|
|
if (timestamp_size_ == 0) {
|
|
AppendInternalKey(
|
|
&last_key, ParsedInternalKey(saved_key_.GetUserKey(), sequence_,
|
|
kValueTypeForSeek));
|
|
} else {
|
|
AppendInternalKeyWithDifferentTimestamp(
|
|
&last_key,
|
|
ParsedInternalKey(saved_key_.GetUserKey(), sequence_,
|
|
kValueTypeForSeek),
|
|
*timestamp_ub_);
|
|
}
|
|
}
|
|
iter_.Seek(last_key);
|
|
RecordTick(statistics_, NUMBER_OF_RESEEKS_IN_ITERATION);
|
|
} else {
|
|
iter_.Next();
|
|
}
|
|
} while (iter_.Valid());
|
|
|
|
valid_ = false;
|
|
return iter_.status().ok();
|
|
}
|
|
|
|
// Merge values of the same user key starting from the current iter_ position
|
|
// Scan from the newer entries to older entries.
|
|
// PRE: iter_.key() points to the first merge type entry
|
|
// saved_key_ stores the user key
|
|
// iter_.PrepareValue() has been called
|
|
// POST: saved_value_ has the merged value for the user key
|
|
// iter_ points to the next entry (or invalid)
|
|
bool DBIter::MergeValuesNewToOld() {
|
|
if (!merge_operator_) {
|
|
ROCKS_LOG_ERROR(logger_, "Options::merge_operator is null.");
|
|
status_ = Status::InvalidArgument("merge_operator_ must be set.");
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
// Temporarily pin the blocks that hold merge operands
|
|
TempPinData();
|
|
merge_context_.Clear();
|
|
// Start the merge process by pushing the first operand
|
|
merge_context_.PushOperand(
|
|
iter_.value(), iter_.iter()->IsValuePinned() /* operand_pinned */);
|
|
TEST_SYNC_POINT("DBIter::MergeValuesNewToOld:PushedFirstOperand");
|
|
|
|
ParsedInternalKey ikey;
|
|
for (iter_.Next(); iter_.Valid(); iter_.Next()) {
|
|
TEST_SYNC_POINT("DBIter::MergeValuesNewToOld:SteppedToNextOperand");
|
|
if (!ParseKey(&ikey)) {
|
|
return false;
|
|
}
|
|
|
|
if (!user_comparator_.Equal(ikey.user_key, saved_key_.GetUserKey())) {
|
|
// hit the next user key, stop right here
|
|
break;
|
|
}
|
|
if (kTypeDeletion == ikey.type || kTypeSingleDeletion == ikey.type ||
|
|
range_del_agg_.ShouldDelete(
|
|
ikey, RangeDelPositioningMode::kForwardTraversal)) {
|
|
// hit a delete with the same user key, stop right here
|
|
// iter_ is positioned after delete
|
|
iter_.Next();
|
|
break;
|
|
}
|
|
if (!iter_.PrepareValue()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
if (kTypeValue == ikey.type) {
|
|
// hit a put, merge the put value with operands and store the
|
|
// final result in saved_value_. We are done!
|
|
const Slice val = iter_.value();
|
|
Status s = Merge(&val, ikey.user_key);
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
// iter_ is positioned after put
|
|
iter_.Next();
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
return true;
|
|
} else if (kTypeMerge == ikey.type) {
|
|
// hit a merge, add the value as an operand and run associative merge.
|
|
// when complete, add result to operands and continue.
|
|
merge_context_.PushOperand(
|
|
iter_.value(), iter_.iter()->IsValuePinned() /* operand_pinned */);
|
|
PERF_COUNTER_ADD(internal_merge_count, 1);
|
|
} else if (kTypeBlobIndex == ikey.type) {
|
|
if (expose_blob_index_) {
|
|
status_ =
|
|
Status::NotSupported("BlobDB does not support merge operator.");
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
// hit a put, merge the put value with operands and store the
|
|
// final result in saved_value_. We are done!
|
|
if (!SetBlobValueIfNeeded(ikey.user_key, iter_.value())) {
|
|
return false;
|
|
}
|
|
valid_ = true;
|
|
const Slice blob_value = value();
|
|
Status s = Merge(&blob_value, ikey.user_key);
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
is_blob_ = false;
|
|
// iter_ is positioned after put
|
|
iter_.Next();
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
return true;
|
|
} else if (kTypeWideColumnEntity == ikey.type) {
|
|
// TODO: support wide-column entities
|
|
status_ = Status::NotSupported(
|
|
"Merge currently not supported for wide-column entities");
|
|
valid_ = false;
|
|
return false;
|
|
} else {
|
|
valid_ = false;
|
|
status_ = Status::Corruption(
|
|
"Unrecognized value type: " +
|
|
std::to_string(static_cast<unsigned int>(ikey.type)));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
// we either exhausted all internal keys under this user key, or hit
|
|
// a deletion marker.
|
|
// feed null as the existing value to the merge operator, such that
|
|
// client can differentiate this scenario and do things accordingly.
|
|
Status s = Merge(nullptr, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
assert(status_.ok());
|
|
return true;
|
|
}
|
|
|
|
void DBIter::Prev() {
|
|
assert(valid_);
|
|
assert(status_.ok());
|
|
|
|
PERF_CPU_TIMER_GUARD(iter_prev_cpu_nanos, clock_);
|
|
ReleaseTempPinnedData();
|
|
ResetInternalKeysSkippedCounter();
|
|
bool ok = true;
|
|
if (direction_ == kForward) {
|
|
if (!ReverseToBackward()) {
|
|
ok = false;
|
|
}
|
|
}
|
|
if (ok) {
|
|
Slice prefix;
|
|
if (prefix_same_as_start_) {
|
|
assert(prefix_extractor_ != nullptr);
|
|
prefix = prefix_.GetUserKey();
|
|
}
|
|
PrevInternal(prefix_same_as_start_ ? &prefix : nullptr);
|
|
}
|
|
|
|
if (statistics_ != nullptr) {
|
|
local_stats_.prev_count_++;
|
|
if (valid_) {
|
|
local_stats_.prev_found_count_++;
|
|
local_stats_.bytes_read_ += (key().size() + value().size());
|
|
}
|
|
}
|
|
}
|
|
|
|
bool DBIter::ReverseToForward() {
|
|
assert(iter_.status().ok());
|
|
|
|
// When moving backwards, iter_ is positioned on _previous_ key, which may
|
|
// not exist or may have different prefix than the current key().
|
|
// If that's the case, seek iter_ to current key.
|
|
if (!expect_total_order_inner_iter() || !iter_.Valid()) {
|
|
IterKey last_key;
|
|
ParsedInternalKey pikey(saved_key_.GetUserKey(), kMaxSequenceNumber,
|
|
kValueTypeForSeek);
|
|
if (timestamp_size_ > 0) {
|
|
// TODO: pre-create kTsMax.
|
|
const std::string kTsMax(timestamp_size_, '\xff');
|
|
pikey.SetTimestamp(kTsMax);
|
|
}
|
|
last_key.SetInternalKey(pikey);
|
|
iter_.Seek(last_key.GetInternalKey());
|
|
RecordTick(statistics_, NUMBER_OF_RESEEKS_IN_ITERATION);
|
|
}
|
|
|
|
direction_ = kForward;
|
|
// Skip keys less than the current key() (a.k.a. saved_key_).
|
|
while (iter_.Valid()) {
|
|
ParsedInternalKey ikey;
|
|
if (!ParseKey(&ikey)) {
|
|
return false;
|
|
}
|
|
if (user_comparator_.Compare(ikey.user_key, saved_key_.GetUserKey()) >= 0) {
|
|
return true;
|
|
}
|
|
iter_.Next();
|
|
}
|
|
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
// Move iter_ to the key before saved_key_.
|
|
bool DBIter::ReverseToBackward() {
|
|
assert(iter_.status().ok());
|
|
|
|
// When current_entry_is_merged_ is true, iter_ may be positioned on the next
|
|
// key, which may not exist or may have prefix different from current.
|
|
// If that's the case, seek to saved_key_.
|
|
if (current_entry_is_merged_ &&
|
|
(!expect_total_order_inner_iter() || !iter_.Valid())) {
|
|
IterKey last_key;
|
|
// Using kMaxSequenceNumber and kValueTypeForSeek
|
|
// (not kValueTypeForSeekForPrev) to seek to a key strictly smaller
|
|
// than saved_key_.
|
|
last_key.SetInternalKey(ParsedInternalKey(
|
|
saved_key_.GetUserKey(), kMaxSequenceNumber, kValueTypeForSeek));
|
|
if (!expect_total_order_inner_iter()) {
|
|
iter_.SeekForPrev(last_key.GetInternalKey());
|
|
} else {
|
|
// Some iterators may not support SeekForPrev(), so we avoid using it
|
|
// when prefix seek mode is disabled. This is somewhat expensive
|
|
// (an extra Prev(), as well as an extra change of direction of iter_),
|
|
// so we may need to reconsider it later.
|
|
iter_.Seek(last_key.GetInternalKey());
|
|
if (!iter_.Valid() && iter_.status().ok()) {
|
|
iter_.SeekToLast();
|
|
}
|
|
}
|
|
RecordTick(statistics_, NUMBER_OF_RESEEKS_IN_ITERATION);
|
|
}
|
|
|
|
direction_ = kReverse;
|
|
return FindUserKeyBeforeSavedKey();
|
|
}
|
|
|
|
void DBIter::PrevInternal(const Slice* prefix) {
|
|
while (iter_.Valid()) {
|
|
saved_key_.SetUserKey(
|
|
ExtractUserKey(iter_.key()),
|
|
!iter_.iter()->IsKeyPinned() || !pin_thru_lifetime_ /* copy */);
|
|
|
|
assert(prefix == nullptr || prefix_extractor_ != nullptr);
|
|
if (prefix != nullptr &&
|
|
prefix_extractor_
|
|
->Transform(StripTimestampFromUserKey(saved_key_.GetUserKey(),
|
|
timestamp_size_))
|
|
.compare(*prefix) != 0) {
|
|
assert(prefix_same_as_start_);
|
|
// Current key does not have the same prefix as start
|
|
valid_ = false;
|
|
return;
|
|
}
|
|
|
|
assert(iterate_lower_bound_ == nullptr || iter_.MayBeOutOfLowerBound() ||
|
|
user_comparator_.CompareWithoutTimestamp(
|
|
saved_key_.GetUserKey(), /*a_has_ts=*/true,
|
|
*iterate_lower_bound_, /*b_has_ts=*/false) >= 0);
|
|
if (iterate_lower_bound_ != nullptr && iter_.MayBeOutOfLowerBound() &&
|
|
user_comparator_.CompareWithoutTimestamp(
|
|
saved_key_.GetUserKey(), /*a_has_ts=*/true, *iterate_lower_bound_,
|
|
/*b_has_ts=*/false) < 0) {
|
|
// We've iterated earlier than the user-specified lower bound.
|
|
valid_ = false;
|
|
return;
|
|
}
|
|
|
|
if (!FindValueForCurrentKey()) { // assigns valid_
|
|
return;
|
|
}
|
|
|
|
// Whether or not we found a value for current key, we need iter_ to end up
|
|
// on a smaller key.
|
|
if (!FindUserKeyBeforeSavedKey()) {
|
|
return;
|
|
}
|
|
|
|
if (valid_) {
|
|
// Found the value.
|
|
return;
|
|
}
|
|
|
|
if (TooManyInternalKeysSkipped(false)) {
|
|
return;
|
|
}
|
|
}
|
|
|
|
// We haven't found any key - iterator is not valid
|
|
valid_ = false;
|
|
}
|
|
|
|
// Used for backwards iteration.
|
|
// Looks at the entries with user key saved_key_ and finds the most up-to-date
|
|
// value for it, or executes a merge, or determines that the value was deleted.
|
|
// Sets valid_ to true if the value is found and is ready to be presented to
|
|
// the user through value().
|
|
// Sets valid_ to false if the value was deleted, and we should try another key.
|
|
// Returns false if an error occurred, and !status().ok() and !valid_.
|
|
//
|
|
// PRE: iter_ is positioned on the last entry with user key equal to saved_key_.
|
|
// POST: iter_ is positioned on one of the entries equal to saved_key_, or on
|
|
// the entry just before them, or on the entry just after them.
|
|
bool DBIter::FindValueForCurrentKey() {
|
|
assert(iter_.Valid());
|
|
merge_context_.Clear();
|
|
current_entry_is_merged_ = false;
|
|
// last entry before merge (could be kTypeDeletion,
|
|
// kTypeDeletionWithTimestamp, kTypeSingleDeletion, kTypeValue,
|
|
// kTypeBlobIndex, or kTypeWideColumnEntity)
|
|
ValueType last_not_merge_type = kTypeDeletion;
|
|
ValueType last_key_entry_type = kTypeDeletion;
|
|
|
|
// If false, it indicates that we have not seen any valid entry, even though
|
|
// last_key_entry_type is initialized to kTypeDeletion.
|
|
bool valid_entry_seen = false;
|
|
|
|
// Temporarily pin blocks that hold (merge operands / the value)
|
|
ReleaseTempPinnedData();
|
|
TempPinData();
|
|
size_t num_skipped = 0;
|
|
while (iter_.Valid()) {
|
|
ParsedInternalKey ikey;
|
|
if (!ParseKey(&ikey)) {
|
|
return false;
|
|
}
|
|
|
|
if (!user_comparator_.EqualWithoutTimestamp(ikey.user_key,
|
|
saved_key_.GetUserKey())) {
|
|
// Found a smaller user key, thus we are done with current user key.
|
|
break;
|
|
}
|
|
|
|
assert(ikey.user_key.size() >= timestamp_size_);
|
|
Slice ts;
|
|
if (timestamp_size_ > 0) {
|
|
ts = Slice(ikey.user_key.data() + ikey.user_key.size() - timestamp_size_,
|
|
timestamp_size_);
|
|
}
|
|
|
|
bool visible = IsVisible(ikey.sequence, ts);
|
|
if (!visible &&
|
|
(timestamp_lb_ == nullptr ||
|
|
user_comparator_.CompareTimestamp(ts, *timestamp_ub_) > 0)) {
|
|
// Found an invisible version of the current user key, and it must have
|
|
// a higher sequence number or timestamp. Therefore, we are done with the
|
|
// current user key.
|
|
break;
|
|
}
|
|
|
|
if (!ts.empty()) {
|
|
saved_timestamp_.assign(ts.data(), ts.size());
|
|
}
|
|
|
|
if (TooManyInternalKeysSkipped()) {
|
|
return false;
|
|
}
|
|
|
|
// This user key has lots of entries.
|
|
// We're going from old to new, and it's taking too long. Let's do a Seek()
|
|
// and go from new to old. This helps when a key was overwritten many times.
|
|
if (num_skipped >= max_skip_) {
|
|
return FindValueForCurrentKeyUsingSeek();
|
|
}
|
|
|
|
if (!iter_.PrepareValue()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
if (timestamp_lb_ != nullptr) {
|
|
// Only needed when timestamp_lb_ is not null
|
|
[[maybe_unused]] const bool ret = ParseKey(&ikey_);
|
|
saved_ikey_.assign(iter_.key().data(), iter_.key().size());
|
|
// Since the preceding ParseKey(&ikey) succeeds, so must this.
|
|
assert(ret);
|
|
}
|
|
|
|
valid_entry_seen = true;
|
|
last_key_entry_type = ikey.type;
|
|
switch (last_key_entry_type) {
|
|
case kTypeValue:
|
|
case kTypeBlobIndex:
|
|
case kTypeWideColumnEntity:
|
|
if (range_del_agg_.ShouldDelete(
|
|
ikey, RangeDelPositioningMode::kBackwardTraversal)) {
|
|
last_key_entry_type = kTypeRangeDeletion;
|
|
PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
|
|
} else if (iter_.iter()->IsValuePinned()) {
|
|
pinned_value_ = iter_.value();
|
|
} else {
|
|
valid_ = false;
|
|
status_ = Status::NotSupported(
|
|
"Backward iteration not supported if underlying iterator's value "
|
|
"cannot be pinned.");
|
|
}
|
|
merge_context_.Clear();
|
|
last_not_merge_type = last_key_entry_type;
|
|
if (!status_.ok()) {
|
|
return false;
|
|
}
|
|
break;
|
|
case kTypeDeletion:
|
|
case kTypeDeletionWithTimestamp:
|
|
case kTypeSingleDeletion:
|
|
merge_context_.Clear();
|
|
last_not_merge_type = last_key_entry_type;
|
|
PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
|
|
break;
|
|
case kTypeMerge:
|
|
if (range_del_agg_.ShouldDelete(
|
|
ikey, RangeDelPositioningMode::kBackwardTraversal)) {
|
|
merge_context_.Clear();
|
|
last_key_entry_type = kTypeRangeDeletion;
|
|
last_not_merge_type = last_key_entry_type;
|
|
PERF_COUNTER_ADD(internal_delete_skipped_count, 1);
|
|
} else {
|
|
assert(merge_operator_ != nullptr);
|
|
merge_context_.PushOperandBack(
|
|
iter_.value(),
|
|
iter_.iter()->IsValuePinned() /* operand_pinned */);
|
|
PERF_COUNTER_ADD(internal_merge_count, 1);
|
|
}
|
|
break;
|
|
default:
|
|
valid_ = false;
|
|
status_ = Status::Corruption(
|
|
"Unknown value type: " +
|
|
std::to_string(static_cast<unsigned int>(last_key_entry_type)));
|
|
return false;
|
|
}
|
|
|
|
PERF_COUNTER_ADD(internal_key_skipped_count, 1);
|
|
iter_.Prev();
|
|
++num_skipped;
|
|
|
|
if (visible && timestamp_lb_ != nullptr) {
|
|
// If timestamp_lb_ is not nullptr, we do not have to look further for
|
|
// another internal key. We can return this current internal key. Yet we
|
|
// still keep the invariant that iter_ is positioned before the returned
|
|
// key.
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
if (!valid_entry_seen) {
|
|
// Since we haven't seen any valid entry, last_key_entry_type remains
|
|
// unchanged and the same as its initial value.
|
|
assert(last_key_entry_type == kTypeDeletion);
|
|
assert(last_not_merge_type == kTypeDeletion);
|
|
valid_ = false;
|
|
return true;
|
|
}
|
|
|
|
if (timestamp_lb_ != nullptr) {
|
|
assert(last_key_entry_type == ikey_.type ||
|
|
last_key_entry_type == kTypeRangeDeletion);
|
|
}
|
|
|
|
Status s;
|
|
s.PermitUncheckedError();
|
|
is_blob_ = false;
|
|
switch (last_key_entry_type) {
|
|
case kTypeDeletion:
|
|
case kTypeDeletionWithTimestamp:
|
|
case kTypeSingleDeletion:
|
|
case kTypeRangeDeletion:
|
|
if (timestamp_lb_ == nullptr) {
|
|
valid_ = false;
|
|
} else {
|
|
saved_key_.SetInternalKey(saved_ikey_);
|
|
valid_ = true;
|
|
}
|
|
return true;
|
|
case kTypeMerge:
|
|
current_entry_is_merged_ = true;
|
|
if (last_not_merge_type == kTypeDeletion ||
|
|
last_not_merge_type == kTypeSingleDeletion ||
|
|
last_not_merge_type == kTypeRangeDeletion) {
|
|
s = Merge(nullptr, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
return true;
|
|
} else if (last_not_merge_type == kTypeBlobIndex) {
|
|
if (expose_blob_index_) {
|
|
status_ =
|
|
Status::NotSupported("BlobDB does not support merge operator.");
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
if (!SetBlobValueIfNeeded(saved_key_.GetUserKey(), pinned_value_)) {
|
|
return false;
|
|
}
|
|
valid_ = true;
|
|
const Slice blob_value = value();
|
|
s = Merge(&blob_value, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
is_blob_ = false;
|
|
return true;
|
|
} else if (last_not_merge_type == kTypeWideColumnEntity) {
|
|
// TODO: support wide-column entities
|
|
status_ = Status::NotSupported(
|
|
"Merge currently not supported for wide-column entities");
|
|
valid_ = false;
|
|
return false;
|
|
} else {
|
|
assert(last_not_merge_type == kTypeValue);
|
|
s = Merge(&pinned_value_, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
break;
|
|
case kTypeValue:
|
|
// do nothing - we've already has value in pinned_value_
|
|
if (timestamp_lb_ != nullptr) {
|
|
saved_key_.SetInternalKey(saved_ikey_);
|
|
}
|
|
break;
|
|
case kTypeBlobIndex:
|
|
if (!SetBlobValueIfNeeded(saved_key_.GetUserKey(), pinned_value_)) {
|
|
return false;
|
|
}
|
|
break;
|
|
case kTypeWideColumnEntity:
|
|
if (!SetWideColumnValueIfNeeded(pinned_value_)) {
|
|
return false;
|
|
}
|
|
break;
|
|
default:
|
|
valid_ = false;
|
|
status_ = Status::Corruption(
|
|
"Unknown value type: " +
|
|
std::to_string(static_cast<unsigned int>(last_key_entry_type)));
|
|
return false;
|
|
}
|
|
if (!s.ok()) {
|
|
valid_ = false;
|
|
status_ = s;
|
|
return false;
|
|
}
|
|
valid_ = true;
|
|
return true;
|
|
}
|
|
|
|
// This function is used in FindValueForCurrentKey.
|
|
// We use Seek() function instead of Prev() to find necessary value
|
|
// TODO: This is very similar to FindNextUserEntry() and MergeValuesNewToOld().
|
|
// Would be nice to reuse some code.
|
|
bool DBIter::FindValueForCurrentKeyUsingSeek() {
|
|
// FindValueForCurrentKey will enable pinning before calling
|
|
// FindValueForCurrentKeyUsingSeek()
|
|
assert(pinned_iters_mgr_.PinningEnabled());
|
|
std::string last_key;
|
|
if (0 == timestamp_size_) {
|
|
AppendInternalKey(&last_key,
|
|
ParsedInternalKey(saved_key_.GetUserKey(), sequence_,
|
|
kValueTypeForSeek));
|
|
} else {
|
|
AppendInternalKeyWithDifferentTimestamp(
|
|
&last_key,
|
|
ParsedInternalKey(saved_key_.GetUserKey(), sequence_,
|
|
kValueTypeForSeek),
|
|
timestamp_lb_ == nullptr ? *timestamp_ub_ : *timestamp_lb_);
|
|
}
|
|
iter_.Seek(last_key);
|
|
RecordTick(statistics_, NUMBER_OF_RESEEKS_IN_ITERATION);
|
|
|
|
// In case read_callback presents, the value we seek to may not be visible.
|
|
// Find the next value that's visible.
|
|
ParsedInternalKey ikey;
|
|
is_blob_ = false;
|
|
while (true) {
|
|
if (!iter_.Valid()) {
|
|
valid_ = false;
|
|
return iter_.status().ok();
|
|
}
|
|
|
|
if (!ParseKey(&ikey)) {
|
|
return false;
|
|
}
|
|
assert(ikey.user_key.size() >= timestamp_size_);
|
|
Slice ts;
|
|
if (timestamp_size_ > 0) {
|
|
ts = Slice(ikey.user_key.data() + ikey.user_key.size() - timestamp_size_,
|
|
timestamp_size_);
|
|
}
|
|
|
|
if (!user_comparator_.EqualWithoutTimestamp(ikey.user_key,
|
|
saved_key_.GetUserKey())) {
|
|
// No visible values for this key, even though FindValueForCurrentKey()
|
|
// has seen some. This is possible if we're using a tailing iterator, and
|
|
// the entries were discarded in a compaction.
|
|
valid_ = false;
|
|
return true;
|
|
}
|
|
|
|
if (IsVisible(ikey.sequence, ts)) {
|
|
break;
|
|
}
|
|
|
|
iter_.Next();
|
|
}
|
|
|
|
if (ikey.type == kTypeDeletion || ikey.type == kTypeSingleDeletion ||
|
|
range_del_agg_.ShouldDelete(
|
|
ikey, RangeDelPositioningMode::kBackwardTraversal) ||
|
|
kTypeDeletionWithTimestamp == ikey.type) {
|
|
if (timestamp_lb_ == nullptr) {
|
|
valid_ = false;
|
|
} else {
|
|
valid_ = true;
|
|
saved_key_.SetInternalKey(ikey);
|
|
}
|
|
return true;
|
|
}
|
|
if (!iter_.PrepareValue()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
if (timestamp_size_ > 0) {
|
|
Slice ts = ExtractTimestampFromUserKey(ikey.user_key, timestamp_size_);
|
|
saved_timestamp_.assign(ts.data(), ts.size());
|
|
}
|
|
if (ikey.type == kTypeValue || ikey.type == kTypeBlobIndex ||
|
|
ikey.type == kTypeWideColumnEntity) {
|
|
assert(iter_.iter()->IsValuePinned());
|
|
pinned_value_ = iter_.value();
|
|
if (ikey.type == kTypeBlobIndex) {
|
|
if (!SetBlobValueIfNeeded(ikey.user_key, pinned_value_)) {
|
|
return false;
|
|
}
|
|
} else if (ikey_.type == kTypeWideColumnEntity) {
|
|
if (!SetWideColumnValueIfNeeded(pinned_value_)) {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
if (timestamp_lb_ != nullptr) {
|
|
saved_key_.SetInternalKey(ikey);
|
|
}
|
|
|
|
valid_ = true;
|
|
return true;
|
|
}
|
|
|
|
// kTypeMerge. We need to collect all kTypeMerge values and save them
|
|
// in operands
|
|
assert(ikey.type == kTypeMerge);
|
|
current_entry_is_merged_ = true;
|
|
merge_context_.Clear();
|
|
merge_context_.PushOperand(
|
|
iter_.value(), iter_.iter()->IsValuePinned() /* operand_pinned */);
|
|
while (true) {
|
|
iter_.Next();
|
|
|
|
if (!iter_.Valid()) {
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
break;
|
|
}
|
|
if (!ParseKey(&ikey)) {
|
|
return false;
|
|
}
|
|
if (!user_comparator_.Equal(ikey.user_key, saved_key_.GetUserKey())) {
|
|
break;
|
|
}
|
|
if (ikey.type == kTypeDeletion || ikey.type == kTypeSingleDeletion ||
|
|
range_del_agg_.ShouldDelete(
|
|
ikey, RangeDelPositioningMode::kForwardTraversal)) {
|
|
break;
|
|
}
|
|
if (!iter_.PrepareValue()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
if (ikey.type == kTypeValue) {
|
|
const Slice val = iter_.value();
|
|
Status s = Merge(&val, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
return true;
|
|
} else if (ikey.type == kTypeMerge) {
|
|
merge_context_.PushOperand(
|
|
iter_.value(), iter_.iter()->IsValuePinned() /* operand_pinned */);
|
|
PERF_COUNTER_ADD(internal_merge_count, 1);
|
|
} else if (ikey.type == kTypeBlobIndex) {
|
|
if (expose_blob_index_) {
|
|
status_ =
|
|
Status::NotSupported("BlobDB does not support merge operator.");
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
if (!SetBlobValueIfNeeded(ikey.user_key, iter_.value())) {
|
|
return false;
|
|
}
|
|
valid_ = true;
|
|
const Slice blob_value = value();
|
|
Status s = Merge(&blob_value, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
is_blob_ = false;
|
|
return true;
|
|
} else if (ikey.type == kTypeWideColumnEntity) {
|
|
// TODO: support wide-column entities
|
|
status_ = Status::NotSupported(
|
|
"Merge currently not supported for wide-column entities");
|
|
valid_ = false;
|
|
return false;
|
|
} else {
|
|
valid_ = false;
|
|
status_ = Status::Corruption(
|
|
"Unknown value type: " +
|
|
std::to_string(static_cast<unsigned int>(ikey.type)));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
Status s = Merge(nullptr, saved_key_.GetUserKey());
|
|
if (!s.ok()) {
|
|
return false;
|
|
}
|
|
|
|
// Make sure we leave iter_ in a good state. If it's valid and we don't care
|
|
// about prefixes, that's already good enough. Otherwise it needs to be
|
|
// seeked to the current key.
|
|
if (!expect_total_order_inner_iter() || !iter_.Valid()) {
|
|
if (!expect_total_order_inner_iter()) {
|
|
iter_.SeekForPrev(last_key);
|
|
} else {
|
|
iter_.Seek(last_key);
|
|
if (!iter_.Valid() && iter_.status().ok()) {
|
|
iter_.SeekToLast();
|
|
}
|
|
}
|
|
RecordTick(statistics_, NUMBER_OF_RESEEKS_IN_ITERATION);
|
|
}
|
|
|
|
valid_ = true;
|
|
return true;
|
|
}
|
|
|
|
Status DBIter::Merge(const Slice* val, const Slice& user_key) {
|
|
Status s = MergeHelper::TimedFullMerge(
|
|
merge_operator_, user_key, val, merge_context_.GetOperands(),
|
|
&saved_value_, logger_, statistics_, clock_, &pinned_value_, true);
|
|
if (!s.ok()) {
|
|
valid_ = false;
|
|
status_ = s;
|
|
return s;
|
|
}
|
|
valid_ = true;
|
|
return s;
|
|
}
|
|
|
|
// Move backwards until the key smaller than saved_key_.
|
|
// Changes valid_ only if return value is false.
|
|
bool DBIter::FindUserKeyBeforeSavedKey() {
|
|
assert(status_.ok());
|
|
size_t num_skipped = 0;
|
|
while (iter_.Valid()) {
|
|
ParsedInternalKey ikey;
|
|
if (!ParseKey(&ikey)) {
|
|
return false;
|
|
}
|
|
|
|
if (CompareKeyForSkip(ikey.user_key, saved_key_.GetUserKey()) < 0) {
|
|
return true;
|
|
}
|
|
|
|
if (TooManyInternalKeysSkipped()) {
|
|
return false;
|
|
}
|
|
|
|
assert(ikey.sequence != kMaxSequenceNumber);
|
|
assert(ikey.user_key.size() >= timestamp_size_);
|
|
Slice ts;
|
|
if (timestamp_size_ > 0) {
|
|
ts = Slice(ikey.user_key.data() + ikey.user_key.size() - timestamp_size_,
|
|
timestamp_size_);
|
|
}
|
|
if (!IsVisible(ikey.sequence, ts)) {
|
|
PERF_COUNTER_ADD(internal_recent_skipped_count, 1);
|
|
} else {
|
|
PERF_COUNTER_ADD(internal_key_skipped_count, 1);
|
|
}
|
|
|
|
if (num_skipped >= max_skip_) {
|
|
num_skipped = 0;
|
|
IterKey last_key;
|
|
ParsedInternalKey pikey(saved_key_.GetUserKey(), kMaxSequenceNumber,
|
|
kValueTypeForSeek);
|
|
if (timestamp_size_ > 0) {
|
|
// TODO: pre-create kTsMax.
|
|
const std::string kTsMax(timestamp_size_, '\xff');
|
|
pikey.SetTimestamp(kTsMax);
|
|
}
|
|
last_key.SetInternalKey(pikey);
|
|
// It would be more efficient to use SeekForPrev() here, but some
|
|
// iterators may not support it.
|
|
iter_.Seek(last_key.GetInternalKey());
|
|
RecordTick(statistics_, NUMBER_OF_RESEEKS_IN_ITERATION);
|
|
if (!iter_.Valid()) {
|
|
break;
|
|
}
|
|
} else {
|
|
++num_skipped;
|
|
}
|
|
|
|
iter_.Prev();
|
|
}
|
|
|
|
if (!iter_.status().ok()) {
|
|
valid_ = false;
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool DBIter::TooManyInternalKeysSkipped(bool increment) {
|
|
if ((max_skippable_internal_keys_ > 0) &&
|
|
(num_internal_keys_skipped_ > max_skippable_internal_keys_)) {
|
|
valid_ = false;
|
|
status_ = Status::Incomplete("Too many internal keys skipped.");
|
|
return true;
|
|
} else if (increment) {
|
|
num_internal_keys_skipped_++;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
bool DBIter::IsVisible(SequenceNumber sequence, const Slice& ts,
|
|
bool* more_recent) {
|
|
// Remember that comparator orders preceding timestamp as larger.
|
|
// TODO(yanqin): support timestamp in read_callback_.
|
|
bool visible_by_seq = (read_callback_ == nullptr)
|
|
? sequence <= sequence_
|
|
: read_callback_->IsVisible(sequence);
|
|
|
|
bool visible_by_ts =
|
|
(timestamp_ub_ == nullptr ||
|
|
user_comparator_.CompareTimestamp(ts, *timestamp_ub_) <= 0) &&
|
|
(timestamp_lb_ == nullptr ||
|
|
user_comparator_.CompareTimestamp(ts, *timestamp_lb_) >= 0);
|
|
|
|
if (more_recent) {
|
|
*more_recent = !visible_by_seq;
|
|
}
|
|
return visible_by_seq && visible_by_ts;
|
|
}
|
|
|
|
void DBIter::SetSavedKeyToSeekTarget(const Slice& target) {
|
|
is_key_seqnum_zero_ = false;
|
|
SequenceNumber seq = sequence_;
|
|
saved_key_.Clear();
|
|
saved_key_.SetInternalKey(target, seq, kValueTypeForSeek, timestamp_ub_);
|
|
|
|
if (iterate_lower_bound_ != nullptr &&
|
|
user_comparator_.CompareWithoutTimestamp(
|
|
saved_key_.GetUserKey(), /*a_has_ts=*/true, *iterate_lower_bound_,
|
|
/*b_has_ts=*/false) < 0) {
|
|
// Seek key is smaller than the lower bound.
|
|
saved_key_.Clear();
|
|
saved_key_.SetInternalKey(*iterate_lower_bound_, seq, kValueTypeForSeek,
|
|
timestamp_ub_);
|
|
}
|
|
}
|
|
|
|
void DBIter::SetSavedKeyToSeekForPrevTarget(const Slice& target) {
|
|
is_key_seqnum_zero_ = false;
|
|
saved_key_.Clear();
|
|
// now saved_key is used to store internal key.
|
|
saved_key_.SetInternalKey(target, 0 /* sequence_number */,
|
|
kValueTypeForSeekForPrev, timestamp_ub_);
|
|
|
|
if (timestamp_size_ > 0) {
|
|
const std::string kTsMin(timestamp_size_, '\0');
|
|
Slice ts = kTsMin;
|
|
saved_key_.UpdateInternalKey(
|
|
/*seq=*/0, kValueTypeForSeekForPrev,
|
|
timestamp_lb_ == nullptr ? &ts : timestamp_lb_);
|
|
}
|
|
|
|
if (iterate_upper_bound_ != nullptr &&
|
|
user_comparator_.CompareWithoutTimestamp(
|
|
saved_key_.GetUserKey(), /*a_has_ts=*/true, *iterate_upper_bound_,
|
|
/*b_has_ts=*/false) >= 0) {
|
|
saved_key_.Clear();
|
|
saved_key_.SetInternalKey(*iterate_upper_bound_, kMaxSequenceNumber,
|
|
kValueTypeForSeekForPrev, timestamp_ub_);
|
|
if (timestamp_size_ > 0) {
|
|
const std::string kTsMax(timestamp_size_, '\xff');
|
|
Slice ts = kTsMax;
|
|
saved_key_.UpdateInternalKey(
|
|
kMaxSequenceNumber, kValueTypeForSeekForPrev,
|
|
timestamp_lb_ != nullptr ? timestamp_lb_ : &ts);
|
|
}
|
|
}
|
|
}
|
|
|
|
void DBIter::Seek(const Slice& target) {
|
|
PERF_CPU_TIMER_GUARD(iter_seek_cpu_nanos, clock_);
|
|
StopWatch sw(clock_, statistics_, DB_SEEK);
|
|
|
|
#ifndef ROCKSDB_LITE
|
|
if (db_impl_ != nullptr && cfd_ != nullptr) {
|
|
// TODO: What do we do if this returns an error?
|
|
Slice lower_bound, upper_bound;
|
|
if (iterate_lower_bound_ != nullptr) {
|
|
lower_bound = *iterate_lower_bound_;
|
|
} else {
|
|
lower_bound = Slice("");
|
|
}
|
|
if (iterate_upper_bound_ != nullptr) {
|
|
upper_bound = *iterate_upper_bound_;
|
|
} else {
|
|
upper_bound = Slice("");
|
|
}
|
|
db_impl_->TraceIteratorSeek(cfd_->GetID(), target, lower_bound, upper_bound)
|
|
.PermitUncheckedError();
|
|
}
|
|
#endif // ROCKSDB_LITE
|
|
|
|
status_ = Status::OK();
|
|
ReleaseTempPinnedData();
|
|
ResetInternalKeysSkippedCounter();
|
|
|
|
// Seek the inner iterator based on the target key.
|
|
{
|
|
PERF_TIMER_GUARD(seek_internal_seek_time);
|
|
|
|
SetSavedKeyToSeekTarget(target);
|
|
iter_.Seek(saved_key_.GetInternalKey());
|
|
|
|
range_del_agg_.InvalidateRangeDelMapPositions();
|
|
RecordTick(statistics_, NUMBER_DB_SEEK);
|
|
}
|
|
if (!iter_.Valid()) {
|
|
valid_ = false;
|
|
return;
|
|
}
|
|
direction_ = kForward;
|
|
|
|
// Now the inner iterator is placed to the target position. From there,
|
|
// we need to find out the next key that is visible to the user.
|
|
ClearSavedValue();
|
|
if (prefix_same_as_start_) {
|
|
// The case where the iterator needs to be invalidated if it has exhausted
|
|
// keys within the same prefix of the seek key.
|
|
assert(prefix_extractor_ != nullptr);
|
|
Slice target_prefix = prefix_extractor_->Transform(target);
|
|
FindNextUserEntry(false /* not skipping saved_key */,
|
|
&target_prefix /* prefix */);
|
|
if (valid_) {
|
|
// Remember the prefix of the seek key for the future Next() call to
|
|
// check.
|
|
prefix_.SetUserKey(target_prefix);
|
|
}
|
|
} else {
|
|
FindNextUserEntry(false /* not skipping saved_key */, nullptr);
|
|
}
|
|
if (!valid_) {
|
|
return;
|
|
}
|
|
|
|
// Updating stats and perf context counters.
|
|
if (statistics_ != nullptr) {
|
|
// Decrement since we don't want to count this key as skipped
|
|
RecordTick(statistics_, NUMBER_DB_SEEK_FOUND);
|
|
RecordTick(statistics_, ITER_BYTES_READ, key().size() + value().size());
|
|
}
|
|
PERF_COUNTER_ADD(iter_read_bytes, key().size() + value().size());
|
|
}
|
|
|
|
void DBIter::SeekForPrev(const Slice& target) {
|
|
PERF_CPU_TIMER_GUARD(iter_seek_cpu_nanos, clock_);
|
|
StopWatch sw(clock_, statistics_, DB_SEEK);
|
|
|
|
#ifndef ROCKSDB_LITE
|
|
if (db_impl_ != nullptr && cfd_ != nullptr) {
|
|
// TODO: What do we do if this returns an error?
|
|
Slice lower_bound, upper_bound;
|
|
if (iterate_lower_bound_ != nullptr) {
|
|
lower_bound = *iterate_lower_bound_;
|
|
} else {
|
|
lower_bound = Slice("");
|
|
}
|
|
if (iterate_upper_bound_ != nullptr) {
|
|
upper_bound = *iterate_upper_bound_;
|
|
} else {
|
|
upper_bound = Slice("");
|
|
}
|
|
db_impl_
|
|
->TraceIteratorSeekForPrev(cfd_->GetID(), target, lower_bound,
|
|
upper_bound)
|
|
.PermitUncheckedError();
|
|
}
|
|
#endif // ROCKSDB_LITE
|
|
|
|
status_ = Status::OK();
|
|
ReleaseTempPinnedData();
|
|
ResetInternalKeysSkippedCounter();
|
|
|
|
// Seek the inner iterator based on the target key.
|
|
{
|
|
PERF_TIMER_GUARD(seek_internal_seek_time);
|
|
SetSavedKeyToSeekForPrevTarget(target);
|
|
iter_.SeekForPrev(saved_key_.GetInternalKey());
|
|
range_del_agg_.InvalidateRangeDelMapPositions();
|
|
RecordTick(statistics_, NUMBER_DB_SEEK);
|
|
}
|
|
if (!iter_.Valid()) {
|
|
valid_ = false;
|
|
return;
|
|
}
|
|
direction_ = kReverse;
|
|
|
|
// Now the inner iterator is placed to the target position. From there,
|
|
// we need to find out the first key that is visible to the user in the
|
|
// backward direction.
|
|
ClearSavedValue();
|
|
if (prefix_same_as_start_) {
|
|
// The case where the iterator needs to be invalidated if it has exhausted
|
|
// keys within the same prefix of the seek key.
|
|
assert(prefix_extractor_ != nullptr);
|
|
Slice target_prefix = prefix_extractor_->Transform(target);
|
|
PrevInternal(&target_prefix);
|
|
if (valid_) {
|
|
// Remember the prefix of the seek key for the future Prev() call to
|
|
// check.
|
|
prefix_.SetUserKey(target_prefix);
|
|
}
|
|
} else {
|
|
PrevInternal(nullptr);
|
|
}
|
|
|
|
// Report stats and perf context.
|
|
if (statistics_ != nullptr && valid_) {
|
|
RecordTick(statistics_, NUMBER_DB_SEEK_FOUND);
|
|
RecordTick(statistics_, ITER_BYTES_READ, key().size() + value().size());
|
|
PERF_COUNTER_ADD(iter_read_bytes, key().size() + value().size());
|
|
}
|
|
}
|
|
|
|
void DBIter::SeekToFirst() {
|
|
if (iterate_lower_bound_ != nullptr) {
|
|
Seek(*iterate_lower_bound_);
|
|
return;
|
|
}
|
|
PERF_CPU_TIMER_GUARD(iter_seek_cpu_nanos, clock_);
|
|
// Don't use iter_::Seek() if we set a prefix extractor
|
|
// because prefix seek will be used.
|
|
if (!expect_total_order_inner_iter()) {
|
|
max_skip_ = std::numeric_limits<uint64_t>::max();
|
|
}
|
|
status_ = Status::OK();
|
|
direction_ = kForward;
|
|
ReleaseTempPinnedData();
|
|
ResetInternalKeysSkippedCounter();
|
|
ClearSavedValue();
|
|
is_key_seqnum_zero_ = false;
|
|
|
|
{
|
|
PERF_TIMER_GUARD(seek_internal_seek_time);
|
|
iter_.SeekToFirst();
|
|
range_del_agg_.InvalidateRangeDelMapPositions();
|
|
}
|
|
|
|
RecordTick(statistics_, NUMBER_DB_SEEK);
|
|
if (iter_.Valid()) {
|
|
saved_key_.SetUserKey(
|
|
ExtractUserKey(iter_.key()),
|
|
!iter_.iter()->IsKeyPinned() || !pin_thru_lifetime_ /* copy */);
|
|
FindNextUserEntry(false /* not skipping saved_key */,
|
|
nullptr /* no prefix check */);
|
|
if (statistics_ != nullptr) {
|
|
if (valid_) {
|
|
RecordTick(statistics_, NUMBER_DB_SEEK_FOUND);
|
|
RecordTick(statistics_, ITER_BYTES_READ, key().size() + value().size());
|
|
PERF_COUNTER_ADD(iter_read_bytes, key().size() + value().size());
|
|
}
|
|
}
|
|
} else {
|
|
valid_ = false;
|
|
}
|
|
if (valid_ && prefix_same_as_start_) {
|
|
assert(prefix_extractor_ != nullptr);
|
|
prefix_.SetUserKey(prefix_extractor_->Transform(
|
|
StripTimestampFromUserKey(saved_key_.GetUserKey(), timestamp_size_)));
|
|
}
|
|
}
|
|
|
|
void DBIter::SeekToLast() {
|
|
if (iterate_upper_bound_ != nullptr) {
|
|
// Seek to last key strictly less than ReadOptions.iterate_upper_bound.
|
|
SeekForPrev(*iterate_upper_bound_);
|
|
const bool is_ikey = (timestamp_size_ > 0 && timestamp_lb_ != nullptr);
|
|
Slice k = Valid() ? key() : Slice();
|
|
if (is_ikey && Valid()) {
|
|
k.remove_suffix(kNumInternalBytes + timestamp_size_);
|
|
}
|
|
while (Valid() && 0 == user_comparator_.CompareWithoutTimestamp(
|
|
*iterate_upper_bound_, /*a_has_ts=*/false, k,
|
|
/*b_has_ts=*/false)) {
|
|
ReleaseTempPinnedData();
|
|
PrevInternal(nullptr);
|
|
|
|
k = key();
|
|
if (is_ikey) {
|
|
k.remove_suffix(kNumInternalBytes + timestamp_size_);
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
|
|
PERF_CPU_TIMER_GUARD(iter_seek_cpu_nanos, clock_);
|
|
// Don't use iter_::Seek() if we set a prefix extractor
|
|
// because prefix seek will be used.
|
|
if (!expect_total_order_inner_iter()) {
|
|
max_skip_ = std::numeric_limits<uint64_t>::max();
|
|
}
|
|
status_ = Status::OK();
|
|
direction_ = kReverse;
|
|
ReleaseTempPinnedData();
|
|
ResetInternalKeysSkippedCounter();
|
|
ClearSavedValue();
|
|
is_key_seqnum_zero_ = false;
|
|
|
|
{
|
|
PERF_TIMER_GUARD(seek_internal_seek_time);
|
|
iter_.SeekToLast();
|
|
range_del_agg_.InvalidateRangeDelMapPositions();
|
|
}
|
|
PrevInternal(nullptr);
|
|
if (statistics_ != nullptr) {
|
|
RecordTick(statistics_, NUMBER_DB_SEEK);
|
|
if (valid_) {
|
|
RecordTick(statistics_, NUMBER_DB_SEEK_FOUND);
|
|
RecordTick(statistics_, ITER_BYTES_READ, key().size() + value().size());
|
|
PERF_COUNTER_ADD(iter_read_bytes, key().size() + value().size());
|
|
}
|
|
}
|
|
if (valid_ && prefix_same_as_start_) {
|
|
assert(prefix_extractor_ != nullptr);
|
|
prefix_.SetUserKey(prefix_extractor_->Transform(
|
|
StripTimestampFromUserKey(saved_key_.GetUserKey(), timestamp_size_)));
|
|
}
|
|
}
|
|
|
|
Iterator* NewDBIterator(Env* env, const ReadOptions& read_options,
|
|
const ImmutableOptions& ioptions,
|
|
const MutableCFOptions& mutable_cf_options,
|
|
const Comparator* user_key_comparator,
|
|
InternalIterator* internal_iter, const Version* version,
|
|
const SequenceNumber& sequence,
|
|
uint64_t max_sequential_skip_in_iterations,
|
|
ReadCallback* read_callback, DBImpl* db_impl,
|
|
ColumnFamilyData* cfd, bool expose_blob_index) {
|
|
DBIter* db_iter =
|
|
new DBIter(env, read_options, ioptions, mutable_cf_options,
|
|
user_key_comparator, internal_iter, version, sequence, false,
|
|
max_sequential_skip_in_iterations, read_callback, db_impl, cfd,
|
|
expose_blob_index);
|
|
return db_iter;
|
|
}
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|