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9358178edc
Summary: This PR allows RocksDB to run in single-primary, multi-secondary process mode. The writer is a regular RocksDB (e.g. an `DBImpl`) instance playing the role of a primary. Multiple `DBImplSecondary` processes (secondaries) share the same set of SST files, MANIFEST, WAL files with the primary. Secondaries tail the MANIFEST of the primary and apply updates to their own in-memory state of the file system, e.g. `VersionStorageInfo`. This PR has several components: 1. (Originally in #4745). Add a `PathNotFound` subcode to `IOError` to denote the failure when a secondary tries to open a file which has been deleted by the primary. 2. (Similar to #4602). Add `FragmentBufferedReader` to handle partially-read, trailing record at the end of a log from where future read can continue. 3. (Originally in #4710 and #4820). Add implementation of the secondary, i.e. `DBImplSecondary`. 3.1 Tail the primary's MANIFEST during recovery. 3.2 Tail the primary's MANIFEST during normal processing by calling `ReadAndApply`. 3.3 Tailing WAL will be in a future PR. 4. Add an example in 'examples/multi_processes_example.cc' to demonstrate the usage of secondary RocksDB instance in a multi-process setting. Instructions to run the example can be found at the beginning of the source code. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4899 Differential Revision: D14510945 Pulled By: riversand963 fbshipit-source-id: 4ac1c5693e6012ad23f7b4b42d3c374fecbe8886
152 lines
5.6 KiB
C++
152 lines
5.6 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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#pragma once
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#ifndef ROCKSDB_LITE
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#include <string>
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#include <vector>
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#include "db/db_impl.h"
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namespace rocksdb {
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class DBImplSecondary : public DBImpl {
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public:
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DBImplSecondary(const DBOptions& options, const std::string& dbname);
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~DBImplSecondary() override;
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Status Recover(const std::vector<ColumnFamilyDescriptor>& column_families,
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bool read_only, bool error_if_log_file_exist,
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bool error_if_data_exists_in_logs) override;
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// Implementations of the DB interface
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using DB::Get;
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Status Get(const ReadOptions& options, ColumnFamilyHandle* column_family,
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const Slice& key, PinnableSlice* value) override;
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Status GetImpl(const ReadOptions& options, ColumnFamilyHandle* column_family,
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const Slice& key, PinnableSlice* value);
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using DBImpl::NewIterator;
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Iterator* NewIterator(const ReadOptions&,
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ColumnFamilyHandle* column_family) override;
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ArenaWrappedDBIter* NewIteratorImpl(const ReadOptions& read_options,
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ColumnFamilyData* cfd,
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SequenceNumber snapshot,
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ReadCallback* read_callback);
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Status NewIterators(const ReadOptions& options,
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const std::vector<ColumnFamilyHandle*>& column_families,
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std::vector<Iterator*>* iterators) override;
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using DBImpl::Put;
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Status Put(const WriteOptions& /*options*/,
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ColumnFamilyHandle* /*column_family*/, const Slice& /*key*/,
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const Slice& /*value*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::Merge;
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Status Merge(const WriteOptions& /*options*/,
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ColumnFamilyHandle* /*column_family*/, const Slice& /*key*/,
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const Slice& /*value*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::Delete;
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Status Delete(const WriteOptions& /*options*/,
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ColumnFamilyHandle* /*column_family*/,
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const Slice& /*key*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::SingleDelete;
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Status SingleDelete(const WriteOptions& /*options*/,
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ColumnFamilyHandle* /*column_family*/,
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const Slice& /*key*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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Status Write(const WriteOptions& /*options*/,
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WriteBatch* /*updates*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::CompactRange;
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Status CompactRange(const CompactRangeOptions& /*options*/,
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ColumnFamilyHandle* /*column_family*/,
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const Slice* /*begin*/, const Slice* /*end*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::CompactFiles;
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Status CompactFiles(
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const CompactionOptions& /*compact_options*/,
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ColumnFamilyHandle* /*column_family*/,
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const std::vector<std::string>& /*input_file_names*/,
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const int /*output_level*/, const int /*output_path_id*/ = -1,
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std::vector<std::string>* const /*output_file_names*/ = nullptr,
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CompactionJobInfo* /*compaction_job_info*/ = nullptr) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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Status DisableFileDeletions() override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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Status EnableFileDeletions(bool /*force*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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Status GetLiveFiles(std::vector<std::string>&,
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uint64_t* /*manifest_file_size*/,
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bool /*flush_memtable*/ = true) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::Flush;
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Status Flush(const FlushOptions& /*options*/,
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ColumnFamilyHandle* /*column_family*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DBImpl::SyncWAL;
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Status SyncWAL() override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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using DB::IngestExternalFile;
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Status IngestExternalFile(
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ColumnFamilyHandle* /*column_family*/,
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const std::vector<std::string>& /*external_files*/,
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const IngestExternalFileOptions& /*ingestion_options*/) override {
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return Status::NotSupported("Not supported operation in read only mode.");
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}
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// Try to catch up with the primary by reading as much as possible from the
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// log files until there is nothing more to read or encounters an error. If
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// the amount of information in the log files to process is huge, this
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// method can take long time due to all the I/O and CPU costs.
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Status TryCatchUpWithPrimary() override;
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private:
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friend class DB;
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// No copying allowed
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DBImplSecondary(const DBImplSecondary&);
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void operator=(const DBImplSecondary&);
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using DBImpl::Recover;
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std::unique_ptr<log::FragmentBufferedReader> manifest_reader_;
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std::unique_ptr<log::Reader::Reporter> manifest_reporter_;
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std::unique_ptr<Status> manifest_reader_status_;
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};
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} // namespace rocksdb
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#endif // !ROCKSDB_LITE
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