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Enhance partial merge to support multiple arguments

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Summary:
* PartialMerge api now takes a list of operands instead of two operands.
* Add min_pertial_merge_operands to Options, indicating the minimum
  number of operands to trigger partial merge.
* This diff is based on Schalk's previous diff (D14601), but it also
  includes necessary changes such as updating the pure C api for
  partial merge.

Test Plan:
* make check all
* develop tests for cases where partial merge takes more than two
  operands.

TODOs (from Schalk):
* Add test with min_partial_merge_operands > 2.
* Perform benchmarks to measure the performance improvements (can probably
  use results of task #2837810.)
* Add description of problem to doc/index.html.
* Change wiki pages to reflect the interface changes.

Reviewers: haobo, igor, vamsi

Reviewed By: haobo

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D16815
This commit is contained in:
Yueh-Hsuan Chiang 2014-03-24 17:57:13 -07:00
parent e6d4b006b6
commit cda4006e87
20 changed files with 297 additions and 168 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
db/builder.cc
View file

@ -73,6 +73,7 @@ Status BuildTable(const std::string& dbname, Env* env, const Options& options,
MergeHelper merge(internal_comparator.user_comparator(),
options.merge_operator.get(), options.info_log.get(),
options.min_partial_merge_operands,
true /* internal key corruption is not ok */);
if (purge) {

58
db/c.cc
View file

@ -159,11 +159,9 @@ struct rocksdb_mergeoperator_t : public MergeOperator {
const char* const* operands_list, const size_t* operands_list_length,
int num_operands,
unsigned char* success, size_t* new_value_length);
char* (*partial_merge_)(
void*,
const char* key, size_t key_length,
const char* left_operand, size_t left_operand_length,
const char* right_operand, size_t right_operand_length,
char* (*partial_merge_)(void*, const char* key, size_t key_length,
const char* const* operands_list,
const size_t* operands_list_length, int num_operands,
unsigned char* success, size_t* new_value_length);
void (*delete_value_)(
void*,
@ -219,21 +217,23 @@ struct rocksdb_mergeoperator_t : public MergeOperator {
return success;
}
virtual bool PartialMerge(
const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const {
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const {
size_t operand_count = operand_list.size();
std::vector<const char*> operand_pointers(operand_count);
std::vector<size_t> operand_sizes(operand_count);
for (size_t i = 0; i < operand_count; ++i) {
Slice operand(operand_list[i]);
operand_pointers[i] = operand.data();
operand_sizes[i] = operand.size();
}
unsigned char success;
size_t new_value_len;
char* tmp_new_value = (*partial_merge_)(
state_,
key.data(), key.size(),
left_operand.data(), left_operand.size(),
right_operand.data(), right_operand.size(),
&success, &new_value_len);
state_, key.data(), key.size(), &operand_pointers[0], &operand_sizes[0],
operand_count, &success, &new_value_len);
new_value->assign(tmp_new_value, new_value_len);
if (delete_value_ != nullptr) {
@ -1094,24 +1094,18 @@ rocksdb_filterpolicy_t* rocksdb_filterpolicy_create_bloom(int bits_per_key) {
}
rocksdb_mergeoperator_t* rocksdb_mergeoperator_create(
void* state,
void (*destructor)(void*),
char* (*full_merge)(
void*,
const char* key, size_t key_length,
const char* existing_value, size_t existing_value_length,
const char* const* operands_list, const size_t* operands_list_length,
int num_operands,
void* state, void (*destructor)(void*),
char* (*full_merge)(void*, const char* key, size_t key_length,
const char* existing_value,
size_t existing_value_length,
const char* const* operands_list,
const size_t* operands_list_length, int num_operands,
unsigned char* success, size_t* new_value_length),
char* (*partial_merge)(
void*,
const char* key, size_t key_length,
const char* left_operand, size_t left_operand_length,
const char* right_operand, size_t right_operand_length,
char* (*partial_merge)(void*, const char* key, size_t key_length,
const char* const* operands_list,
const size_t* operands_list_length, int num_operands,
unsigned char* success, size_t* new_value_length),
void (*delete_value)(
void*,
const char* value, size_t value_length),
void (*delete_value)(void*, const char* value, size_t value_length),
const char* (*name)(void*)) {
rocksdb_mergeoperator_t* result = new rocksdb_mergeoperator_t;
result->state_ = state;

4
db/c_test.c
View file

@ -175,8 +175,8 @@ static char* MergeOperatorFullMerge(
static char* MergeOperatorPartialMerge(
void* arg,
const char* key, size_t key_length,
const char* left_operand, size_t left_operand_length,
const char* right_operand, size_t right_operand_length,
const char* const* operands_list, const size_t* operands_list_length,
int num_operands,
unsigned char* success, size_t* new_value_length) {
*new_value_length = 4;
*success = 1;

1
db/db_impl.cc
View file

@ -2463,6 +2463,7 @@ Status DBImpl::DoCompactionWork(CompactionState* compact,
std::vector<char> delete_key; // for compaction filter
MergeHelper merge(user_comparator(), options_.merge_operator.get(),
options_.info_log.get(),
options_.min_partial_merge_operands,
false /* internal key corruption is expected */);
auto compaction_filter = options_.compaction_filter;
std::unique_ptr<CompactionFilter> compaction_filter_from_factory = nullptr;

15
db/db_iter.cc
View file

@ -313,21 +313,6 @@ void DBIter::MergeValuesNewToOld() {
// when complete, add result to operands and continue.
const Slice& value = iter_->value();
operands.push_front(value.ToString());
while(operands.size() >= 2) {
// Call user associative-merge until it returns false
if (user_merge_operator_->PartialMerge(ikey.user_key,
Slice(operands[0]),
Slice(operands[1]),
&merge_result,
logger_)) {
operands.pop_front();
swap(operands.front(), merge_result);
} else {
// Associative merge returns false ==> stack the operands
break;
}
}
}
}

11
db/memtable.cc
View file

@ -353,17 +353,6 @@ static bool SaveValue(void* arg, const char* entry) {
Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
*(s->merge_in_progress) = true;
merge_context->PushOperand(v);
while (merge_context->GetNumOperands() >= 2) {
// Attempt to associative merge. (Returns true if successful)
if (merge_operator->PartialMerge(
s->key->user_key(), merge_context->GetOperand(0),
merge_context->GetOperand(1), &merge_result, s->logger)) {
merge_context->PushPartialMergeResult(merge_result);
} else {
// Stack them because user can't associative merge
break;
}
}
return true;
}
default:

8
db/merge_context.h
View file

@ -25,12 +25,12 @@ public:
operand_list->clear();
}
}
// Replace the first two operands of merge_result, which are expected be the
// merge results of them.
// Replace all operands with merge_result, which are expected to be the
// merge result of them.
void PushPartialMergeResult(std::string& merge_result) {
assert (operand_list);
operand_list->pop_front();
swap(operand_list->front(), merge_result);
operand_list->clear();
operand_list->push_front(std::move(merge_result));
}
// Push a merge operand
void PushOperand(const Slice& operand_slice) {

39
db/merge_helper.cc
View file

@ -129,28 +129,10 @@ void MergeHelper::MergeUntil(Iterator* iter, SequenceNumber stop_before,
// => then continue because we haven't yet seen a Put/Delete.
assert(!operands_.empty()); // Should have at least one element in it
// keep queuing keys and operands until we either meet a put / delete
// request or later did a partial merge.
keys_.push_front(iter->key().ToString());
operands_.push_front(iter->value().ToString());
while (operands_.size() >= 2) {
// Returns false when the merge_operator can no longer process it
if (user_merge_operator_->PartialMerge(ikey.user_key,
Slice(operands_[0]),
Slice(operands_[1]),
&merge_result,
logger_)) {
// Merging of operands (associative merge) was successful.
// Replace these frontmost two operands with the merge result
keys_.pop_front();
operands_.pop_front();
swap(operands_.front(), merge_result);
} else {
// Merging of operands (associative merge) returned false.
// The user merge_operator does not know how to merge these operands.
// So we just stack them up until we find a Put/Delete or end of key.
break;
}
}
continue;
}
}
@ -192,6 +174,23 @@ void MergeHelper::MergeUntil(Iterator* iter, SequenceNumber stop_before,
RecordTick(stats, NUMBER_MERGE_FAILURES);
// Do nothing if not success_. Leave keys() and operands() as they are.
}
} else {
// We haven't seen the beginning of the key nor a Put/Delete.
// Attempt to use the user's associative merge function to
// merge the stacked merge operands into a single operand.
if (operands_.size() >= 2 &&
operands_.size() >= min_partial_merge_operands_ &&
user_merge_operator_->PartialMergeMulti(
ikey.user_key,
std::deque<Slice>(operands_.begin(), operands_.end()),
&merge_result, logger_)) {
// Merging of operands (associative merge) was successful.
// Replace operands with the merge result
operands_.clear();
operands_.push_front(std::move(merge_result));
keys_.erase(keys_.begin(), keys_.end() - 1);
}
}
}

6
db/merge_helper.h
View file

@ -22,12 +22,13 @@ class Statistics;
class MergeHelper {
public:
MergeHelper(const Comparator* user_comparator,
const MergeOperator* user_merge_operator,
Logger* logger,
const MergeOperator* user_merge_operator, Logger* logger,
unsigned min_partial_merge_operands,
bool assert_valid_internal_key)
: user_comparator_(user_comparator),
user_merge_operator_(user_merge_operator),
logger_(logger),
min_partial_merge_operands_(min_partial_merge_operands),
assert_valid_internal_key_(assert_valid_internal_key),
keys_(),
operands_(),
@ -88,6 +89,7 @@ class MergeHelper {
const Comparator* user_comparator_;
const MergeOperator* user_merge_operator_;
Logger* logger_;
unsigned min_partial_merge_operands_;
bool assert_valid_internal_key_; // enforce no internal key corruption?
// the scratch area that holds the result of MergeUntil

23
db/merge_operator.cc
View file

@ -11,6 +11,28 @@
namespace rocksdb {
// The default implementation of PartialMergeMulti, which invokes
// PartialMerge multiple times internally and merges two operands at
// a time.
bool MergeOperator::PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value,
Logger* logger) const {
// Simply loop through the operands
std::string temp_value;
Slice temp_slice;
for (const auto& operand : operand_list) {
if (!PartialMerge(key, temp_slice, operand, &temp_value, logger)) {
return false;
}
swap(temp_value, *new_value);
temp_slice = Slice(*new_value);
}
// The result will be in *new_value. All merges succeeded.
return true;
}
// Given a "real" merge from the library, call the user's
// associative merge function one-by-one on each of the operands.
// NOTE: It is assumed that the client's merge-operator will handle any errors.
@ -46,7 +68,6 @@ bool AssociativeMergeOperator::PartialMerge(
const Slice& right_operand,
std::string* new_value,
Logger* logger) const {
return Merge(key, &left_operand, right_operand, new_value, logger);
}

91
db/merge_test.cc
View file

@ -24,10 +24,14 @@ using namespace rocksdb;
namespace {
int numMergeOperatorCalls;
void resetNumMergeOperatorCalls() {
numMergeOperatorCalls = 0;
}
int num_partial_merge_calls;
void resetNumPartialMergeCalls() {
num_partial_merge_calls = 0;
}
}
class CountMergeOperator : public AssociativeMergeOperator {
@ -42,6 +46,11 @@ class CountMergeOperator : public AssociativeMergeOperator {
std::string* new_value,
Logger* logger) const override {
++numMergeOperatorCalls;
if (existing_value == nullptr) {
new_value->assign(value.data(), value.size());
return true;
}
return mergeOperator_->PartialMerge(
key,
*existing_value,
@ -50,6 +59,14 @@ class CountMergeOperator : public AssociativeMergeOperator {
logger);
}
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const {
++num_partial_merge_calls;
return mergeOperator_->PartialMergeMulti(key, operand_list, new_value,
logger);
}
virtual const char* Name() const override {
return "UInt64AddOperator";
}
@ -58,16 +75,16 @@ class CountMergeOperator : public AssociativeMergeOperator {
std::shared_ptr<MergeOperator> mergeOperator_;
};
std::shared_ptr<DB> OpenDb(
const string& dbname,
const bool ttl = false,
const unsigned max_successive_merges = 0) {
std::shared_ptr<DB> OpenDb(const string& dbname, const bool ttl = false,
const size_t max_successive_merges = 0,
const uint32_t min_partial_merge_operands = 2) {
DB* db;
StackableDB* sdb;
Options options;
options.create_if_missing = true;
options.merge_operator = std::make_shared<CountMergeOperator>();
options.max_successive_merges = max_successive_merges;
options.min_partial_merge_operands = min_partial_merge_operands;
Status s;
DestroyDB(dbname, Options());
if (ttl) {
@ -306,6 +323,44 @@ void testSuccessiveMerge(
}
}
void testPartialMerge(Counters* counters, DB* db, int max_merge, int min_merge,
int count) {
FlushOptions o;
o.wait = true;
// Test case 1: partial merge should be called when the number of merge
// operands exceeds the threshold.
uint64_t tmp_sum = 0;
resetNumPartialMergeCalls();
for (int i = 1; i <= count; i++) {
counters->assert_add("b", i);
tmp_sum += i;
}
db->Flush(o);
db->CompactRange(nullptr, nullptr);
ASSERT_EQ(tmp_sum, counters->assert_get("b"));
if (count > max_merge) {
// in this case, FullMerge should be called instead.
ASSERT_EQ(num_partial_merge_calls, 0);
} else {
// if count >= min_merge, then partial merge should be called once.
ASSERT_EQ((count >= min_merge), (num_partial_merge_calls == 1));
}
// Test case 2: partial merge should not be called when a put is found.
resetNumPartialMergeCalls();
tmp_sum = 0;
db->Put(rocksdb::WriteOptions(), "c", "10");
for (int i = 1; i <= count; i++) {
counters->assert_add("c", i);
tmp_sum += i;
}
db->Flush(o);
db->CompactRange(nullptr, nullptr);
ASSERT_EQ(tmp_sum, counters->assert_get("c"));
ASSERT_EQ(num_partial_merge_calls, 0);
}
void testSingleBatchSuccessiveMerge(
DB* db,
int max_num_merges,
@ -370,20 +425,40 @@ void runTest(int argc, const string& dbname, const bool use_ttl = false) {
{
cout << "Test merge in memtable... \n";
unsigned maxMerge = 5;
auto db = OpenDb(dbname, use_ttl, maxMerge);
size_t max_merge = 5;
auto db = OpenDb(dbname, use_ttl, max_merge);
MergeBasedCounters counters(db, 0);
testCounters(counters, db.get(), compact);
testSuccessiveMerge(counters, maxMerge, maxMerge * 2);
testSuccessiveMerge(counters, max_merge, max_merge * 2);
testSingleBatchSuccessiveMerge(db.get(), 5, 7);
DestroyDB(dbname, Options());
}
{
cout << "Test Partial-Merge\n";
size_t max_merge = 100;
for (uint32_t min_merge = 5; min_merge < 25; min_merge += 5) {
for (uint32_t count = min_merge - 1; count <= min_merge + 1; count++) {
auto db = OpenDb(dbname, use_ttl, max_merge, min_merge);
MergeBasedCounters counters(db, 0);
testPartialMerge(&counters, db.get(), max_merge, min_merge, count);
DestroyDB(dbname, Options());
}
{
auto db = OpenDb(dbname, use_ttl, max_merge, min_merge);
MergeBasedCounters counters(db, 0);
testPartialMerge(&counters, db.get(), max_merge, min_merge,
min_merge * 10);
DestroyDB(dbname, Options());
}
}
}
}
int main(int argc, char *argv[]) {
//TODO: Make this test like a general rocksdb unit-test
runTest(argc, test::TmpDir() + "/merge_testdb");
runTest(argc, test::TmpDir() + "/merge_testdbttl", true); // Run test on TTL database
printf("Passed all tests!\n");
return 0;
}

11
db/version_set.cc
View file

@ -419,17 +419,6 @@ static bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
assert(s->state == kNotFound || s->state == kMerge);
s->state = kMerge;
merge_contex->PushOperand(v);
while (merge_contex->GetNumOperands() >= 2) {
// Attempt to merge operands together via user associateive merge
if (s->merge_operator->PartialMerge(
s->user_key, merge_contex->GetOperand(0),
merge_contex->GetOperand(1), &merge_result, s->logger)) {
merge_contex->PushPartialMergeResult(merge_result);
} else {
// Associative merge returns false ==> stack the operands
break;
}
}
return true;
default:

4
include/rocksdb/c.h
View file

@ -425,8 +425,8 @@ extern rocksdb_mergeoperator_t* rocksdb_mergeoperator_create(
char* (*partial_merge)(
void*,
const char* key, size_t key_length,
const char* left_operand, size_t left_operand_length,
const char* right_operand, size_t right_operand_length,
const char* const* operands_list, const size_t* operands_list_length,
int num_operands,
unsigned char* success, size_t* new_value_length),
void (*delete_value)(
void*,

51
include/rocksdb/merge_operator.h
View file

@ -32,9 +32,9 @@ class Logger;
//
// b) MergeOperator - the generic class for all the more abstract / complex
// operations; one method (FullMerge) to merge a Put/Delete value with a
// merge operand; and another method (PartialMerge) that merges two
// operands together. this is especially useful if your key values have a
// complex structure but you would still like to support client-specific
// merge operand; and another method (PartialMerge) that merges multiple
// operands together. this is especially useful if your key values have
// complex structures but you would still like to support client-specific
// incremental updates.
//
// AssociativeMergeOperator is simpler to implement. MergeOperator is simply
@ -80,6 +80,13 @@ class MergeOperator {
// DB::Merge(key, *new_value) would yield the same result as a call
// to DB::Merge(key, left_op) followed by DB::Merge(key, right_op).
//
// The default implementation of PartialMergeMulti will use this function
// as a helper, for backward compatibility. Any successor class of
// MergeOperator should either implement PartialMerge or PartialMergeMulti,
// although implementing PartialMergeMulti is suggested as it is in general
// more effective to merge multiple operands at a time instead of two
// operands at a time.
//
// If it is impossible or infeasible to combine the two operations,
// leave new_value unchanged and return false. The library will
// internally keep track of the operations, and apply them in the
@ -89,12 +96,38 @@ class MergeOperator {
// and simply "return false". For now, the client should simply return
// false in any case it cannot perform partial-merge, regardless of reason.
// If there is corruption in the data, handle it in the FullMerge() function,
// and return false there.
virtual bool PartialMerge(const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const = 0;
// and return false there. The default implementation of PartialMerge will
// always return false.
virtual bool PartialMerge(const Slice& key, const Slice& left_operand,
const Slice& right_operand, std::string* new_value,
Logger* logger) const {
return false;
}
// This function performs merge when all the operands are themselves merge
// operation types that you would have passed to a DB::Merge() call in the
// same order (front() first)
// (i.e. DB::Merge(key, operand_list[0]), followed by
// DB::Merge(key, operand_list[1]), ...)
//
// PartialMergeMulti should combine them into a single merge operation that is
// saved into *new_value, and then it should return true. *new_value should
// be constructed such that a call to DB::Merge(key, *new_value) would yield
// the same result as subquential individual calls to DB::Merge(key, operand)
// for each operand in operand_list from front() to back().
//
// The PartialMergeMulti function will be called only when the list of
// operands are long enough. The minimum amount of operands that will be
// passed to the function are specified by the "min_partial_merge_operands"
// option.
//
// In the default implementation, PartialMergeMulti will invoke PartialMerge
// multiple times, where each time it only merges two operands. Developers
// should either implement PartialMergeMulti, or implement PartialMerge which
// is served as the helper function of the default PartialMergeMulti.
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const;
// The name of the MergeOperator. Used to check for MergeOperator
// mismatches (i.e., a DB created with one MergeOperator is

9
include/rocksdb/options.h
View file

@ -723,6 +723,15 @@ struct Options {
// Default: 0 (disabled)
size_t max_successive_merges;
// The number of partial merge operands to accumulate before partial
// merge will be performed. Partial merge will not be called
// if the list of values to merge is less than min_partial_merge_operands.
//
// If min_partial_merge_operands < 2, then it will be treated as 2.
//
// Default: 2
uint32_t min_partial_merge_operands;
// Allow RocksDB to use thread local storage to optimize performance.
// Default: true
bool allow_thread_local;

10
util/options.cc
View file

@ -30,8 +30,7 @@ Options::Options()
: comparator(BytewiseComparator()),
merge_operator(nullptr),
compaction_filter(nullptr),
compaction_filter_factory(
std::shared_ptr<CompactionFilterFactory>(
compaction_filter_factory(std::shared_ptr<CompactionFilterFactory>(
new DefaultCompactionFilterFactory())),
create_if_missing(false),
error_if_exists(false),
@ -39,7 +38,7 @@ Options::Options()
env(Env::Default()),
info_log(nullptr),
info_log_level(INFO),
write_buffer_size(4<<20),
write_buffer_size(4 << 20),
max_write_buffer_number(2),
min_write_buffer_number_to_merge(1),
max_open_files(1000),
@ -95,7 +94,7 @@ Options::Options()
is_fd_close_on_exec(true),
skip_log_error_on_recovery(false),
stats_dump_period_sec(3600),
block_size_deviation (10),
block_size_deviation(10),
advise_random_on_open(true),
access_hint_on_compaction_start(NORMAL),
use_adaptive_mutex(false),
@ -113,6 +112,7 @@ Options::Options()
memtable_prefix_bloom_bits(0),
memtable_prefix_bloom_probes(6),
max_successive_merges(0),
min_partial_merge_operands(2),
allow_thread_local(true) {
assert(memtable_factory.get() != nullptr);
}
@ -306,6 +306,8 @@ Options::Dump(Logger* log) const
inplace_update_support);
Log(log, " Options.inplace_update_num_locks: %zd",
inplace_update_num_locks);
Log(log, " Options.min_partial_merge_operands: %u",
min_partial_merge_operands);
// TODO: easier config for bloom (maybe based on avg key/value size)
Log(log, " Options.memtable_prefix_bloom_bits: %d",
memtable_prefix_bloom_bits);

14
utilities/merge_operators/put.cc
View file

@ -1,3 +1,8 @@
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include <memory>
#include "rocksdb/slice.h"
#include "rocksdb/merge_operator.h"
@ -38,6 +43,15 @@ class PutOperator : public MergeOperator {
return true;
}
using MergeOperator::PartialMergeMulti;
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const
override {
new_value->assign(operand_list.back().data(), operand_list.back().size());
return true;
}
virtual const char* Name() const override {
return "PutOperator";
}

41
utilities/merge_operators/string_append/stringappend2.cc
View file

@ -6,6 +6,7 @@
#include "stringappend2.h"
#include <memory>
#include <string>
#include <assert.h>
#include "rocksdb/slice.h"
@ -61,31 +62,39 @@ bool StringAppendTESTOperator::FullMerge(
return true;
}
bool StringAppendTESTOperator::PartialMerge(const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const {
bool StringAppendTESTOperator::PartialMergeMulti(
const Slice& key, const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const {
return false;
}
// A version of PartialMerge that actually performs "partial merging".
// Use this to simulate the exact behaviour of the StringAppendOperator.
bool StringAppendTESTOperator::_AssocPartialMerge(const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const {
// Clear the *new_value for writing.
bool StringAppendTESTOperator::_AssocPartialMergeMulti(
const Slice& key, const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const {
// Clear the *new_value for writing
assert(new_value);
new_value->clear();
assert(operand_list.size() >= 2);
// Generic append
// Reserve correct size for *new_value, and apply concatenation.
new_value->reserve(left_operand.size() + 1 + right_operand.size());
new_value->assign(left_operand.data(), left_operand.size());
new_value->append(1,delim_);
new_value->append(right_operand.data(), right_operand.size());
// Determine and reserve correct size for *new_value.
size_t size = 0;
for (const auto& operand : operand_list) {
size += operand.size();
}
size += operand_list.size() - 1; // Delimiters
new_value->reserve(size);
// Apply concatenation
new_value->assign(operand_list.front().data(), operand_list.front().size());
for (std::deque<Slice>::const_iterator it = operand_list.begin() + 1;
it != operand_list.end(); ++it) {
new_value->append(1, delim_);
new_value->append(it->data(), it->size());
}
return true;
}

24
utilities/merge_operators/string_append/stringappend2.h
View file

@ -11,6 +11,9 @@
*/
#pragma once
#include <deque>
#include <string>
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice.h"
@ -18,8 +21,8 @@ namespace rocksdb {
class StringAppendTESTOperator : public MergeOperator {
public:
StringAppendTESTOperator(char delim_char); /// Constructor with delimiter
// Constructor with delimiter
explicit StringAppendTESTOperator(char delim_char);
virtual bool FullMerge(const Slice& key,
const Slice* existing_value,
@ -27,22 +30,19 @@ class StringAppendTESTOperator : public MergeOperator {
std::string* new_value,
Logger* logger) const override;
virtual bool PartialMerge(const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const override;
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const
override;
virtual const char* Name() const override;
private:
// A version of PartialMerge that actually performs "partial merging".
// Use this to simulate the exact behaviour of the StringAppendOperator.
bool _AssocPartialMerge(const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const;
bool _AssocPartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const;
char delim_; // The delimiter is inserted between elements

26
utilities/ttl/db_ttl.h
View file

@ -3,6 +3,9 @@
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <deque>
#include <string>
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/compaction_filter.h"
@ -268,24 +271,27 @@ class TtlMergeOperator : public MergeOperator {
}
}
virtual bool PartialMerge(const Slice& key,
const Slice& left_operand,
const Slice& right_operand,
std::string* new_value,
Logger* logger) const override {
virtual bool PartialMergeMulti(const Slice& key,
const std::deque<Slice>& operand_list,
std::string* new_value, Logger* logger) const
override {
const uint32_t ts_len = DBWithTTL::kTSLength;
std::deque<Slice> operands_without_ts;
if (left_operand.size() < ts_len || right_operand.size() < ts_len) {
for (const auto& operand : operand_list) {
if (operand.size() < ts_len) {
Log(logger, "Error: Could not remove timestamp from value.");
return false;
}
operands_without_ts.push_back(
Slice(operand.data(), operand.size() - ts_len));
}
// Apply the user partial-merge operator (store result in *new_value)
assert(new_value);
Slice left_without_ts(left_operand.data(), left_operand.size() - ts_len);
Slice right_without_ts(right_operand.data(), right_operand.size() - ts_len);
if (!user_merge_op_->PartialMerge(key, left_without_ts, right_without_ts,
new_value, logger)) {
if (!user_merge_op_->PartialMergeMulti(key, operands_without_ts, new_value,
logger)) {
return false;
}