You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 
rocksdb/table/flush_block_policy.cc

72 lines
2.6 KiB

// Copyright (c) 2011-present, 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 "rocksdb/options.h"
#include "rocksdb/flush_block_policy.h"
#include "rocksdb/slice.h"
#include "table/block_builder.h"
#include <cassert>
namespace rocksdb {
// Flush block by size
class FlushBlockBySizePolicy : public FlushBlockPolicy {
public:
// @params block_size: Approximate size of user data packed per
// block.
// @params block_size_deviation: This is used to close a block before it
// reaches the configured
FlushBlockBySizePolicy(const uint64_t block_size,
const uint64_t block_size_deviation,
const BlockBuilder& data_block_builder) :
block_size_(block_size),
block_size_deviation_(block_size_deviation),
data_block_builder_(data_block_builder) {
}
virtual bool Update(const Slice& key,
const Slice& value) override {
// it makes no sense to flush when the data block is empty
if (data_block_builder_.empty()) {
return false;
}
auto curr_size = data_block_builder_.CurrentSizeEstimate();
// Do flush if one of the below two conditions is true:
// 1) if the current estimated size already exceeds the block size,
// 2) block_size_deviation is set and the estimated size after appending
// the kv will exceed the block size and the current size is under the
// the deviation.
return curr_size >= block_size_ || BlockAlmostFull(key, value);
}
private:
bool BlockAlmostFull(const Slice& key, const Slice& value) const {
const auto curr_size = data_block_builder_.CurrentSizeEstimate();
const auto estimated_size_after =
data_block_builder_.EstimateSizeAfterKV(key, value);
return
estimated_size_after > block_size_ &&
block_size_deviation_ > 0 &&
curr_size * 100 > block_size_ * (100 - block_size_deviation_);
}
const uint64_t block_size_;
const uint64_t block_size_deviation_;
const BlockBuilder& data_block_builder_;
};
FlushBlockPolicy* FlushBlockBySizePolicyFactory::NewFlushBlockPolicy(
const BlockBasedTableOptions& table_options,
const BlockBuilder& data_block_builder) const {
return new FlushBlockBySizePolicy(
table_options.block_size, table_options.block_size_deviation,
data_block_builder);
}
} // namespace rocksdb