71 lines
2.5 KiB
C++
71 lines
2.5 KiB
C++
// 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 "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 BlockBuilder& data_block_builder) const {
|
|
return new FlushBlockBySizePolicy(block_size_,
|
|
block_size_deviation_,
|
|
data_block_builder);
|
|
}
|
|
|
|
} // namespace rocksdb
|