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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "rocksdb/flush_block_policy.h"
#include "rocksdb/options.h"
#include "rocksdb/slice.h"
#include "table/block_based/block_builder.h"
#include "table/format.h"
#include <cassert>
namespace ROCKSDB_NAMESPACE {
// 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 bool align,
const BlockBuilder& data_block_builder)
: block_size_(block_size),
block_size_deviation_limit_(
((block_size * (100 - block_size_deviation)) + 99) / 100),
align_(align),
data_block_builder_(data_block_builder) {}
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 {
if (block_size_deviation_limit_ == 0) {
return false;
}
const auto curr_size = data_block_builder_.CurrentSizeEstimate();
auto estimated_size_after =
data_block_builder_.EstimateSizeAfterKV(key, value);
if (align_) {
estimated_size_after += kBlockTrailerSize;
return estimated_size_after > block_size_;
}
return estimated_size_after > block_size_ &&
curr_size > block_size_deviation_limit_;
}
const uint64_t block_size_;
const uint64_t block_size_deviation_limit_;
const bool align_;
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,
table_options.block_align, data_block_builder);
}
FlushBlockPolicy* FlushBlockBySizePolicyFactory::NewFlushBlockPolicy(
const uint64_t size, const int deviation,
const BlockBuilder& data_block_builder) {
return new FlushBlockBySizePolicy(size, deviation, false, data_block_builder);
}
} // namespace ROCKSDB_NAMESPACE
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