mirror of https://github.com/facebook/rocksdb.git
73 lines
2.6 KiB
C++
73 lines
2.6 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#include "rocksdb/options.h"
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#include "rocksdb/flush_block_policy.h"
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#include "rocksdb/slice.h"
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#include "table/block_builder.h"
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#include <cassert>
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namespace rocksdb {
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// Flush block by size
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class FlushBlockBySizePolicy : public FlushBlockPolicy {
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public:
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// @params block_size: Approximate size of user data packed per
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// block.
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// @params block_size_deviation: This is used to close a block before it
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// reaches the configured
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FlushBlockBySizePolicy(const uint64_t block_size,
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const uint64_t block_size_deviation,
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const BlockBuilder& data_block_builder) :
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block_size_(block_size),
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block_size_deviation_(block_size_deviation),
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data_block_builder_(data_block_builder) {
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}
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virtual bool Update(const Slice& key,
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const Slice& value) override {
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// it makes no sense to flush when the data block is empty
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if (data_block_builder_.empty()) {
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return false;
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}
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auto curr_size = data_block_builder_.CurrentSizeEstimate();
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// Do flush if one of the below two conditions is true:
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// 1) if the current estimated size already exceeds the block size,
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// 2) block_size_deviation is set and the estimated size after appending
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// the kv will exceed the block size and the current size is under the
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// the deviation.
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return curr_size >= block_size_ || BlockAlmostFull(key, value);
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}
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private:
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bool BlockAlmostFull(const Slice& key, const Slice& value) const {
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const auto curr_size = data_block_builder_.CurrentSizeEstimate();
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const auto estimated_size_after =
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data_block_builder_.EstimateSizeAfterKV(key, value);
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return
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estimated_size_after > block_size_ &&
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block_size_deviation_ > 0 &&
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curr_size * 100 > block_size_ * (100 - block_size_deviation_);
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}
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const uint64_t block_size_;
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const uint64_t block_size_deviation_;
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const BlockBuilder& data_block_builder_;
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};
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FlushBlockPolicy* FlushBlockBySizePolicyFactory::NewFlushBlockPolicy(
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const BlockBasedTableOptions& table_options,
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const BlockBuilder& data_block_builder) const {
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return new FlushBlockBySizePolicy(
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table_options.block_size, table_options.block_size_deviation,
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data_block_builder);
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}
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} // namespace rocksdb
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