Summary: Allow block based table to configure the way flushing the blocks. This feature will allow us to add support for prefix-aligned block. Test Plan: make check Reviewers: dhruba, haobo, sdong, igor Reviewed By: sdong CC: leveldb Differential Revision: https://reviews.facebook.net/D13875main
Kai Liu
11 years ago
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// Copyright (c) 2013, 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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#pragma once |
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#include <string> |
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namespace rocksdb { |
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class Slice; |
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class BlockBuilder; |
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// FlushBlockPolicy provides a configurable way to determine when to flush a
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// block in the block based tables,
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class FlushBlockPolicy { |
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public: |
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// Keep track of the key/value sequences and return the boolean value to
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// determine if table builder should flush current data block.
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virtual bool Update(const Slice& key, |
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const Slice& value) = 0; |
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virtual ~FlushBlockPolicy() { } |
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}; |
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class FlushBlockPolicyFactory { |
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public: |
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// Return the name of the flush block policy.
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virtual const char* Name() const = 0; |
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// Return a new block flush policy that flushes data blocks by data size.
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// FlushBlockPolicy may need to access the metadata of the data block
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// builder to determine when to flush the blocks.
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//
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// Callers must delete the result after any database that is using the
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// result has been closed.
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virtual FlushBlockPolicy* NewFlushBlockPolicy( |
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const BlockBuilder& data_block_builder) const = 0; |
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virtual ~FlushBlockPolicyFactory() { } |
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}; |
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class FlushBlockBySizePolicyFactory : public FlushBlockPolicyFactory { |
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public: |
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FlushBlockBySizePolicyFactory(const uint64_t block_size, |
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const uint64_t block_size_deviation) : |
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block_size_(block_size), |
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block_size_deviation_(block_size_deviation) { |
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} |
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virtual const char* Name() const override { |
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return "FlushBlockBySizePolicyFactory"; |
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} |
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virtual FlushBlockPolicy* NewFlushBlockPolicy( |
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const BlockBuilder& data_block_builder) const override; |
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private: |
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const uint64_t block_size_; |
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const uint64_t block_size_deviation_; |
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}; |
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} // rocksdb
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// Copyright (c) 2013, 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/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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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 BlockBuilder& data_block_builder) const { |
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return new FlushBlockBySizePolicy(block_size_, |
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block_size_deviation_, |
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data_block_builder); |
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} |
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} // namespace rocksdb
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