c292dc8540
Summary: The patch reduces the contention over prepared_mutex_ using these techniques: 1) Move ::RemovePrepared() to be called from the commit callback when we have two write queues. 2) Use two separate mutex for PreparedHeap, one prepared_mutex_ needed for ::RemovePrepared, and one ::push_pop_mutex() needed for ::AddPrepared(). Given that we call ::AddPrepared only from the first write queue and ::RemovePrepared mostly from the 2nd, this will result into each the two write queues not competing with each other over a single mutex. ::RemovePrepared might occasionally need to acquire ::push_pop_mutex() if ::erase() ends up with calling ::pop() 3) Acquire ::push_pop_mutex() on the first callback of the write queue and release it on the last. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5420 Differential Revision: D15741985 Pulled By: maysamyabandeh fbshipit-source-id: 84ce8016007e88bb6e10da5760ba1f0d26347735
39 lines
1.6 KiB
C++
39 lines
1.6 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#include "rocksdb/status.h"
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namespace rocksdb {
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class DB;
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class PreReleaseCallback {
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public:
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virtual ~PreReleaseCallback() {}
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// Will be called while on the write thread after the write to the WAL and
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// before the write to memtable. This is useful if any operation needs to be
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// done before the write gets visible to the readers, or if we want to reduce
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// the overhead of locking by updating something sequentially while we are on
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// the write thread. If the callback fails, this function returns a non-OK
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// status, the sequence number will not be released, and same status will be
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// propagated to all the writers in the write group.
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// seq is the sequence number that is used for this write and will be
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// released.
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// is_mem_disabled is currently used for debugging purposes to assert that
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// the callback is done from the right write queue.
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// If non-zero, log_number indicates the WAL log to which we wrote.
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// index >= 0 specifies the order of callback in the same write thread.
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// total > index specifies the total number of callbacks in the same write
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// thread. Together with index, could be used to reduce the redundant
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// operations among the callbacks.
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virtual Status Callback(SequenceNumber seq, bool is_mem_disabled,
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uint64_t log_number, size_t index, size_t total) = 0;
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};
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} // namespace rocksdb
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