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dee91c259d
Summary: This diff just moves the write thread control out of the DBImpl. I will need this as I will control column family data concurrency by only accessing some data in the write thread. That way, we won't have to lock our accesses to column family hash table (mappings from IDs to CFDs). Test Plan: make check Reviewers: sdong, yhchiang, ljin Reviewed By: ljin Subscribers: leveldb Differential Revision: https://reviews.facebook.net/D23301
81 lines
2.6 KiB
C++
81 lines
2.6 KiB
C++
// 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 <stdint.h>
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#include <deque>
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#include <limits>
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#include "rocksdb/status.h"
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#include "db/write_batch_internal.h"
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#include "util/autovector.h"
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#include "port/port.h"
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namespace rocksdb {
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class WriteThread {
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public:
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static const uint64_t kNoTimeOut = std::numeric_limits<uint64_t>::max();
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// Information kept for every waiting writer
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struct Writer {
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Status status;
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WriteBatch* batch;
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bool sync;
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bool disableWAL;
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bool in_batch_group;
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bool done;
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uint64_t timeout_hint_us;
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port::CondVar cv;
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explicit Writer(port::Mutex* mu)
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: batch(nullptr),
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sync(false),
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disableWAL(false),
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in_batch_group(false),
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done(false),
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timeout_hint_us(kNoTimeOut),
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cv(mu) {}
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};
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WriteThread() = default;
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~WriteThread() = default;
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// Before applying write operation (such as DBImpl::Write, DBImpl::Flush)
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// thread should grab the mutex_ and be the first on writers queue.
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// EnterWriteThread is used for it.
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// Be aware! Writer's job can be done by other thread (see DBImpl::Write
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// for examples), so check it via w.done before applying changes.
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//
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// Writer* w: writer to be placed in the queue
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// uint64_t expiration_time: maximum time to be in the queue
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// See also: ExitWriteThread
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// REQUIRES: db mutex held
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Status EnterWriteThread(Writer* w, uint64_t expiration_time);
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// After doing write job, we need to remove already used writers from
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// writers_ queue and notify head of the queue about it.
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// ExitWriteThread is used for this.
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//
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// Writer* w: Writer, that was added by EnterWriteThread function
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// Writer* last_writer: Since we can join a few Writers (as DBImpl::Write
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// does)
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// we should pass last_writer as a parameter to
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// ExitWriteThread
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// (if you don't touch other writers, just pass w)
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// Status status: Status of write operation
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// See also: EnterWriteThread
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// REQUIRES: db mutex held
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void ExitWriteThread(Writer* w, Writer* last_writer, Status status);
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void BuildBatchGroup(Writer** last_writer,
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autovector<WriteBatch*>* write_batch_group);
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private:
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// Queue of writers.
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std::deque<Writer*> writers_;
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};
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} // namespace rocksdb
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