dc9d70de65
Summary: Optimistic transactions supporting begin/commit/rollback semantics. Currently relies on checking the memtable to determine if there are any collisions at commit time. Not yet implemented would be a way of enuring the memtable has some minimum amount of history so that we won't fail to commit when the memtable is empty. You should probably start with transaction.h to get an overview of what is currently supported. Test Plan: Added a new test, but still need to look into stress testing. Reviewers: yhchiang, igor, rven, sdong Reviewed By: sdong Subscribers: adamretter, MarkCallaghan, leveldb, dhruba Differential Revision: https://reviews.facebook.net/D33435
84 lines
2.7 KiB
C++
84 lines
2.7 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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#include "util/instrumented_mutex.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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bool has_callback;
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uint64_t timeout_hint_us;
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InstrumentedCondVar cv;
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explicit Writer(InstrumentedMutex* 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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has_callback(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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