5aea98ddd8
Summary: In one of our recent meetings, we discussed deprecating features that are not being actively used. One of those features, at least within Facebook, is timeout_hint. The feature is really nicely implemented, but if nobody needs it, we should remove it from our code-base (until we get a valid use-case). Some arguments: * Less code == better icache hit rate, smaller builds, simpler code * The motivation for adding timeout_hint_us was to work-around RocksDB's stall issue. However, we're currently addressing the stall issue itself (see @sdong's recent work on stall write_rate), so we should never see sharp lock-ups in the future. * Nobody is using the feature within Facebook's code-base. Googling for `timeout_hint_us` also doesn't yield any users. Test Plan: make check Reviewers: anthony, kradhakrishnan, sdong, yhchiang Reviewed By: yhchiang Subscribers: sdong, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D41937
81 lines
2.5 KiB
C++
81 lines
2.5 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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// 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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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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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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// See also: ExitWriteThread
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// REQUIRES: db mutex held
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void EnterWriteThread(Writer* w);
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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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// return total batch group size
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size_t 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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