4e60663b31
Summary: In C++, `extern` is redundant in a number of cases: * "Global" function declarations and definitions * "Global" variable definitions when already declared `extern` For consistency and simplicity, I've removed these in code that *we own*. In a couple of cases, I removed obsolete declarations, and for MagicNumber constants, I have consolidated the declarations into a header file (format.h) as standard best practice would prescribe. Pull Request resolved: https://github.com/facebook/rocksdb/pull/12300 Test Plan: no functional changes, CI Reviewed By: ajkr Differential Revision: D53148629 Pulled By: pdillinger fbshipit-source-id: fb8d927959892e03af09b0c0d542b0a3b38fd886
67 lines
2.5 KiB
C++
67 lines
2.5 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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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <functional>
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#include "rocksdb/rocksdb_namespace.h"
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namespace ROCKSDB_NAMESPACE {
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/*
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* ThreadPool is a component that will spawn N background threads that will
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* be used to execute scheduled work, The number of background threads could
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* be modified by calling SetBackgroundThreads().
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* */
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class ThreadPool {
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public:
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virtual ~ThreadPool() {}
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// Wait for all threads to finish.
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// Discard those threads that did not start
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// executing
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virtual void JoinAllThreads() = 0;
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// Set the number of background threads that will be executing the
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// scheduled jobs.
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virtual void SetBackgroundThreads(int num) = 0;
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virtual int GetBackgroundThreads() = 0;
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// Get the number of jobs scheduled in the ThreadPool queue.
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virtual unsigned int GetQueueLen() const = 0;
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// Waits for all jobs to complete those
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// that already started running and those that did not
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// start yet. This ensures that everything that was thrown
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// on the TP runs even though
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// we may not have specified enough threads for the amount
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// of jobs
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virtual void WaitForJobsAndJoinAllThreads() = 0;
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// Submit a fire and forget jobs
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// This allows to submit the same job multiple times
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virtual void SubmitJob(const std::function<void()>&) = 0;
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// This moves the function in for efficiency
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virtual void SubmitJob(std::function<void()>&&) = 0;
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// Reserve available background threads. This function does not ensure
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// so many threads can be reserved, instead it will return the number of
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// threads that can be reserved against the desired one. In other words,
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// the number of available threads could be less than the input.
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virtual int ReserveThreads(int /*threads_to_be_reserved*/) { return 0; }
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// Release a specific number of reserved threads
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virtual int ReleaseThreads(int /*threads_to_be_released*/) { return 0; }
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};
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// NewThreadPool() is a function that could be used to create a ThreadPool
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// with `num_threads` background threads.
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ThreadPool* NewThreadPool(int num_threads);
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} // namespace ROCKSDB_NAMESPACE
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