Coverage Report

Created: 2025-06-13 06:23

/src/brpc/src/bthread/butex.h
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// Licensed to the Apache Software Foundation (ASF) under one
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// or more contributor license agreements.  See the NOTICE file
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// distributed with this work for additional information
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// regarding copyright ownership.  The ASF licenses this file
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// to you under the Apache License, Version 2.0 (the
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// "License"); you may not use this file except in compliance
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// with the License.  You may obtain a copy of the License at
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//
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//   http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied.  See the License for the
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// specific language governing permissions and limitations
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// under the License.
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// bthread - An M:N threading library to make applications more concurrent.
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// Date: Tue Jul 22 17:30:12 CST 2014
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#ifndef BTHREAD_BUTEX_H
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#define BTHREAD_BUTEX_H
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#include <errno.h>                               // users need to check errno
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#include <time.h>                                // timespec
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#include "butil/macros.h"                         // BAIDU_CASSERT
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#include "bthread/types.h"                       // bthread_t
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namespace bthread {
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// If a thread would suspend for less than so many microseconds, return
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// ETIMEDOUT directly.
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// Use 1: sleeping for less than 2 microsecond is inefficient and useless.
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static const int64_t MIN_SLEEP_US = 2;
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// Create a butex which is a futex-like 32-bit primitive for synchronizing
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// bthreads/pthreads.
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// Returns a pointer to 32-bit data, NULL on failure.
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// NOTE: all butexes are private(not inter-process).
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void* butex_create();
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// Check width of user type before casting.
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template <typename T> T* butex_create_checked() {
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    BAIDU_CASSERT(sizeof(T) == sizeof(int), sizeof_T_must_equal_int);
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    return static_cast<T*>(butex_create());
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}
Unexecuted instantiation: unsigned int* bthread::butex_create_checked<unsigned int>()
Unexecuted instantiation: butil::atomic<int>* bthread::butex_create_checked<butil::atomic<int> >()
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// Destroy the butex.
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void butex_destroy(void* butex);
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// Wake up at most 1 thread waiting on |butex|.
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// Returns # of threads woken up.
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int butex_wake(void* butex, bool nosignal = false);
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// Wake up all threads waiting on |butex| if n is zero,
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// Otherwise, wake up at most n thread waiting on |butex|.
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// Returns # of threads woken up.
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int butex_wake_n(void* butex, size_t n, bool nosignal = false);
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// Wake up all threads waiting on |butex|.
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// Returns # of threads woken up.
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int butex_wake_all(void* butex, bool nosignal = false);
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// Wake up all threads waiting on |butex| except a bthread whose identifier
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// is |excluded_bthread|. This function does not yield.
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// Returns # of threads woken up.
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int butex_wake_except(void* butex, bthread_t excluded_bthread);
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// Wake up at most 1 thread waiting on |butex1|, let all other threads wait
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// on |butex2| instead.
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// Returns # of threads woken up.
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int butex_requeue(void* butex1, void* butex2);
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// Atomically wait on |butex| if *butex equals |expected_value|, until the
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// butex is woken up by butex_wake*, or CLOCK_REALTIME reached |abstime| if
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// abstime is not NULL.
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// About |abstime|:
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//   Different from FUTEX_WAIT, butex_wait uses absolute time.
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// About |prepend|:
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//   If |prepend| is true, queue the bthread at the head of the queue,
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//   otherwise at the tail.
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// Returns 0 on success, -1 otherwise and errno is set.
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int butex_wait(void* butex, int expected_value,
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               const timespec* abstime,
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               bool prepend = false);
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}  // namespace bthread
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#endif  // BTHREAD_BUTEX_H