d27c7413a9
Using heap allocation during signal handlers is unsafe. This PR purpose is to replace all the heap allocations done within the signal handlers raised upon server crash and assertions. These were added in #12453. writeStacktraces(): allocates the stacktraces output array on the calling thread's stack and assigns the address to a global variable. It calls `ThreadsManager_runOnThreads()` that invokes `collect_stacktrace_data()` by each thread: each thread writes to a different location in the above array to allow sync writes. get_ready_to_signal_threads_tids(): instead of allocating the `tids` array, it receives it as a fixed size array parameter, allocated on on the stack of the calling function, and returns the number of valid threads. The array size is hard-coded to 50. `ThreadsManager_runOnThreads():` To avoid the outputs array allocation, the **callback signature** was changed. Now it should return void. This function return type has also changed to int - returns 1 if successful, and 0 otherwise. Other unsafe calls will be handled in following PRs
70 lines
2.9 KiB
C
70 lines
2.9 KiB
C
/*
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* Copyright (c) 2021, Redis Ltd.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Redis nor the names of its contributors may be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include "fmacros.h"
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#include <sys/types.h>
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#include <unistd.h>
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/** This is an API to invoke callback on a list of threads using a user defined signal handler.
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* NOTE: This is API is only supported only in linux systems.
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* Calling the functions below on any other system does nothing.
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*/
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#define THREADS_SIGNAL SIGUSR2
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/* Callback signature */
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typedef void(*run_on_thread_cb)(void);
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/* Register the process to THREADS_SIGNAL */
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void ThreadsManager_init(void);
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/** @brief Invoke callback by each thread in tids.
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*
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* @param tids An array of threads that need to invoke callback.
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* @param tids_len The number of threads in @param tids.
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* @param callback A callback to be invoked by each thread in @param tids.
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*
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* NOTES:
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* It is assumed that all the threads don't block or ignore THREADS_SIGNAL.
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*
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* It is safe to include the calling thread in @param tids. However, be aware that subsequent tids will
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* not be signaled until the calling thread returns from the callback invocation.
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* Hence, it is recommended to place the calling thread last in @param tids.
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*
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* The function returns only when @param tids_len threads have returned from @param callback.
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*
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* @return 1 if successful, 0 If ThreadsManager_runOnThreads is already in the middle of execution.
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*
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**/
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int ThreadsManager_runOnThreads(pid_t *tids, size_t tids_len, run_on_thread_cb callback);
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