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llvm-project/lld/Common/Threads.cpp

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Wait for all threads to terminate before exitting. I think it is not defined what would happen to detached threads when the main thread tries to exit. That means it was not guaranteed that unlinkAsync correctly removes a temporary file. It was also reported that this unlinkAsync caused a crash on Windows. This patch adds a few new functions so that the main thread always waits for non-main threads before exitting. I don't actually like the new two functions, runBackground and waitForBackgroundThreads, because it looks like it is a bit overdesigned. After all, what we are doing with these functions is to just remove a file. An alternative would be to do fork(2) and make the child process remove a file asynchronously. However, it has its own problems. Correctly forking and reclaiming a resource using waitpid(2) is not doable unless we know our process-wide settings (such as signal mask), but we can't make any assumption on it when lld is embedded to other process. So I chose to stick with threads instead of multi-processes. Differential Revision: https://reviews.llvm.org/D38571 llvm-svn: 315033
2017-10-06 07:01:11 +08:00
//===- Threads.cpp --------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
[lld] Move Threads to Common Summary: This will allow using the functionality from other linkers. It is also a prerequisite for sharing the error logging code. Reviewers: ruiu Reviewed By: ruiu Subscribers: emaste, mgorny, llvm-commits Differential Revision: https://reviews.llvm.org/D38822 llvm-svn: 315725
2017-10-14 02:22:55 +08:00
#include "lld/Common/Threads.h"
Wait for all threads to terminate before exitting. I think it is not defined what would happen to detached threads when the main thread tries to exit. That means it was not guaranteed that unlinkAsync correctly removes a temporary file. It was also reported that this unlinkAsync caused a crash on Windows. This patch adds a few new functions so that the main thread always waits for non-main threads before exitting. I don't actually like the new two functions, runBackground and waitForBackgroundThreads, because it looks like it is a bit overdesigned. After all, what we are doing with these functions is to just remove a file. An alternative would be to do fork(2) and make the child process remove a file asynchronously. However, it has its own problems. Correctly forking and reclaiming a resource using waitpid(2) is not doable unless we know our process-wide settings (such as signal mask), but we can't make any assumption on it when lld is embedded to other process. So I chose to stick with threads instead of multi-processes. Differential Revision: https://reviews.llvm.org/D38571 llvm-svn: 315033
2017-10-06 07:01:11 +08:00
[lld] Move Threads to Common Summary: This will allow using the functionality from other linkers. It is also a prerequisite for sharing the error logging code. Reviewers: ruiu Reviewed By: ruiu Subscribers: emaste, mgorny, llvm-commits Differential Revision: https://reviews.llvm.org/D38822 llvm-svn: 315725
2017-10-14 02:22:55 +08:00
bool lld::ThreadsEnabled = true;