llvm-project/libcxx/test/support/external_threads.cpp

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//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
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#define _LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL
#include <__threading_support>
[libcxx] Introduce an externally-threaded libc++ variant. This patch further decouples libc++ from pthread, allowing libc++ to be built against other threading systems. There are two main use cases: - Building libc++ against a thread library other than pthreads. - Building libc++ with an "external" thread API, allowing a separate library to provide the implementation of that API. The two use cases are quite similar, the second one being sligtly more de-coupled than the first. The cmake option LIBCXX_HAS_EXTERNAL_THREAD_API enables both kinds of builds. One needs to place an <__external_threading> header file containing an implementation of the "libc++ thread API" declared in the <__threading_support> header. For the second use case, the implementation of the libc++ thread API can delegate to a custom "external" thread API where the implementation of this external API is provided in a seperate library. This mechanism allows toolchain vendors to distribute a build of libc++ with a custom thread-porting-layer API (which is the "external" API above), platform vendors (recipients of the toolchain/libc++) are then required to provide their implementation of this API to be linked with (end-user) C++ programs. Note that the second use case still requires establishing the basic types that get passed between the external thread library and the libc++ library (e.g. __libcpp_mutex_t). These cannot be opaque pointer types (libc++ sources won't compile otherwise). It should also be noted that the second use case can have a slight performance penalty; as all the thread constructs need to cross a library boundary through an additional function call. When the header <__external_threading> is omitted, libc++ is built with the "libc++ thread API" (declared in <__threading_support>) as the "external" thread API (basic types are pthread based). An implementation (pthread based) of this API is provided in test/support/external_threads.cpp, which is built into a separate DSO and linked in when running the libc++ test suite. A test run therefore demonstrates the second use case (less the intermediate custom API). Differential revision: https://reviews.llvm.org/D21968 Reviewers: bcraig, compnerd, EricWF, mclow.lists llvm-svn: 281179 2016-09-12 05:46:40 +08:00			`//===----------------------------------------------------------------------===//`
			`//`
Update more file headers across all of the LLVM projects in the monorepo to reflect the new license. These used slightly different spellings that defeated my regular expressions. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351648 2019-01-19 18:56:40 +08:00			`// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.`
			`// See https://llvm.org/LICENSE.txt for license information.`
			`// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception`
[libcxx] Introduce an externally-threaded libc++ variant. This patch further decouples libc++ from pthread, allowing libc++ to be built against other threading systems. There are two main use cases: - Building libc++ against a thread library other than pthreads. - Building libc++ with an "external" thread API, allowing a separate library to provide the implementation of that API. The two use cases are quite similar, the second one being sligtly more de-coupled than the first. The cmake option LIBCXX_HAS_EXTERNAL_THREAD_API enables both kinds of builds. One needs to place an <__external_threading> header file containing an implementation of the "libc++ thread API" declared in the <__threading_support> header. For the second use case, the implementation of the libc++ thread API can delegate to a custom "external" thread API where the implementation of this external API is provided in a seperate library. This mechanism allows toolchain vendors to distribute a build of libc++ with a custom thread-porting-layer API (which is the "external" API above), platform vendors (recipients of the toolchain/libc++) are then required to provide their implementation of this API to be linked with (end-user) C++ programs. Note that the second use case still requires establishing the basic types that get passed between the external thread library and the libc++ library (e.g. __libcpp_mutex_t). These cannot be opaque pointer types (libc++ sources won't compile otherwise). It should also be noted that the second use case can have a slight performance penalty; as all the thread constructs need to cross a library boundary through an additional function call. When the header <__external_threading> is omitted, libc++ is built with the "libc++ thread API" (declared in <__threading_support>) as the "external" thread API (basic types are pthread based). An implementation (pthread based) of this API is provided in test/support/external_threads.cpp, which is built into a separate DSO and linked in when running the libc++ test suite. A test run therefore demonstrates the second use case (less the intermediate custom API). Differential revision: https://reviews.llvm.org/D21968 Reviewers: bcraig, compnerd, EricWF, mclow.lists llvm-svn: 281179 2016-09-12 05:46:40 +08:00			`//`
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[libc++] Cleanup and document <__threading_support> Summary: This patch attempts to clean up the macro configuration mess in `<__threading_support>`, specifically the mess involving external threading variants. Additionally this patch adds design documentation for `<__threading_support>` and the configuration macros it uses. The primary change in this patch is separating the idea of an "external API" provided by `<__external_threading>` and the idea of having an external threading library. Now `_LIBCPP_HAS_THREAD_API_EXTERNAL` means that libc++ should use `<__external_threading>` and that the header is expected to exist. Additionally the new macro `_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL` is now used to configure for using an "external library" with the default threading API. Reviewers: compnerd, rmaprath Subscribers: smeenai, cfe-commits, mgorny Differential Revision: https://reviews.llvm.org/D28316 llvm-svn: 291275 2017-01-07 04:05:40 +08:00			`#define _LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL`
[libcxx] Introduce an externally-threaded libc++ variant. This patch further decouples libc++ from pthread, allowing libc++ to be built against other threading systems. There are two main use cases: - Building libc++ against a thread library other than pthreads. - Building libc++ with an "external" thread API, allowing a separate library to provide the implementation of that API. The two use cases are quite similar, the second one being sligtly more de-coupled than the first. The cmake option LIBCXX_HAS_EXTERNAL_THREAD_API enables both kinds of builds. One needs to place an <__external_threading> header file containing an implementation of the "libc++ thread API" declared in the <__threading_support> header. For the second use case, the implementation of the libc++ thread API can delegate to a custom "external" thread API where the implementation of this external API is provided in a seperate library. This mechanism allows toolchain vendors to distribute a build of libc++ with a custom thread-porting-layer API (which is the "external" API above), platform vendors (recipients of the toolchain/libc++) are then required to provide their implementation of this API to be linked with (end-user) C++ programs. Note that the second use case still requires establishing the basic types that get passed between the external thread library and the libc++ library (e.g. __libcpp_mutex_t). These cannot be opaque pointer types (libc++ sources won't compile otherwise). It should also be noted that the second use case can have a slight performance penalty; as all the thread constructs need to cross a library boundary through an additional function call. When the header <__external_threading> is omitted, libc++ is built with the "libc++ thread API" (declared in <__threading_support>) as the "external" thread API (basic types are pthread based). An implementation (pthread based) of this API is provided in test/support/external_threads.cpp, which is built into a separate DSO and linked in when running the libc++ test suite. A test run therefore demonstrates the second use case (less the intermediate custom API). Differential revision: https://reviews.llvm.org/D21968 Reviewers: bcraig, compnerd, EricWF, mclow.lists llvm-svn: 281179 2016-09-12 05:46:40 +08:00			`#include <__threading_support>`