Atlas - SDL_systhread.cpp
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1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <[email protected]>
4
5  This software is provided 'as-is', without any express or implied
6  warranty.  In no event will the authors be held liable for any damages
7  arising from the use of this software.
8
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12
13  1. The origin of this software must not be misrepresented; you must not
14     claim that you wrote the original software. If you use this software
15     in a product, an acknowledgment in the product documentation would be
16     appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18     misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20*/
21#include "../../SDL_internal.h"
22
23/* Thread management routines for SDL */
24
25extern "C" {
26#include "SDL_thread.h"
27#include "../SDL_thread_c.h"
28#include "../SDL_systhread.h"
29#include "SDL_log.h"
30}
31
32#include <mutex>
33#include <thread>
34#include <system_error>
35
36#ifdef __WINRT__
37#include <Windows.h>
38#endif
39
40static void
41RunThread(void *args)
42{
43    SDL_RunThread(args);
44}
45
46extern "C"
47int
48SDL_SYS_CreateThread(SDL_Thread * thread, void *args)
49{
50    try {
51        // !!! FIXME: no way to set a thread stack size here.
52        std::thread cpp_thread(RunThread, args);
53        thread->handle = (void *) new std::thread(std::move(cpp_thread));
54        return 0;
55    } catch (std::system_error & ex) {
56        SDL_SetError("unable to start a C++ thread: code=%d; %s", ex.code(), ex.what());
57        return -1;
58    } catch (std::bad_alloc &) {
59        SDL_OutOfMemory();
60        return -1;
61    }
62}
63
64extern "C"
65void
66SDL_SYS_SetupThread(const char *name)
67{
68    // Make sure a thread ID gets assigned ASAP, for debugging purposes:
69    SDL_ThreadID();
70    return;
71}
72
73extern "C"
74SDL_threadID
75SDL_ThreadID(void)
76{
77#ifdef __WINRT__
78    return GetCurrentThreadId();
79#else
80    // HACK: Mimick a thread ID, if one isn't otherwise available.
81    static thread_local SDL_threadID current_thread_id = 0;
82    static SDL_threadID next_thread_id = 1;
83    static std::mutex next_thread_id_mutex;
84
85    if (current_thread_id == 0) {
86        std::lock_guard<std::mutex> lock(next_thread_id_mutex);
87        current_thread_id = next_thread_id;
88        ++next_thread_id;
89    }
90
91    return current_thread_id;
92#endif
93}
94
95extern "C"
96int
97SDL_SYS_SetThreadPriority(SDL_ThreadPriority priority)
98{
99    // Thread priorities do not look to be settable via C++11's thread
100    // interface, at least as of this writing (Nov 2012).  std::thread does
101    // provide access to the OS' native handle, however, and some form of
102    // priority-setting could, in theory, be done through this interface.
103    //
104    // WinRT: UPDATE (Aug 20, 2013): thread priorities cannot be changed
105    // on WinRT, at least not for any thread that's already been created.
106    // WinRT threads appear to be based off of the WinRT class,
107    // ThreadPool, more info on which can be found at:
108    // http://msdn.microsoft.com/en-us/library/windows/apps/windows.system.threading.threadpool.aspx
109    //
110    // For compatibility sake, 0 will be returned here.
111    return (0);
112}
113
114extern "C"
115void
116SDL_SYS_WaitThread(SDL_Thread * thread)
117{
118    if ( ! thread) {
119        return;
120    }
121
122    try {
123        std::thread * cpp_thread = (std::thread *) thread->handle;
124        if (cpp_thread->joinable()) {
125            cpp_thread->join();
126        }
127    } catch (std::system_error &) {
128        // An error occurred when joining the thread.  SDL_WaitThread does not,
129        // however, seem to provide a means to report errors to its callers
130        // though!
131    }
132}
133
134extern "C"
135void
136SDL_SYS_DetachThread(SDL_Thread * thread)
137{
138    if ( ! thread) {
139        return;
140    }
141
142    try {
143        std::thread * cpp_thread = (std::thread *) thread->handle;
144        if (cpp_thread->joinable()) {
145            cpp_thread->detach();
146        }
147    } catch (std::system_error &) {
148        // An error occurred when detaching the thread.  SDL_DetachThread does not,
149        // however, seem to provide a means to report errors to its callers
150        // though!
151    }
152}
153
154extern "C"
155SDL_TLSData *
156SDL_SYS_GetTLSData(void)
157{
158    return SDL_Generic_GetTLSData();
159}
160
161extern "C"
162int
163SDL_SYS_SetTLSData(SDL_TLSData *data)
164{
165    return SDL_Generic_SetTLSData(data);
166}
167
168/* vi: set ts=4 sw=4 expandtab: */
169
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