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Diffstat (limited to 'src/systhread.c')
| -rw-r--r-- | src/systhread.c | 417 |
1 files changed, 417 insertions, 0 deletions
diff --git a/src/systhread.c b/src/systhread.c new file mode 100644 index 00000000000..a2c556fd8e3 --- /dev/null +++ b/src/systhread.c @@ -0,0 +1,417 @@ +/* System thread definitions +Copyright (C) 2012-2016 Free Software Foundation, Inc. + +This file is part of GNU Emacs. + +GNU Emacs is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, either version 3 of the License, or +(at your option) any later version. + +GNU Emacs is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ + +#include <config.h> +#include <setjmp.h> +#include "lisp.h" + +#ifndef THREADS_ENABLED + +void +sys_mutex_init (sys_mutex_t *m) +{ + *m = 0; +} + +void +sys_mutex_lock (sys_mutex_t *m) +{ +} + +void +sys_mutex_unlock (sys_mutex_t *m) +{ +} + +void +sys_mutex_destroy (sys_mutex_t *m) +{ +} + +void +sys_cond_init (sys_cond_t *c) +{ + *c = 0; +} + +void +sys_cond_wait (sys_cond_t *c, sys_mutex_t *m) +{ +} + +void +sys_cond_signal (sys_cond_t *c) +{ +} + +void +sys_cond_broadcast (sys_cond_t *c) +{ +} + +void +sys_cond_destroy (sys_cond_t *c) +{ +} + +sys_thread_t +sys_thread_self (void) +{ + return 0; +} + +int +sys_thread_equal (sys_thread_t x, sys_thread_t y) +{ + return x == y; +} + +int +sys_thread_create (sys_thread_t *t, const char *name, + thread_creation_function *func, void *datum) +{ + return 0; +} + +void +sys_thread_yield (void) +{ +} + +#elif defined (HAVE_PTHREAD) + +#include <sched.h> + +#ifdef HAVE_SYS_PRCTL_H +#include <sys/prctl.h> +#endif + +void +sys_mutex_init (sys_mutex_t *mutex) +{ + pthread_mutex_init (mutex, NULL); +} + +void +sys_mutex_lock (sys_mutex_t *mutex) +{ + pthread_mutex_lock (mutex); +} + +void +sys_mutex_unlock (sys_mutex_t *mutex) +{ + pthread_mutex_unlock (mutex); +} + +void +sys_mutex_destroy (sys_mutex_t *mutex) +{ + pthread_mutex_destroy (mutex); +} + +void +sys_cond_init (sys_cond_t *cond) +{ + pthread_cond_init (cond, NULL); +} + +void +sys_cond_wait (sys_cond_t *cond, sys_mutex_t *mutex) +{ + pthread_cond_wait (cond, mutex); +} + +void +sys_cond_signal (sys_cond_t *cond) +{ + pthread_cond_signal (cond); +} + +void +sys_cond_broadcast (sys_cond_t *cond) +{ + pthread_cond_broadcast (cond); +} + +void +sys_cond_destroy (sys_cond_t *cond) +{ + pthread_cond_destroy (cond); +} + +sys_thread_t +sys_thread_self (void) +{ + return pthread_self (); +} + +int +sys_thread_equal (sys_thread_t one, sys_thread_t two) +{ + return pthread_equal (one, two); +} + +int +sys_thread_create (sys_thread_t *thread_ptr, const char *name, + thread_creation_function *func, void *arg) +{ + pthread_attr_t attr; + int result = 0; + + if (pthread_attr_init (&attr)) + return 0; + + if (!pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED)) + { + result = pthread_create (thread_ptr, &attr, func, arg) == 0; +#if defined (HAVE_SYS_PRCTL_H) && defined (HAVE_PRCTL) && defined (PR_SET_NAME) + if (result && name != NULL) + prctl (PR_SET_NAME, name); +#endif + } + + pthread_attr_destroy (&attr); + + return result; +} + +void +sys_thread_yield (void) +{ + sched_yield (); +} + +#elif defined (WINDOWSNT) + +#include <windows.h> + +/* Cannot include <process.h> because of the local header by the same + name, sigh. */ +uintptr_t _beginthread (void (__cdecl *)(void *), unsigned, void *); + +/* Mutexes are implemented as critical sections, because they are + faster than Windows mutex objects (implemented in userspace), and + satisfy the requirements, since we only need to synchronize within a + single process. */ +void +sys_mutex_init (sys_mutex_t *mutex) +{ + InitializeCriticalSection ((LPCRITICAL_SECTION)mutex); +} + +void +sys_mutex_lock (sys_mutex_t *mutex) +{ + /* FIXME: What happens if the owning thread exits without releasing + the mutex? According to MSDN, the result is undefined behavior. */ + EnterCriticalSection ((LPCRITICAL_SECTION)mutex); +} + +void +sys_mutex_unlock (sys_mutex_t *mutex) +{ + LeaveCriticalSection ((LPCRITICAL_SECTION)mutex); +} + +void +sys_mutex_destroy (sys_mutex_t *mutex) +{ + /* FIXME: According to MSDN, deleting a critical session that is + owned by a thread leaves the other threads waiting for the + critical session in an undefined state. Posix docs seem to say + the same about pthread_mutex_destroy. Do we need to protect + against such calamities? */ + DeleteCriticalSection ((LPCRITICAL_SECTION)mutex); +} + +void +sys_cond_init (sys_cond_t *cond) +{ + cond->initialized = false; + cond->wait_count = 0; + /* Auto-reset event for signal. */ + cond->events[CONDV_SIGNAL] = CreateEvent (NULL, FALSE, FALSE, NULL); + /* Manual-reset event for broadcast. */ + cond->events[CONDV_BROADCAST] = CreateEvent (NULL, TRUE, FALSE, NULL); + if (!cond->events[CONDV_SIGNAL] || !cond->events[CONDV_BROADCAST]) + return; + InitializeCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + cond->initialized = true; +} + +void +sys_cond_wait (sys_cond_t *cond, sys_mutex_t *mutex) +{ + DWORD wait_result; + bool last_thread_waiting; + + if (!cond->initialized) + return; + + /* Increment the wait count avoiding race conditions. */ + EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + cond->wait_count++; + LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + + /* Release the mutex and wait for either the signal or the broadcast + event. */ + LeaveCriticalSection ((LPCRITICAL_SECTION)mutex); + wait_result = WaitForMultipleObjects (2, cond->events, FALSE, INFINITE); + + /* Decrement the wait count and see if we are the last thread + waiting on the condition variable. */ + EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + cond->wait_count--; + last_thread_waiting = + wait_result == WAIT_OBJECT_0 + CONDV_BROADCAST + && cond->wait_count == 0; + LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + + /* Broadcast uses a manual-reset event, so when the last thread is + released, we must manually reset that event. */ + if (last_thread_waiting) + ResetEvent (cond->events[CONDV_BROADCAST]); + + /* Per the API, re-acquire the mutex. */ + EnterCriticalSection ((LPCRITICAL_SECTION)mutex); +} + +void +sys_cond_signal (sys_cond_t *cond) +{ + bool threads_waiting; + + if (!cond->initialized) + return; + + EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + threads_waiting = cond->wait_count > 0; + LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + + if (threads_waiting) + SetEvent (cond->events[CONDV_SIGNAL]); +} + +void +sys_cond_broadcast (sys_cond_t *cond) +{ + bool threads_waiting; + + if (!cond->initialized) + return; + + EnterCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + threads_waiting = cond->wait_count > 0; + LeaveCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); + + if (threads_waiting) + SetEvent (cond->events[CONDV_BROADCAST]); +} + +void +sys_cond_destroy (sys_cond_t *cond) +{ + if (cond->events[CONDV_SIGNAL]) + CloseHandle (cond->events[CONDV_SIGNAL]); + if (cond->events[CONDV_BROADCAST]) + CloseHandle (cond->events[CONDV_BROADCAST]); + + if (!cond->initialized) + return; + + /* FIXME: What if wait_count is non-zero, i.e. there are still + threads waiting on this condition variable? */ + DeleteCriticalSection ((LPCRITICAL_SECTION)&cond->wait_count_lock); +} + +sys_thread_t +sys_thread_self (void) +{ + return (sys_thread_t) GetCurrentThreadId (); +} + +int +sys_thread_equal (sys_thread_t one, sys_thread_t two) +{ + return one == two; +} + +static thread_creation_function *thread_start_address; + +/* _beginthread wants a void function, while we are passed a function + that returns a pointer. So we use a wrapper. */ +static void +w32_beginthread_wrapper (void *arg) +{ + (void)thread_start_address (arg); +} + +int +sys_thread_create (sys_thread_t *thread_ptr, const char *name, + thread_creation_function *func, void *arg) +{ + /* FIXME: Do threads that run Lisp require some minimum amount of + stack? Zero here means each thread will get the same amount as + the main program. On GNU/Linux, it seems like the stack is 2MB + by default, overridden by RLIMIT_STACK at program start time. + Not sure what to do with this. See also the comment in + w32proc.c:new_child. */ + const unsigned stack_size = 0; + uintptr_t thandle; + + thread_start_address = func; + + /* We use _beginthread rather than CreateThread because the former + arranges for the thread handle to be automatically closed when + the thread exits, thus preventing handle leaks and/or the need to + track all the threads and close their handles when they exit. + Also, MSDN seems to imply that code which uses CRT _must_ call + _beginthread, although if that is true, we already violate that + rule in many places... */ + thandle = _beginthread (w32_beginthread_wrapper, stack_size, arg); + if (thandle == (uintptr_t)-1L) + return 0; + + /* Kludge alert! We use the Windows thread ID, an unsigned 32-bit + number, as the sys_thread_t type, because that ID is the only + unique identifier of a thread on Windows. But _beginthread + returns a handle of the thread, and there's no easy way of + getting the thread ID given a handle (GetThreadId is available + only since Vista, so we cannot use it portably). Fortunately, + the value returned by sys_thread_create is not used by its + callers; instead, run_thread, which runs in the context of the + new thread, calls sys_thread_self and uses its return value; + sys_thread_self in this implementation calls GetCurrentThreadId. + Therefore, we return some more or less arbitrary value of the + thread ID from this function. */ + *thread_ptr = thandle & 0xFFFFFFFF; + return 1; +} + +void +sys_thread_yield (void) +{ + Sleep (0); +} + +#else + +#error port me + +#endif |