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Diffstat (limited to 'intl/lock.c')
| -rw-r--r-- | intl/lock.c | 924 |
1 files changed, 924 insertions, 0 deletions
diff --git a/intl/lock.c b/intl/lock.c new file mode 100644 index 0000000..a860459 --- /dev/null +++ b/intl/lock.c @@ -0,0 +1,924 @@ +/* Locking in multithreaded situations. + Copyright (C) 2005 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify it + under the terms of the GNU Library General Public License as published + by the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, + USA. */ + +/* Written by Bruno Haible <bruno@clisp.org>, 2005. + Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h, + gthr-win32.h. */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include "lock.h" + +/* ========================================================================= */ + +#if USE_POSIX_THREADS + +/* Use the POSIX threads library. */ + +# if PTHREAD_IN_USE_DETECTION_HARD + +/* The function to be executed by a dummy thread. */ +static void * +dummy_thread_func (void *arg) +{ + return arg; +} + +int +glthread_in_use (void) +{ + static int tested; + static int result; /* 1: linked with -lpthread, 0: only with libc */ + + if (!tested) + { + pthread_t thread; + + if (pthread_create (&thread, NULL, dummy_thread_func, NULL) != 0) + /* Thread creation failed. */ + result = 0; + else + { + /* Thread creation works. */ + void *retval; + if (pthread_join (thread, &retval) != 0) + abort (); + result = 1; + } + tested = 1; + } + return result; +} + +# endif + +/* -------------------------- gl_lock_t datatype -------------------------- */ + +/* ------------------------- gl_rwlock_t datatype ------------------------- */ + +# if HAVE_PTHREAD_RWLOCK + +# if !defined PTHREAD_RWLOCK_INITIALIZER + +void +glthread_rwlock_init (gl_rwlock_t *lock) +{ + if (pthread_rwlock_init (&lock->rwlock, NULL) != 0) + abort (); + lock->initialized = 1; +} + +void +glthread_rwlock_rdlock (gl_rwlock_t *lock) +{ + if (!lock->initialized) + { + if (pthread_mutex_lock (&lock->guard) != 0) + abort (); + if (!lock->initialized) + glthread_rwlock_init (lock); + if (pthread_mutex_unlock (&lock->guard) != 0) + abort (); + } + if (pthread_rwlock_rdlock (&lock->rwlock) != 0) + abort (); +} + +void +glthread_rwlock_wrlock (gl_rwlock_t *lock) +{ + if (!lock->initialized) + { + if (pthread_mutex_lock (&lock->guard) != 0) + abort (); + if (!lock->initialized) + glthread_rwlock_init (lock); + if (pthread_mutex_unlock (&lock->guard) != 0) + abort (); + } + if (pthread_rwlock_wrlock (&lock->rwlock) != 0) + abort (); +} + +void +glthread_rwlock_unlock (gl_rwlock_t *lock) +{ + if (!lock->initialized) + abort (); + if (pthread_rwlock_unlock (&lock->rwlock) != 0) + abort (); +} + +void +glthread_rwlock_destroy (gl_rwlock_t *lock) +{ + if (!lock->initialized) + abort (); + if (pthread_rwlock_destroy (&lock->rwlock) != 0) + abort (); + lock->initialized = 0; +} + +# endif + +# else + +void +glthread_rwlock_init (gl_rwlock_t *lock) +{ + if (pthread_mutex_init (&lock->lock, NULL) != 0) + abort (); + if (pthread_cond_init (&lock->waiting_readers, NULL) != 0) + abort (); + if (pthread_cond_init (&lock->waiting_writers, NULL) != 0) + abort (); + lock->waiting_writers_count = 0; + lock->runcount = 0; +} + +void +glthread_rwlock_rdlock (gl_rwlock_t *lock) +{ + if (pthread_mutex_lock (&lock->lock) != 0) + abort (); + /* Test whether only readers are currently running, and whether the runcount + field will not overflow. */ + /* POSIX says: "It is implementation-defined whether the calling thread + acquires the lock when a writer does not hold the lock and there are + writers blocked on the lock." Let's say, no: give the writers a higher + priority. */ + while (!(lock->runcount + 1 > 0 && lock->waiting_writers_count == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_readers. */ + if (pthread_cond_wait (&lock->waiting_readers, &lock->lock) != 0) + abort (); + } + lock->runcount++; + if (pthread_mutex_unlock (&lock->lock) != 0) + abort (); +} + +void +glthread_rwlock_wrlock (gl_rwlock_t *lock) +{ + if (pthread_mutex_lock (&lock->lock) != 0) + abort (); + /* Test whether no readers or writers are currently running. */ + while (!(lock->runcount == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_writers. */ + lock->waiting_writers_count++; + if (pthread_cond_wait (&lock->waiting_writers, &lock->lock) != 0) + abort (); + lock->waiting_writers_count--; + } + lock->runcount--; /* runcount becomes -1 */ + if (pthread_mutex_unlock (&lock->lock) != 0) + abort (); +} + +void +glthread_rwlock_unlock (gl_rwlock_t *lock) +{ + if (pthread_mutex_lock (&lock->lock) != 0) + abort (); + if (lock->runcount < 0) + { + /* Drop a writer lock. */ + if (!(lock->runcount == -1)) + abort (); + lock->runcount = 0; + } + else + { + /* Drop a reader lock. */ + if (!(lock->runcount > 0)) + abort (); + lock->runcount--; + } + if (lock->runcount == 0) + { + /* POSIX recommends that "write locks shall take precedence over read + locks", to avoid "writer starvation". */ + if (lock->waiting_writers_count > 0) + { + /* Wake up one of the waiting writers. */ + if (pthread_cond_signal (&lock->waiting_writers) != 0) + abort (); + } + else + { + /* Wake up all waiting readers. */ + if (pthread_cond_broadcast (&lock->waiting_readers) != 0) + abort (); + } + } + if (pthread_mutex_unlock (&lock->lock) != 0) + abort (); +} + +void +glthread_rwlock_destroy (gl_rwlock_t *lock) +{ + if (pthread_mutex_destroy (&lock->lock) != 0) + abort (); + if (pthread_cond_destroy (&lock->waiting_readers) != 0) + abort (); + if (pthread_cond_destroy (&lock->waiting_writers) != 0) + abort (); +} + +# endif + +/* --------------------- gl_recursive_lock_t datatype --------------------- */ + +# if HAVE_PTHREAD_MUTEX_RECURSIVE + +# if !(defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER || defined PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP) + +void +glthread_recursive_lock_init (gl_recursive_lock_t *lock) +{ + pthread_mutexattr_t attributes; + + if (pthread_mutexattr_init (&attributes) != 0) + abort (); + if (pthread_mutexattr_settype (&attributes, PTHREAD_MUTEX_RECURSIVE) != 0) + abort (); + if (pthread_mutex_init (&lock->recmutex, &attributes) != 0) + abort (); + if (pthread_mutexattr_destroy (&attributes) != 0) + abort (); + lock->initialized = 1; +} + +void +glthread_recursive_lock_lock (gl_recursive_lock_t *lock) +{ + if (!lock->initialized) + { + if (pthread_mutex_lock (&lock->guard) != 0) + abort (); + if (!lock->initialized) + glthread_recursive_lock_init (lock); + if (pthread_mutex_unlock (&lock->guard) != 0) + abort (); + } + if (pthread_mutex_lock (&lock->recmutex) != 0) + abort (); +} + +void +glthread_recursive_lock_unlock (gl_recursive_lock_t *lock) +{ + if (!lock->initialized) + abort (); + if (pthread_mutex_unlock (&lock->recmutex) != 0) + abort (); +} + +void +glthread_recursive_lock_destroy (gl_recursive_lock_t *lock) +{ + if (!lock->initialized) + abort (); + if (pthread_mutex_destroy (&lock->recmutex) != 0) + abort (); + lock->initialized = 0; +} + +# endif + +# else + +void +glthread_recursive_lock_init (gl_recursive_lock_t *lock) +{ + if (pthread_mutex_init (&lock->mutex, NULL) != 0) + abort (); + lock->owner = (pthread_t) 0; + lock->depth = 0; +} + +void +glthread_recursive_lock_lock (gl_recursive_lock_t *lock) +{ + pthread_t self = pthread_self (); + if (lock->owner != self) + { + if (pthread_mutex_lock (&lock->mutex) != 0) + abort (); + lock->owner = self; + } + if (++(lock->depth) == 0) /* wraparound? */ + abort (); +} + +void +glthread_recursive_lock_unlock (gl_recursive_lock_t *lock) +{ + if (lock->owner != pthread_self ()) + abort (); + if (lock->depth == 0) + abort (); + if (--(lock->depth) == 0) + { + lock->owner = (pthread_t) 0; + if (pthread_mutex_unlock (&lock->mutex) != 0) + abort (); + } +} + +void +glthread_recursive_lock_destroy (gl_recursive_lock_t *lock) +{ + if (lock->owner != (pthread_t) 0) + abort (); + if (pthread_mutex_destroy (&lock->mutex) != 0) + abort (); +} + +# endif + +/* -------------------------- gl_once_t datatype -------------------------- */ + +static const pthread_once_t fresh_once = PTHREAD_ONCE_INIT; + +int +glthread_once_singlethreaded (pthread_once_t *once_control) +{ + /* We don't know whether pthread_once_t is an integer type, a floating-point + type, a pointer type, or a structure type. */ + char *firstbyte = (char *)once_control; + if (*firstbyte == *(const char *)&fresh_once) + { + /* First time use of once_control. Invert the first byte. */ + *firstbyte = ~ *(const char *)&fresh_once; + return 1; + } + else + return 0; +} + +#endif + +/* ========================================================================= */ + +#if USE_PTH_THREADS + +/* Use the GNU Pth threads library. */ + +/* -------------------------- gl_lock_t datatype -------------------------- */ + +/* ------------------------- gl_rwlock_t datatype ------------------------- */ + +/* --------------------- gl_recursive_lock_t datatype --------------------- */ + +/* -------------------------- gl_once_t datatype -------------------------- */ + +void +glthread_once_call (void *arg) +{ + void (**gl_once_temp_addr) (void) = (void (**) (void)) arg; + void (*initfunction) (void) = *gl_once_temp_addr; + initfunction (); +} + +int +glthread_once_singlethreaded (pth_once_t *once_control) +{ + /* We know that pth_once_t is an integer type. */ + if (*once_control == PTH_ONCE_INIT) + { + /* First time use of once_control. Invert the marker. */ + *once_control = ~ PTH_ONCE_INIT; + return 1; + } + else + return 0; +} + +#endif + +/* ========================================================================= */ + +#if USE_SOLARIS_THREADS + +/* Use the old Solaris threads library. */ + +/* -------------------------- gl_lock_t datatype -------------------------- */ + +/* ------------------------- gl_rwlock_t datatype ------------------------- */ + +/* --------------------- gl_recursive_lock_t datatype --------------------- */ + +void +glthread_recursive_lock_init (gl_recursive_lock_t *lock) +{ + if (mutex_init (&lock->mutex, USYNC_THREAD, NULL) != 0) + abort (); + lock->owner = (thread_t) 0; + lock->depth = 0; +} + +void +glthread_recursive_lock_lock (gl_recursive_lock_t *lock) +{ + thread_t self = thr_self (); + if (lock->owner != self) + { + if (mutex_lock (&lock->mutex) != 0) + abort (); + lock->owner = self; + } + if (++(lock->depth) == 0) /* wraparound? */ + abort (); +} + +void +glthread_recursive_lock_unlock (gl_recursive_lock_t *lock) +{ + if (lock->owner != thr_self ()) + abort (); + if (lock->depth == 0) + abort (); + if (--(lock->depth) == 0) + { + lock->owner = (thread_t) 0; + if (mutex_unlock (&lock->mutex) != 0) + abort (); + } +} + +void +glthread_recursive_lock_destroy (gl_recursive_lock_t *lock) +{ + if (lock->owner != (thread_t) 0) + abort (); + if (mutex_destroy (&lock->mutex) != 0) + abort (); +} + +/* -------------------------- gl_once_t datatype -------------------------- */ + +void +glthread_once (gl_once_t *once_control, void (*initfunction) (void)) +{ + if (!once_control->inited) + { + /* Use the mutex to guarantee that if another thread is already calling + the initfunction, this thread waits until it's finished. */ + if (mutex_lock (&once_control->mutex) != 0) + abort (); + if (!once_control->inited) + { + once_control->inited = 1; + initfunction (); + } + if (mutex_unlock (&once_control->mutex) != 0) + abort (); + } +} + +int +glthread_once_singlethreaded (gl_once_t *once_control) +{ + /* We know that gl_once_t contains an integer type. */ + if (!once_control->inited) + { + /* First time use of once_control. Invert the marker. */ + once_control->inited = ~ 0; + return 1; + } + else + return 0; +} + +#endif + +/* ========================================================================= */ + +#if USE_WIN32_THREADS + +/* -------------------------- gl_lock_t datatype -------------------------- */ + +void +glthread_lock_init (gl_lock_t *lock) +{ + InitializeCriticalSection (&lock->lock); + lock->guard.done = 1; +} + +void +glthread_lock_lock (gl_lock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glthread_lock_init (lock); + else + /* Yield the CPU while waiting for another thread to finish + initializing this lock. */ + while (!lock->guard.done) + Sleep (0); + } + EnterCriticalSection (&lock->lock); +} + +void +glthread_lock_unlock (gl_lock_t *lock) +{ + if (!lock->guard.done) + abort (); + LeaveCriticalSection (&lock->lock); +} + +void +glthread_lock_destroy (gl_lock_t *lock) +{ + if (!lock->guard.done) + abort (); + DeleteCriticalSection (&lock->lock); + lock->guard.done = 0; +} + +/* ------------------------- gl_rwlock_t datatype ------------------------- */ + +static inline void +gl_waitqueue_init (gl_waitqueue_t *wq) +{ + wq->array = NULL; + wq->count = 0; + wq->alloc = 0; + wq->offset = 0; +} + +/* Enqueues the current thread, represented by an event, in a wait queue. + Returns INVALID_HANDLE_VALUE if an allocation failure occurs. */ +static HANDLE +gl_waitqueue_add (gl_waitqueue_t *wq) +{ + HANDLE event; + unsigned int index; + + if (wq->count == wq->alloc) + { + unsigned int new_alloc = 2 * wq->alloc + 1; + HANDLE *new_array = + (HANDLE *) realloc (wq->array, new_alloc * sizeof (HANDLE)); + if (new_array == NULL) + /* No more memory. */ + return INVALID_HANDLE_VALUE; + /* Now is a good opportunity to rotate the array so that its contents + starts at offset 0. */ + if (wq->offset > 0) + { + unsigned int old_count = wq->count; + unsigned int old_alloc = wq->alloc; + unsigned int old_offset = wq->offset; + unsigned int i; + if (old_offset + old_count > old_alloc) + { + unsigned int limit = old_offset + old_count - old_alloc; + for (i = 0; i < limit; i++) + new_array[old_alloc + i] = new_array[i]; + } + for (i = 0; i < old_count; i++) + new_array[i] = new_array[old_offset + i]; + wq->offset = 0; + } + wq->array = new_array; + wq->alloc = new_alloc; + } + event = CreateEvent (NULL, TRUE, FALSE, NULL); + if (event == INVALID_HANDLE_VALUE) + /* No way to allocate an event. */ + return INVALID_HANDLE_VALUE; + index = wq->offset + wq->count; + if (index >= wq->alloc) + index -= wq->alloc; + wq->array[index] = event; + wq->count++; + return event; +} + +/* Notifies the first thread from a wait queue and dequeues it. */ +static inline void +gl_waitqueue_notify_first (gl_waitqueue_t *wq) +{ + SetEvent (wq->array[wq->offset + 0]); + wq->offset++; + wq->count--; + if (wq->count == 0 || wq->offset == wq->alloc) + wq->offset = 0; +} + +/* Notifies all threads from a wait queue and dequeues them all. */ +static inline void +gl_waitqueue_notify_all (gl_waitqueue_t *wq) +{ + unsigned int i; + + for (i = 0; i < wq->count; i++) + { + unsigned int index = wq->offset + i; + if (index >= wq->alloc) + index -= wq->alloc; + SetEvent (wq->array[index]); + } + wq->count = 0; + wq->offset = 0; +} + +void +glthread_rwlock_init (gl_rwlock_t *lock) +{ + InitializeCriticalSection (&lock->lock); + gl_waitqueue_init (&lock->waiting_readers); + gl_waitqueue_init (&lock->waiting_writers); + lock->runcount = 0; + lock->guard.done = 1; +} + +void +glthread_rwlock_rdlock (gl_rwlock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glthread_rwlock_init (lock); + else + /* Yield the CPU while waiting for another thread to finish + initializing this lock. */ + while (!lock->guard.done) + Sleep (0); + } + EnterCriticalSection (&lock->lock); + /* Test whether only readers are currently running, and whether the runcount + field will not overflow. */ + if (!(lock->runcount + 1 > 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_readers. */ + HANDLE event = gl_waitqueue_add (&lock->waiting_readers); + if (event != INVALID_HANDLE_VALUE) + { + DWORD result; + LeaveCriticalSection (&lock->lock); + /* Wait until another thread signals this event. */ + result = WaitForSingleObject (event, INFINITE); + if (result == WAIT_FAILED || result == WAIT_TIMEOUT) + abort (); + CloseHandle (event); + /* The thread which signalled the event already did the bookkeeping: + removed us from the waiting_readers, incremented lock->runcount. */ + if (!(lock->runcount > 0)) + abort (); + return; + } + else + { + /* Allocation failure. Weird. */ + do + { + LeaveCriticalSection (&lock->lock); + Sleep (1); + EnterCriticalSection (&lock->lock); + } + while (!(lock->runcount + 1 > 0)); + } + } + lock->runcount++; + LeaveCriticalSection (&lock->lock); +} + +void +glthread_rwlock_wrlock (gl_rwlock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glthread_rwlock_init (lock); + else + /* Yield the CPU while waiting for another thread to finish + initializing this lock. */ + while (!lock->guard.done) + Sleep (0); + } + EnterCriticalSection (&lock->lock); + /* Test whether no readers or writers are currently running. */ + if (!(lock->runcount == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_writers. */ + HANDLE event = gl_waitqueue_add (&lock->waiting_writers); + if (event != INVALID_HANDLE_VALUE) + { + DWORD result; + LeaveCriticalSection (&lock->lock); + /* Wait until another thread signals this event. */ + result = WaitForSingleObject (event, INFINITE); + if (result == WAIT_FAILED || result == WAIT_TIMEOUT) + abort (); + CloseHandle (event); + /* The thread which signalled the event already did the bookkeeping: + removed us from the waiting_writers, set lock->runcount = -1. */ + if (!(lock->runcount == -1)) + abort (); + return; + } + else + { + /* Allocation failure. Weird. */ + do + { + LeaveCriticalSection (&lock->lock); + Sleep (1); + EnterCriticalSection (&lock->lock); + } + while (!(lock->runcount == 0)); + } + } + lock->runcount--; /* runcount becomes -1 */ + LeaveCriticalSection (&lock->lock); +} + +void +glthread_rwlock_unlock (gl_rwlock_t *lock) +{ + if (!lock->guard.done) + abort (); + EnterCriticalSection (&lock->lock); + if (lock->runcount < 0) + { + /* Drop a writer lock. */ + if (!(lock->runcount == -1)) + abort (); + lock->runcount = 0; + } + else + { + /* Drop a reader lock. */ + if (!(lock->runcount > 0)) + abort (); + lock->runcount--; + } + if (lock->runcount == 0) + { + /* POSIX recommends that "write locks shall take precedence over read + locks", to avoid "writer starvation". */ + if (lock->waiting_writers.count > 0) + { + /* Wake up one of the waiting writers. */ + lock->runcount--; + gl_waitqueue_notify_first (&lock->waiting_writers); + } + else + { + /* Wake up all waiting readers. */ + lock->runcount += lock->waiting_readers.count; + gl_waitqueue_notify_all (&lock->waiting_readers); + } + } + LeaveCriticalSection (&lock->lock); +} + +void +glthread_rwlock_destroy (gl_rwlock_t *lock) +{ + if (!lock->guard.done) + abort (); + if (lock->runcount != 0) + abort (); + DeleteCriticalSection (&lock->lock); + if (lock->waiting_readers.array != NULL) + free (lock->waiting_readers.array); + if (lock->waiting_writers.array != NULL) + free (lock->waiting_writers.array); + lock->guard.done = 0; +} + +/* --------------------- gl_recursive_lock_t datatype --------------------- */ + +void +glthread_recursive_lock_init (gl_recursive_lock_t *lock) +{ + lock->owner = 0; + lock->depth = 0; + InitializeCriticalSection (&lock->lock); + lock->guard.done = 1; +} + +void +glthread_recursive_lock_lock (gl_recursive_lock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glthread_recursive_lock_init (lock); + else + /* Yield the CPU while waiting for another thread to finish + initializing this lock. */ + while (!lock->guard.done) + Sleep (0); + } + { + DWORD self = GetCurrentThreadId (); + if (lock->owner != self) + { + EnterCriticalSection (&lock->lock); + lock->owner = self; + } + if (++(lock->depth) == 0) /* wraparound? */ + abort (); + } +} + +void +glthread_recursive_lock_unlock (gl_recursive_lock_t *lock) +{ + if (lock->owner != GetCurrentThreadId ()) + abort (); + if (lock->depth == 0) + abort (); + if (--(lock->depth) == 0) + { + lock->owner = 0; + LeaveCriticalSection (&lock->lock); + } +} + +void +glthread_recursive_lock_destroy (gl_recursive_lock_t *lock) +{ + if (lock->owner != 0) + abort (); + DeleteCriticalSection (&lock->lock); + lock->guard.done = 0; +} + +/* -------------------------- gl_once_t datatype -------------------------- */ + +void +glthread_once (gl_once_t *once_control, void (*initfunction) (void)) +{ + if (once_control->inited <= 0) + { + if (InterlockedIncrement (&once_control->started) == 0) + { + /* This thread is the first one to come to this once_control. */ + InitializeCriticalSection (&once_control->lock); + EnterCriticalSection (&once_control->lock); + once_control->inited = 0; + initfunction (); + once_control->inited = 1; + LeaveCriticalSection (&once_control->lock); + } + else + { + /* Undo last operation. */ + InterlockedDecrement (&once_control->started); + /* Some other thread has already started the initialization. + Yield the CPU while waiting for the other thread to finish + initializing and taking the lock. */ + while (once_control->inited < 0) + Sleep (0); + if (once_control->inited <= 0) + { + /* Take the lock. This blocks until the other thread has + finished calling the initfunction. */ + EnterCriticalSection (&once_control->lock); + LeaveCriticalSection (&once_control->lock); + if (!(once_control->inited > 0)) + abort (); + } + } + } +} + +#endif + +/* ========================================================================= */ |