diff options
Diffstat (limited to 'tests/windows-timedrwlock.c')
| -rw-r--r-- | tests/windows-timedrwlock.c | 669 |
1 files changed, 669 insertions, 0 deletions
diff --git a/tests/windows-timedrwlock.c b/tests/windows-timedrwlock.c new file mode 100644 index 00000000..e818407c --- /dev/null +++ b/tests/windows-timedrwlock.c @@ -0,0 +1,669 @@ +/* Timed read-write locks (native Windows implementation). + Copyright (C) 2005-2024 Free Software Foundation, Inc. + + This file is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + This file 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 Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Bruno Haible <bruno@clisp.org>, 2019. */ + +#include <config.h> + +/* Specification. */ +#include "windows-timedrwlock.h" + +#include <errno.h> +#include <stdlib.h> +#include <sys/time.h> + +/* Don't assume that UNICODE is not defined. */ +#undef CreateEvent +#define CreateEvent CreateEventA + +/* In this file, the waitqueues are implemented as linked lists. */ +#define glwthread_waitqueue_t glwthread_clinked_waitqueue_t + +/* All links of a circular list, except the anchor, are of this type, carrying + a payload. */ +struct glwthread_waitqueue_element +{ + struct glwthread_waitqueue_link link; /* must be the first field! */ + HANDLE event; /* Waiting thread, represented by an event. + This field is immutable once initialized. */ +}; + +static void +glwthread_waitqueue_init (glwthread_waitqueue_t *wq) +{ + wq->wq_list.wql_next = &wq->wq_list; + wq->wq_list.wql_prev = &wq->wq_list; + wq->count = 0; +} + +/* Enqueues the current thread, represented by an event, in a wait queue. + Returns NULL if an allocation failure occurs. */ +static struct glwthread_waitqueue_element * +glwthread_waitqueue_add (glwthread_waitqueue_t *wq) +{ + struct glwthread_waitqueue_element *elt; + HANDLE event; + + /* Allocate the memory for the waitqueue element on the heap, not on the + thread's stack. If the thread exits unexpectedly, we prefer to leak + some memory rather than to access unavailable memory and crash. */ + elt = + (struct glwthread_waitqueue_element *) + malloc (sizeof (struct glwthread_waitqueue_element)); + if (elt == NULL) + /* No more memory. */ + return NULL; + + /* Whether the created event is a manual-reset one or an auto-reset one, + does not matter, since we will wait on it only once. */ + event = CreateEvent (NULL, TRUE, FALSE, NULL); + if (event == INVALID_HANDLE_VALUE) + { + /* No way to allocate an event. */ + free (elt); + return NULL; + } + elt->event = event; + /* Insert elt at the end of the circular list. */ + (elt->link.wql_prev = wq->wq_list.wql_prev)->wql_next = &elt->link; + (elt->link.wql_next = &wq->wq_list)->wql_prev = &elt->link; + wq->count++; + return elt; +} + +/* Removes the current thread, represented by a + 'struct glwthread_waitqueue_element *', from a wait queue. + Returns true if is was found and removed, false if it was not present. */ +static bool +glwthread_waitqueue_remove (glwthread_waitqueue_t *wq, + struct glwthread_waitqueue_element *elt) +{ + if (elt->link.wql_next != NULL && elt->link.wql_prev != NULL) + { + /* Remove elt from the circular list. */ + struct glwthread_waitqueue_link *prev = elt->link.wql_prev; + struct glwthread_waitqueue_link *next = elt->link.wql_next; + prev->wql_next = next; + next->wql_prev = prev; + elt->link.wql_next = NULL; + elt->link.wql_prev = NULL; + wq->count--; + return true; + } + else + return false; +} + +/* Notifies the first thread from a wait queue and dequeues it. */ +static void +glwthread_waitqueue_notify_first (glwthread_waitqueue_t *wq) +{ + if (wq->wq_list.wql_next != &wq->wq_list) + { + struct glwthread_waitqueue_element *elt = + (struct glwthread_waitqueue_element *) wq->wq_list.wql_next; + struct glwthread_waitqueue_link *prev; + struct glwthread_waitqueue_link *next; + + /* Remove elt from the circular list. */ + prev = &wq->wq_list; /* = elt->link.wql_prev; */ + next = elt->link.wql_next; + prev->wql_next = next; + next->wql_prev = prev; + elt->link.wql_next = NULL; + elt->link.wql_prev = NULL; + wq->count--; + + SetEvent (elt->event); + /* After the SetEvent, this thread cannot access *elt any more, because + the woken-up thread will quickly call free (elt). */ + } +} + +/* Notifies all threads from a wait queue and dequeues them all. */ +static void +glwthread_waitqueue_notify_all (glwthread_waitqueue_t *wq) +{ + struct glwthread_waitqueue_link *l; + + for (l = wq->wq_list.wql_next; l != &wq->wq_list; ) + { + struct glwthread_waitqueue_element *elt = + (struct glwthread_waitqueue_element *) l; + struct glwthread_waitqueue_link *prev; + struct glwthread_waitqueue_link *next; + + /* Remove elt from the circular list. */ + prev = &wq->wq_list; /* = elt->link.wql_prev; */ + next = elt->link.wql_next; + prev->wql_next = next; + next->wql_prev = prev; + elt->link.wql_next = NULL; + elt->link.wql_prev = NULL; + wq->count--; + + SetEvent (elt->event); + /* After the SetEvent, this thread cannot access *elt any more, because + the woken-up thread will quickly call free (elt). */ + + l = next; + } + if (!(wq->wq_list.wql_next == &wq->wq_list + && wq->wq_list.wql_prev == &wq->wq_list + && wq->count == 0)) + abort (); +} + +void +glwthread_timedrwlock_init (glwthread_timedrwlock_t *lock) +{ + InitializeCriticalSection (&lock->lock); + glwthread_waitqueue_init (&lock->waiting_readers); + glwthread_waitqueue_init (&lock->waiting_writers); + lock->runcount = 0; + lock->guard.done = 1; +} + +int +glwthread_timedrwlock_rdlock (glwthread_timedrwlock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glwthread_timedrwlock_init (lock); + else + { + /* Don't let lock->guard.started grow and wrap around. */ + InterlockedDecrement (&lock->guard.started); + /* 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, and whether no writer is waiting. The latter + condition is because POSIX recommends that "write locks shall take + precedence over read locks", to avoid "writer starvation". */ + if (!(lock->runcount + 1 > 0 && lock->waiting_writers.count == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_readers. */ + struct glwthread_waitqueue_element *elt = + glwthread_waitqueue_add (&lock->waiting_readers); + if (elt != NULL) + { + HANDLE event = elt->event; + 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); + free (elt); + /* 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 0; + } + else + { + /* Allocation failure. Weird. */ + do + { + LeaveCriticalSection (&lock->lock); + Sleep (1); + EnterCriticalSection (&lock->lock); + } + while (!(lock->runcount + 1 > 0)); + } + } + lock->runcount++; + LeaveCriticalSection (&lock->lock); + return 0; +} + +int +glwthread_timedrwlock_wrlock (glwthread_timedrwlock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glwthread_timedrwlock_init (lock); + else + { + /* Don't let lock->guard.started grow and wrap around. */ + InterlockedDecrement (&lock->guard.started); + /* 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. */ + struct glwthread_waitqueue_element *elt = + glwthread_waitqueue_add (&lock->waiting_writers); + if (elt != NULL) + { + HANDLE event = elt->event; + 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); + free (elt); + /* 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 0; + } + 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); + return 0; +} + +int +glwthread_timedrwlock_tryrdlock (glwthread_timedrwlock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glwthread_timedrwlock_init (lock); + else + { + /* Don't let lock->guard.started grow and wrap around. */ + InterlockedDecrement (&lock->guard.started); + /* Yield the CPU while waiting for another thread to finish + initializing this lock. */ + while (!lock->guard.done) + Sleep (0); + } + } + /* It's OK to wait for this critical section, because it is never taken for a + long time. */ + EnterCriticalSection (&lock->lock); + /* Test whether only readers are currently running, and whether the runcount + field will not overflow, and whether no writer is waiting. The latter + condition is because POSIX recommends that "write locks shall take + precedence over read locks", to avoid "writer starvation". */ + if (!(lock->runcount + 1 > 0 && lock->waiting_writers.count == 0)) + { + /* This thread would have to wait for a while. Return instead. */ + LeaveCriticalSection (&lock->lock); + return EBUSY; + } + lock->runcount++; + LeaveCriticalSection (&lock->lock); + return 0; +} + +int +glwthread_timedrwlock_trywrlock (glwthread_timedrwlock_t *lock) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glwthread_timedrwlock_init (lock); + else + { + /* Don't let lock->guard.started grow and wrap around. */ + InterlockedDecrement (&lock->guard.started); + /* Yield the CPU while waiting for another thread to finish + initializing this lock. */ + while (!lock->guard.done) + Sleep (0); + } + } + /* It's OK to wait for this critical section, because it is never taken for a + long time. */ + EnterCriticalSection (&lock->lock); + /* Test whether no readers or writers are currently running. */ + if (!(lock->runcount == 0)) + { + /* This thread would have to wait for a while. Return instead. */ + LeaveCriticalSection (&lock->lock); + return EBUSY; + } + lock->runcount--; /* runcount becomes -1 */ + LeaveCriticalSection (&lock->lock); + return 0; +} + +int +glwthread_timedrwlock_timedrdlock (glwthread_timedrwlock_t *lock, + const struct timespec *abstime) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glwthread_timedrwlock_init (lock); + else + { + /* Don't let lock->guard.started grow and wrap around. */ + InterlockedDecrement (&lock->guard.started); + /* 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, and whether no writer is waiting. The latter + condition is because POSIX recommends that "write locks shall take + precedence over read locks", to avoid "writer starvation". */ + if (!(lock->runcount + 1 > 0 && lock->waiting_writers.count == 0)) + { + /* This thread has to wait for a while. Enqueue it among the + waiting_readers. */ + struct glwthread_waitqueue_element *elt = + glwthread_waitqueue_add (&lock->waiting_readers); + if (elt != NULL) + { + HANDLE event = elt->event; + struct timeval currtime; + DWORD timeout; + DWORD result; + int retval; + + LeaveCriticalSection (&lock->lock); + + gettimeofday (&currtime, NULL); + + /* Wait until another thread signals this event or until the + abstime passes. */ + if (currtime.tv_sec > abstime->tv_sec) + timeout = 0; + else + { + unsigned long seconds = abstime->tv_sec - currtime.tv_sec; + timeout = seconds * 1000; + if (timeout / 1000 != seconds) /* overflow? */ + timeout = INFINITE; + else + { + long milliseconds = + abstime->tv_nsec / 1000000 - currtime.tv_usec / 1000; + if (milliseconds >= 0) + { + timeout += milliseconds; + if (timeout < milliseconds) /* overflow? */ + timeout = INFINITE; + } + else + { + if (timeout >= - milliseconds) + timeout -= (- milliseconds); + else + timeout = 0; + } + } + } + if (timeout != 0) + { + /* WaitForSingleObject + <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-waitforsingleobject> */ + result = WaitForSingleObject (event, timeout); + if (result == WAIT_FAILED) + abort (); + if (result != WAIT_TIMEOUT) + { + CloseHandle (event); + free (elt); + /* 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 0; + } + } + EnterCriticalSection (&lock->lock); + /* Remove ourselves from the waiting_readers. */ + if (glwthread_waitqueue_remove (&lock->waiting_readers, elt)) + retval = ETIMEDOUT; + else + /* The event was signalled just now. */ + retval = 0; + LeaveCriticalSection (&lock->lock); + CloseHandle (event); + free (elt); + if (retval == 0) + /* Same assertion as above. */ + if (!(lock->runcount > 0)) + abort (); + return retval; + } + else + { + /* Allocation failure. Weird. */ + do + { + LeaveCriticalSection (&lock->lock); + Sleep (1); + EnterCriticalSection (&lock->lock); + } + while (!(lock->runcount + 1 > 0)); + } + } + lock->runcount++; + LeaveCriticalSection (&lock->lock); + return 0; +} + +int +glwthread_timedrwlock_timedwrlock (glwthread_timedrwlock_t *lock, + const struct timespec *abstime) +{ + if (!lock->guard.done) + { + if (InterlockedIncrement (&lock->guard.started) == 0) + /* This thread is the first one to need this lock. Initialize it. */ + glwthread_timedrwlock_init (lock); + else + { + /* Don't let lock->guard.started grow and wrap around. */ + InterlockedDecrement (&lock->guard.started); + /* 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. */ + struct glwthread_waitqueue_element *elt = + glwthread_waitqueue_add (&lock->waiting_writers); + if (elt != NULL) + { + HANDLE event = elt->event; + struct timeval currtime; + DWORD timeout; + DWORD result; + int retval; + + LeaveCriticalSection (&lock->lock); + + gettimeofday (&currtime, NULL); + + /* Wait until another thread signals this event or until the + abstime passes. */ + if (currtime.tv_sec > abstime->tv_sec) + timeout = 0; + else + { + unsigned long seconds = abstime->tv_sec - currtime.tv_sec; + timeout = seconds * 1000; + if (timeout / 1000 != seconds) /* overflow? */ + timeout = INFINITE; + else + { + long milliseconds = + abstime->tv_nsec / 1000000 - currtime.tv_usec / 1000; + if (milliseconds >= 0) + { + timeout += milliseconds; + if (timeout < milliseconds) /* overflow? */ + timeout = INFINITE; + } + else + { + if (timeout >= - milliseconds) + timeout -= (- milliseconds); + else + timeout = 0; + } + } + } + if (timeout != 0) + { + /* WaitForSingleObject + <https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-waitforsingleobject> */ + result = WaitForSingleObject (event, timeout); + if (result == WAIT_FAILED) + abort (); + if (result != WAIT_TIMEOUT) + { + CloseHandle (event); + free (elt); + /* 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 0; + } + } + EnterCriticalSection (&lock->lock); + /* Remove ourselves from the waiting_writers. */ + if (glwthread_waitqueue_remove (&lock->waiting_writers, elt)) + retval = ETIMEDOUT; + else + /* The event was signalled just now. */ + retval = 0; + LeaveCriticalSection (&lock->lock); + CloseHandle (event); + free (elt); + if (retval == 0) + /* Same assertion as above. */ + if (!(lock->runcount == -1)) + abort (); + return retval; + } + 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); + return 0; +} + +int +glwthread_timedrwlock_unlock (glwthread_timedrwlock_t *lock) +{ + if (!lock->guard.done) + return EINVAL; + 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)) + { + LeaveCriticalSection (&lock->lock); + return EPERM; + } + 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--; + glwthread_waitqueue_notify_first (&lock->waiting_writers); + } + else + { + /* Wake up all waiting readers. */ + lock->runcount += lock->waiting_readers.count; + glwthread_waitqueue_notify_all (&lock->waiting_readers); + } + } + LeaveCriticalSection (&lock->lock); + return 0; +} + +int +glwthread_timedrwlock_destroy (glwthread_timedrwlock_t *lock) +{ + if (!lock->guard.done) + return EINVAL; + if (lock->runcount != 0) + return EBUSY; + DeleteCriticalSection (&lock->lock); + lock->guard.done = 0; + return 0; +} |