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win: replace CRITICAL_SECTION+Semaphore with SRWLock (#3383)

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Fixes: https://github.com/libuv/libuv/issues/3382
This commit is contained in:
David Machaj 2022-01-12 07:07:17 -08:00 committed by GitHub
parent 2e42847f4e
commit a3e02e5e4a
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 27 additions and 87 deletions
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23
include/uv/win.h
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@ -263,21 +263,14 @@ typedef union {
} unused_; /* TODO: retained for ABI compatibility; remove me in v2.x. */
} uv_cond_t;
typedef union {
struct {
unsigned int num_readers_;
CRITICAL_SECTION num_readers_lock_;
HANDLE write_semaphore_;
} state_;
/* TODO: remove me in v2.x. */
struct {
SRWLOCK unused_;
} unused1_;
/* TODO: remove me in v2.x. */
struct {
uv_mutex_t unused1_;
uv_mutex_t unused2_;
} unused2_;
typedef struct {
SRWLOCK read_write_lock_;
/* TODO: retained for ABI compatibility; remove me in v2.x */
#ifdef _WIN64
unsigned char padding_[72];
#else
unsigned char padding_[44];
#endif
} uv_rwlock_t;
typedef struct {

91
src/win/thread.c
View File

@ -248,113 +248,60 @@ void uv_mutex_unlock(uv_mutex_t* mutex) {
LeaveCriticalSection(mutex);
}
/* Ensure that the ABI for this type remains stable in v1.x */
#ifdef _WIN64
STATIC_ASSERT(sizeof(uv_rwlock_t) == 80);
#else
STATIC_ASSERT(sizeof(uv_rwlock_t) == 48);
#endif
int uv_rwlock_init(uv_rwlock_t* rwlock) {
/* Initialize the semaphore that acts as the write lock. */
HANDLE handle = CreateSemaphoreW(NULL, 1, 1, NULL);
if (handle == NULL)
return uv_translate_sys_error(GetLastError());
rwlock->state_.write_semaphore_ = handle;
/* Initialize the critical section protecting the reader count. */
InitializeCriticalSection(&rwlock->state_.num_readers_lock_);
/* Initialize the reader count. */
rwlock->state_.num_readers_ = 0;
memset(rwlock, 0, sizeof(*rwlock));
InitializeSRWLock(&rwlock->read_write_lock_);
return 0;
}
void uv_rwlock_destroy(uv_rwlock_t* rwlock) {
DeleteCriticalSection(&rwlock->state_.num_readers_lock_);
CloseHandle(rwlock->state_.write_semaphore_);
/* SRWLock does not need explicit destruction so long as there are no waiting threads
See: https://docs.microsoft.com/windows/win32/api/synchapi/nf-synchapi-initializesrwlock#remarks */
}
void uv_rwlock_rdlock(uv_rwlock_t* rwlock) {
/* Acquire the lock that protects the reader count. */
EnterCriticalSection(&rwlock->state_.num_readers_lock_);
/* Increase the reader count, and lock for write if this is the first
* reader.
*/
if (++rwlock->state_.num_readers_ == 1) {
DWORD r = WaitForSingleObject(rwlock->state_.write_semaphore_, INFINITE);
if (r != WAIT_OBJECT_0)
uv_fatal_error(GetLastError(), "WaitForSingleObject");
}
/* Release the lock that protects the reader count. */
LeaveCriticalSection(&rwlock->state_.num_readers_lock_);
AcquireSRWLockShared(&rwlock->read_write_lock_);
}
int uv_rwlock_tryrdlock(uv_rwlock_t* rwlock) {
int err;
if (!TryEnterCriticalSection(&rwlock->state_.num_readers_lock_))
if (!TryAcquireSRWLockShared(&rwlock->read_write_lock_))
return UV_EBUSY;
err = 0;
if (rwlock->state_.num_readers_ == 0) {
/* Currently there are no other readers, which means that the write lock
* needs to be acquired.
*/
DWORD r = WaitForSingleObject(rwlock->state_.write_semaphore_, 0);
if (r == WAIT_OBJECT_0)
rwlock->state_.num_readers_++;
else if (r == WAIT_TIMEOUT)
err = UV_EBUSY;
else if (r == WAIT_FAILED)
uv_fatal_error(GetLastError(), "WaitForSingleObject");
} else {
/* The write lock has already been acquired because there are other
* active readers.
*/
rwlock->state_.num_readers_++;
}
LeaveCriticalSection(&rwlock->state_.num_readers_lock_);
return err;
return 0;
}
void uv_rwlock_rdunlock(uv_rwlock_t* rwlock) {
EnterCriticalSection(&rwlock->state_.num_readers_lock_);
if (--rwlock->state_.num_readers_ == 0) {
if (!ReleaseSemaphore(rwlock->state_.write_semaphore_, 1, NULL))
uv_fatal_error(GetLastError(), "ReleaseSemaphore");
}
LeaveCriticalSection(&rwlock->state_.num_readers_lock_);
ReleaseSRWLockShared(&rwlock->read_write_lock_);
}
void uv_rwlock_wrlock(uv_rwlock_t* rwlock) {
DWORD r = WaitForSingleObject(rwlock->state_.write_semaphore_, INFINITE);
if (r != WAIT_OBJECT_0)
uv_fatal_error(GetLastError(), "WaitForSingleObject");
AcquireSRWLockExclusive(&rwlock->read_write_lock_);
}
int uv_rwlock_trywrlock(uv_rwlock_t* rwlock) {
DWORD r = WaitForSingleObject(rwlock->state_.write_semaphore_, 0);
if (r == WAIT_OBJECT_0)
return 0;
else if (r == WAIT_TIMEOUT)
if (!TryAcquireSRWLockExclusive(&rwlock->read_write_lock_))
return UV_EBUSY;
else
uv_fatal_error(GetLastError(), "WaitForSingleObject");
return 0;
}
void uv_rwlock_wrunlock(uv_rwlock_t* rwlock) {
if (!ReleaseSemaphore(rwlock->state_.write_semaphore_, 1, NULL))
uv_fatal_error(GetLastError(), "ReleaseSemaphore");
ReleaseSRWLockExclusive(&rwlock->read_write_lock_);
}