summaryrefslogtreecommitdiffstats
path: root/ipc/glue/CrossProcessSemaphore_posix.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'ipc/glue/CrossProcessSemaphore_posix.cpp')
-rw-r--r--ipc/glue/CrossProcessSemaphore_posix.cpp164
1 files changed, 164 insertions, 0 deletions
diff --git a/ipc/glue/CrossProcessSemaphore_posix.cpp b/ipc/glue/CrossProcessSemaphore_posix.cpp
new file mode 100644
index 0000000000..d74e9326f9
--- /dev/null
+++ b/ipc/glue/CrossProcessSemaphore_posix.cpp
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CrossProcessSemaphore.h"
+#include "mozilla/Unused.h"
+#include "nsDebug.h"
+#include "nsISupportsImpl.h"
+#include <errno.h>
+
+static const uint64_t kNsPerMs = 1000000;
+static const uint64_t kNsPerSec = 1000000000;
+
+namespace {
+
+struct SemaphoreData {
+ sem_t mSemaphore;
+ mozilla::Atomic<int32_t> mRefCount;
+ uint32_t mInitialValue;
+};
+
+} // namespace
+
+namespace mozilla {
+
+/* static */
+CrossProcessSemaphore* CrossProcessSemaphore::Create(const char*,
+ uint32_t aInitialValue) {
+ RefPtr<ipc::SharedMemoryBasic> sharedBuffer = new ipc::SharedMemoryBasic;
+ if (!sharedBuffer->Create(sizeof(SemaphoreData))) {
+ return nullptr;
+ }
+
+ if (!sharedBuffer->Map(sizeof(SemaphoreData))) {
+ return nullptr;
+ }
+
+ SemaphoreData* data = static_cast<SemaphoreData*>(sharedBuffer->memory());
+
+ if (!data) {
+ return nullptr;
+ }
+
+ if (sem_init(&data->mSemaphore, 1, aInitialValue)) {
+ return nullptr;
+ }
+
+ CrossProcessSemaphore* sem = new CrossProcessSemaphore;
+ sem->mSharedBuffer = sharedBuffer;
+ sem->mSemaphore = &data->mSemaphore;
+ sem->mRefCount = &data->mRefCount;
+ *sem->mRefCount = 1;
+
+ data->mInitialValue = aInitialValue;
+
+ return sem;
+}
+
+/* static */
+CrossProcessSemaphore* CrossProcessSemaphore::Create(
+ CrossProcessSemaphoreHandle aHandle) {
+ RefPtr<ipc::SharedMemoryBasic> sharedBuffer = new ipc::SharedMemoryBasic;
+
+ if (!sharedBuffer->IsHandleValid(aHandle)) {
+ return nullptr;
+ }
+
+ if (!sharedBuffer->SetHandle(std::move(aHandle),
+ ipc::SharedMemory::RightsReadWrite)) {
+ return nullptr;
+ }
+
+ if (!sharedBuffer->Map(sizeof(SemaphoreData))) {
+ return nullptr;
+ }
+
+ sharedBuffer->CloseHandle();
+
+ SemaphoreData* data = static_cast<SemaphoreData*>(sharedBuffer->memory());
+
+ if (!data) {
+ return nullptr;
+ }
+
+ int32_t oldCount = data->mRefCount++;
+ if (oldCount == 0) {
+ // The other side has already let go of their CrossProcessSemaphore, so now
+ // mSemaphore is garbage. We need to re-initialize it.
+ if (sem_init(&data->mSemaphore, 1, data->mInitialValue)) {
+ data->mRefCount--;
+ return nullptr;
+ }
+ }
+
+ CrossProcessSemaphore* sem = new CrossProcessSemaphore;
+ sem->mSharedBuffer = sharedBuffer;
+ sem->mSemaphore = &data->mSemaphore;
+ sem->mRefCount = &data->mRefCount;
+ return sem;
+}
+
+CrossProcessSemaphore::CrossProcessSemaphore()
+ : mSemaphore(nullptr), mRefCount(nullptr) {
+ MOZ_COUNT_CTOR(CrossProcessSemaphore);
+}
+
+CrossProcessSemaphore::~CrossProcessSemaphore() {
+ int32_t oldCount = --(*mRefCount);
+
+ if (oldCount == 0) {
+ // Nothing can be done if the destroy fails so ignore return code.
+ Unused << sem_destroy(mSemaphore);
+ }
+
+ MOZ_COUNT_DTOR(CrossProcessSemaphore);
+}
+
+bool CrossProcessSemaphore::Wait(const Maybe<TimeDuration>& aWaitTime) {
+ MOZ_ASSERT(*mRefCount > 0,
+ "Attempting to wait on a semaphore with zero ref count");
+ int ret;
+ if (aWaitTime.isSome()) {
+ struct timespec ts;
+ if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
+ return false;
+ }
+
+ ts.tv_nsec += (kNsPerMs * aWaitTime->ToMilliseconds());
+ ts.tv_sec += ts.tv_nsec / kNsPerSec;
+ ts.tv_nsec %= kNsPerSec;
+
+ while ((ret = sem_timedwait(mSemaphore, &ts)) == -1 && errno == EINTR) {
+ }
+ } else {
+ while ((ret = sem_wait(mSemaphore)) == -1 && errno == EINTR) {
+ }
+ }
+ return ret == 0;
+}
+
+void CrossProcessSemaphore::Signal() {
+ MOZ_ASSERT(*mRefCount > 0,
+ "Attempting to signal a semaphore with zero ref count");
+ sem_post(mSemaphore);
+}
+
+CrossProcessSemaphoreHandle CrossProcessSemaphore::CloneHandle() {
+ CrossProcessSemaphoreHandle result = ipc::SharedMemoryBasic::NULLHandle();
+
+ if (mSharedBuffer) {
+ result = mSharedBuffer->CloneHandle();
+ if (!result) {
+ MOZ_CRASH();
+ }
+ }
+
+ return result;
+}
+
+void CrossProcessSemaphore::CloseHandle() { mSharedBuffer->CloseHandle(); }
+
+} // namespace mozilla