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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 "mozilla/Logging.h"
#include "WindowsMutex.h"
namespace mozilla::default_agent {
using mozilla::LogLevel;
static LazyLogModule gWindowsMutexLog("WindowsMutex");
NS_IMPL_ISUPPORTS(WindowsMutexFactory, nsIWindowsMutexFactory)
NS_IMETHODIMP
WindowsMutexFactory::CreateMutex(const nsAString& aName,
nsIWindowsMutex** aWindowsMutex) {
nsAutoHandle mutex;
auto name = PromiseFlatString(aName);
mutex.own(CreateMutexW(nullptr, FALSE, name.get()));
if (mutex.get() == nullptr) {
MOZ_LOG(gWindowsMutexLog, LogLevel::Error,
("Couldn't open mutex \"%s\": %#lX",
NS_ConvertUTF16toUTF8(name).get(), GetLastError()));
return NS_ERROR_NOT_AVAILABLE;
}
RefPtr<WindowsMutex> nsMutex = new WindowsMutex(name, mutex);
nsMutex.forget(aWindowsMutex);
return NS_OK;
}
WindowsMutex::WindowsMutex(const nsString& aName, nsAutoHandle& aMutex)
: mName(NS_ConvertUTF16toUTF8(aName)), mLocked(false) {
mMutex.steal(aMutex);
}
WindowsMutex::~WindowsMutex() {
Unlock();
// nsAutoHandle will take care of closing the mutex's handle.
}
NS_IMPL_ISUPPORTS(WindowsMutex, nsIWindowsMutex)
NS_IMETHODIMP
WindowsMutex::TryLock() {
// This object may be used on the main thread, so don't wait if it's
// not signaled.
DWORD mutexStatus = WaitForSingleObject(mMutex.get(), 0);
if (mutexStatus == WAIT_OBJECT_0) {
mLocked = true;
} else if (mutexStatus == WAIT_TIMEOUT) {
MOZ_LOG(gWindowsMutexLog, LogLevel::Warning,
("Timed out waiting for mutex \"%s\"", mName.get()));
} else if (mutexStatus == WAIT_ABANDONED) {
// This status code means that we are supposed to check our data for
// consistency as the last locking process didn't signal intentional
// unlocking which might indicate it crashed mid-operation. Current uses of
// this `WindowsMutex` don't need to worry about corruption of the locked
// object, if needed the `nsIWindowsMutex` interface should be extended.
MOZ_LOG(gWindowsMutexLog, LogLevel::Warning,
("Found abandoned mutex \"%s\". Continuing...", mName.get()));
mLocked = true;
} else {
// The only other documented status code is WAIT_FAILED. In the case that
// we somehow get some other code, that is also an error.
MOZ_LOG(gWindowsMutexLog, LogLevel::Error,
("Failed to wait on mutex: mName: %s, error %#lX", mName.get(),
GetLastError()));
}
return mLocked ? NS_OK : NS_ERROR_NOT_AVAILABLE;
}
NS_IMETHODIMP
WindowsMutex::IsLocked(bool* aLocked) {
*aLocked = mLocked;
return NS_OK;
}
NS_IMETHODIMP
WindowsMutex::Unlock() {
nsresult rv = NS_OK;
if (mLocked) {
BOOL success = ReleaseMutex(mMutex.get());
if (!success) {
MOZ_LOG(gWindowsMutexLog, LogLevel::Error,
("Failed to release mutex \"%s\"", mName.get()));
rv = NS_ERROR_UNEXPECTED;
}
mLocked = false;
}
return rv;
}
} // namespace mozilla::default_agent
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