void SignalPipeWatcher::StopWatching()
{
MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
// Close sDumpPipeWriteFd /after/ setting the fd to -1.
// Otherwise we have the (admittedly far-fetched) race where we
//
// 1) close sDumpPipeWriteFd
// 2) open a new fd with the same number as sDumpPipeWriteFd
// had.
// 3) receive a signal, then write to the fd.
int pipeWriteFd = sDumpPipeWriteFd.exchange(-1);
close(pipeWriteFd);
FdWatcher::StopWatching();
}
void RunWriter(void* arg)
{
PR_SetCurrentThreadName("Shutdown Statistics Writer");
MOZ_LSAN_INTENTIONALLY_LEAK_OBJECT(arg);
// Shutdown will generally complete before we have a chance to
// deallocate. This is not a leak.
// Setup destinationPath and tmpFilePath
nsCString destinationPath(static_cast<char*>(arg));
nsAutoCString tmpFilePath;
tmpFilePath.Append(destinationPath);
tmpFilePath.AppendLiteral(".tmp");
// Cleanup any file leftover from a previous run
Unused << PR_Delete(tmpFilePath.get());
Unused << PR_Delete(destinationPath.get());
while (true) {
//
// Check whether we have received data from the main thread.
//
// We perform the check before waiting on `gWriteReady` as we may
// have received data while we were busy writing.
//
// Also note that gWriteData may have been modified several times
// since we last checked. That's ok, we are not losing any important
// data (since we keep adding data), and we are not leaking memory
// (since the main thread deallocates any data that hasn't been
// consumed by the writer thread).
//
UniquePtr<nsCString> data(gWriteData.exchange(nullptr));
if (!data) {
// Data is not available yet.
// Wait until the main thread provides it.
PR_EnterMonitor(gWriteReady);
PR_Wait(gWriteReady, PR_INTERVAL_NO_TIMEOUT);
PR_ExitMonitor(gWriteReady);
continue;
}
MOZ_LSAN_INTENTIONALLY_LEAK_OBJECT(data.get());
// Shutdown may complete before we have a chance to deallocate.
// This is not a leak.
//
// Write to a temporary file
//
// In case of any error, we simply give up. Since the data is
// hardly critical, we don't want to spend too much effort
// salvaging it.
//
UniquePtr<PRFileDesc, PR_CloseDelete>
tmpFileDesc(PR_Open(tmpFilePath.get(),
PR_WRONLY | PR_TRUNCATE | PR_CREATE_FILE,
00600));
// Shutdown may complete before we have a chance to close the file.
// This is not a leak.
MOZ_LSAN_INTENTIONALLY_LEAK_OBJECT(tmpFileDesc.get());
if (tmpFileDesc == nullptr) {
break;
}
if (PR_Write(tmpFileDesc.get(), data->get(), data->Length()) == -1) {
break;
}
tmpFileDesc.reset();
//
// Rename on top of destination file.
//
// This is not sufficient to guarantee that the destination file
// will be written correctly, but, again, we don't care enough
// about the data to make more efforts.
//
if (PR_Rename(tmpFilePath.get(), destinationPath.get()) != PR_SUCCESS) {
break;
}
}
}
MemoryPressureState
NS_GetPendingMemoryPressure()
{
int32_t value = sMemoryPressurePending.exchange(MemPressure_None);
return MemoryPressureState(value);
}
