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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/. */
#ifndef PollableEvent_h__
#define PollableEvent_h__
#include "mozilla/Mutex.h"
#include "mozilla/TimeStamp.h"
struct PRFileDesc;
namespace mozilla {
namespace net {
// class must be called locked
class PollableEvent {
public:
PollableEvent();
~PollableEvent();
// Signal/Clear return false only if they fail
bool Signal();
// This is called only when we get non-null out_flags for the socket pair
bool Clear();
bool Valid() { return mWriteFD && mReadFD; }
// We want to detect if writing to one of the socket pair sockets takes
// too long to be received by the other socket from the pair.
// Hence, we remember the timestamp of the earliest write by a call to
// MarkFirstSignalTimestamp() from Signal(). After waking up from poll()
// we check how long it took get the 'readable' signal on the socket pair.
void MarkFirstSignalTimestamp();
// Called right before we enter poll() to exclude any possible delay between
// the earlist call to Signal() and entering poll() caused by processing
// of events dispatched to the socket transport thread.
void AdjustFirstSignalTimestamp();
// This returns false on following conditions:
// - PR_Write has failed
// - no out_flags were signalled on the socket pair for too long after
// the earliest Signal()
bool IsSignallingAlive(TimeDuration const& timeout);
PRFileDesc* PollableFD() { return mReadFD; }
private:
PRFileDesc* mWriteFD{nullptr};
PRFileDesc* mReadFD{nullptr};
bool mSignaled{false};
// true when PR_Write to the socket pair has failed (status < 1)
bool mWriteFailed{false};
// Set true after AdjustFirstSignalTimestamp() was called
// Set false after Clear() was called
// Ensures shifting the timestamp before entering poll() only once
// between Clear()'ings.
bool mSignalTimestampAdjusted{false};
// Timestamp of the first call to Signal() (or time we enter poll())
// that happened after the last Clear() call
TimeStamp mFirstSignalAfterClear;
};
} // namespace net
} // namespace mozilla
#endif
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