109 lines
3.3 KiB
C++
109 lines
3.3 KiB
C++
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
|
|
/*
|
|
* Copyright (c) 2008 University of Washington
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation;
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
|
|
#ifndef SYSTEM_CONDITION_H
|
|
#define SYSTEM_CONDITION_H
|
|
|
|
#include "ptr.h"
|
|
|
|
namespace ns3 {
|
|
|
|
class SystemConditionPrivate;
|
|
|
|
/**
|
|
* @brief A class which provides a relatively platform-independent
|
|
* conditional-wait thread synchronization primitive.
|
|
*
|
|
* It is often desirable to have a mechanism by which a thread can suspend its
|
|
* execution and relinquish the process until some condition to becomes true.
|
|
* We provide platform-independent access to this OS-dependent capability with
|
|
* the SystemCondition class.
|
|
*
|
|
* There are two ways to tell the underlying primitive that the condition has
|
|
* become true: Signal and Broadcast. Signal will only wake up one thread
|
|
* waiting on the condition (according to the OS scheduling policy);
|
|
* Broadcast will wake up all of the threads waiting on the condition
|
|
* (cf. "The Thundering Herd").
|
|
*
|
|
* In order to wait for the underlying condition, you also have two
|
|
* alternatives: Wait and TimedWait. The Wait call will wait forever for the
|
|
* condition to become true; but the TimedWait has a timeout.
|
|
*
|
|
* The condition underlying this class is a simple boolean variable. It is
|
|
* set to false in each call to Wait and TimedWait. It is set to true in each
|
|
* call to Signal and Broadcast. This is a fairly simple-minded condition
|
|
* designed for
|
|
*
|
|
* A typical use case will be to call Wait() or TimedWait() in one thread
|
|
* context and put the processor to sleep until an event happens somewhere
|
|
* else that
|
|
*/
|
|
class SystemCondition
|
|
{
|
|
public:
|
|
SystemCondition ();
|
|
~SystemCondition ();
|
|
|
|
/**
|
|
* Set the value of the underlying condition.
|
|
* \param condition value
|
|
*/
|
|
void SetCondition (bool condition);
|
|
|
|
/**
|
|
* Get the value of the underlying condition.
|
|
*/
|
|
bool GetCondition (void);
|
|
|
|
/**
|
|
* Release one thread if waiting for the condition to be true. If you want
|
|
* a waiting thread to return, you should have done a SetCondition (true)
|
|
* prior to calling.
|
|
*/
|
|
void Signal (void);
|
|
|
|
/**
|
|
* Release all threads waiting for the condition to be true. If you want
|
|
* all waiting threads to return, you should have done a SetCondition (true)
|
|
* prior to calling.
|
|
*/
|
|
void Broadcast (void);
|
|
|
|
/**
|
|
* Wait, possibly forever, for the condition to be true.
|
|
*/
|
|
void Wait (void);
|
|
|
|
/**
|
|
* Wait a maximum of ns nanoseconds for the condition to be true. If the
|
|
* wait times out, return true else return false.
|
|
* \param ns maximum of nanoseconds to wait
|
|
*/
|
|
bool TimedWait (uint64_t ns);
|
|
|
|
|
|
private:
|
|
SystemConditionPrivate * m_priv;
|
|
};
|
|
|
|
} // namespace ns3
|
|
|
|
#endif /* SYSTEM_CONDITION_H */
|
|
|
|
|