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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* 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/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
#ifndef INCLUDED_FRAMEWORK_INC_THREADHELP_GATE_HXX
#define INCLUDED_FRAMEWORK_INC_THREADHELP_GATE_HXX
#include <threadhelp/igate.h>
#include <boost/noncopyable.hpp>
#include <osl/mutex.hxx>
#include <osl/conditn.hxx>
namespace framework{
/*-************************************************************************************************************
@short implement a gate to block multiple threads at same time or unblock all
@descr A gate can be used as a negative-condition! You can open a "door" - wait() will not block ...
or you can close it - wait() blocks till open() is called again.
As a special feature you can open the gate a little bit by sing openGap().
Then all currently waiting threads are running immediately - but new ones are blocked!
@attention To prevent us against wrong using, the default ctor, copy ctor and the =operator are maked private!
@implements IGate
@base IGate
@devstatus ready to use
*//*-*************************************************************************************************************/
class Gate : public IGate
, private boost::noncopyable
{
// public methods
public:
/*-****************************************************************************************************
@short ctor
@descr These initialize the object right as an open gate.
*//*-*****************************************************************************************************/
inline Gate()
: m_bClosed ( sal_False )
, m_bGapOpen ( sal_False )
{
open();
}
/*-****************************************************************************************************
@short dtor
@descr Is user forget it - we open the gate ...
blocked threads can running ... but I don't know
if it's right - we are destroyed yet!?
*//*-*****************************************************************************************************/
inline virtual ~Gate()
{
open();
}
/*-****************************************************************************************************
@interface IGate
@short open the gate
@descr A wait() call will not block then.
@seealso method close()
*//*-*****************************************************************************************************/
virtual void open() SAL_OVERRIDE
{
// We must safe access to our internal member!
::osl::MutexGuard aLock( m_aAccessLock );
// Set condition -> wait don't block any longer -> gate is open
m_aPassage.set();
// Check if operation was successful!
// Check returns false if condition isn't set => m_bClosed will be true then => we must return false; opening failed
m_bClosed = !m_aPassage.check();
}
/*-****************************************************************************************************
@interface IGate
@short close the gate
@descr A wait() call will block then.
@seealso method open()
*//*-*****************************************************************************************************/
virtual void close() SAL_OVERRIDE
{
// We must safe access to our internal member!
::osl::MutexGuard aLock( m_aAccessLock );
// Reset condition -> wait blocks now -> gate is closed
m_aPassage.reset();
// Check if operation was successful!
// Check returns false if condition was reseted => m_bClosed will be true then => we can return true; closing ok
m_bClosed = !m_aPassage.check();
}
/*-****************************************************************************************************
@interface IGate
@short open gate for current waiting threads
@descr All current waiting threads stand in wait() at line "m_aPassage.wait()" ...
With this call you can open the passage for these waiting ones.
The "gap" is closed by any new thread which call wait() automaticly!
@seealso method wait()
@seealso method open()
*//*-*****************************************************************************************************/
virtual void openGap() SAL_OVERRIDE
{
// We must safe access to our internal member!
::osl::MutexGuard aLock( m_aAccessLock );
// Open passage for current waiting threads.
m_aPassage.set();
// Check state of condition.
// If condition is set check() returns true => m_bGapOpen will be true too => we can use it as return value.
m_bGapOpen = m_aPassage.check();
}
/*-****************************************************************************************************
@interface IGate
@short must be called to pass the gate
@descr If gate "open" => wait() will not block.
If gate "closed" => wait() will block till somewhere open it again.
If gap "open" => currently waiting threads unblocked, new ones blocked
@seealso method wait()
@seealso method open()
@param "pTimeOut", optional parameter to wait a certain time
@return true, if wait was successful (gate was opened)
false, if condition has an error or timeout was reached!
@onerror We return false.
*//*-*****************************************************************************************************/
virtual sal_Bool wait( const TimeValue* pTimeOut = NULL ) SAL_OVERRIDE
{
// We must safe access to our internal member!
::osl::ClearableMutexGuard aLock( m_aAccessLock );
// If gate not closed - caller can pass it.
sal_Bool bSuccessful = sal_True;
if( m_bClosed == sal_True )
{
// Otherwise first new thread must close an open gap!
if( m_bGapOpen == sal_True )
{
m_bGapOpen = sal_False;
m_aPassage.reset();
}
// Then we must release used access lock -
// because next call will block ...
// and if we hold the access lock nobody else can use this object without a dadlock!
aLock.clear();
// Wait for opening gate ...
bSuccessful = ( m_aPassage.wait( pTimeOut ) == ::osl::Condition::result_ok );
}
return bSuccessful;
}
// private member
private:
::osl::Mutex m_aAccessLock;
::osl::Condition m_aPassage;
sal_Bool m_bClosed;
sal_Bool m_bGapOpen;
}; // class Gate
} // namespace framework
#endif // INCLUDED_FRAMEWORK_INC_THREADHELP_GATE_HXX
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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