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/*
* Copyright (c) 2013 SURFnet bv
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*****************************************************************************
Generation.cpp
Helper for generation number handling.
*****************************************************************************/
#include "config.h"
#include "log.h"
#include "Generation.h"
// Factory
Generation* Generation::create(const std::string path, bool isToken /* = false */)
{
Generation* gen = new Generation(path, isToken);
if ((gen != NULL) && isToken && (gen->genMutex == NULL))
{
delete gen;
return NULL;
}
return gen;
}
// Destructor
Generation::~Generation()
{
if (isToken)
{
MutexFactory::i()->recycleMutex(genMutex);
}
}
// Synchronize from locked disk file
bool Generation::sync(File &objectFile)
{
if (isToken)
{
ERROR_MSG("Generation sync() called for a token");
return false;
}
unsigned long onDisk;
if (!objectFile.readULong(onDisk))
{
if (objectFile.isEOF())
{
onDisk = 0;
}
else
{
return false;
}
}
currentValue = onDisk;
return objectFile.seek(0L);
}
// Check if the target was updated
bool Generation::wasUpdated()
{
if (isToken)
{
MutexLocker lock(genMutex);
File genFile(path);
if (!genFile.isValid())
{
return true;
}
genFile.lock();
unsigned long onDisk;
if (!genFile.readULong(onDisk))
{
return true;
}
if (onDisk != currentValue)
{
currentValue = onDisk;
return true;
}
return false;
}
else
{
File objectFile(path);
if (!objectFile.isValid())
{
return true;
}
objectFile.lock();
unsigned long onDisk;
if (!objectFile.readULong(onDisk))
{
return true;
}
return (onDisk != currentValue);
}
}
// Update
void Generation::update()
{
pendingUpdate = true;
}
// Commit
void Generation::commit()
{
if (isToken)
{
MutexLocker lock(genMutex);
File genFile(path, true, true, true, false);
if (!genFile.isValid())
{
return;
}
genFile.lock();
if (genFile.isEmpty())
{
currentValue++;
if (currentValue == 0)
{
currentValue++;
}
pendingUpdate = false;
(void) genFile.writeULong(currentValue);
genFile.unlock();
return;
}
unsigned long onDisk;
bool bOK = true;
bOK = bOK && genFile.readULong(onDisk);
bOK = bOK && genFile.seek(0L);
if (pendingUpdate)
{
onDisk++;
if (onDisk == 0)
{
onDisk++;
}
}
bOK = bOK && genFile.writeULong(onDisk);
if (bOK)
{
currentValue = onDisk;
pendingUpdate = false;
}
genFile.unlock();
}
}
// Set the current value when read from disk
void Generation::set(unsigned long onDisk)
{
currentValue = onDisk;
}
// Return new value
unsigned long Generation::get()
{
pendingUpdate = false;
currentValue++;
if (currentValue == 0)
{
currentValue = 1;
}
return currentValue;
}
// Rollback (called when the new value failed to be written)
void Generation::rollback()
{
pendingUpdate = true;
if (currentValue != 1)
{
currentValue--;
}
}
// Constructor
Generation::Generation(const std::string inPath, bool inIsToken)
{
path = inPath;
isToken = inIsToken;
pendingUpdate = false;
currentValue = 0;
genMutex = NULL;
if (isToken)
{
genMutex = MutexFactory::i()->getMutex();
if (genMutex != NULL)
{
commit();
}
}
}
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