114 lines
3.1 KiB
C++
114 lines
3.1 KiB
C++
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/*
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* synergy -- mouse and keyboard sharing utility
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* Copyright (C) 2002 Chris Schoeneman
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*
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* This package is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* found in the file COPYING that should have accompanied this file.
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*
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* This package is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include "CJobList.h"
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#include "IJob.h"
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#include "CArch.h"
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//
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// CJobList
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//
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CJobList::CJobList()
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{
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m_mutex = ARCH->newMutex();
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}
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CJobList::~CJobList()
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{
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ARCH->closeMutex(m_mutex);
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}
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void
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CJobList::addJob(IJob* job)
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{
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// ignore bogus job
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if (job == NULL) {
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return;
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}
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// make a temporary list with the job. later we'll splice this
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// list into our jobs list. since splice() never throws we
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// don't have to try/catch to unlock the mutex.
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CJobs tmpList;
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tmpList.push_front(job);
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// add job to list
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ARCH->lockMutex(m_mutex);
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m_jobs.splice(m_jobs.begin(), tmpList);
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ARCH->unlockMutex(m_mutex);
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}
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void
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CJobList::removeJob(IJob* job)
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{
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if (job != NULL) {
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ARCH->lockMutex(m_mutex);
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m_jobs.remove(job);
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ARCH->unlockMutex(m_mutex);
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}
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}
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void
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CJobList::runJobs() const
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{
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// this is a little tricky. to allow any number of threads to
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// traverse the list while jobs are added and removed while
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// not holding the mutex when running a job (so other threads
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// or the running job can add and remove jobs), we insert a
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// new element into the list. this element has a NULL job and
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// is a "safe place" while we traverse the list. the safe place
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// is inserted at the start of the list (with the mutex locked)
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// then, for each job, we lock the mutex and move the safe place
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// past the next job, unlock the mutex, run the job and repeat
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// until there are no more jobs. the safe place will not be
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// removed by any other thread and is after every job that has
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// been run and before every job that still needs to run. when
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// all the jobs have been run we remove the safe place.
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// add the safe place
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CJobs tmpList;
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tmpList.push_front(NULL);
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ARCH->lockMutex(m_mutex);
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m_jobs.splice(m_jobs.begin(), tmpList);
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CJobs::iterator safePlace = m_jobs.begin();
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// find the next non-NULL job (NULL jobs are safe places)
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CJobs::iterator next = safePlace;
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while (next != m_jobs.end() && *next == NULL)
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++next;
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while (next != m_jobs.end()) {
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// found a job. run it without holding a lock. note the
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// race condition here: we release the lock, allowing
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// removeJob() to remove this job before we run the job.
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// therefore the caller cannot safely destroy the job
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// until all runJobs() complete.
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IJob* job = *next;
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++next;
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m_jobs.splice(next, m_jobs, safePlace);
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ARCH->unlockMutex(m_mutex);
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job->run();
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// next real job
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ARCH->lockMutex(m_mutex);
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next = safePlace;
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while (next != m_jobs.end() && *next == NULL)
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++next;
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}
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// remove the safe place
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m_jobs.erase(safePlace);
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ARCH->unlockMutex(m_mutex);
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}
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