308 lines
9.7 KiB
C++
308 lines
9.7 KiB
C++
/*
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* Copyright 2008, 2011, 2014 Free Software Foundation, Inc.
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* Copyright 2014 Range Networks, Inc.
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*
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* This software is distributed under the terms of the GNU Affero Public License.
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* See the COPYING file in the main directory for details.
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*
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* This use of this software may be subject to additional restrictions.
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* See the LEGAL file in the main directory for details.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program 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 Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef THREADS_H
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#define THREADS_H
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#include <stdio.h>
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#include <pthread.h>
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#include <iostream>
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#include <assert.h>
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#include <unistd.h>
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class Mutex;
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/**@name Multithreaded access for standard streams. */
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//@{
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extern int gMutexLogLevel; // The mutexes cannot call gConfig or gGetLoggingLevel so we have to get the log level indirectly.
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/**@name Functions for gStreamLock. */
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//@{
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extern Mutex gStreamLock; ///< global lock for cout and cerr
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void lockCerr(); ///< call prior to writing cerr
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void unlockCerr(); ///< call after writing cerr
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void lockCout(); ///< call prior to writing cout
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void unlockCout(); ///< call after writing cout
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//@}
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/**@name Macros for standard messages. */
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//@{
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#define COUT(text) { lockCout(); std::cout << text; unlockCout(); }
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#define CERR(text) { lockCerr(); std::cerr << __FILE__ << ":" << __LINE__ << ": " << text; unlockCerr(); }
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#ifdef NDEBUG
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#define DCOUT(text) {}
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#define OBJDCOUT(text) {}
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#else
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#define DCOUT(text) { COUT(__FILE__ << ":" << __LINE__ << " " << text); }
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#define OBJDCOUT(text) { DCOUT(this << " " << text); }
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#endif
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//@}
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//@}
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/**@defgroup C++ wrappers for pthread mechanisms. */
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//@{
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/** A class for recursive mutexes based on pthread_mutex. */
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// If at all possible, do not call lock/unlock from this class directly; use a ScopedLock instead.
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class Mutex {
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private:
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pthread_mutex_t mMutex;
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pthread_mutexattr_t mAttribs;
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int mLockCnt;
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int mMutexLogLevel; // We cant use LOG inside the Mutex because LOG itself uses mutexes, so get the LOG level at mutex creation time
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// and use it for this mutex from then on.
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static const int maxLocks = 5; // Just the maximum number of recursive locks we report during debugging, not the max possible.
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const char *mLockerFile[maxLocks];
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unsigned mLockerLine[maxLocks];
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const char *lockerFile() { int i = mLockCnt-1; return (i >= 0 && i < maxLocks) ? mLockerFile[i] : NULL; }
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//unused: bool anyDebugging() { for (int i = 0; i < maxLocks; i++) { if (mLockerFile[i]) return true; return false; } }
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// pthread_mutex_trylock returns 0 and trylock returns true if the lock was acquired.
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public:
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bool trylock(const char *file=0, unsigned line=0);
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Mutex();
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~Mutex();
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void _lock() { pthread_mutex_lock(&mMutex); }
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// (pat) Like the above but report blocking; to see report you must set both Log.Level to DEBUG for both Threads.cpp and the file.
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void lock(const char *file=0, unsigned line=0);
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std::string mutext() const;
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// Returns true if the lock was acquired, or false if it timed out.
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bool timedlock(int msecs);
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void unlock();
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// (pat) I use this to assert that the Mutex is locked on entry to some method that requres it, but only in debug mode.
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int lockcnt() { return mLockCnt; }
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friend class Signal;
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};
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/** A class for reader/writer based on pthread_rwlock. */
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class RWLock {
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private:
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pthread_rwlock_t mRWLock;
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pthread_rwlockattr_t mAttribs;
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public:
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RWLock();
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~RWLock();
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const char * wlock() { pthread_rwlock_wrlock(&mRWLock); return ""; }
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const char * rlock() { pthread_rwlock_rdlock(&mRWLock); return ""; }
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bool trywlock() { return pthread_rwlock_trywrlock(&mRWLock)==0; }
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bool tryrlock() { return pthread_rwlock_tryrdlock(&mRWLock)==0; }
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const char * unlock() { pthread_rwlock_unlock(&mRWLock); return ""; }
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};
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#if 0
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// (pat) NOT FINISHED OR TESTED. A pointer that releases a specified mutex when it goes out of scope.
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template<class PointsTo>
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class ScopedPointer {
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Mutex &mControllingMutex; // A pointer to the mutex for the object being protected.
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PointsTo *mPtr;
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public:
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ScopedPointer(Mutex& wMutex) :mControllingMutex(wMutex) { mControllingMutex.lock(); }
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// Requisite Copy Constructor: The mutex is already locked, but we need to lock it again because the
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// other ScopedPointer is about to go out of scope and will call unlock.
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ScopedPointer(ScopedPointer &other) :mControllingMutex(other.mControllingMutex) { mControllingMutex.lock(); }
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~ScopedPointer() { mControllingMutex.unlock(); }
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// You are allowed to assign and derference the underlying pointer - it still holds the Mutex locked.
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PointsTo *operator->() const { return mPtr; }
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PointsTo * operator=(PointsTo *other) { mPtr = other; }
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PointsTo& operator*() { return *mPtr; }
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};
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#endif
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// Class to acquire a Mutex lock and release it automatically when this goes out of scope.
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// ScopedLock should be used preferentially to Mutex::lock() and Mutex::unlock() in case a try-catch throw passes through
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// the containing procedure while the lock is held; ScopedLock releases the lock in that case.
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// "We dont use try-catch" you say? Yes we do - C++ string and many standard containers use throw to handle unexpected arguments.
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class ScopedLock {
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Mutex& mMutex;
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public:
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ScopedLock(Mutex& wMutex) :mMutex(wMutex) { mMutex.lock(); }
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// Like the above but report blocking; to see report you must set both Log.Level to DEBUG for both Threads.cpp and the file.
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ScopedLock(Mutex& wMutex,const char *file, unsigned line):mMutex(wMutex) { mMutex.lock(file,line); }
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~ScopedLock() { mMutex.unlock(); }
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};
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// Lock multiple mutexes simultaneously.
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class ScopedLockMultiple {
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Mutex garbage; // Someplace to point mC if only two mutexes are specified.
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Mutex *mA[3];
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bool ownA[3]; // If set, expect mA to be locked by this thread on entry.
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bool state[3]; // Current state, true if our thread has locked the associated Mutex; doesnt say if Mutex is locked by other threads.
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const char *_file; unsigned _line;
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void _lock(int which);
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bool _trylock(int which);
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void _unlock(int which);
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void _saveState();
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void _restoreState();
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void _lockAll();
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void _init(int wOwner, Mutex& wA, Mutex&wB, Mutex&wCa);
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public:
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// Do not return until all three mutexes are locked.
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// On entry, the caller may optionally already have locked mutexes, as specified by the wOwner flag bits.
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// If owner&1, caller owns wA, if owner&2 caller owns wB, if owner&4 caller owns wC.
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// There wouldnt be much point of this class if the caller already owned all three mutexes.
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// Note that the mutexes may be temporarily surrendered during this call as the methodology to avoid deadlock,
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// but in that case all will be re-acquired before this returns.
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ScopedLockMultiple(int wOwner, Mutex&wA, Mutex&wB, Mutex&wC) : _file(NULL), _line(0) {
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_init(wOwner,wA,wB,wC);
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_lockAll();
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}
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// Like the above but report blocking; to see report you must set both Log.Level to DEBUG for both Threads.cpp and the file.
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// Use like this: ScopedLockMultiple lock(bits,mutexa,mutexb,__FILE__,__LINE__);
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ScopedLockMultiple(int wOwner, Mutex&wA, Mutex&wB, Mutex&wC, const char *wFile, int wLine) : _file(wFile), _line(wLine) {
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_init(wOwner,wA,wB,wC);
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_lockAll();
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}
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// Like the above but for two mutexes intead of three.
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ScopedLockMultiple(int wOwner, Mutex& wA, Mutex&wB) : _file(NULL), _line(0) {
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_init(wOwner,wA,wB,garbage);
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_lockAll();
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}
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ScopedLockMultiple(int wOwner, Mutex&wA, Mutex&wB, const char *wFile, int wLine) : _file(wFile), _line(wLine) {
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_init(wOwner,wA,wB,garbage);
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_lockAll();
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}
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~ScopedLockMultiple() { _restoreState(); }
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};
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/** A C++ interthread signal based on pthread condition variables. */
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class Signal {
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private:
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mutable pthread_cond_t mSignal;
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public:
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Signal() { int s = pthread_cond_init(&mSignal,NULL); assert(!s); }
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~Signal() { pthread_cond_destroy(&mSignal); }
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/**
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Block for the signal up to the cancellation timeout.
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Under Linux, spurious returns are possible.
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*/
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void wait(Mutex& wMutex, long timeout) const;
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/**
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Block for the signal.
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Under Linux, spurious returns are possible.
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*/
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void wait(Mutex& wMutex) const
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{ pthread_cond_wait(&mSignal,&wMutex.mMutex); }
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void signal() { pthread_cond_signal(&mSignal); }
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void broadcast() { pthread_cond_broadcast(&mSignal); }
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};
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#define START_THREAD(thread,function,argument) \
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thread.start((void *(*)(void*))function, (void*)argument);
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/** A C++ wrapper for pthread threads. */
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class Thread {
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private:
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pthread_t mThread;
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pthread_attr_t mAttrib;
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// FIXME -- Can this be reduced now?
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size_t mStackSize;
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public:
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// (pat) This is the type of the function argument to pthread_create.
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typedef void *(*Task_t)(void*);
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/** Create a thread in a non-running state. */
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Thread(size_t wStackSize = (65536*4)):mThread((pthread_t)0) {
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pthread_attr_init(&mAttrib); // (pat) moved this here.
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mStackSize=wStackSize;
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}
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/**
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Destroy the Thread.
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It should be stopped and joined.
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*/
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// (pat) If the Thread is destroyed without being started, then mAttrib is undefined. Oops.
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~Thread() { pthread_attr_destroy(&mAttrib); }
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/** Start the thread on a task. */
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void start(Task_t task, void *arg);
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void start2(Task_t task, void *arg, int stacksize);
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/** Join a thread that will stop on its own. */
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void join() { int s = pthread_join(mThread,NULL); assert(!s); mThread = 0; }
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};
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#endif
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// vim: ts=4 sw=4
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