Mutex.cxx

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/*
 * Copyright (c) 2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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
 *
 */

#include "Mutex.hxx"
#include "Assert.hxx"
#include "xtime.hxx"
#include "ErrSystem.hxx"

namespace CLAM
{

        Mutex::Mutex()
        {
                int res = 0;

                res = pthread_mutex_init( &mMutex, 0 );

                CLAM_ASSERT( res == 0, "Not able to initialize mutex" );
        }

        Mutex::~Mutex()
        {
                int res = 0;

                res = pthread_mutex_destroy( &mMutex );

                CLAM_ASSERT( res == 0, "Not able to destroy mutex" );
        }

        void Mutex::DoLock()
        {
                int res = 0;
                
                res = pthread_mutex_lock( &mMutex );

                if ( res == EDEADLK )
                        throw LockError(); // What is EDEADLK????

                CLAM_ASSERT( res == 0, "Not able to lock the mutex" );
        }
        
        void Mutex::DoUnlock()
        {
                int res = 0;
                
                res = pthread_mutex_unlock( &mMutex );

                if ( res == EPERM )
                        throw LockError(); // What is EPERM?????

                CLAM_ASSERT( res == 0, "Not able to Unlock the mutex" );
        }

        void Mutex::DoLock( ConditionVar& state )
        {
                // Does nothing
        }

        void Mutex::DoUnlock( ConditionVar& state )
        {
                state.pmutex = &mMutex;
        }
        
        TryMutex::TryMutex()
        {
                int res = 0;

                res = pthread_mutex_init( &mMutex, 0 );

                CLAM_ASSERT( res == 0, "Not able to initialize mutex" );
                
        }

        TryMutex::~TryMutex()
        {
                int res = 0;

                res = pthread_mutex_destroy( &mMutex );

                CLAM_ASSERT( res == 0, "Not able to destroy mutex" );

        }

        void TryMutex::DoLock()
        {
                int res = 0;
                res = pthread_mutex_lock( &mMutex );
                if ( res == EDEADLK )
                        throw LockError();

                CLAM_ASSERT( res == 0, "Not able to lock mutex" );
        }

        bool TryMutex::DoTryLock()
        {
                int res = 0;

                res = pthread_mutex_trylock(&mMutex );

                if ( res == EDEADLK )
                        throw LockError();

                CLAM_ASSERT ( (res == 0) || (res == EBUSY), "Not able to try-lock the mutex" );

                return res == 0;
        }

        void TryMutex::DoUnlock()
        {
                int res = 0;
                
                res = pthread_mutex_unlock( &mMutex );

                if ( res == EPERM )
                        throw LockError(); // What is EPERM?????

                CLAM_ASSERT( res == 0, "Not able to Unlock the mutex" );
        }

        void TryMutex::DoLock( ConditionVar& state )
        {
                // Does nothing
        }

        void TryMutex::DoUnlock( ConditionVar& state )
        {
                state.pmutex = &mMutex;
        }

        TimedMutex::TimedMutex()
                : mLocked( false )
        {
                int res = 0;

                res = pthread_mutex_init( &mMutex, 0 );

                CLAM_ASSERT( res==0, "Not able to initilize the mutex" );

                res = pthread_cond_init( &mCondition, 0 );

                if ( res!= 0 )
                        {
                                pthread_mutex_destroy( &mMutex );
                                throw ThreadResourceError("Unable to initialize Condition " );
                        }
        }

        TimedMutex::~TimedMutex()
        {
                CLAM_ASSERT( !mLocked, "Mutex was locked while attempting to destroy it!" );
                
                int res = 0;

                res = pthread_mutex_destroy(&mMutex );

                CLAM_ASSERT( res == 0, "Unable to destroy the mutex!" );

                res = pthread_cond_destroy( &mCondition );

                CLAM_ASSERT( res == 0, "Unable to destroy the Condition variable" );
        }
        
        void TimedMutex::DoLock( )
        {
                int res = 0;

                res = pthread_mutex_lock( &mMutex );
                CLAM_ASSERT( res == 0, "Unable to lock mutex (already locked) " );

                while( mLocked )
                        {
                                res = pthread_cond_wait( &mCondition, &mMutex );
                                CLAM_ASSERT( res == 0, "Wait failed"  );
                        }

                CLAM_ASSERT( !mLocked, "Spurious value for loop condition" );
                mLocked = true;

                res = pthread_mutex_unlock( &mMutex );
                CLAM_ASSERT( res ==0, "Unable to unlock the mutex" );
        } 
        
        bool TimedMutex::DoTryLock()
        {
                int res = 0;

                res = pthread_mutex_lock( &mMutex );

                CLAM_ASSERT( res == 0, "Unable to lock the mutex" );

                bool ret = false;

                if ( !mLocked )
                        {
                                mLocked = true;
                                ret = true;
                        }

                res = pthread_mutex_unlock( &mMutex );
                CLAM_ASSERT( res==0, "Unable to unlock the mutex" );

                return ret;
        }

        bool TimedMutex::DoTimedLock( const xtime& xt )
        {
                int res = 0;
                res = pthread_mutex_lock( &mMutex );
                CLAM_ASSERT( res == 0, "Unable to lock the mutex" );

                timespec ts;
                to_timespec(xt, ts);

                while (mLocked)
                        {
                                res = pthread_cond_timedwait(&mCondition, &mMutex, &ts);
                                CLAM_ASSERT(res == 0 || res == ETIMEDOUT, "Low level error");

                                if (res == ETIMEDOUT)
                                        break;
                        }

                bool ret = false;
                if (!mLocked)
                        {
                                mLocked = true;
                                ret = true;
                        }

                res = pthread_mutex_unlock(&mMutex);
                CLAM_ASSERT(res == 0, "Something low level failed!");
                return ret;
        }

        void TimedMutex::DoUnlock()
        {
                int res = 0;
                res = pthread_mutex_lock(&mMutex);
                CLAM_ASSERT(res == 0, "Unable to lock the mutex");

                CLAM_ASSERT(mLocked, "No condition spurious value change");
                mLocked = false;

                res = pthread_cond_signal(&mCondition);
                CLAM_ASSERT(res == 0, "Not able to change the condition var value");

                res = pthread_mutex_unlock(&mMutex);
                CLAM_ASSERT(res == 0, "Unable to unlock the mutex");
        }

        void TimedMutex::DoLock(ConditionVar& v)
        {
                int res = 0;
                while (mLocked)
                {
                        res = pthread_cond_wait(&mCondition, &mMutex);
                        CLAM_ASSERT(res == 0, "pthread_cond_wait call failed!");
                }

                CLAM_ASSERT(!mLocked, "Spurious value change");
                mLocked = true;

                res = pthread_mutex_unlock(&mMutex);
                CLAM_ASSERT(res == 0, "pthread_mutex_unlock call failed!");
        }

        void TimedMutex::DoUnlock(ConditionVar& state)
        {
                int res = 0;
                res = pthread_mutex_lock(&mMutex);
                CLAM_ASSERT(res == 0, "pthread_mutex_lock call failed");

                CLAM_ASSERT(mLocked, "Spurious value change!");
                mLocked = false;

                res = pthread_cond_signal(&mCondition);
                CLAM_ASSERT(res == 0, "pthread_cond_signal call failed!");

                state.pmutex = &mMutex;
        }

} // end of namespace CLAM