posix_threads.cpp

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/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 Source Code 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 3 of the License, or
(at your option) any later version.

Doom 3 Source Code 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 Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>
#include <dirent.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <pwd.h>
#include <pthread.h>

#include "../../idlib/precompiled.h"
#include "posix_public.h"

#if defined(_DEBUG)
// #define ID_VERBOSE_PTHREADS 
#endif

/*
======================================================
locks
======================================================
*/

// we use an extra lock for the local stuff
const int MAX_LOCAL_CRITICAL_SECTIONS = MAX_CRITICAL_SECTIONS + 1;
static pthread_mutex_t global_lock[ MAX_LOCAL_CRITICAL_SECTIONS ];

/*
==================
Sys_EnterCriticalSection
==================
*/
void Sys_EnterCriticalSection( int index ) {
        assert( index >= 0 && index < MAX_LOCAL_CRITICAL_SECTIONS );
#ifdef ID_VERBOSE_PTHREADS      
        if ( pthread_mutex_trylock( &global_lock[index] ) == EBUSY ) {
                Sys_Printf( "busy lock %d in thread '%s'\n", index, Sys_GetThreadName() );
                if ( pthread_mutex_lock( &global_lock[index] ) == EDEADLK ) {
                        Sys_Printf( "FATAL: DEADLOCK %d, in thread '%s'\n", index, Sys_GetThreadName() );
                }
        }       
#else
        pthread_mutex_lock( &global_lock[index] );
#endif
}

/*
==================
Sys_LeaveCriticalSection
==================
*/
void Sys_LeaveCriticalSection( int index ) {
        assert( index >= 0 && index < MAX_LOCAL_CRITICAL_SECTIONS );
#ifdef ID_VERBOSE_PTHREADS
        if ( pthread_mutex_unlock( &global_lock[index] ) == EPERM ) {
                Sys_Printf( "FATAL: NOT LOCKED %d, in thread '%s'\n", index, Sys_GetThreadName() );
        }
#else
        pthread_mutex_unlock( &global_lock[index] );
#endif
}

/*
======================================================
wait and trigger events
we use a single lock to manipulate the conditions, MAX_LOCAL_CRITICAL_SECTIONS-1

the semantics match the win32 version. signals raised while no one is waiting stay raised until a wait happens (which then does a simple pass-through)

NOTE: we use the same mutex for all the events. I don't think this would become much of a problem
cond_wait unlocks atomically with setting the wait condition, and locks it back before exiting the function
the potential for time wasting lock waits is very low
======================================================
*/

pthread_cond_t  event_cond[ MAX_TRIGGER_EVENTS ];
bool                    signaled[ MAX_TRIGGER_EVENTS ];
bool                    waiting[ MAX_TRIGGER_EVENTS ];

/*
==================
Sys_WaitForEvent
==================
*/
void Sys_WaitForEvent( int index ) {
        assert( index >= 0 && index < MAX_TRIGGER_EVENTS );
        Sys_EnterCriticalSection( MAX_LOCAL_CRITICAL_SECTIONS - 1 );
        assert( !waiting[ index ] );    // WaitForEvent from multiple threads? that wouldn't be good
        if ( signaled[ index ] ) {
                // emulate windows behaviour: signal has been raised already. clear and keep going
                signaled[ index ] = false;
        } else {
                waiting[ index ] = true;
                pthread_cond_wait( &event_cond[ index ], &global_lock[ MAX_LOCAL_CRITICAL_SECTIONS - 1 ] );
                waiting[ index ] = false;
        }
        Sys_LeaveCriticalSection( MAX_LOCAL_CRITICAL_SECTIONS - 1 );
}

/*
==================
Sys_TriggerEvent
==================
*/
void Sys_TriggerEvent( int index ) {
        assert( index >= 0 && index < MAX_TRIGGER_EVENTS );
        Sys_EnterCriticalSection( MAX_LOCAL_CRITICAL_SECTIONS - 1 );
        if ( waiting[ index ] ) {               
                pthread_cond_signal( &event_cond[ index ] );
        } else {
                // emulate windows behaviour: if no thread is waiting, leave the signal on so next wait keeps going
                signaled[ index ] = true;
        }
        Sys_LeaveCriticalSection( MAX_LOCAL_CRITICAL_SECTIONS - 1 );
}

/*
======================================================
thread create and destroy
======================================================
*/

// not a hard limit, just what we keep track of for debugging
#define MAX_THREADS 10
xthreadInfo *g_threads[MAX_THREADS];

int g_thread_count = 0;

typedef void *(*pthread_function_t) (void *);

/*
==================
Sys_CreateThread
==================
*/
void Sys_CreateThread( xthread_t function, void *parms, xthreadPriority priority, xthreadInfo& info, const char *name, xthreadInfo **threads, int *thread_count ) {
        Sys_EnterCriticalSection( );            
        pthread_attr_t attr;
        pthread_attr_init( &attr );
        if ( pthread_attr_setdetachstate( &attr, PTHREAD_CREATE_JOINABLE ) != 0 ) {
                common->Error( "ERROR: pthread_attr_setdetachstate %s failed\n", name );
        }
        if ( pthread_create( ( pthread_t* )&info.threadHandle, &attr, ( pthread_function_t )function, parms ) != 0 ) {
                common->Error( "ERROR: pthread_create %s failed\n", name );
        }
        pthread_attr_destroy( &attr );
        info.name = name;
        if ( *thread_count < MAX_THREADS ) {
                threads[ ( *thread_count )++ ] = &info;
        } else {
                common->DPrintf( "WARNING: MAX_THREADS reached\n" );
        }
        Sys_LeaveCriticalSection( );
}

/*
==================
Sys_DestroyThread
==================
*/
void Sys_DestroyThread( xthreadInfo& info ) {
        // the target thread must have a cancelation point, otherwise pthread_cancel is useless
        assert( info.threadHandle );
        if ( pthread_cancel( ( pthread_t )info.threadHandle ) != 0 ) {
                common->Error( "ERROR: pthread_cancel %s failed\n", info.name );
        }
        if ( pthread_join( ( pthread_t )info.threadHandle, NULL ) != 0 ) {
                common->Error( "ERROR: pthread_join %s failed\n", info.name );
        }
        info.threadHandle = 0;
        Sys_EnterCriticalSection( );
        for( int i = 0 ; i < g_thread_count ; i++ ) {
                if ( &info == g_threads[ i ] ) {
                        g_threads[ i ] = NULL;
                        int j;
                        for( j = i+1 ; j < g_thread_count ; j++ ) {
                                g_threads[ j-1 ] = g_threads[ j ];
                        }
                        g_threads[ j-1 ] = NULL;
                        g_thread_count--;
                        Sys_LeaveCriticalSection( );
                        return;
                }
        }
        Sys_LeaveCriticalSection( );
}

/*
==================
Sys_GetThreadName
find the name of the calling thread
==================
*/
const char* Sys_GetThreadName( int *index ) {
        Sys_EnterCriticalSection( );
        pthread_t thread = pthread_self();
        for( int i = 0 ; i < g_thread_count ; i++ ) {
                if ( thread == (pthread_t)g_threads[ i ]->threadHandle ) {
                        if ( index ) {
                                *index = i;
                        }
                        Sys_LeaveCriticalSection( );
                        return g_threads[ i ]->name;
                }
        }
        if ( index ) {
                *index = -1;
        }
        Sys_LeaveCriticalSection( );
        return "main";
}

/*
=========================================================
Async Thread
=========================================================
*/

xthreadInfo asyncThread;

/*
=================
Posix_StartAsyncThread
=================
*/
void Posix_StartAsyncThread() {
        if ( asyncThread.threadHandle == 0 ) {
                Sys_CreateThread( (xthread_t)Sys_AsyncThread, NULL, THREAD_NORMAL, asyncThread, "Async", g_threads, &g_thread_count );
        } else {
                common->Printf( "Async thread already running\n" );
        }
        common->Printf( "Async thread started\n" );
}

/*
==================
Posix_InitPThreads
==================
*/
void Posix_InitPThreads( ) {
        int i;
        pthread_mutexattr_t attr;

        // init critical sections
        for ( i = 0; i < MAX_LOCAL_CRITICAL_SECTIONS; i++ ) {
                pthread_mutexattr_init( &attr );
                pthread_mutexattr_settype( &attr, PTHREAD_MUTEX_ERRORCHECK );
                pthread_mutex_init( &global_lock[i], &attr );
                pthread_mutexattr_destroy( &attr );
        }

        // init event sleep/triggers
        for ( i = 0; i < MAX_TRIGGER_EVENTS; i++ ) {
                pthread_cond_init( &event_cond[ i ], NULL );
                signaled[i] = false;
                waiting[i] = false;
        }

        // init threads table
        for ( i = 0; i < MAX_THREADS; i++ ) {
                g_threads[ i ] = NULL;
        }       
}