147 lines
3.0 KiB
C
147 lines
3.0 KiB
C
/* Support for thread stuff.
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*
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* JC & KM 9/5/94
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* Modified:
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* 28/11/94 JC
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* - return(0) missing from tidy_thread_info()
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* 4/8/99 RP JC
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* - reorganised for POSIX
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* 28/3/11
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* - moved to vips_ namespace
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 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 Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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/*
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#define DEBUG_IO
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <errno.h>
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#include <vips/vips.h>
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#include <vips/thread.h>
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void
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vips_semaphore_init( VipsSemaphore *s, int v, char *name )
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{
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s->v = v;
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s->name = name;
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s->mutex = vips_g_mutex_new();
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s->cond = vips_g_cond_new();
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}
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void
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vips_semaphore_destroy( VipsSemaphore *s )
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{
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VIPS_FREEF( vips_g_mutex_free, s->mutex );
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VIPS_FREEF( vips_g_cond_free, s->cond );
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}
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/* Add n to the semaphore and signal any threads that are blocked waiting
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* a change.
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*/
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int
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vips_semaphore_upn( VipsSemaphore *s, int n )
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{
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int value_after_op;
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g_mutex_lock( s->mutex );
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s->v += n;
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value_after_op = s->v;
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/* If we are only incrementing by one, we only need to wake a single
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* thread. If we are incrementing by a lot, we must wake all threads.
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*/
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if( n == 1 )
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g_cond_signal( s->cond );
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else
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g_cond_broadcast( s->cond );
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g_mutex_unlock( s->mutex );
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#ifdef DEBUG_IO
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printf( "vips_semaphore_upn(\"%s\",%d) = %d\n",
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s->name, n, value_after_op );
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if( value_after_op > 1 )
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vips_error( "vips_semaphore_upn", "up over 1!" );
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#endif /*DEBUG_IO*/
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return( value_after_op );
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}
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/* Increment the semaphore.
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*/
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int
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vips_semaphore_up( VipsSemaphore *s )
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{
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return( vips_semaphore_upn( s, 1 ) );
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}
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/* Wait for sem>n, then subtract n.
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*/
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int
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vips_semaphore_downn( VipsSemaphore *s, int n )
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{
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int value_after_op;
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VIPS_GATE_START( "vips_semaphore_downn: wait" );
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g_mutex_lock( s->mutex );
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while( s->v < n )
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g_cond_wait( s->cond, s->mutex );
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s->v -= n;
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value_after_op = s->v;
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g_mutex_unlock( s->mutex );
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#ifdef DEBUG_IO
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printf( "vips_semaphore_downn(\"%s\",%d): %d\n",
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s->name, n, value_after_op );
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#endif /*DEBUG_IO*/
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VIPS_GATE_STOP( "vips_semaphore_downn: wait" );
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return( value_after_op );
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}
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/* Wait for sem > 0, then decrement.
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*/
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int
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vips_semaphore_down( VipsSemaphore *s )
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{
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return( vips_semaphore_downn( s, 1 ) );
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}
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