mirror of https://github.com/python/cpython
358 lines
7.5 KiB
C
358 lines
7.5 KiB
C
#include <kernel/OS.h>
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#include <support/SupportDefs.h>
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#include <errno.h>
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/* ----------------------------------------------------------------------
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* Fast locking mechanism described by Benoit Schillings (benoit@be.com)
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* in the Be Developer's Newsletter, Issue #26 (http://www.be.com/).
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*/
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typedef struct benaphore {
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sem_id _sem;
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int32 _atom;
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} benaphore_t;
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static status_t benaphore_create( const char *name, benaphore_t *ben );
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static status_t benaphore_destroy( benaphore_t *ben );
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static status_t benaphore_lock( benaphore_t *ben );
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static status_t benaphore_timedlock( benaphore_t *ben, bigtime_t micros );
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static status_t benaphore_unlock( benaphore_t *ben );
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static status_t benaphore_create( const char *name, benaphore_t *ben )
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{
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if( ben != NULL ) {
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ben->_atom = 0;
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ben->_sem = create_sem( 0, name );
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if( ben->_sem < B_NO_ERROR ) {
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return B_BAD_SEM_ID;
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}
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} else {
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return EFAULT;
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}
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return EOK;
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}
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static status_t benaphore_destroy( benaphore_t *ben )
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{
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if( ben->_sem >= B_NO_ERROR ) {
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status_t retval = benaphore_timedlock( ben, 0 );
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if( retval == EOK || retval == EWOULDBLOCK ) {
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status_t del_retval = delete_sem( ben->_sem );
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return del_retval;
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}
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}
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return B_BAD_SEM_ID;
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}
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static status_t benaphore_lock( benaphore_t *ben )
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{
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int32 prev = atomic_add( &(ben->_atom), 1 );
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if( prev > 0 ) {
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return acquire_sem( ben->_sem );
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}
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return EOK;
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}
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static status_t benaphore_timedlock( benaphore_t *ben, bigtime_t micros )
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{
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int32 prev = atomic_add( &(ben->_atom), 1 );
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if( prev > 0 ) {
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status_t retval = acquire_sem_etc( ben->_sem, 1, B_TIMEOUT, micros );
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switch( retval ) {
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case B_WOULD_BLOCK: /* Fall through... */
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case B_TIMED_OUT:
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return EWOULDBLOCK;
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break;
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case B_OK:
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return EOK;
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break;
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default:
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return retval;
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break;
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}
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}
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return EOK;
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}
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static status_t benaphore_unlock( benaphore_t *ben )
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{
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int32 prev = atomic_add( &(ben->_atom), -1 );
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if( prev > 1 ) {
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return release_sem( ben->_sem );
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}
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return EOK;
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}
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/* ----------------------------------------------------------------------
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* Initialization.
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*/
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static void PyThread__init_thread( void )
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{
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/* Do nothing. */
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return;
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}
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/* ----------------------------------------------------------------------
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* Thread support.
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*
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* Only ANSI C, renamed functions here; you can't use K&R on BeOS,
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* and there's no legacy thread module to support.
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*/
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static int32 thread_count = 0;
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long PyThread_start_new_thread( void (*func)(void *), void *arg )
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{
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status_t success = 0;
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thread_id tid;
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char name[B_OS_NAME_LENGTH];
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int32 this_thread;
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dprintf(("PyThread_start_new_thread called\n"));
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/* We are so very thread-safe... */
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this_thread = atomic_add( &thread_count, 1 );
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PyOS_snprintf(name, sizeof(name),
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"python thread (%d)", this_thread );
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tid = spawn_thread( (thread_func)func, name,
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B_NORMAL_PRIORITY, arg );
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if( tid > B_NO_ERROR ) {
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success = resume_thread( tid );
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}
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return ( success == B_NO_ERROR ? tid : -1 );
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}
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long PyThread_get_thread_ident( void )
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{
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/* Presumed to return the current thread's ID... */
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thread_id tid;
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tid = find_thread( NULL );
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return ( tid != B_NAME_NOT_FOUND ? tid : -1 );
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}
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static void do_PyThread_exit_thread( int no_cleanup )
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{
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int32 threads;
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dprintf(("PyThread_exit_thread called\n"));
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/* Thread-safe way to read a variable without a mutex: */
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threads = atomic_add( &thread_count, 0 );
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if( threads == 0 ) {
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/* No threads around, so exit main(). */
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if( no_cleanup ) {
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_exit(0);
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} else {
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exit(0);
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}
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} else {
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/* Oh, we're a thread, let's try to exit gracefully... */
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exit_thread( B_NO_ERROR );
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}
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}
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void PyThread_exit_thread( void )
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{
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do_PyThread_exit_thread(0);
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}
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void PyThread__exit_thread( void )
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{
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do_PyThread_exit_thread(1);
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}
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#ifndef NO_EXIT_PROG
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static void do_PyThread_exit_prog( int status, int no_cleanup )
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{
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dprintf(("PyThread_exit_prog(%d) called\n", status));
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/* No need to do anything, the threads get torn down if main() exits. */
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if (no_cleanup) {
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_exit(status);
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} else {
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exit(status);
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}
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}
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void PyThread_exit_prog( int status )
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{
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do_PyThread_exit_prog(status, 0);
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}
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void PyThread__exit_prog( int status )
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{
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do_PyThread_exit_prog(status, 1);
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}
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#endif /* NO_EXIT_PROG */
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/* ----------------------------------------------------------------------
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* Lock support.
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*/
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static int32 lock_count = 0;
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PyThread_type_lock PyThread_allocate_lock( void )
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{
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benaphore_t *lock;
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status_t retval;
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char name[B_OS_NAME_LENGTH];
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int32 this_lock;
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dprintf(("PyThread_allocate_lock called\n"));
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lock = (benaphore_t *)malloc( sizeof( benaphore_t ) );
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if( lock == NULL ) {
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/* TODO: that's bad, raise MemoryError */
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return (PyThread_type_lock)NULL;
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}
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this_lock = atomic_add( &lock_count, 1 );
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PyOS_snprintf(name, sizeof(name), "python lock (%d)", this_lock);
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retval = benaphore_create( name, lock );
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if( retval != EOK ) {
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/* TODO: that's bad, raise an exception */
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return (PyThread_type_lock)NULL;
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}
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dprintf(("PyThread_allocate_lock() -> %p\n", lock));
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return (PyThread_type_lock) lock;
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}
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void PyThread_free_lock( PyThread_type_lock lock )
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{
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status_t retval;
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dprintf(("PyThread_free_lock(%p) called\n", lock));
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retval = benaphore_destroy( (benaphore_t *)lock );
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if( retval != EOK ) {
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/* TODO: that's bad, raise an exception */
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return;
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}
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}
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int PyThread_acquire_lock( PyThread_type_lock lock, int waitflag )
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{
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int success;
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status_t retval;
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dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag));
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if( waitflag ) {
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retval = benaphore_lock( (benaphore_t *)lock );
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} else {
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retval = benaphore_timedlock( (benaphore_t *)lock, 0 );
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}
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if( retval == EOK ) {
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success = 1;
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} else {
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success = 0;
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/* TODO: that's bad, raise an exception */
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}
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dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success));
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return success;
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}
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void PyThread_release_lock( PyThread_type_lock lock )
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{
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status_t retval;
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dprintf(("PyThread_release_lock(%p) called\n", lock));
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retval = benaphore_unlock( (benaphore_t *)lock );
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if( retval != EOK ) {
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/* TODO: that's bad, raise an exception */
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return;
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}
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}
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/* ----------------------------------------------------------------------
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* Semaphore support.
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*
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* Guido says not to implement this because it's not used anywhere;
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* I'll do it anyway, you never know when it might be handy, and it's
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* easy...
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*/
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PyThread_type_sema PyThread_allocate_sema( int value )
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{
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sem_id sema;
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dprintf(("PyThread_allocate_sema called\n"));
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sema = create_sem( value, "python semaphore" );
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if( sema < B_NO_ERROR ) {
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/* TODO: that's bad, raise an exception */
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return 0;
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}
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dprintf(("PyThread_allocate_sema() -> %p\n", sema));
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return (PyThread_type_sema) sema;
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}
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void PyThread_free_sema( PyThread_type_sema sema )
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{
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status_t retval;
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dprintf(("PyThread_free_sema(%p) called\n", sema));
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retval = delete_sem( (sem_id)sema );
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if( retval != B_NO_ERROR ) {
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/* TODO: that's bad, raise an exception */
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return;
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}
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}
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int PyThread_down_sema( PyThread_type_sema sema, int waitflag )
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{
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status_t retval;
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dprintf(("PyThread_down_sema(%p, %d) called\n", sema, waitflag));
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if( waitflag ) {
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retval = acquire_sem( (sem_id)sema );
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} else {
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retval = acquire_sem_etc( (sem_id)sema, 1, B_TIMEOUT, 0 );
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}
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if( retval != B_NO_ERROR ) {
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/* TODO: that's bad, raise an exception */
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return 0;
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}
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dprintf(("PyThread_down_sema(%p) return\n", sema));
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return -1;
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}
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void PyThread_up_sema( PyThread_type_sema sema )
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{
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status_t retval;
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dprintf(("PyThread_up_sema(%p)\n", sema));
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retval = release_sem( (sem_id)sema );
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if( retval != B_NO_ERROR ) {
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/* TODO: that's bad, raise an exception */
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return;
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}
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}
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