Function cmd_sem_lock

v2/engine/make1.c:1390–1422

#ifdef OPT_SEMAPHORE

static int cmd_sem_lock( TARGET * t )
{
    CMD * cmd = (CMD *)t->cmds;
    TARGETS * iter;
    /* Check whether all the semaphores required for updating
     * this target are free.
     */
    for ( iter = cmd->lock; iter; iter = iter->next )
    {
        if ( iter->target->asynccnt > 0 )
        {
            if ( DEBUG_EXECCMD )
                printf( "SEM: %s is busy, delaying launch of %s\n",
                    object_str( iter->target->name ), object_str( t->name ) );
            iter->target->parents = targetentry( iter->target->parents, t );
            return 0;
        }
    }
    /* Lock the semaphores. */
    for ( iter = cmd->lock; iter; iter = iter->next )
    {
        ++iter->target->asynccnt;
        if ( DEBUG_EXECCMD )
            printf( "SEM: %s now used by %s\n", object_str( iter->target->name
                ), object_str( t->name ) );
    }
    /* A cmd only needs to be locked around its execution.
     * clearing cmd->lock here makes it safe to call cmd_sem_lock
     * twice.
     */
    cmd->lock = NULL;
    return 1;
}

static void cmd_sem_unlock( TARGET * t )
{