threads.c

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/*
Copyright(c) 1997-2001 Id Software, Inc.
Copyright(c) 2002 The Quakeforge Project.
Copyright(c) 2006 Quake2World.

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 <SDL_thread.h>

#include "bsp.h"

#define MAX_THREADS 8

threadstate_t threadstate;

static int GetThreadWork (void)
{
    int r;
    int f;

    ThreadLock();

    if (threadstate.workindex == threadstate.workcount) {  /* done */
        ThreadUnlock();
        return -1;
    }

    /* update work fraction and output progress if desired */
    f = 10 * threadstate.workindex / threadstate.workcount;
    if (f != threadstate.workfrac) {
        threadstate.workfrac = f;
        if (threadstate.progress) {
            fprintf(stdout, "%i...", f);
            fflush(stdout);
        }
    } else if (threadstate.progress && threadstate.workindex % threadstate.worktick == 0) {
        fprintf(stdout, "%c\b", "-\\|/"[(threadstate.workindex / threadstate.worktick) & 3]);
        fflush(stdout);
    }

    /* assign the next work iteration */
    r = threadstate.workindex;
    threadstate.workindex++;

    ThreadUnlock();

    return r;
}


static void (*WorkFunction) (unsigned int);


static int ThreadWork (void *p)
{
    while (qtrue) {
        int work = GetThreadWork();
        if (work == -1)
            break;
        WorkFunction(work);
    }

    return 0;
}


static SDL_mutex *lock = NULL;

static void ThreadInit (void)
{
    if (lock != NULL)
        Sys_Error("Mutex already created!");

    lock = SDL_CreateMutex();

    if (lock == NULL)
        Sys_Error("Couldn't create mutex!");
}

static void ThreadRelease (void)
{
    SDL_DestroyMutex(lock);
    lock = NULL;
}

void ThreadLock (void)
{
    if (threadstate.numthreads == 1) {
        /* do nothing */
    } else if (lock != NULL && SDL_mutexP(lock) != -1) {
        /* already locked */
    } else {
        Sys_Error("Couldn't lock mutex (%p)!", lock);
    }
}

void ThreadUnlock (void)
{
    if (threadstate.numthreads == 1) {
        /* do nothing */
    } else if (lock != NULL && SDL_mutexV(lock) != -1) {
        /* already locked */
    } else {
        Sys_Error("Couldn't unlock mutex (%p)!", lock);
    }
}

static void RunThreads (void)
{
    SDL_Thread *threads[MAX_THREADS];
    int i;

    if (threadstate.numthreads == 1) {
        ThreadWork(0);
        return;
    }

    ThreadInit();

    for (i = 0; i < threadstate.numthreads; i++)
        threads[i] = SDL_CreateThread(ThreadWork, NULL);

    for (i = 0; i < threadstate.numthreads; i++)
        SDL_WaitThread(threads[i], NULL);

    ThreadRelease();
}


void RunThreadsOn (void (*func)(unsigned int), int unsigned workcount, qboolean progress, const char *id)
{
    int start, end;

    if (threadstate.numthreads < 1)  /* ensure safe thread counts */
        threadstate.numthreads = 1;

    if (threadstate.numthreads > MAX_THREADS)
        threadstate.numthreads = MAX_THREADS;

    threadstate.workindex = 0;
    threadstate.workcount = workcount;
    threadstate.workfrac = -1;
    threadstate.progress = progress;
    threadstate.worktick = sqrt(workcount) + 1;

    WorkFunction = func;

    start = time(NULL);

    if (threadstate.progress) {
        fprintf(stdout, "%10s: ", id);
        fflush(stdout);
    }

    RunThreads();

    end = time(NULL);

    if (threadstate.progress) {
        Verb_Printf(VERB_NORMAL, " (time: %6is, #: %i)\n", end - start, workcount);
    }
}

void RunSingleThreadOn (void (*func)(unsigned int), int unsigned workcount, qboolean progress, const char *id)
{
    int saved_numthreads = threadstate.numthreads;

    threadstate.numthreads = 1;

    RunThreadsOn(func, workcount, progress, id);

    threadstate.numthreads = saved_numthreads;
}