#include <config.h>

#include "threadpool.h"
#include "memory.h"
#include "threads.h"
#include "virterror_internal.h"

#define VIR_FROM_THIS VIR_FROM_NONE

typedef struct _virThreadPoolJob virThreadPoolJob;
typedef virThreadPoolJob *virThreadPoolJobPtr;

struct _virThreadPoolJob {
    virThreadPoolJobPtr next;

    void *data;
};

struct _virThreadPool {
    int quit;

    virThreadPoolJobFunc jobFunc;
    void *jobOpaque;
    virThreadPoolJobPtr jobList;

    virMutex mutex;
    virCond cond;
    virCond quit_cond;

    size_t maxWorkers;
    size_t freeWorkers;
    size_t nWorkers;
    virThreadPtr workers;
};

static void virThreadPoolWorker(void *opaque)
{
    virThreadPoolPtr pool = opaque;

    virMutexLock(&pool->mutex);

    while (1) {
        while (!pool->quit &&
               !pool->jobList) {
            pool->freeWorkers++;
            if (virCondWait(&pool->cond, &pool->mutex) < 0) {
                pool->freeWorkers--;
                break;
            }
            pool->freeWorkers--;
        }

        if (pool->quit)
            break;

        virThreadPoolJobPtr job = pool->jobList;
        pool->jobList = pool->jobList->next;
        job->next = NULL;

        virMutexUnlock(&pool->mutex);
        (pool->jobFunc)(job->data, pool->jobOpaque);
        VIR_FREE(job);
        virMutexLock(&pool->mutex);
    }

    pool->nWorkers--;
    if (pool->nWorkers == 0)
        virCondSignal(&pool->quit_cond);
    virMutexUnlock(&pool->mutex);
}

virThreadPoolPtr virThreadPoolNew(size_t minWorkers,
                                  size_t maxWorkers,
                                  virThreadPoolJobFunc func,
                                  void *opaque)
{
    virThreadPoolPtr pool;
    int i;

    if (VIR_ALLOC(pool) < 0) {
        virReportOOMError();
        return NULL;
    }

    pool->jobFunc = func;
    pool->jobOpaque = opaque;

    if (virMutexInit(&pool->mutex) < 0)
        goto error;
    if (virCondInit(&pool->cond) < 0)
        goto error;
    if (virCondInit(&pool->quit_cond) < 0)
        goto error;

    if (VIR_ALLOC_N(pool->workers, minWorkers) < 0)
        goto error;

    pool->maxWorkers = maxWorkers;
    for (i = 0; i < minWorkers; i++) {
        if (virThreadCreate(&pool->workers[i],
                            true,
                            virThreadPoolWorker,
                            pool) < 0)
            goto error;
        pool->nWorkers++;
    }

    return pool;

error:
    virThreadPoolFree(pool);
    return NULL;
}

void virThreadPoolFree(virThreadPoolPtr pool)
{
    virMutexLock(&pool->mutex);
    pool->quit = 1;
    if (pool->nWorkers > 0) {
        virCondBroadcast(&pool->cond);
        if (virCondWait(&pool->quit_cond, &pool->mutex) < 0)
        {}
    }
    VIR_FREE(pool->workers);
    virMutexUnlock(&pool->mutex);
    VIR_FREE(pool);
}

int virThreadPoolSendJob(virThreadPoolPtr pool,
                         void *jobData)
{
    virThreadPoolJobPtr job;
    virThreadPoolJobPtr tmp;

    virMutexLock(&pool->mutex);
    if (pool->quit)
        goto error;

    if (pool->freeWorkers == 0 &&
        pool->nWorkers < pool->maxWorkers) {
        if (VIR_EXPAND_N(pool->workers, pool->nWorkers, 1) < 0) {
            virReportOOMError();
            goto error;
        }

        if (virThreadCreate(&pool->workers[pool->nWorkers],
                            true,
                            virThreadPoolWorker,
                            pool) < 0)
            goto error;
        pool->nWorkers++;
    }

    if (VIR_ALLOC(job) < 0) {
        virReportOOMError();
        goto error;
    }

    job->data = jobData;

    tmp = pool->jobList;
    while (tmp && tmp->next)
        tmp = tmp->next;
    if (tmp)
        tmp->next = job;
    else
        pool->jobList = job;

    virCondSignal(&pool->cond);
    virMutexUnlock(&pool->mutex);

    return 0;

error:
    virMutexUnlock(&pool->mutex);
    return -1;
}