diff --git a/include/block/thread-pool.h b/include/block/thread-pool.h index 6f27eb085b..dd48cf07e8 100644 --- a/include/block/thread-pool.h +++ b/include/block/thread-pool.h @@ -38,5 +38,56 @@ BlockAIOCB *thread_pool_submit_aio(ThreadPoolFunc *func, void *arg, int coroutine_fn thread_pool_submit_co(ThreadPoolFunc *func, void *arg); void thread_pool_update_params(ThreadPoolAio *pool, struct AioContext *ctx); +/* ------------------------------------------- */ +/* Generic thread pool types and methods below */ +typedef struct ThreadPool ThreadPool; + +/* Create a new thread pool. Never returns NULL. */ +ThreadPool *thread_pool_new(void); + +/* + * Free the thread pool. + * Waits for all the previously submitted work to complete before performing + * the actual freeing operation. + */ +void thread_pool_free(ThreadPool *pool); + +/* + * Submit a new work (task) for the pool. + * + * @opaque_destroy is an optional GDestroyNotify for the @opaque argument + * to the work function at @func. + */ +void thread_pool_submit(ThreadPool *pool, ThreadPoolFunc *func, + void *opaque, GDestroyNotify opaque_destroy); + +/* + * Submit a new work (task) for the pool, making sure it starts getting + * processed immediately, launching a new thread for it if necessary. + * + * @opaque_destroy is an optional GDestroyNotify for the @opaque argument + * to the work function at @func. + */ +void thread_pool_submit_immediate(ThreadPool *pool, ThreadPoolFunc *func, + void *opaque, GDestroyNotify opaque_destroy); + +/* + * Wait for all previously submitted work to complete before returning. + * + * Can be used as a barrier between two sets of tasks executed on a thread + * pool without destroying it or in a performance sensitive path where the + * caller just wants to wait for all tasks to complete while deferring the + * pool free operation for later, less performance sensitive time. + */ +void thread_pool_wait(ThreadPool *pool); + +/* Set the maximum number of threads in the pool. */ +bool thread_pool_set_max_threads(ThreadPool *pool, int max_threads); + +/* + * Adjust the maximum number of threads in the pool to give each task its + * own thread (exactly one thread per task). + */ +bool thread_pool_adjust_max_threads_to_work(ThreadPool *pool); #endif diff --git a/util/thread-pool.c b/util/thread-pool.c index 908194dc07..d2ead6b728 100644 --- a/util/thread-pool.c +++ b/util/thread-pool.c @@ -374,3 +374,122 @@ void thread_pool_free_aio(ThreadPoolAio *pool) qemu_mutex_destroy(&pool->lock); g_free(pool); } + +struct ThreadPool { + GThreadPool *t; + size_t cur_work; + QemuMutex cur_work_lock; + QemuCond all_finished_cond; +}; + +typedef struct { + ThreadPoolFunc *func; + void *opaque; + GDestroyNotify opaque_destroy; +} ThreadPoolElement; + +static void thread_pool_func(gpointer data, gpointer user_data) +{ + ThreadPool *pool = user_data; + g_autofree ThreadPoolElement *el = data; + + el->func(el->opaque); + + if (el->opaque_destroy) { + el->opaque_destroy(el->opaque); + } + + QEMU_LOCK_GUARD(&pool->cur_work_lock); + + assert(pool->cur_work > 0); + pool->cur_work--; + + if (pool->cur_work == 0) { + qemu_cond_signal(&pool->all_finished_cond); + } +} + +ThreadPool *thread_pool_new(void) +{ + ThreadPool *pool = g_new(ThreadPool, 1); + + pool->cur_work = 0; + qemu_mutex_init(&pool->cur_work_lock); + qemu_cond_init(&pool->all_finished_cond); + + pool->t = g_thread_pool_new(thread_pool_func, pool, 0, TRUE, NULL); + /* + * g_thread_pool_new() can only return errors if initial thread(s) + * creation fails but we ask for 0 initial threads above. + */ + assert(pool->t); + + return pool; +} + +void thread_pool_free(ThreadPool *pool) +{ + /* + * With _wait = TRUE this effectively waits for all + * previously submitted work to complete first. + */ + g_thread_pool_free(pool->t, FALSE, TRUE); + + qemu_cond_destroy(&pool->all_finished_cond); + qemu_mutex_destroy(&pool->cur_work_lock); + + g_free(pool); +} + +void thread_pool_submit(ThreadPool *pool, ThreadPoolFunc *func, + void *opaque, GDestroyNotify opaque_destroy) +{ + ThreadPoolElement *el = g_new(ThreadPoolElement, 1); + + el->func = func; + el->opaque = opaque; + el->opaque_destroy = opaque_destroy; + + WITH_QEMU_LOCK_GUARD(&pool->cur_work_lock) { + pool->cur_work++; + } + + /* + * Ignore the return value since this function can only return errors + * if creation of an additional thread fails but even in this case the + * provided work is still getting queued (just for the existing threads). + */ + g_thread_pool_push(pool->t, el, NULL); +} + +void thread_pool_submit_immediate(ThreadPool *pool, ThreadPoolFunc *func, + void *opaque, GDestroyNotify opaque_destroy) +{ + thread_pool_submit(pool, func, opaque, opaque_destroy); + thread_pool_adjust_max_threads_to_work(pool); +} + +void thread_pool_wait(ThreadPool *pool) +{ + QEMU_LOCK_GUARD(&pool->cur_work_lock); + + while (pool->cur_work > 0) { + qemu_cond_wait(&pool->all_finished_cond, + &pool->cur_work_lock); + } +} + +bool thread_pool_set_max_threads(ThreadPool *pool, + int max_threads) +{ + assert(max_threads > 0); + + return g_thread_pool_set_max_threads(pool->t, max_threads, NULL); +} + +bool thread_pool_adjust_max_threads_to_work(ThreadPool *pool) +{ + QEMU_LOCK_GUARD(&pool->cur_work_lock); + + return thread_pool_set_max_threads(pool, pool->cur_work); +}