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// worker_queue.cpp
#define WORKER_TASK_PROC(name) isize name(void *data)
typedef WORKER_TASK_PROC(WorkerTaskProc);
struct WorkerTask {
WorkerTaskProc *do_work;
void *data;
isize result;
};
struct ThreadPool {
gbMutex mutex;
gbSemaphore sem_available;
gbAtomic32 processing_work_count;
bool is_running;
gbAllocator allocator;
MPMCQueue<WorkerTask> tasks;
gbThread *threads;
isize thread_count;
char worker_prefix[10];
i32 worker_prefix_len;
};
void thread_pool_init(ThreadPool *pool, gbAllocator const &a, isize thread_count, char const *worker_prefix = nullptr);
void thread_pool_destroy(ThreadPool *pool);
void thread_pool_start(ThreadPool *pool);
void thread_pool_join(ThreadPool *pool);
void thread_pool_add_task(ThreadPool *pool, WorkerTaskProc *proc, void *data);
GB_THREAD_PROC(worker_thread_internal);
void thread_pool_init(ThreadPool *pool, gbAllocator const &a, isize thread_count, char const *worker_prefix) {
pool->allocator = a;
mpmc_init(&pool->tasks, a, 1024);
pool->thread_count = gb_max(thread_count, 0);
pool->threads = gb_alloc_array(a, gbThread, pool->thread_count);
gb_mutex_init(&pool->mutex);
gb_semaphore_init(&pool->sem_available);
pool->is_running = true;
pool->worker_prefix_len = 0;
if (worker_prefix) {
i32 worker_prefix_len = cast(i32)gb_strlen(worker_prefix);
worker_prefix_len = gb_min(worker_prefix_len, 10);
gb_memmove(pool->worker_prefix, worker_prefix, worker_prefix_len);
pool->worker_prefix_len = worker_prefix_len;
}
for (isize i = 0; i < pool->thread_count; i++) {
gbThread *t = &pool->threads[i];
gb_thread_init(t);
t->user_index = i;
#if 0
// TODO(bill): Fix this on Linux as it causes a seg-fault
if (pool->worker_prefix_len > 0) {
char worker_name[16] = {};
gb_snprintf(worker_name, gb_size_of(worker_name), "%.*s%u", pool->worker_prefix_len, pool->worker_prefix, cast(u16)i);
gb_thread_set_name(t, worker_name);
}
#endif
}
}
void thread_pool_start(ThreadPool *pool) {
for (isize i = 0; i < pool->thread_count; i++) {
gbThread *t = &pool->threads[i];
gb_thread_start(t, worker_thread_internal, pool);
}
}
void thread_pool_join(ThreadPool *pool) {
pool->is_running = false;
gb_semaphore_post(&pool->sem_available, cast(i32)pool->thread_count);
gb_yield();
for (isize i = 0; i < pool->thread_count; i++) {
gbThread *t = &pool->threads[i];
gb_thread_join(t);
}
}
void thread_pool_destroy(ThreadPool *pool) {
thread_pool_join(pool);
gb_semaphore_destroy(&pool->sem_available);
gb_mutex_destroy(&pool->mutex);
gb_free(pool->allocator, pool->threads);
pool->thread_count = 0;
mpmc_destroy(&pool->tasks);
}
void thread_pool_add_task(ThreadPool *pool, WorkerTaskProc *proc, void *data) {
gb_mutex_lock(&pool->mutex);
WorkerTask task = {};
task.do_work = proc;
task.data = data;
mpmc_enqueue(&pool->tasks, task);
gb_semaphore_post(&pool->sem_available, 1);
gb_mutex_unlock(&pool->mutex);
}
bool thread_pool_try_and_pop_task(ThreadPool *pool, WorkerTask *task) {
bool got_task = false;
if (mpmc_dequeue(&pool->tasks, task)) {
gb_atomic32_fetch_add(&pool->processing_work_count, +1);
got_task = true;
}
return got_task;
}
void thread_pool_do_work(ThreadPool *pool, WorkerTask *task) {
task->result = task->do_work(task->data);
gb_atomic32_fetch_add(&pool->processing_work_count, -1);
}
void thread_pool_wait_to_process(ThreadPool *pool) {
while (pool->tasks.count.load(std::memory_order_relaxed) > 0 || gb_atomic32_load(&pool->processing_work_count) != 0) {
WorkerTask task = {};
if (thread_pool_try_and_pop_task(pool, &task)) {
thread_pool_do_work(pool, &task);
}
// Safety-kick
while (pool->tasks.count.load(std::memory_order_relaxed) > 0 && gb_atomic32_load(&pool->processing_work_count) == 0) {
gb_mutex_lock(&pool->mutex);
gb_semaphore_post(&pool->sem_available, cast(i32)pool->tasks.count.load(std::memory_order_relaxed));
gb_mutex_unlock(&pool->mutex);
}
gb_yield();
}
thread_pool_join(pool);
}
GB_THREAD_PROC(worker_thread_internal) {
ThreadPool *pool = cast(ThreadPool *)thread->user_data;
while (pool->is_running) {
gb_semaphore_wait(&pool->sem_available);
WorkerTask task = {};
if (thread_pool_try_and_pop_task(pool, &task)) {
thread_pool_do_work(pool, &task);
}
}
// Cascade
gb_semaphore_release(&pool->sem_available);
return 0;
}
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