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// thread_pool.cpp
#define WORKER_TASK_PROC(name) isize name(void *data)
typedef WORKER_TASK_PROC(WorkerTaskProc);
#if defined(GB_SYSTEM_WINDOWS)
#define THREAD_POOL_SYNC_FETCH_AND_ADD InterlockedAdd
#else
#define THREAD_POOL_SYNC_FETCH_AND_ADD __sync_fetch_and_add
#endif
struct WorkerTask {
WorkerTask *next_task;
WorkerTaskProc *do_work;
void *data;
};
struct ThreadPool {
volatile i32 outstanding_task_count;
WorkerTask *next_task;
BlockingMutex task_list_mutex;
};
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_wait(ThreadPool *pool);
void thread_pool_add_task(ThreadPool *pool, WorkerTaskProc *proc, void *data);
void worker_thread_internal();
void thread_pool_thread_entry(ThreadPool *pool) {
while (pool->outstanding_task_count) {
mutex_lock(&pool->task_list_mutex);
if (pool->next_task) {
WorkerTask *task = pool->next_task;
pool->next_task = task->next_task;
mutex_unlock(&pool->task_list_mutex);
task->do_work(task->data);
THREAD_POOL_SYNC_FETCH_AND_ADD(&pool->outstanding_task_count, -1);
free(task);
} else {
mutex_unlock(&pool->task_list_mutex);
yield();
}
}
}
#if defined(GB_SYSTEM_WINDOWS)
DWORD __stdcall thread_pool_thread_entry_platform(void *arg) {
thread_pool_thread_entry((ThreadPool *) arg);
return 0;
}
void thread_pool_start_thread(ThreadPool *pool) {
CloseHandle(CreateThread(NULL, 0, thread_pool_thread_entry_platform, pool, 0, NULL));
}
#else
void *thread_pool_thread_entry_platform(void *arg) {
thread_pool_thread_entry((ThreadPool *) arg);
return NULL;
}
void thread_pool_start_thread(ThreadPool *pool) {
pthread_t handle;
pthread_create(&handle, NULL, thread_pool_thread_entry_platform, pool);
pthread_detach(handle);
}
#endif
void thread_pool_init(ThreadPool *pool, gbAllocator const &a, isize thread_count, char const *worker_prefix) {
memset(pool, 0, sizeof(ThreadPool));
mutex_init(&pool->task_list_mutex);
pool->outstanding_task_count = 1;
for (int i = 0; i < thread_count; i++) {
thread_pool_start_thread(pool);
}
}
void thread_pool_destroy(ThreadPool *pool) {
mutex_destroy(&pool->task_list_mutex);
}
void thread_pool_wait(ThreadPool *pool) {
THREAD_POOL_SYNC_FETCH_AND_ADD(&pool->outstanding_task_count, -1);
while (pool->outstanding_task_count) {
yield();
}
}
void thread_pool_add_task(ThreadPool *pool, WorkerTaskProc *proc, void *data) {
WorkerTask *task = (WorkerTask *) calloc(1, sizeof(WorkerTask));
task->do_work = proc;
task->data = data;
mutex_lock(&pool->task_list_mutex);
task->next_task = pool->next_task;
pool->next_task = task;
THREAD_POOL_SYNC_FETCH_AND_ADD(&pool->outstanding_task_count, 1);
mutex_unlock(&pool->task_list_mutex);
}
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