wip model loading + workers

src/twn_workers.c

@@ -0,0 +1,69 @@
+#include "twn_util.h"
+#include "twn_workers_c.h"
+#include "rendering/twn_draw_c.h"
+
+SDL_sem *workers_job_semaphore;
+
+static SDL_Thread *workers_pool[MAX_WORKERS];
+static size_t workers_pool_size;
+static SDL_mutex *workers_mutex;
+static bool workers_should_exit;
+
+/* logic is such that when job is posted, worker threads attempt to grab it from any possible entry point */
+/* if it did something, which is signaled by `true` return, go back to waiting on semaphore, so that it's decremented properly */
+static int worker_thread(void *udata) {
+    (void)udata;
+
+    while (true) {
+        /* check whether loop should end */
+        SDL_LockMutex(workers_mutex);
+        if (workers_should_exit) {
+            SDL_UnlockMutex(workers_mutex);
+            break;
+        }
+        SDL_UnlockMutex(workers_mutex);
+
+        /* wait and occasionally go back to check whether it all should end */
+        if (SDL_SemWaitTimeout(workers_job_semaphore, 100) == SDL_MUTEX_TIMEDOUT)
+            continue;
+
+        if (model_load_workers_thread())
+            continue;
+    }
+
+    return 0;
+}
+
+
+/* TODO: have a path for platforms without thread support? */
+/* TODO: limit stack size? */
+bool workers_init(size_t worker_count) {
+    SDL_assert(workers_pool_size == 0);
+
+    if (worker_count > MAX_WORKERS)
+        worker_count = MAX_WORKERS;
+
+    /* spawn a bunch of detached threads without references to them */
+    for (size_t i = 0; i < worker_count; ++i) {
+        SDL_Thread *thread = SDL_CreateThread(worker_thread, "worker", NULL);
+        SDL_assert_always(thread);
+        SDL_DetachThread(thread);
+    }
+
+    workers_pool_size = worker_count;
+    workers_job_semaphore = SDL_CreateSemaphore(0);
+    workers_mutex = SDL_CreateMutex();
+    return true;
+}
+
+
+void workers_deinit(void) {
+    SDL_LockMutex(workers_mutex);
+    workers_should_exit = true;
+    SDL_UnlockMutex(workers_mutex);
+
+    /* TODO: that's not correct */
+    SDL_DestroyMutex(workers_mutex);
+    SDL_DestroySemaphore(workers_job_semaphore);
+    workers_pool_size = 0;
+}