core: thread: wrap the pthreads API

Create wrapper functions over the pthread API so that the engine only
has to provide an integer ID for threads and mutexes. The thread and
mutex handles should be handled internally so that the end user never
sees the underlying datatypes.

Signed-off-by: Danny Holman <dholman@gymli.org>

2 files changed, 246 insertions, 0 deletions

diff --git a/core/thread.c b/core/thread.c
new file mode 100644
index 0000000..59f50b5
--- /dev/null
+++ b/core/thread.c
@@ -0,0 +1,192 @@
+#include <rune/core/thread.h>
+#include <rune/core/logging.h>
+#include <rune/core/alloc.h>
+#include <pthread.h>
+#include <string.h>
+#include <stdatomic.h>
+
+static struct thread *threads = NULL;
+static struct mutex *mutexes = NULL;
+static int next_tid = 0;
+static int next_mid = 0;
+
+struct start_args {
+        struct thread *thread;
+        void* (*thread_fn)(void*);
+        void *thread_args;
+};
+
+struct thread* _find_thread_by_handle(void *handle) {
+        if (threads == NULL)
+                return NULL;
+
+        struct list_head *temp = &threads->list;
+        struct thread *ret;
+        while (temp != NULL) {
+                ret = (struct thread*)((void*)temp - offsetof(struct thread, list));
+                if (pthread_equal(*(pthread_t*)ret->thread_handle, *(pthread_t*)handle) == 1)
+                        return ret;
+                temp = temp->next;
+        }
+        return NULL;
+}
+
+struct thread* _find_thread_by_id(int ID) {
+        if (threads == NULL)
+                return NULL;
+
+        struct list_head *temp = &threads->list;
+        struct thread *ret;
+        while (temp != NULL) {
+                ret = (struct thread*)((void*)temp - offsetof(struct thread, list));
+                if (ret->ID == ID)
+                        return ret;
+                temp = temp->next;
+        }
+        return NULL;
+}
+
+struct mutex* _find_mutex_by_id(int ID) {
+        if (mutexes == NULL)
+                return NULL;
+
+        struct list_head *temp = &mutexes->list;
+        struct mutex *ret;
+        while (temp != NULL) {
+                ret = (struct mutex*)((void*)temp - offsetof(struct mutex, list));
+                if (ret->ID == ID)
+                        return ret;
+                temp = temp->next;
+        }
+        return NULL;
+}
+
+
+void _cleanup_pthread(void *arg) {
+        struct thread *thread = (struct thread*)arg;
+        list_del(&thread->list);
+        rune_free(thread->thread_handle);
+        rune_free(thread);
+}
+
+void* _startup_pthread(void *arg) {
+        struct start_args *start_args = (struct start_args*)arg;
+
+        void* (*thread_fn)(void *data) = start_args->thread_fn;
+        pthread_cleanup_push(_cleanup_pthread, start_args->thread);
+        if (thread_fn != NULL)
+                (*thread_fn)(start_args->thread_args);
+        pthread_cleanup_pop(1);
+        return NULL;
+}
+
+void rune_init_thread_api(void) {
+        threads = rune_alloc(sizeof(struct thread));
+        threads->ID = next_tid++;
+        threads->detached = 0;
+        threads->thread_handle = rune_alloc(sizeof(pthread_t));
+        *(pthread_t*)threads->thread_handle = pthread_self();
+        pthread_cleanup_push(_cleanup_pthread, threads);
+        pthread_cleanup_pop(0);
+}
+
+int rune_thread_init(void* (*thread_fn)(void *data), void *data, int detached) {
+        struct thread *thread = rune_alloc(sizeof(struct thread));
+        thread->ID = next_tid++;
+        thread->detached = detached;
+        thread->thread_handle = rune_alloc(sizeof(pthread_t));
+        list_add(&thread->list, &threads->list);
+
+        struct start_args *args = rune_alloc(sizeof(struct start_args));
+        args->thread = thread;
+        args->thread_fn = thread_fn;
+        args->thread_args = data;
+        int retval = pthread_create(thread->thread_handle, NULL, _startup_pthread, args);
+        rune_free(args);
+        if (retval != 0) {
+                log_output(LOG_ERROR, "Thread creation failed: %s", strerror(retval));
+                return -1;
+        }
+        log_output(LOG_DEBUG, "Initialized new thread with ID=%d", thread->ID);
+        if (detached == 1) {
+                log_output(LOG_DEBUG, "Thread %d has been detached, join no longer possible");
+                pthread_detach(*(pthread_t*)thread->thread_handle);
+        }
+        return thread->ID;
+}
+
+int rune_thread_cancel(int ID) {
+        log_output(LOG_DEBUG, "Received cancel request for thread %d", ID);
+        struct thread *thread = _find_thread_by_id(ID);
+        if (thread == NULL) {
+                log_output(LOG_ERROR, "Thread %d does not exist", ID);
+                return -1;
+        }
+        pthread_cancel(*((pthread_t*)thread->thread_handle));
+        return 0;
+}
+
+int rune_thread_join(int ID, void **retval) {
+        struct thread *thread = _find_thread_by_id(ID);
+        if (thread == NULL)
+                return 0;
+
+        if (thread->detached == 1) {
+                log_output(LOG_ERROR, "Cannot join thread %d, detached", thread->ID);
+                return -1;
+        }
+        pthread_join(*((pthread_t*)thread->thread_handle), retval);
+        return 0;
+}
+
+int rune_thread_self(void) {
+        pthread_t cur = pthread_self();
+        struct thread *ret = _find_thread_by_handle((void*)&cur);
+        if (ret != NULL)
+                return ret->ID;
+        return -1;
+}
+
+void rune_thread_exit(void *retval) {
+        pthread_t cur = pthread_self();
+        struct thread *self = _find_thread_by_handle((void*)&cur);
+        log_output(LOG_DEBUG, "Thread %d called thread_exit", self->ID);
+        pthread_exit(retval);
+}
+
+int rune_mutex_init(void) {
+        struct mutex *mutex = rune_alloc(sizeof(struct mutex));
+        mutex->ID = next_mid++;
+        mutex->mutex_handle = rune_alloc(sizeof(pthread_mutex_t));
+        pthread_mutex_init((pthread_mutex_t*)mutex->mutex_handle, NULL);
+        if (mutexes == NULL)
+                mutexes = mutex;
+        else
+                list_add(&mutex->list, &mutexes->list);
+        return mutex->ID;
+}
+
+int rune_mutex_destroy(int ID) {
+        struct mutex *mutex = _find_mutex_by_id(ID);
+        rune_free(mutex->mutex_handle);
+        list_del(&mutex->list);
+        rune_free(mutex);
+}
+
+int rune_mutex_lock(int ID) {
+        struct mutex *mutex = _find_mutex_by_id(ID);
+        int retval = pthread_mutex_lock((pthread_mutex_t*)mutex->mutex_handle);
+        if (retval != 0) {
+                char *str = strerror(retval);
+                log_output(LOG_ERROR, "Cannot lock mutex %d: %s", mutex->ID, str);
+        }
+}
+
+int rune_mutex_unlock(int ID) {
+        struct mutex *mutex = _find_mutex_by_id(ID);
+        int retval = pthread_mutex_unlock((pthread_mutex_t*)mutex->mutex_handle);
+        if (retval != 0) {
+                char *str = strerror(retval);
+                log_output(LOG_ERROR, "Cannot unlock mutex %d: %s", mutex->ID, str);
+        }
+}
diff --git a/include/rune/core/thread.h b/include/rune/core/thread.h
new file mode 100644
index 0000000..698136c
--- /dev/null
+++ b/include/rune/core/thread.h
@@ -0,0 +1,54 @@
+/*
+ * Rune Game Engine
+ * Copyright 2024 Danny Holman <dholman@gymli.org>
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ */
+
+#ifndef RUNE_CORE_THREAD_H
+#define RUNE_CORE_THREAD_H
+
+#include <rune/util/types.h>
+#include <rune/util/list.h>
+
+struct thread {
+        int ID;
+        int detached;
+        void *thread_handle;
+        struct list_head list;
+};
+
+struct mutex {
+        int ID;
+        void *mutex_handle;
+        struct list_head list;
+};
+
+RAPI void rune_init_thread_api(void);
+
+RAPI int rune_thread_init(void* (*thread_fn)(void *data), void *data, int detached);
+RAPI int rune_thread_cancel(int ID);
+RAPI int rune_thread_join(int ID, void **retval);
+RAPI int rune_thread_self(void);
+RAPI void rune_thread_exit(void *retval);
+
+RAPI int rune_mutex_init(void);
+RAPI int rune_mutex_destroy(int ID);
+RAPI int rune_mutex_lock(int ID);
+RAPI int rune_mutex_unlock(int ID);
+
+#endif