Fix and refactoring of thread-starting

The error result of _beginthreadex() is not -1 but 0.
Fix to classify conn->buf into ctx_memory.
Each worker thread can retrieve phys_ctx and own thread_index from mg_connection.

src/civetweb.c

@@ -2759,8 +2759,6 @@ struct mg_connection {
 #if defined(USE_LUA) && defined(USE_WEBSOCKET)
 	void *lua_websocket_state; /* Lua_State for a websocket connection */
 #endif
-
-	int thread_index; /* Thread index within ctx */
 };
 
 
@@ -5489,9 +5487,9 @@ mg_start_thread_with_id(unsigned(__stdcall *f)(void *),
 	HANDLE threadhandle;
 	int result = -1;
 
-	uip = _beginthreadex(NULL, 0, (unsigned(__stdcall *)(void *))f, p, 0, NULL);
+	uip = _beginthreadex(NULL, 0, f, p, 0, NULL);
 	threadhandle = (HANDLE)uip;
-	if ((uip != (uintptr_t)(-1L)) && (threadidptr != NULL)) {
+	if ((uip != 0) && (threadidptr != NULL)) {
 		*threadidptr = threadhandle;
 		result = 0;
 	}
@@ -17818,17 +17816,11 @@ produce_socket(struct mg_context *ctx, const struct socket *sp)
 #endif /* ALTERNATIVE_QUEUE */
 
 
-struct worker_thread_args {
-	struct mg_context *ctx;
-	int index;
-};
-
-
-static void *
-worker_thread_run(struct worker_thread_args *thread_args)
+static void
+worker_thread_run(struct mg_connection *conn)
 {
-	struct mg_context *ctx = thread_args->ctx;
-	struct mg_connection *conn;
+	struct mg_context *ctx = conn->phys_ctx;
+	int thread_index;
 	struct mg_workerTLS tls;
 #if defined(MG_LEGACY_INTERFACE)
 	uint32_t addr;
@@ -17851,15 +17843,15 @@ worker_thread_run(struct worker_thread_args *thread_args)
 	}
 
 	/* Connection structure has been pre-allocated */
-	if (((int)thread_args->index < 0)
-	    || ((unsigned)thread_args->index
+	thread_index = (int)(conn - ctx->worker_connections);
+	if ((thread_index < 0)
+	    || ((unsigned)thread_index
 	        >= (unsigned)ctx->cfg_worker_threads)) {
 		mg_cry_internal(fc(ctx),
 		                "Internal error: Invalid worker index %i",
-		                (int)thread_args->index);
-		return NULL;
+		                thread_index);
+		return;
 	}
-	conn = ctx->worker_connections + thread_args->index;
 
 	/* Request buffers are not pre-allocated. They are private to the
 	 * request and do not contain any state information that might be
@@ -17868,16 +17860,14 @@ worker_thread_run(struct worker_thread_args *thread_args)
 	if (conn->buf == NULL) {
 		mg_cry_internal(fc(ctx),
 		                "Out of memory: Cannot allocate buffer for worker %i",
-		                (int)thread_args->index);
-		return NULL;
+		                thread_index);
+		return;
 	}
 	conn->buf_size = (int)ctx->max_request_size;
 
-	conn->phys_ctx = ctx;
 	conn->dom_ctx = &(ctx->dd); /* Use default domain and default host */
 	conn->host = NULL;          /* until we have more information. */
 
-	conn->thread_index = thread_args->index;
 	conn->request_info.user_data = ctx->user_data;
 	/* Allocate a mutex for this connection to allow communication both
 	 * within the request handler and from elsewhere in the application
@@ -17885,7 +17875,7 @@ worker_thread_run(struct worker_thread_args *thread_args)
 	if (0 != pthread_mutex_init(&conn->mutex, &pthread_mutex_attr)) {
 		mg_free(conn->buf);
 		mg_cry_internal(fc(ctx), "%s", "Cannot create mutex");
-		return NULL;
+		return;
 	}
 
 #if defined(USE_SERVER_STATS)
@@ -17895,7 +17885,7 @@ worker_thread_run(struct worker_thread_args *thread_args)
 	/* Call consume_socket() even when ctx->stop_flag > 0, to let it
 	 * signal sq_empty condvar to wake up the master waiting in
 	 * produce_socket() */
-	while (consume_socket(ctx, &conn->client, conn->thread_index)) {
+	while (consume_socket(ctx, &conn->client, thread_index)) {
 
 		conn->conn_birth_time = time(NULL);
 
@@ -17986,7 +17976,6 @@ worker_thread_run(struct worker_thread_args *thread_args)
 #endif
 
 	DEBUG_TRACE("%s", "exiting");
-	return NULL;
 }
 
 
@@ -17994,18 +17983,13 @@ worker_thread_run(struct worker_thread_args *thread_args)
 #if defined(_WIN32)
 static unsigned __stdcall worker_thread(void *thread_func_param)
 {
-	struct worker_thread_args *pwta =
-	    (struct worker_thread_args *)thread_func_param;
-	worker_thread_run(pwta);
-	mg_free(thread_func_param);
+	worker_thread_run((struct mg_connection *)thread_func_param);
 	return 0;
 }
 #else
 static void *
 worker_thread(void *thread_func_param)
 {
-	struct worker_thread_args *pwta =
-	    (struct worker_thread_args *)thread_func_param;
 	struct sigaction sa;
 
 	/* Ignore SIGPIPE */
@@ -18013,8 +17997,7 @@ worker_thread(void *thread_func_param)
 	sa.sa_handler = SIG_IGN;
 	sigaction(SIGPIPE, &sa, NULL);
 
-	worker_thread_run(pwta);
-	mg_free(thread_func_param);
+	worker_thread_run((struct mg_connection *)thread_func_param);
 	return NULL;
 }
 #endif /* _WIN32 */
@@ -18106,9 +18089,8 @@ accept_new_connection(const struct socket *listener, struct mg_context *ctx)
 
 
 static void
-master_thread_run(void *thread_func_param)
+master_thread_run(struct mg_context *ctx)
 {
-	struct mg_context *ctx = (struct mg_context *)thread_func_param;
 	struct mg_workerTLS tls;
 	struct mg_pollfd *pfd;
 	unsigned int i;
@@ -18230,7 +18212,7 @@ master_thread_run(void *thread_func_param)
 #if defined(_WIN32)
 static unsigned __stdcall master_thread(void *thread_func_param)
 {
-	master_thread_run(thread_func_param);
+	master_thread_run((struct mg_context *)thread_func_param);
 	return 0;
 }
 #else
@@ -18244,7 +18226,7 @@ master_thread(void *thread_func_param)
 	sa.sa_handler = SIG_IGN;
 	sigaction(SIGPIPE, &sa, NULL);
 
-	master_thread_run(thread_func_param);
+	master_thread_run((struct mg_context *)thread_func_param);
 	return NULL;
 }
 #endif /* _WIN32 */
@@ -18738,24 +18720,13 @@ mg_start(const struct mg_callbacks *callbacks,
 
 	/* Start worker threads */
 	for (i = 0; i < ctx->cfg_worker_threads; i++) {
-		struct worker_thread_args *wta = (struct worker_thread_args *)
-		    mg_malloc_ctx(sizeof(struct worker_thread_args), ctx);
-		if (wta) {
-			wta->ctx = ctx;
-			wta->index = (int)i;
-		}
-
-		if ((wta == NULL)
-		    || (mg_start_thread_with_id(worker_thread,
-		                                wta,
-		                                &ctx->worker_threadids[i])
-		        != 0)) {
+		/* worker_thread sets up the other fields */
+		ctx->worker_connections[i].phys_ctx = ctx;
+		if (mg_start_thread_with_id(worker_thread,
+		                            &ctx->worker_connections[i],
+		                            &ctx->worker_threadids[i]) != 0) {
 
 			/* thread was not created */
-			if (wta != NULL) {
-				mg_free(wta);
-			}
-
 			if (i > 0) {
 				mg_cry_internal(fc(ctx),
 				                "Cannot start worker thread %i: error %ld",