client API: add returning of data from async commands

This was not done sooner out of laziness.

DOCS/client-api-changes.rst

@@ -33,6 +33,9 @@ API changes
 ::
 
  --- mpv 0.29.0 ---
+ 1.102  - redo handling of async commands
+        - add mpv_event_command and make it possible to return values from
+          commands issued with mpv_command_async() or mpv_command_node_async()
  1.101  - add MPV_RENDER_PARAM_ADVANCED_CONTROL and related API
         - add MPV_RENDER_PARAM_NEXT_FRAME_INFO and related symbols
         - add MPV_RENDER_PARAM_BLOCK_FOR_TARGET_TIME

libmpv/client.h

@@ -223,7 +223,7 @@ extern "C" {
  * relational operators (<, >, <=, >=).
  */
 #define MPV_MAKE_VERSION(major, minor) (((major) << 16) | (minor) | 0UL)
-#define MPV_CLIENT_API_VERSION MPV_MAKE_VERSION(1, 101)
+#define MPV_CLIENT_API_VERSION MPV_MAKE_VERSION(1, 102)
 
 /**
  * The API user is allowed to "#define MPV_ENABLE_DEPRECATED 0" before
@@ -967,10 +967,11 @@ int mpv_command_string(mpv_handle *ctx, const char *args);
  * Same as mpv_command, but run the command asynchronously.
  *
  * Commands are executed asynchronously. You will receive a
- * MPV_EVENT_COMMAND_REPLY event. (This event will also have an
- * error code set if running the command failed.)
+ * MPV_EVENT_COMMAND_REPLY event. This event will also have an
+ * error code set if running the command failed. For commands that
+ * return data, the data is put into mpv_event_command.result.
  *
- * * Safe to be called from mpv render API threads.
+ * Safe to be called from mpv render API threads.
  *
  * @param reply_userdata the value mpv_event.reply_userdata of the reply will
  *                       be set to (see section about asynchronous calls)
@@ -985,8 +986,7 @@ int mpv_command_async(mpv_handle *ctx, uint64_t reply_userdata,
  * function is to mpv_command_node() what mpv_command_async() is to
  * mpv_command().
  *
- * See mpv_command_async() for details. Retrieving the result is not
- * supported yet.
+ * See mpv_command_async() for details.
  *
  * Safe to be called from mpv render API threads.
  *
@@ -1211,7 +1211,8 @@ typedef enum mpv_event_id {
      */
     MPV_EVENT_SET_PROPERTY_REPLY = 4,
     /**
-     * Reply to a mpv_command_async() request.
+     * Reply to a mpv_command_async() or mpv_command_node_async() request.
+     * See also mpv_event and mpv_event_command.
      */
     MPV_EVENT_COMMAND_REPLY     = 5,
     /**
@@ -1558,6 +1559,17 @@ typedef struct mpv_event_hook {
     uint64_t id;
 } mpv_event_hook;
 
+// Since API version 1.102.
+typedef struct mpv_event_command {
+    /**
+     * Result data of the command. Note that success/failure is signaled
+     * separately via mpv_event.error. This field is only for result data
+     * in case of success. Most commands leave it at MPV_FORMAT_NONE. Set
+     * to MPV_FORMAT_NONE on failure.
+     */
+    mpv_node result;
+} mpv_event_command;
+
 typedef struct mpv_event {
     /**
      * One of mpv_event. Keep in mind that later ABI compatible releases might
@@ -1595,6 +1607,7 @@ typedef struct mpv_event {
      *  MPV_EVENT_CLIENT_MESSAGE:         mpv_event_client_message*
      *  MPV_EVENT_END_FILE:               mpv_event_end_file*
      *  MPV_EVENT_HOOK:                   mpv_event_hook*
+     *  MPV_EVENT_COMMAND_REPLY*          mpv_event_command*
      *  other: NULL
      *
      * Note: future enhancements might add new event structs for existing or new

player/client.c

@@ -1108,7 +1108,6 @@ int mpv_command_string(mpv_handle *ctx, const char *args)
 struct async_cmd_request {
     struct MPContext *mpctx;
     struct mp_cmd *cmd;
-    int status;
     struct mpv_handle *reply_ctx;
     uint64_t userdata;
 };
@@ -1117,11 +1116,17 @@ static void async_cmd_complete(struct mp_cmd_ctx *cmd)
 {
     struct async_cmd_request *req = cmd->on_completion_priv;
 
-    req->status = cmd->success ? 0 : MPV_ERROR_COMMAND;
+    struct mpv_event_command *data = talloc_zero(NULL, struct mpv_event_command);
+    data->result = cmd->result;
+    cmd->result = (mpv_node){0};
+    talloc_steal(data, node_get_alloc(&data->result));
 
-    // Async command invocation - send a reply message.
-    status_reply(req->reply_ctx, MPV_EVENT_COMMAND_REPLY,
-                 req->userdata, req->status);
+    struct mpv_event reply = {
+        .event_id = MPV_EVENT_COMMAND_REPLY,
+        .data = data,
+        .error = cmd->success ? 0 : MPV_ERROR_COMMAND,
+    };
+    send_reply(req->reply_ctx, req->userdata, &reply);
 
     talloc_free(req);
 }