impl-node: add backwards compat for old clients

Bump the client-node version to 6. Older clients expect the server to
prepare the activation counters so make a flag to do that.

src/modules/module-client-node/client-node.c

@@ -1799,6 +1799,13 @@ struct pw_impl_client_node *pw_impl_client_node_new(struct pw_resource *resource
 
 	this->node->remote = true;
 	this->flags = 0;
+	if (resource->version < 5) {
+		pw_log_warn("using server side driver for old client version %d", resource->version);
+	}
+	if (resource->version < 6) {
+		this->node->server_prepare = true;
+		pw_log_warn("using server side prepare for old client version %d", resource->version);
+	}
 
 	pw_resource_add_listener(this->resource,
 				&impl->resource_listener,

src/pipewire/extensions/client-node.h

@@ -22,7 +22,12 @@ extern "C" {
  */
 #define PW_TYPE_INTERFACE_ClientNode		PW_TYPE_INFO_INTERFACE_BASE "ClientNode"
 
-#define PW_VERSION_CLIENT_NODE			5
+/*
+ * version 4: new port_set_mix_info event added
+ * version 5: driver nodes are scheduled on the client
+ * version 6: nodes activate peer links themselves when ready
+ */
+#define PW_VERSION_CLIENT_NODE			6
 struct pw_client_node;
 
 #define PW_EXTENSION_MODULE_CLIENT_NODE		PIPEWIRE_MODULE_PREFIX "module-client-node"

src/pipewire/impl-node.c

@@ -154,17 +154,19 @@ do_node_prepare(struct spa_loop *loop, bool async, uint32_t seq,
 	if (this->rt.prepared)
 		return 0;
 
-	/* clear the eventfd in case it was written to while the node was stopped */
+	if (!this->server_prepare) {
-	res = spa_system_eventfd_read(this->rt.target.system, this->source.fd, &dummy);
+		/* clear the eventfd in case it was written to while the node was stopped */
-	if (SPA_UNLIKELY(res != -EAGAIN && res != 0))
+		res = spa_system_eventfd_read(this->rt.target.system, this->source.fd, &dummy);
-		pw_log_warn("%p: read failed %m", this);
+		if (SPA_UNLIKELY(res != -EAGAIN && res != 0))
+			pw_log_warn("%p: read failed %m", this);
 
+		spa_loop_add_source(loop, &this->source);
+	}
 	SPA_ATOMIC_STORE(this->rt.target.activation->status, PW_NODE_ACTIVATION_FINISHED);
-	spa_loop_add_source(loop, &this->source);
 
 	spa_list_for_each(t, &this->rt.target_list, link) {
 		/* we can now trigger ourself */
-		if (t->id == this->info.id)
+		if (t->id == this->info.id || this->server_prepare)
 			activate_target(this, t);
 	}
 
@@ -200,7 +202,8 @@ do_node_unprepare(struct spa_loop *loop, bool async, uint32_t seq,
 	spa_list_for_each(t, &this->rt.target_list, link)
 		deactivate_target(this, t, trigger);
 
-	spa_loop_remove_source(loop, &this->source);
+	if (!this->server_prepare)
+		spa_loop_remove_source(loop, &this->source);
 
 	this->rt.prepared = false;
 	return 0;
@@ -208,7 +211,7 @@ do_node_unprepare(struct spa_loop *loop, bool async, uint32_t seq,
 
 static void add_node_to_graph(struct pw_impl_node *node)
 {
-	if (node->remote)
+	if (node->remote && !node->server_prepare)
 		return;
 
 	pw_loop_invoke(node->data_loop, do_node_prepare, 1, NULL, 0, true, node);
@@ -216,7 +219,7 @@ static void add_node_to_graph(struct pw_impl_node *node)
 
 static void remove_node_from_graph(struct pw_impl_node *node)
 {
-	if (node->remote)
+	if (node->remote && !node->server_prepare)
 		return;
 
 	pw_loop_invoke(node->data_loop, do_node_unprepare, 1, NULL, 0, true, node);

src/pipewire/private.h

@@ -740,6 +740,7 @@ struct pw_impl_node {
 	unsigned int sync:1;		/**< the sync-groups are active */
 	unsigned int transport:1;	/**< the transport is active */
 	unsigned int async:1;		/**< async processing, one cycle latency */
+	unsigned int server_prepare:1;	/**< prepare links server side for old clients */
 
 	uint32_t port_user_data_size;	/**< extra size for port user data */