Use message mechanism to request plugin state updates

Replaces highly questionable cross-thread use of the request_update flag.

7 files changed, 21 insertions, 43 deletions

diff --git a/src/comm.h b/src/comm.h
index 11d7dc3..d570b3a 100644
--- a/src/comm.h
+++ b/src/comm.h
@@ -23,6 +23,7 @@ typedef enum {
   CONTROL_PORT_CHANGE, ///< Value change for a control port (float)
   EVENT_TRANSFER,      ///< Event transfer for a sequence port (atom)
   LATENCY_CHANGE,      ///< Change to plugin latency
+  STATE_REQUEST,       ///< Request for a plugin state update (no payload)
 } JalvMessageType;
 
 /**
diff --git a/src/jack.c b/src/jack.c
index a138f57..5ea9065 100644
--- a/src/jack.c
+++ b/src/jack.c
@@ -199,11 +199,6 @@ jack_process_cb(jack_nframes_t nframes, void* data)
           &iter, 0, 0, lv2_pos->type, lv2_pos->size, LV2_ATOM_BODY(lv2_pos));
       }
 
-      if (port->is_primary && jalv->request_update) {
-        // Plugin state has changed, request an update
-        jalv_write_get_message(&iter, &jalv->urids);
-      }
-
       if (port->sys_port) {
         // Write Jack MIDI input
         void* buf = jack_port_get_buffer(port->sys_port, nframes);
@@ -219,7 +214,6 @@ jack_process_cb(jack_nframes_t nframes, void* data)
       lv2_evbuf_reset(port->evbuf, false);
     }
   }
-  jalv->request_update = false;
 
   // Run plugin for this cycle
   const bool send_ui_updates = jalv_run(jalv, nframes);
diff --git a/src/jalv_internal.h b/src/jalv_internal.h
index 77f9993..db9ec68 100644
--- a/src/jalv_internal.h
+++ b/src/jalv_internal.h
@@ -116,7 +116,6 @@ struct JalvImpl {
   bool                rolling;         ///< Transport speed (0=stop, 1=play)
   bool                buf_size_set;    ///< True iff buffer size callback fired
   bool                has_ui;          ///< True iff a control UI is present
-  bool                request_update;  ///< True iff a plugin update is needed
   bool                safe_restore;    ///< Plugin restore() is thread-safe
   JalvFeatures        features;
   const LV2_Feature** feature_list;
diff --git a/src/portaudio.c b/src/portaudio.c
index 0a7fa5a..d0c4aa3 100644
--- a/src/portaudio.c
+++ b/src/portaudio.c
@@ -49,19 +49,10 @@ pa_process_cb(const void*                     inputs,
         lilv_instance_connect_port(
           jalv->instance, i, ((float**)outputs)[out_index++]);
       }
-    } else if (port->type == TYPE_EVENT && port->flow == FLOW_INPUT) {
-      lv2_evbuf_reset(port->evbuf, true);
-      if (port->is_primary && jalv->request_update) {
-        // Plugin state has changed, request an update
-        LV2_Evbuf_Iterator iter = lv2_evbuf_begin(port->evbuf);
-        jalv_write_get_message(&iter, &jalv->urids);
-      }
     } else if (port->type == TYPE_EVENT) {
-      // Clear event output for plugin to write to
-      lv2_evbuf_reset(port->evbuf, false);
+      lv2_evbuf_reset(port->evbuf, port->flow == FLOW_INPUT);
     }
   }
-  jalv->request_update = false;
 
   // Run plugin for this cycle
   const bool send_ui_updates = jalv_run(jalv, nframes);
diff --git a/src/process.c b/src/process.c
index 2b5a11e..49e5a1f 100644
--- a/src/process.c
+++ b/src/process.c
@@ -18,19 +18,6 @@
 #include <assert.h>
 #include <stddef.h>
 
-int
-jalv_write_get_message(LV2_Evbuf_Iterator* const iter,
-                       const JalvURIDs* const    urids)
-{
-  const LV2_Atom_Object get = {
-    {sizeof(LV2_Atom_Object_Body), urids->atom_Object},
-    {0U, urids->patch_Get},
-  };
-
-  return lv2_evbuf_write(
-    iter, 0, 0, get.atom.type, get.atom.size, LV2_ATOM_BODY_CONST(&get));
-}
-
 static int
 ring_error(const char* const message)
 {
@@ -79,6 +66,21 @@ apply_ui_events(Jalv* const jalv, const uint32_t nframes)
       lv2_evbuf_write(
         &e, nframes, 0U, atom->type, atom->size, LV2_ATOM_BODY_CONST(atom));
 
+    } else if (header.type == STATE_REQUEST) {
+      JalvPort* const port = &jalv->ports[jalv->control_in];
+      assert(port->type == TYPE_EVENT);
+      assert(port->flow == FLOW_INPUT);
+      assert(port->evbuf);
+
+      LV2_Evbuf_Iterator    iter = lv2_evbuf_end(port->evbuf);
+      const LV2_Atom_Object get  = {
+        {sizeof(LV2_Atom_Object_Body), jalv->urids.atom_Object},
+        {0U, jalv->urids.patch_Get},
+      };
+
+      lv2_evbuf_write(
+        &iter, nframes, 0U, get.atom.type, get.atom.size, &get.body);
+
     } else {
       return ring_error("Unknown message type received from UI ring\n");
     }
diff --git a/src/process.h b/src/process.h
index 35acd24..366d30e 100644
--- a/src/process.h
+++ b/src/process.h
@@ -5,9 +5,7 @@
 #define JALV_PROCESS_H
 
 #include "attributes.h"
-#include "lv2_evbuf.h"
 #include "types.h"
-#include "urids.h"
 
 #include <stdbool.h>
 #include <stdint.h>
@@ -17,15 +15,6 @@ JALV_BEGIN_DECLS
 // Code and data used in the realtime process thread
 
 /**
-   Write a patch:Get message to an event buffer.
-
-   This is used to request an update of plugin state when it has changed or the
-   UI needs updating for whatever reason.
-*/
-int
-jalv_write_get_message(LV2_Evbuf_Iterator* iter, const JalvURIDs* urids);
-
-/**
    Run the plugin for a block of frames.
 
    Applies any pending messages from the UI, runs the plugin instance, and
diff --git a/src/state.c b/src/state.c
index e75ab3c..1bfe6ce 100644
--- a/src/state.c
+++ b/src/state.c
@@ -13,6 +13,7 @@
 #include "lv2/core/lv2.h"
 #include "lv2/state/state.h"
 #include "zix/attributes.h"
+#include "zix/ring.h"
 #include "zix/sem.h"
 #include "zix/status.h"
 
@@ -193,8 +194,9 @@ jalv_apply_state(Jalv* jalv, const LilvState* state)
     state, jalv->instance, set_port_value, jalv, 0, state_features);
 
   if (must_pause) {
-    jalv->request_update = true;
-    jalv->play_state     = JALV_RUNNING;
+    const JalvMessageHeader msg = {STATE_REQUEST, 0U};
+    zix_ring_write(jalv->ui_to_plugin, &msg, sizeof(msg));
+    jalv->play_state = JALV_RUNNING;
   }
 }