[pulseaudio-discuss] [PATCH] Add support of callbacks for operation cancelation

[Favonia]

- Add new API `pa_operation_set_cancel_callback`
  for users to set cancelation callbacks.
---
 src/pulse/context.c   |    9 +++++++--
 src/pulse/internal.h  |    3 +++
 src/pulse/operation.c |   25 ++++++++++++++++++++++++-
 src/pulse/operation.h |    7 +++++++
 4 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/pulse/context.c b/src/pulse/context.c
index 4618635..1ce2738 100644
--- a/src/pulse/context.c
+++ b/src/pulse/context.c
@@ -199,8 +199,13 @@ static void context_unlink(pa_context *c) {
         s = n;
     }
 
-    while (c->operations)
-        pa_operation_cancel(c->operations);
+    while (c->operations) {
+        pa_operation *o = c->operations;
+        if (o->cancel_callback)
+            o->cancel_callback(o, o->cancel_userdata);
+
+        pa_operation_cancel(o);
+    }
 
     if (c->pdispatch) {
         pa_pdispatch_unref(c->pdispatch);
diff --git a/src/pulse/internal.h b/src/pulse/internal.h
index c5bdcb1..c647c96 100644
--- a/src/pulse/internal.h
+++ b/src/pulse/internal.h
@@ -234,6 +234,8 @@ struct pa_operation {
     pa_operation_state_t state;
     void *userdata;
     pa_operation_cb_t callback;
+    void *cancel_userdata;
+    pa_operation_cancel_cb_t cancel_callback;
 
     void *private; /* some operations might need this */
 };
@@ -249,6 +251,7 @@ void pa_command_stream_event(pa_pdispatch *pd, uint32_t command, uint32_t tag, p
 void pa_command_client_event(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_tagstruct *t, void *userdata);
 void pa_command_stream_buffer_attr(pa_pdispatch *pd, uint32_t command, uint32_t tag, pa_tagstruct *t, void *userdata);
 
+pa_operation *pa_operation_new_with_cancel_callback(pa_context *c, pa_stream *s, pa_operation_cb_t callback, void *userdata, pa_operation_cancel_cb_t cancel_callback, void *cancel_userdata);
 pa_operation *pa_operation_new(pa_context *c, pa_stream *s, pa_operation_cb_t callback, void *userdata);
 void pa_operation_done(pa_operation *o);
 
diff --git a/src/pulse/operation.c b/src/pulse/operation.c
index fe160a3..85867f5 100644
--- a/src/pulse/operation.c
+++ b/src/pulse/operation.c
@@ -26,13 +26,14 @@
 #include <pulse/xmalloc.h>
 #include <pulsecore/macro.h>
 #include <pulsecore/flist.h>
+#include <pulse/fork-detect.h>
 
 #include "internal.h"
 #include "operation.h"
 
 PA_STATIC_FLIST_DECLARE(operations, 0, pa_xfree);
 
-pa_operation *pa_operation_new(pa_context *c, pa_stream *s, pa_operation_cb_t cb, void *userdata) {
+pa_operation *pa_operation_new_with_cancel_callback(pa_context *c, pa_stream *s, pa_operation_cb_t cb, void *userdata, pa_operation_cancel_cb_t cancel_cb, void *cancel_userdata) {
     pa_operation *o;
     pa_assert(c);
 
@@ -47,6 +48,8 @@ pa_operation *pa_operation_new(pa_context *c, pa_stream *s, pa_operation_cb_t cb
     o->state = PA_OPERATION_RUNNING;
     o->callback = cb;
     o->userdata = userdata;
+    o->cancel_callback = cancel_cb;
+    o->cancel_userdata = cancel_userdata;
 
     /* Refcounting is strictly one-way: from the "bigger" to the "smaller" object. */
     PA_LLIST_PREPEND(pa_operation, c->operations, o);
@@ -55,6 +58,10 @@ pa_operation *pa_operation_new(pa_context *c, pa_stream *s, pa_operation_cb_t cb
     return o;
 }
 
+pa_operation *pa_operation_new(pa_context *c, pa_stream *s, pa_operation_cb_t cb, void *userdata) {
+    return pa_operation_new_with_cancel_callback(c, s, cb, userdata, NULL, NULL);
+}
+
 pa_operation *pa_operation_ref(pa_operation *o) {
     pa_assert(o);
     pa_assert(PA_REFCNT_VALUE(o) >= 1);
@@ -91,6 +98,8 @@ static void operation_unlink(pa_operation *o) {
     o->stream = NULL;
     o->callback = NULL;
     o->userdata = NULL;
+    o->cancel_callback = NULL;
+    o->cancel_userdata = NULL;
 }
 
 static void operation_set_state(pa_operation *o, pa_operation_state_t st) {
@@ -130,3 +139,17 @@ pa_operation_state_t pa_operation_get_state(pa_operation *o) {
 
     return o->state;
 }
+
+void pa_operation_set_cancel_callback(pa_operation *o, pa_operation_cancel_cb_t cb, void *userdata) {
+    pa_assert(o);
+    pa_assert(PA_REFCNT_VALUE(o) >= 1);
+
+    if (pa_detect_fork())
+        return;
+
+    if (o->state == PA_OPERATION_DONE || o->state == PA_OPERATION_CANCELED)
+        return;
+
+    o->cancel_callback = cb;
+    o->cancel_userdata = userdata;
+}
diff --git a/src/pulse/operation.h b/src/pulse/operation.h
index b6b5691..a5f97fa 100644
--- a/src/pulse/operation.h
+++ b/src/pulse/operation.h
@@ -34,6 +34,9 @@ PA_C_DECL_BEGIN
 /** An asynchronous operation object */
 typedef struct pa_operation pa_operation;
 
+/** A generic callback for operation cancelation */
+typedef void (*pa_operation_cancel_cb_t) (pa_operation *o, void *userdata);
+
 /** Increase the reference count by one */
 pa_operation *pa_operation_ref(pa_operation *o);
 
@@ -50,6 +53,10 @@ void pa_operation_cancel(pa_operation *o);
 /** Return the current status of the operation */
 pa_operation_state_t pa_operation_get_state(pa_operation *o);
 
+/** Set the callback function that is called when the operation
+ * is canceled due to disconnection. \since 3.0 */
+void pa_operation_set_cancel_callback(pa_operation *o, pa_operation_cancel_cb_t cb, void *userdata);
+
 PA_C_DECL_END
 
 #endif
-- 
1.7.9.5