added provider finalize callbacks

include/margo.h

@@ -172,6 +172,45 @@ void margo_push_finalize_callback(
     void(*cb)(void*), 
     void* uargs);
 
+/**
+ * @brief Removes the last finalize callback that was pushed into the margo instance
+ * without calling it. If a callback was remoted, this function returns 1, otherwise
+ * it returns 0.
+ *
+ * @param mid Margo instance.
+ */
+int margo_pop_finalize_callback(
+    margo_instance_id mid);
+
+/**
+ * @brief Installs a callback to be called before the margo instance is finalized.
+ * The owner pointer allows to identify callbacks installed by particular providers.
+ * Note that the same owner can install multiple callbacks. If they are not popped,
+ * they will be called in reverse order of installation by the margo cleanup procedure.
+ *
+ * @param mid The margo instance
+ * @param owner Owner of the callback (to be used when popping callbacks)
+ * @param cb Callback to install
+ * @param uargs User-provider argument to pass to the callback when called
+ */
+void margo_provider_push_finalize_callback(
+    margo_instance_id mid,
+    void* owner,
+    void(*cb)(void*),
+    void* uargs);
+
+/**
+ * @brief Removes the last finalize callback that was pushed into the margo instance
+ * by the specified owner. If a callback was remoted, this function returns 1, otherwise
+ * it returns 0.
+ *
+ * @param mid Margo instance.
+ * @param owner Owner of the callback.
+ */
+int margo_provider_pop_finalize_callback(
+    margo_instance_id mid,
+    void* owner);
+
 /**
  * Allows the passed Margo instance to be shut down remotely
  * using margo_shutdown_remote_instance().

src/margo.c

@@ -48,6 +48,7 @@ struct margo_handle_cache_el
 
 struct margo_finalize_cb
 {
+    void* owner;
     void(*callback)(void*);
     void* uargs;
     struct margo_finalize_cb* next;
@@ -528,6 +529,25 @@ hg_bool_t margo_is_listening(
 
 void margo_push_finalize_callback(
             margo_instance_id mid,
+            void(*cb)(void*),
+            void* uargs)
+{
+    margo_provider_push_finalize_callback(
+            mid,
+            NULL,
+            cb,
+            uargs);
+}
+
+int margo_pop_finalize_callback(
+                    margo_instance_id mid)
+{   
+    return margo_provider_pop_finalize_callback(mid, NULL);
+}
+
+void margo_provider_push_finalize_callback(
+            margo_instance_id mid,
+            void* owner,
             void(*cb)(void*),                  
             void* uargs)
 {
@@ -535,14 +555,35 @@ void margo_push_finalize_callback(
 
     struct margo_finalize_cb* fcb = 
         (struct margo_finalize_cb*)malloc(sizeof(*fcb));
+    fcb->owner    = owner;
     fcb->callback = cb;
-    fcb->uargs = uargs;
+    fcb->uargs    = uargs;
 
     struct margo_finalize_cb* next = mid->finalize_cb;
     fcb->next = next;
     mid->finalize_cb = fcb;
 }
 
+int margo_provider_pop_finalize_callback(
+            margo_instance_id mid,
+            void* owner)
+{
+    struct margo_finalize_cb* prev = NULL;
+    struct margo_finalize_cb* fcb  =  mid->finalize_cb;
+    while(fcb != NULL && fcb->owner != owner) {
+        prev = fcb;
+        fcb = fcb->next;
+    }
+    if(fcb == NULL) return 0;
+    if(prev == NULL) {
+        mid->finalize_cb = fcb->next;
+    } else {
+        prev->next = fcb->next;
+    }
+    free(fcb);
+    return 1;
+}
+
 void margo_enable_remote_shutdown(margo_instance_id mid)
 {
     mid->enable_remote_shutdown = 1;