From 9ec2a520ee3fdc78605db4ee7b0019a1630f1bfd Mon Sep 17 00:00:00 2001
From: Craig Tiller <ctiller@google.com>
Date: Fri, 29 May 2015 22:46:54 -0700
Subject: [PATCH] Add channel refcount debugging

---
 src/core/surface/call.c    |  4 ++--
 src/core/surface/channel.c | 26 +++++++++++++++++++-------
 src/core/surface/channel.h | 15 +++++++++++++++
 src/core/surface/server.c  |  6 +++---
 4 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index eb0651e8562..3a573928f4a 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -280,7 +280,7 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
   }
   call->send_initial_metadata_count = add_initial_metadata_count;
   call->send_deadline = send_deadline;
-  grpc_channel_internal_ref(channel);
+  GRPC_CHANNEL_INTERNAL_REF(channel, "call");
   call->metadata_context = grpc_channel_get_metadata_context(channel);
   grpc_sopb_init(&call->send_ops);
   grpc_sopb_init(&call->recv_ops);
@@ -333,7 +333,7 @@ static void destroy_call(void *call, int ignored_success) {
   size_t i;
   grpc_call *c = call;
   grpc_call_stack_destroy(CALL_STACK_FROM_CALL(c));
-  grpc_channel_internal_unref(c->channel);
+  GRPC_CHANNEL_INTERNAL_UNREF(c->channel, "call");
   gpr_mu_destroy(&c->mu);
   for (i = 0; i < STATUS_SOURCE_COUNT; i++) {
     if (c->status[i].details) {
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index be9da2b7f95..d8fd4427026 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -168,8 +168,14 @@ grpc_call *grpc_channel_create_registered_call(
       grpc_mdelem_ref(rc->authority), deadline);
 }
 
-void grpc_channel_internal_ref(grpc_channel *channel) {
-  gpr_ref(&channel->refs);
+#ifdef GRPC_CHANNEL_REF_COUNT_DEBUG
+void grpc_channel_internal_ref(grpc_channel *c, const char *reason) {
+  gpr_log(GPR_DEBUG, "CHANNEL:   ref %p %d -> %d [%s]", c, c->refs.count,
+          c->refs.count + 1, reason);
+#else
+void grpc_channel_internal_ref(grpc_channel *c) {
+#endif
+  gpr_ref(&c->refs);
 }
 
 static void destroy_channel(void *p, int ok) {
@@ -191,9 +197,15 @@ static void destroy_channel(void *p, int ok) {
   gpr_free(channel);
 }
 
-void grpc_channel_internal_unref(grpc_channel *channel) {
-  if (gpr_unref(&channel->refs)) {
-    grpc_iomgr_add_callback(destroy_channel, channel);
+#ifdef GRPC_CHANNEL_REF_COUNT_DEBUG
+void grpc_channel_internal_unref(grpc_channel *c, const char *reason) {
+  gpr_log(GPR_DEBUG, "CHANNEL: unref %p %d -> %d [%s]", c, c->refs.count,
+          c->refs.count - 1, reason);
+#else
+void grpc_channel_internal_unref(grpc_channel *c) {
+#endif
+  if (gpr_unref(&c->refs)) {
+    grpc_iomgr_add_callback(destroy_channel, c);
   }
 }
 
@@ -213,11 +225,11 @@ void grpc_channel_destroy(grpc_channel *channel) {
   op.dir = GRPC_CALL_DOWN;
   elem->filter->channel_op(elem, NULL, &op);
 
-  grpc_channel_internal_unref(channel);
+  GRPC_CHANNEL_INTERNAL_UNREF(channel, "channel");
 }
 
 void grpc_client_channel_closed(grpc_channel_element *elem) {
-  grpc_channel_internal_unref(CHANNEL_FROM_TOP_ELEM(elem));
+  GRPC_CHANNEL_INTERNAL_UNREF(CHANNEL_FROM_TOP_ELEM(elem), "closed");
 }
 
 grpc_channel_stack *grpc_channel_get_channel_stack(grpc_channel *channel) {
diff --git a/src/core/surface/channel.h b/src/core/surface/channel.h
index 388be357113..e11505a4e4c 100644
--- a/src/core/surface/channel.h
+++ b/src/core/surface/channel.h
@@ -48,7 +48,22 @@ gpr_uint32 grpc_channel_get_max_message_length(grpc_channel *channel);
 
 void grpc_client_channel_closed(grpc_channel_element *elem);
 
+#define GRPC_CHANNEL_REF_COUNT_DEBUG
+
+#ifdef GRPC_CHANNEL_REF_COUNT_DEBUG
+void grpc_channel_internal_ref(grpc_channel *channel, const char *reason);
+void grpc_channel_internal_unref(grpc_channel *channel, const char *reason);
+#define GRPC_CHANNEL_INTERNAL_REF(channel, reason) \
+  grpc_channel_internal_ref(channel, reason)
+#define GRPC_CHANNEL_INTERNAL_UNREF(channel, reason) \
+  grpc_channel_internal_unref(channel, reason)
+#else
 void grpc_channel_internal_ref(grpc_channel *channel);
 void grpc_channel_internal_unref(grpc_channel *channel);
+#define GRPC_CHANNEL_INTERNAL_REF(channel, reason) \
+  grpc_channel_internal_ref(channel)
+#define GRPC_CHANNEL_INTERNAL_UNREF(channel, reason) \
+  grpc_channel_internal_unref(channel)
+#endif
 
 #endif /* GRPC_INTERNAL_CORE_SURFACE_CHANNEL_H */
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 5d172ba9132..fc5b7b0bad4 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -306,7 +306,7 @@ static void orphan_channel(channel_data *chand) {
 static void finish_destroy_channel(void *cd, int success) {
   channel_data *chand = cd;
   grpc_server *server = chand->server;
-  grpc_channel_internal_unref(chand->channel);
+  GRPC_CHANNEL_INTERNAL_UNREF(chand->channel, "server");
   server_unref(server);
 }
 
@@ -573,14 +573,14 @@ static void finish_shutdown_channel(void *p, int success) {
                    grpc_channel_get_channel_stack(sca->chand->channel), 0),
                NULL, &op);
   }
-  grpc_channel_internal_unref(sca->chand->channel);
+  GRPC_CHANNEL_INTERNAL_UNREF(sca->chand->channel, "shutdown");
 }
 
 static void shutdown_channel(channel_data *chand, int send_goaway,
                              int send_disconnect) {
   shutdown_channel_args *sca;
   gpr_log(GPR_DEBUG, "shutdown_channel: %p %d %d", chand, send_goaway, send_disconnect);
-  grpc_channel_internal_ref(chand->channel);
+  GRPC_CHANNEL_INTERNAL_REF(chand->channel, "shutdown");
   sca = gpr_malloc(sizeof(shutdown_channel_args));
   sca->chand = chand;
   sca->send_goaway = send_goaway;