From c2f93e23d00e8a5ef74e9dcb5249ddbd7873e044 Mon Sep 17 00:00:00 2001
From: sky <sky@chromium.org>
Date: Fri, 18 Sep 2015 15:12:55 -0700
Subject: [PATCH] Adds comment for InterfacePtr::PassInterface() as well as
 DCHECK

The DCHECK will help catch errors early.

BUG=533107
TEST=none
R=yzshen@chromium.org

Review URL: https://codereview.chromium.org/1355713002

Cr-Commit-Position: refs/heads/master@{#349781}
---
 third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h      | 5 +++++
 .../mojo/src/mojo/public/cpp/bindings/lib/interface_ptr_internal.h | 5 +++++
 third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc        | 7 ++-----
 third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h         | 5 +++++
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h b/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h
index 00514ddb5427..7908ca8b3d80 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h
@@ -139,7 +139,12 @@ class InterfacePtr {
   // Unbinds the InterfacePtr and returns the information which could be used
   // to setup an InterfacePtr again. This method may be used to move the proxy
   // to a different thread (see class comments for details).
+  //
+  // It is an error to call PassInterface() while there are pending responses.
+  // TODO: fix this restriction, it's not always obvious when there is a
+  // pending response.
   InterfacePtrInfo<Interface> PassInterface() {
+    MOJO_DCHECK(!internal_state_.has_pending_callbacks());
     State state;
     internal_state_.Swap(&state);
 
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/interface_ptr_internal.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/interface_ptr_internal.h
index 5ef6742847b4..1c2cad85845e 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/interface_ptr_internal.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/interface_ptr_internal.h
@@ -119,6 +119,11 @@ class InterfacePtrState {
     router_->set_connection_error_handler(error_handler);
   }
 
+  // Returns true if bound and awaiting a response to a message.
+  bool has_pending_callbacks() const {
+    return router_ && router_->has_pending_responders();
+  }
+
   Router* router_for_testing() {
     ConfigureProxyIfNecessary();
     return router_;
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc
index e64f1fa0a122..5a7c7e2f9743 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc
@@ -87,11 +87,8 @@ Router::Router(ScopedMessagePipeHandle message_pipe,
 Router::~Router() {
   weak_self_.set_value(nullptr);
 
-  for (ResponderMap::const_iterator i = responders_.begin();
-       i != responders_.end();
-       ++i) {
-    delete i->second;
-  }
+  for (auto& pair : responders_)
+    delete pair.second;
 }
 
 bool Router::Accept(Message* message) {
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h
index dcca1f5a293e..d7e5a68d6e25 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h
@@ -76,6 +76,9 @@ class Router : public MessageReceiverWithResponder {
 
   MessagePipeHandle handle() const { return connector_.handle(); }
 
+  // Returns true if this Router has any pending callbacks.
+  bool has_pending_responders() const { return !responders_.empty(); }
+
  private:
   typedef std::map<uint64_t, MessageReceiver*> ResponderMap;
 
@@ -98,6 +101,8 @@ class Router : public MessageReceiverWithResponder {
   Connector connector_;
   SharedData<Router*> weak_self_;
   MessageReceiverWithResponderStatus* incoming_receiver_;
+  // Maps from the id of a response to the MessageReceiver that handles the
+  // response.
   ResponderMap responders_;
   uint64_t next_request_id_;
   bool testing_mode_;
-- 
2.11.4.GIT