Mojo: Armed Watchers

content/child/url_response_body_consumer.cc

Index: content/child/url_response_body_consumer.cc
diff --git a/content/child/url_response_body_consumer.cc b/content/child/url_response_body_consumer.cc
index a51b4f70a36bb43616203c12e30743193268423c..ebc089ca56c0681248c2bd330e25c3fe2e95259e 100644
--- a/content/child/url_response_body_consumer.cc
+++ b/content/child/url_response_body_consumer.cc
@@ -48,15 +48,15 @@ URLResponseBodyConsumer::URLResponseBodyConsumer(
     : request_id_(request_id),
       resource_dispatcher_(resource_dispatcher),
       handle_(std::move(handle)),
-      handle_watcher_(FROM_HERE, task_runner),
+      handle_watcher_(FROM_HERE,
+                      mojo::SimpleWatcher::ArmingPolicy::MANUAL,
+                      task_runner),
       task_runner_(task_runner),
       has_seen_end_of_data_(!handle_.is_valid()) {
-  handle_watcher_.Start(
+  handle_watcher_.Watch(
       handle_.get(), MOJO_HANDLE_SIGNAL_READABLE,
       base::Bind(&URLResponseBodyConsumer::OnReadable, base::Unretained(this)));
-  task_runner_->PostTask(
-      FROM_HERE, base::Bind(&URLResponseBodyConsumer::OnReadable, AsWeakPtr(),
-                            MOJO_RESULT_OK));
+  handle_watcher_.ArmOrNotify();
 }
 
 URLResponseBodyConsumer::~URLResponseBodyConsumer() {}
@@ -91,9 +91,7 @@ void URLResponseBodyConsumer::Reclaim(uint32_t size) {
   if (is_in_on_readable_)
     return;
 
-  task_runner_->PostTask(
-      FROM_HERE, base::Bind(&URLResponseBodyConsumer::OnReadable, AsWeakPtr(),
-                            MOJO_RESULT_OK));
+  handle_watcher_.ArmOrNotify();
 }
 
 void URLResponseBodyConsumer::OnReadable(MojoResult unused) {
@@ -112,8 +110,10 @@ void URLResponseBodyConsumer::OnReadable(MojoResult unused) {
     uint32_t available = 0;
     MojoResult result = mojo::BeginReadDataRaw(
         handle_.get(), &buffer, &available, MOJO_READ_DATA_FLAG_NONE);
-    if (result == MOJO_RESULT_SHOULD_WAIT || result == MOJO_RESULT_BUSY)
+    if (result == MOJO_RESULT_SHOULD_WAIT || result == MOJO_RESULT_BUSY) {

[yhirano, 2017/03/14 05:41:55]

Is ArmOrNotify unnecessary on the MOJO_RESULT_BUSY case?

[Ken Rockot(use gerrit already), 2017/03/14 14:17:40]

No, that implies we're in a two-phase read, which ends with EndReadDataRaw. We
always ArmOrNotify after that.

[yhirano, 2017/03/14 15:32:10]

Sorry, I don't understand: My understanding is "we're in a two-phase read, which
ends with EndReadDataRaw." The EndReadDataRaw is on L88, and this ArmOrNotify
will continue posting tasks until Reclaim is called.

[Ken Rockot(use gerrit already), 2017/03/14 15:52:21]

Ah, sorry, I misunderstood your comment and overlooked this code. I thought you
were suggesting that we did need ArmOrNotify when the result is
MOJO_RESULT_BUSY. You're right to suggest that we don't. Fixed.

+      handle_watcher_.ArmOrNotify();
       return;
+    }
     if (result == MOJO_RESULT_FAILED_PRECONDITION) {
       has_seen_end_of_data_ = true;
       NotifyCompletionIfAppropriate();
@@ -134,9 +134,7 @@ void URLResponseBodyConsumer::OnReadable(MojoResult unused) {
       // to the next task.
       result = mojo::EndReadDataRaw(handle_.get(), 0);
       DCHECK_EQ(result, MOJO_RESULT_OK);
-      task_runner_->PostTask(FROM_HERE,
-                             base::Bind(&URLResponseBodyConsumer::OnReadable,
-                                        AsWeakPtr(), MOJO_RESULT_OK));
+      handle_watcher_.ArmOrNotify();
       return;
     }
     num_bytes_consumed += available;