[NaCl SDK] nacl_io: Add flow control the JavaScript pipes.

native_client_sdk/src/libraries/nacl_io/pipe/pipe_node.cc

Index: native_client_sdk/src/libraries/nacl_io/pipe/pipe_node.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/pipe/pipe_node.cc b/native_client_sdk/src/libraries/nacl_io/pipe/pipe_node.cc
index aeb54d5d37f6e5c7cebe95d9791a495360310a02..ec25f2744c2038315142b7a1d1e0701195683874 100644
--- a/native_client_sdk/src/libraries/nacl_io/pipe/pipe_node.cc
+++ b/native_client_sdk/src/libraries/nacl_io/pipe/pipe_node.cc
@@ -20,9 +20,12 @@ const size_t kDefaultPipeSize = 512 * 1024;
 namespace nacl_io {
 
 PipeNode::PipeNode(Filesystem* fs)
-    : StreamNode(fs), pipe_(new PipeEventEmitter(kDefaultPipeSize)) {}
+    : StreamNode(fs), pipe_(new PipeEventEmitter(kDefaultPipeSize)) {
+}
 
-EventEmitter* PipeNode::GetEventEmitter() { return pipe_.get(); }
+PipeEventEmitter* PipeNode::GetEventEmitter() {
+  return pipe_.get();
+}
 
 Error PipeNode::Read(const HandleAttr& attr,
                      void* buf,
@@ -32,10 +35,12 @@ Error PipeNode::Read(const HandleAttr& attr,
 
   EventListenerLock wait(GetEventEmitter());
   Error err = wait.WaitOnEvent(POLLIN, ms);
+  if (err == ETIMEDOUT)

[binji, 2014/05/01 20:22:31]

Do we want to do this everywhere?

If not, it still might be nice to have a flag to handle this in WaitOnEvent.

[Sam Clegg, 2014/05/01 22:16:55]

There may be test code that expects otherwise but in practice we
want to do this everywhere I think yes.

Might leave that for a separate CL.

+    err = EWOULDBLOCK;
   if (err)
     return err;
 
-  *out_bytes = pipe_->Read_Locked(static_cast<char*>(buf), count);
+  *out_bytes = GetEventEmitter()->Read_Locked(static_cast<char*>(buf), count);
   return 0;
 }
 
@@ -47,10 +52,13 @@ Error PipeNode::Write(const HandleAttr& attr,
 
   EventListenerLock wait(GetEventEmitter());
   Error err = wait.WaitOnEvent(POLLOUT, ms);
+  if (err == ETIMEDOUT)
+    err = EWOULDBLOCK;
   if (err)
     return err;
 
-  *out_bytes = pipe_->Write_Locked(static_cast<const char*>(buf), count);
+  *out_bytes = GetEventEmitter()->Write_Locked(static_cast<const char*>(buf),
+                                               count);
   return 0;
 }