EDK: Add implementation of data pipe producer write threshold stuff.

mojo/edk/system/remote_consumer_data_pipe_impl.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/edk/system/remote_consumer_data_pipe_impl.h"
 
 #include <string.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 239 matching lines @@
   // TODO(vtl): (End of mostly copied code.)
 
   set_producer_two_phase_max_num_bytes_written(0);
   return MOJO_RESULT_OK;
 }
 
 HandleSignalsState RemoteConsumerDataPipeImpl::ProducerGetHandleSignalsState()
     const {
   HandleSignalsState rv;
   if (consumer_open()) {
-    if (consumer_num_bytes_ < capacity_num_bytes() &&
-        !producer_in_two_phase_write())
-      rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
-    rv.satisfiable_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
+    if (!producer_in_two_phase_write()) {
+      // |producer_write_threshold_num_bytes()| is always at least 1.
+      if (capacity_num_bytes() - consumer_num_bytes_ >=
+          producer_write_threshold_num_bytes()) {
+        rv.satisfied_signals |=
+            MOJO_HANDLE_SIGNAL_WRITABLE | MOJO_HANDLE_SIGNAL_WRITE_THRESHOLD;
+      } else if (consumer_num_bytes_ < capacity_num_bytes()) {
+        rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
+      }
+    }
+    rv.satisfiable_signals |=
+        MOJO_HANDLE_SIGNAL_WRITABLE | MOJO_HANDLE_SIGNAL_WRITE_THRESHOLD;
   } else {
     rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_PEER_CLOSED;
   }
   rv.satisfiable_signals |= MOJO_HANDLE_SIGNAL_PEER_CLOSED;
   return rv;
 }
 
 void RemoteConsumerDataPipeImpl::ProducerStartSerialize(
     Channel* channel,
     size_t* max_size,
@@ skipping 151 matching lines @@
   DCHECK(channel_endpoint_);
   SetConsumerClosed();
   channel_endpoint_->DetachFromClient();
   channel_endpoint_ = nullptr;
   if (!producer_in_two_phase_write())
     DestroyBuffer();
 }
 
 }  // namespace system
 }  // namespace mojo