Mojo: Armed Watchers

mojo/edk/system/data_pipe_producer_dispatcher.cc

Index: mojo/edk/system/data_pipe_producer_dispatcher.cc
diff --git a/mojo/edk/system/data_pipe_producer_dispatcher.cc b/mojo/edk/system/data_pipe_producer_dispatcher.cc
index 8c1993aa5d36dd474b904eabeb5f1169465e5a9c..676196ed3dbe78e36b61684de3156f59c3ecddc9 100644
--- a/mojo/edk/system/data_pipe_producer_dispatcher.cc
+++ b/mojo/edk/system/data_pipe_producer_dispatcher.cc
@@ -79,6 +79,7 @@ DataPipeProducerDispatcher::DataPipeProducerDispatcher(
       node_controller_(node_controller),
       control_port_(control_port),
       pipe_id_(pipe_id),
+      watchers_(this),
       shared_ring_buffer_(shared_ring_buffer),
       available_capacity_(options_.capacity_num_bytes) {
   if (initialized) {
@@ -97,28 +98,6 @@ MojoResult DataPipeProducerDispatcher::Close() {
   return CloseNoLock();
 }
 
-MojoResult DataPipeProducerDispatcher::Watch(
-    MojoHandleSignals signals,
-    const Watcher::WatchCallback& callback,
-    uintptr_t context) {
-  base::AutoLock lock(lock_);
-
-  if (is_closed_ || in_transit_)
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return awakable_list_.AddWatcher(
-      signals, callback, context, GetHandleSignalsStateNoLock());
-}
-
-MojoResult DataPipeProducerDispatcher::CancelWatch(uintptr_t context) {
-  base::AutoLock lock(lock_);
-
-  if (is_closed_ || in_transit_)
-    return MOJO_RESULT_INVALID_ARGUMENT;
-
-  return awakable_list_.RemoveWatcher(context);
-}
-
 MojoResult DataPipeProducerDispatcher::WriteData(const void* elements,
                                                  uint32_t* num_bytes,
                                                  MojoWriteDataFlags flags) {
@@ -139,8 +118,15 @@ MojoResult DataPipeProducerDispatcher::WriteData(const void* elements,
 
   if ((flags & MOJO_WRITE_DATA_FLAG_ALL_OR_NONE) &&
       (*num_bytes > available_capacity_)) {
+    if (flags & MOJO_WRITE_DATA_FLAG_CLEAR_SIGNAL) {
+      suppress_writable_signal_ = true;
+      watchers_.NotifyState(GetHandleSignalsStateNoLock());
+    }
     // Don't return "should wait" since you can't wait for a specified amount of
     // data.
+    //
+    // TODO(rockot): Reconsider this case now that we have support for minimum
+    // signaling capacity.
     return MOJO_RESULT_OUT_OF_RANGE;
   }
 
@@ -179,6 +165,7 @@ MojoResult DataPipeProducerDispatcher::WriteData(const void* elements,
   HandleSignalsState new_state = GetHandleSignalsStateNoLock();
   if (!new_state.equals(old_state))
     awakable_list_.AwakeForStateChange(new_state);
+  watchers_.NotifyState(new_state);
 
   base::AutoUnlock unlock(lock_);
   NotifyWrite(num_bytes_to_write);
@@ -193,6 +180,12 @@ MojoResult DataPipeProducerDispatcher::BeginWriteData(
   base::AutoLock lock(lock_);
   if (!shared_ring_buffer_ || in_transit_)
     return MOJO_RESULT_INVALID_ARGUMENT;
+
+  // These flags may not be used in two-phase mode.
+  if ((flags & MOJO_WRITE_DATA_FLAG_ALL_OR_NONE) ||
+      (flags & MOJO_WRITE_DATA_FLAG_CLEAR_SIGNAL))
+    return MOJO_RESULT_INVALID_ARGUMENT;
+
   if (in_two_phase_write_)
     return MOJO_RESULT_BUSY;
   if (peer_closed_)
@@ -251,6 +244,7 @@ MojoResult DataPipeProducerDispatcher::EndWriteData(
   HandleSignalsState new_state = GetHandleSignalsStateNoLock();
   if (new_state.satisfies(MOJO_HANDLE_SIGNAL_WRITABLE))
     awakable_list_.AwakeForStateChange(new_state);
+  watchers_.NotifyState(new_state);
 
   return rv;
 }
@@ -260,6 +254,24 @@ HandleSignalsState DataPipeProducerDispatcher::GetHandleSignalsState() const {
   return GetHandleSignalsStateNoLock();
 }
 
+MojoResult DataPipeProducerDispatcher::AddWatcherRef(
+    const scoped_refptr<WatcherDispatcher>& watcher,
+    uintptr_t context) {
+  base::AutoLock lock(lock_);
+  if (is_closed_ || in_transit_)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+  return watchers_.Add(watcher, context, GetHandleSignalsStateNoLock());
+}
+
+MojoResult DataPipeProducerDispatcher::RemoveWatcherRef(
+    WatcherDispatcher* watcher,
+    uintptr_t context) {
+  base::AutoLock lock(lock_);
+  if (is_closed_ || in_transit_)
+    return MOJO_RESULT_INVALID_ARGUMENT;
+  return watchers_.Remove(watcher, context);
+}
+
 MojoResult DataPipeProducerDispatcher::AddAwakable(
     Awakable* awakable,
     MojoHandleSignals signals,
@@ -356,7 +368,10 @@ void DataPipeProducerDispatcher::CancelTransit() {
   DCHECK(in_transit_);
   in_transit_ = false;
   buffer_handle_for_transit_.reset();
-  awakable_list_.AwakeForStateChange(GetHandleSignalsStateNoLock());
+
+  HandleSignalsState state = GetHandleSignalsStateNoLock();
+  awakable_list_.AwakeForStateChange(state);
+  watchers_.NotifyState(state);
 }
 
 // static
@@ -440,6 +455,7 @@ MojoResult DataPipeProducerDispatcher::CloseNoLock() {
   shared_ring_buffer_ = nullptr;
 
   awakable_list_.CancelAll();
+  watchers_.NotifyClosed();
   if (!transferred_) {
     base::AutoUnlock unlock(lock_);
     node_controller_->ClosePort(control_port_);
@@ -454,7 +470,7 @@ HandleSignalsState DataPipeProducerDispatcher::GetHandleSignalsStateNoLock()
   HandleSignalsState rv;
   if (!peer_closed_) {
     if (!in_two_phase_write_ && shared_ring_buffer_ &&
-        available_capacity_ > 0)
+        available_capacity_ > 0 && !suppress_writable_signal_)
       rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
     rv.satisfiable_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
   } else {
@@ -541,7 +557,10 @@ void DataPipeProducerDispatcher::UpdateSignalsStateNoLock() {
 
   if (peer_closed_ != was_peer_closed ||
       available_capacity_ != previous_capacity) {
-    awakable_list_.AwakeForStateChange(GetHandleSignalsStateNoLock());
+    suppress_writable_signal_ = false;
+    HandleSignalsState state = GetHandleSignalsStateNoLock();
+    awakable_list_.AwakeForStateChange(state);
+    watchers_.NotifyState(state);
   }
 }