Mojo: Move waiting APIs to public library

services/tracing/service.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 "services/tracing/service.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
+#include "mojo/public/cpp/system/wait.h"
 #include "services/service_manager/public/cpp/interface_registry.h"
 
 namespace tracing {
 
 Service::Service() : collector_binding_(this), tracing_active_(false) {}
 Service::~Service() {}
 
 bool Service::OnConnect(const service_manager::ServiceInfo& remote_info,
                         service_manager::InterfaceRegistry* registry) {
   registry->AddInterface<mojom::Factory>(this);
@@ skipping 61 matching lines @@
 
   tracing_active_ = false;
   provider_ptrs_.ForAllPtrs(
       [](mojom::Provider* controller) { controller->StopTracing(); });
 
   // Sending the StopTracing message to registered controllers will request that
   // they send trace data back via the collector interface and, when they are
   // done, close the collector pipe. We don't know how long they will take. We
   // want to read all data that any collector might send until all collectors or
   // closed or an (arbitrary) deadline has passed. Since the bindings don't
-  // support this directly we do our own MojoWaitMany over the handles and read
+  // support this directly we do our own WaitMany over the handles and read
   // individual messages until all are closed or our absolute deadline has
   // elapsed.
   static const MojoDeadline kTimeToWaitMicros = 1000 * 1000;
   MojoTimeTicks end = MojoGetTimeTicksNow() + kTimeToWaitMicros;
 
   while (!recorder_impls_.empty()) {
     MojoTimeTicks now = MojoGetTimeTicksNow();
     if (now >= end)  // Timed out?
       break;
 
-    MojoDeadline mojo_deadline = end - now;
     std::vector<mojo::Handle> handles;
     std::vector<MojoHandleSignals> signals;
     for (const auto& it : recorder_impls_) {
       handles.push_back(it->RecorderHandle());
       signals.push_back(MOJO_HANDLE_SIGNAL_READABLE |
                         MOJO_HANDLE_SIGNAL_PEER_CLOSED);
     }
     std::vector<MojoHandleSignalsState> signals_states(signals.size());
-    const mojo::WaitManyResult wait_many_result =
-        mojo::WaitMany(handles, signals, mojo_deadline, &signals_states);
-    if (wait_many_result.result == MOJO_RESULT_DEADLINE_EXCEEDED) {
-      // Timed out waiting, nothing more to read.
-      LOG(WARNING) << "Timed out waiting for trace flush";
-      break;
-    }
-    if (wait_many_result.IsIndexValid()) {
+    size_t result_index;
+
+    // TODO(rockot): Use a timed wait here to avoid hanging forever in the case
+    // of a misbehaving or unresponsive collector.
+    MojoResult rv =
+        mojo::WaitMany(handles.data(), signals.data(), handles.size(),
+                       &result_index, signals_states.data());
+    if (rv == MOJO_RESULT_OK || rv == MOJO_RESULT_FAILED_PRECONDITION) {
       // Iterate backwards so we can remove closed pipes from |recorder_impls_|
       // without invalidating subsequent offsets.
       for (size_t i = signals_states.size(); i != 0; --i) {
         size_t index = i - 1;
         MojoHandleSignals satisfied = signals_states[index].satisfied_signals;
         // To avoid dropping data, don't close unless there's no
         // readable signal.
         if (satisfied & MOJO_HANDLE_SIGNAL_READABLE)
           recorder_impls_[index]->TryRead();
         else if (satisfied & MOJO_HANDLE_SIGNAL_PEER_CLOSED)
@@ skipping 43 matching lines @@
     const GetStartupPerformanceTimesCallback& callback) {
   callback.Run(startup_performance_times_.Clone());
 }
 
 void Service::AllDataCollected() {
   recorder_impls_.clear();
   sink_.reset();
 }
 
 }  // namespace tracing