Cloning a bunch of stuff from the native_client repository at r6528

ppapi/native_client/src/shared/ppapi_proxy/plugin_upcall.cc

+// Copyright (c) 2011 The Native Client Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
+//
+// This is an early draft of background thread support.
+// Until it is complete, we assume that all proxy functions
+// (except CallOnMainThread) are called on the main PPAPI thread.
+//
+// WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
+
+#include "native_client/src/shared/ppapi_proxy/plugin_upcall.h"
+
+#include <pthread.h>
+#include <map>
+
+#include "native_client/src/include/nacl_macros.h"
+#include "native_client/src/include/portability.h"
+#include "native_client/src/shared/ppapi_proxy/plugin_callback.h"
+#include "native_client/src/shared/ppapi_proxy/plugin_globals.h"
+#include "native_client/src/shared/ppapi_proxy/utility.h"
+#include "native_client/src/shared/srpc/nacl_srpc.h"
+#include "ppapi/c/pp_errors.h"
+#include "srpcgen/ppp_rpc.h"
+#include "srpcgen/upcall.h"
+
+using ppapi_proxy::CompletionCallbackTable;
+
+namespace ppapi_proxy {
+
+namespace {
+
+  class CallOnMainThreadCriticalSection {
+    static pthread_mutex_t mutex_;
+   public:
+    CallOnMainThreadCriticalSection() { pthread_mutex_lock(&mutex_); }
+    ~CallOnMainThreadCriticalSection() { pthread_mutex_unlock(&mutex_); }
+  };
+
+  pthread_mutex_t CallOnMainThreadCriticalSection::mutex_ =
+      PTHREAD_MUTEX_INITIALIZER;
+
+}  // namespace
+
+// The call on main thread is implemented via an RPC to the browser side on the
+// upcall channel, instead of locally to the plugin. This is to ensure that
+// when the callback runs (and potentially calls one of the PPB_ methods
+// over RPC), the browser-side is listening.
+void PluginUpcallCoreCallOnMainThread(int32_t delay_in_milliseconds,
+                                      PP_CompletionCallback callback,
+                                      int32_t result) {
+  // Force PluginUpcallCoreCallOnMainThread, from multiple threads, to occur
+  // one at a time.
+  CallOnMainThreadCriticalSection guard;
+  NaClSrpcChannel* upcall_channel = GetUpcallSrpcChannel();
+  if (upcall_channel == NULL) {
+    DebugPrintf("PluginUpcallCoreCallOnMainThread: NULL channel.\n");
+    return;
+  }
+  int32_t callback_id =
+      ppapi_proxy::CompletionCallbackTable::Get()->AddCallback(callback);
+  if (callback_id == 0) {
+    DebugPrintf("PluginUpcallCoreCallOnMainThread: NULL callback.\n");
+    return;
+  }
+  (void) PppUpcallRpcClient::PPB_Core_CallOnMainThread(
+      upcall_channel, delay_in_milliseconds, callback_id, result);
+}
+
+}  // namespace ppapi_proxy