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

native_client_sdk/src/libraries/nacl_io/devfs/jspipe_event_emitter.h

+// Copyright 2014 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.
+
+#ifndef LIBRARIES_NACL_IO_DEVFS_JSPIPE_EVENT_EMITTER_H_
+#define LIBRARIES_NACL_IO_DEVFS_JSPIPE_EVENT_EMITTER_H_
+
+#include <poll.h>
+#include <ppapi/c/pp_var.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <string>
+
+#include "nacl_io/fifo_char.h"
+#include "nacl_io/pipe/pipe_event_emitter.h"
+
+#include "sdk_util/auto_lock.h"
+#include "sdk_util/macros.h"
+
+namespace nacl_io {
+
+class PepperInterface;
+class MessagingInterface;
+class VarInterface;
+class VarArrayInterface;
+class VarArrayBufferInterface;
+class VarDictionaryInterface;
+
+class JSPipeEventEmitter;
+typedef sdk_util::ScopedRef<JSPipeEventEmitter> ScopedJSPipeEventEmitter;
+
+class JSPipeEventEmitter : public EventEmitter {
+ public:
+  JSPipeEventEmitter(PepperInterface* ppapi, size_t size);
+  virtual void Destroy();
+
+  Error Read_Locked(char* data, size_t len, int* out_bytes);
+  Error Write_Locked(const char* data, size_t len, int* out_bytes);
+
+  size_t GetOSpace() { return post_message_buffer_size_ - BytesOutstanding(); };
+  size_t GetISpace() { return input_fifo_.WriteAvailable(); };
+  Error SetName(const char* name);
+  Error HandleJSMessage(PP_Var message);
+
+ protected:
+  size_t HandleJSWrite(const char* data, size_t len);
+  void HandleJSAck(size_t byte_count);
+  Error HandleJSWrite(PP_Var message);
+  Error HandleJSAck(PP_Var message);
+  void UpdateStatus_Locked();
+  PP_Var VarFromCStr(const char* string);
+  Error SendAckMessage(size_t byte_count);
+  size_t BytesOutstanding() { return bytes_sent_ - bytes_acked_; }
+  Error SendMessageToJS(PP_Var operation, PP_Var payload);
+  Error SendWriteMessage(const void* buf, size_t count);
+  int VarStrcmp(PP_Var a, PP_Var b);
+
+ private:
+  std::string name_;
+  FIFOChar input_fifo_;
+
+  // Number of bytes that to send via PostMessage before and ACK
+  // is required.
+  size_t post_message_buffer_size_;
+  size_t bytes_sent_;
+  size_t bytes_acked_;
+  size_t bytes_read_;
+
+  PepperInterface* ppapi_;
+  MessagingInterface* messaging_iface_;
+  VarInterface* var_iface_;
+  VarArrayInterface* array_iface_;
+  VarArrayBufferInterface* buffer_iface_;
+  VarDictionaryInterface* dict_iface_;
+
+  PP_Var pipe_name_var_;
+  PP_Var pipe_key_;
+  PP_Var operation_key_;
+  PP_Var payload_key_;
+  PP_Var write_var_;
+  PP_Var ack_var_;
+
+  DISALLOW_COPY_AND_ASSIGN(JSPipeEventEmitter);
+};
+
+}  // namespace nacl_io
+
+#endif  // LIBRARIES_NACL_IO_DEVFS_JSPIPE_EVENT_EMITTER_H_