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

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

+// Copyright 2013 The Chromium Authors. All rights reserved.

[binji, 2014/05/01 20:22:31]

2014

[Sam Clegg, 2014/05/01 22:16:55]

Done.

+// 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 <stdint.h>
+#include <stdlib.h>
+
+#include "nacl_io/devfs/fifo_post_message.h"

[binji, 2014/05/01 20:22:31]

file doesn't exist?

+#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);
+
+  size_t Read_Locked(char* data, size_t len);
+  size_t Write_Locked(const char* data, size_t len);
+
+  size_t HandleJSWrite(const char* data, size_t len);
+  void HandleJSAck(int64_t byte_count);
+
+  size_t GetOSpace() { return post_message_buffer_size_ - BytesOutstanding(); };

[binji, 2014/05/01 20:22:31]

these are called {Read,Write}Available in the fifo

[Sam Clegg, 2014/05/01 22:16:55]

These are slightly different. They correspond to the GETOSPACE and GETISPACE
ioctl calls.

GETOSPACE does correspond to WriteAvailable() (i.e. how much can you write()
before you block). 

GITISPACE is different as it tells you how much data can can be injected with
ioctl() before it will fail (i.e. the "input" space available to the JavaScript
side). 

+  size_t GetISpace() { return input_fifo_.WriteAvailable(); };
+  Error SetName(const char* name);
+
+ protected:
+  void UpdateStatus_Locked();
+  Error SendAckMessage(int64_t byte_count);
+  size_t BytesOutstanding() { return bytes_sent_ - bytes_acked_; }
+  Error SendMessageToJS(const char* message_type, PP_Var payload);
+  Error SendWriteMessage(const void* buf, size_t count);
+
+ 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_;
+  int64_t bytes_sent_;

[binji, 2014/05/01 20:22:31]

why not use size_t?

[Sam Clegg, 2014/05/01 22:16:55]

Done.

+  int64_t bytes_acked_;
+  int64_t bytes_read_;
+
+  PepperInterface* ppapi_;
+  MessagingInterface* messaging_iface_;
+  VarInterface* var_iface_;
+  VarArrayInterface* array_iface_;
+  VarArrayBufferInterface* buffer_iface_;
+  VarDictionaryInterface* dict_iface_;
+
+  DISALLOW_COPY_AND_ASSIGN(JSPipeEventEmitter);
+};
+
+}  // namespace nacl_io
+
+#endif  // LIBRARIES_NACL_IO_DEVFS_JSPIPE_EVENT_EMITTER_H_