WIP - Refactor programmatic downloads

content/browser/download/download_request_model.h

+// Copyright 2013 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 CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_MODEL_H_
+#define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_MODEL_H_
+
+#include "base/callback_forward.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/timer/timer.h"
+#include "content/public/browser/download_interrupt_reasons.h"
+#include "content/public/browser/download_save_info.h"
+#include "content/public/common/page_transition_types.h"
+#include "net/url_request/url_request.h"
+
+class GURL;
+
+namespace net {
+class IOBuffer;
+class URLRequestStatus;
+}
+
+namespace content {
+
+class ByteStreamWriter;
+struct DownloadCreateInfo;
+struct DownloadSaveInfo;
+class DownloadUrlParameters;
+
+class DownloadRequestModel {
+ public:
+  enum ReadState {
+    READY_TO_READ,
+    WAIT_FOR_RESUME
+  };
+
+  // Size of the buffer used between the DownloadResourceHandler and the
+  // downstream receiver of its output.
+  static const int kDownloadByteStreamSize;
+
+  typedef base::Closure ResumeRequestCallback;
+
+  DownloadRequestModel(net::URLRequest* request,
+                       scoped_ptr<DownloadSaveInfo> save_info);
+  ~DownloadRequestModel();
+
+  static scoped_ptr<net::URLRequest> CreateRequest(
+      const DownloadUrlParameters& parameters,
+      net::URLRequest::Delegate* delegate);
+
+  static bool IsRequestAllowed(const GURL& url, int child_process_id);
+
+  // Assumes that the request is allowed.
+  void OnRequestRedirected(const GURL& url);
+
+  // The response data for the request is available. Returns a
+  // DownloadCreateInfo which can be used to construct a DownloadItem.
+  // |resume_callback| is invoked when the internal ByteStream is ready to
+  // accept more data. See OnReadCompleted. |resume_callback| is guaranteed to
+  // not be invoked after DownloadRequestModel has been deleted.
+  scoped_ptr<DownloadCreateInfo> OnResponseStarted(
+      const std::string& sniffed_mime_type,
+      bool has_user_gesture,
+      PageTransition page_transition,
+      const ResumeRequestCallback& resume_callback);
+
+  void OnWillRead(net::IOBuffer** buf, int* buf_size, int min_size);
+  ReadState OnReadCompleted(int bytes_read);
+  DownloadInterruptReason OnResponseCompleted();
+  void OnPauseRequest();
+  ReadState OnResumeRequest();
+  void OnDownloadInterrupted(DownloadInterruptReason reason);
+
+  std::string DebugString() const;
+
+  net::URLRequest* request() { return request_; }
+
+ private:
+  ReadState read_state() const;
+
+  net::URLRequest* request_;
+
+  scoped_ptr<DownloadSaveInfo> save_info_;
+
+  // Data flow
+  scoped_refptr<net::IOBuffer> read_buffer_;    // From URLRequest.
+  scoped_ptr<ByteStreamWriter> stream_writer_;  // To rest of system.
+
+  // The following are used to collect stats.
+  base::TimeTicks download_start_time_;
+  base::TimeTicks last_read_time_;
+  base::TimeTicks last_stream_pause_time_;
+  base::TimeDelta total_pause_time_;
+  size_t last_buffer_size_;
+  int64 bytes_read_;
+
+  int pause_count_;
+  DownloadInterruptReason last_interrupt_reason_;
+
+  static const int kReadBufSize = 32768;   // bytes
+  static const int kThrottleTimeMs = 200;  // milliseconds
+};
+
+}  // namespace content
+
+#endif