WIP - Refactor programmatic downloads

content/browser/download/url_downloader.cc

Index: content/browser/download/url_downloader.cc
diff --git a/content/browser/download/url_downloader.cc b/content/browser/download/url_downloader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fd6d0dfdc4ed8ea9f18c67384974bd240492d5e1
--- /dev/null
+++ b/content/browser/download/url_downloader.cc
@@ -0,0 +1,233 @@
+// 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.
+
+#include "content/browser/download/url_downloader.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "content/browser/download/download_create_info.h"
+#include "content/browser/download/download_interrupt_reasons_impl.h"
+#include "content/browser/download/download_request_handle.h"
+#include "content/browser/download/download_request_model.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/download_url_parameters.h"
+#include "net/url_request/url_request.h"
+
+namespace content {
+
+class UrlDownloader::RequestHandle : public DownloadRequestHandle {
+ public:
+  RequestHandle(scoped_ptr<UrlDownloader> downloader);
+  virtual ~RequestHandle();
+
+ private:
+  // DownloadRequestHandle.
+  virtual void Start(const RequestStartedCallback& callback) OVERRIDE;
+  virtual void PauseRequest() const OVERRIDE;
+  virtual void ResumeRequest() const OVERRIDE;
+  virtual void CancelRequest() const OVERRIDE;
+  virtual std::string DebugString() const OVERRIDE;
+
+  scoped_ptr<UrlDownloader> downloader_;
+
+  DISALLOW_COPY_AND_ASSIGN(RequestHandle);
+};
+
+UrlDownloader::RequestHandle::RequestHandle(
+    scoped_ptr<UrlDownloader> downloader)
+    : downloader_(downloader.Pass()) {}
+
+UrlDownloader::RequestHandle::~RequestHandle() {
+  BrowserThread::DeleteSoon(
+      BrowserThread::IO, FROM_HERE, downloader_.release());
+}
+
+void UrlDownloader::RequestHandle::Start(
+    const RequestStartedCallback& callback) {
+  BrowserThread::PostTask(BrowserThread::IO,
+                          FROM_HERE,
+                          base::Bind(&UrlDownloader::Start,
+                                     base::Unretained(downloader_.get()),
+                                     callback));
+}
+
+void UrlDownloader::RequestHandle::PauseRequest() const {
+  BrowserThread::PostTask(BrowserThread::IO,
+                          FROM_HERE,
+                          base::Bind(&UrlDownloader::PauseRequest,
+                                     base::Unretained(downloader_.get())));
+}
+
+void UrlDownloader::RequestHandle::ResumeRequest() const {
+  BrowserThread::PostTask(BrowserThread::IO,
+                          FROM_HERE,
+                          base::Bind(&UrlDownloader::ResumeRequest,
+                                     base::Unretained(downloader_.get())));
+}
+
+void UrlDownloader::RequestHandle::CancelRequest() const {
+  BrowserThread::PostTask(BrowserThread::IO,
+                          FROM_HERE,
+                          base::Bind(&UrlDownloader::CancelRequest,
+                                     base::Unretained(downloader_.get())));
+}
+
+std::string UrlDownloader::RequestHandle::DebugString() const {
+  return std::string();
+}
+
+// static
+scoped_ptr<DownloadRequestHandle> UrlDownloader::CreateDownloadRequest(
+    scoped_ptr<DownloadUrlParameters> params) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  scoped_ptr<UrlDownloader> downloader(new UrlDownloader(params.Pass()));
+  scoped_ptr<DownloadRequestHandle> request_handle(
+      new RequestHandle(downloader.Pass()));
+  return request_handle.Pass();
+}
+
+UrlDownloader::UrlDownloader(scoped_ptr<DownloadUrlParameters> params)
+    : params_(params.Pass()),
+      child_process_id_(params_->render_process_host_id()),
+      is_request_active_(true) {
+  // Can be created on the UI thread.
+}
+
+UrlDownloader::~UrlDownloader() {}
+
+void UrlDownloader::Start(const RequestStartedCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  started_callback_ = callback;
+  request_ = DownloadRequestModel::CreateRequest(*params_, this).Pass();
+  if (!request_) {
+    scoped_ptr<DownloadCreateInfo> empty_create_info;
+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(callback,
+                   DOWNLOAD_INTERRUPT_REASON_NETWORK_INVALID_REQUEST,
+                   base::Passed(&empty_create_info)));
+    return;
+  }
+
+  scoped_ptr<DownloadSaveInfo> save_info(new DownloadSaveInfo());
+  save_info->file_path = params_->file_path();
+  save_info->suggested_name = params_->suggested_name();
+  save_info->offset = params_->offset();
+  save_info->hash_state = params_->hash_state();
+  save_info->prompt_for_save_location = params_->prompt();
+  save_info->file_stream = params_->GetFileStream();
+
+  // TODO(asanka): This request will not have the LOAD_MAYBE_USER_GESTURE flag
+  // set. This is correct since this is a programmatic download. Make sure that
+  // this doesn't affect resumption since a download that was considered safe
+  // before may be considered dangerous on resumption.
+
+  request_model_.reset(
+      new DownloadRequestModel(request_.get(), save_info.Pass()));
+  request_->Start();
+}
+
+void UrlDownloader::OnReceivedRedirect(net::URLRequest* request,
+                                       const GURL& new_url,
+                                       bool* defer_redirect) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!DownloadRequestModel::IsRequestAllowed(new_url, child_process_id_)) {
+    request_model_->OnDownloadInterrupted(
+        DOWNLOAD_INTERRUPT_REASON_NETWORK_INVALID_REQUEST);
+    request_->Cancel();
+    return;
+  }
+  request_model_->OnRequestRedirected(new_url);
+}
+
+void UrlDownloader::OnResponseStarted(net::URLRequest* request) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!request_->status().is_success()) {
+    DownloadInterruptReason reason = ConvertNetErrorToInterruptReason(
+        static_cast<net::Error>(request_->status().error()),
+        DOWNLOAD_INTERRUPT_FROM_NETWORK);
+    scoped_ptr<DownloadCreateInfo> empty_create_info;
+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(
+            started_callback_, reason, base::Passed(&empty_create_info)));
+    request_->Cancel();
+    return;
+  }
+
+  scoped_ptr<DownloadCreateInfo> create_info =
+      request_model_->OnResponseStarted(
+          std::string(),
+          false,
+          PAGE_TRANSITION_LINK,
+          base::Bind(&UrlDownloader::ResumeRequest, base::Unretained(this)));
+  BrowserThread::PostTask(BrowserThread::UI,
+                          FROM_HERE,
+                          base::Bind(started_callback_,
+                                     DOWNLOAD_INTERRUPT_REASON_NONE,
+                                     base::Passed(&create_info)));
+  ReadNextChunk();
+}
+
+void UrlDownloader::OnReadCompleted(net::URLRequest* request, int bytes_read) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  HandleCompletedRead(bytes_read);
+  ReadNextChunk();
+}
+
+void UrlDownloader::PauseRequest() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  request_model_->OnPauseRequest();
+}
+
+void UrlDownloader::ResumeRequest() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (request_model_->OnResumeRequest() ==
+          DownloadRequestModel::READY_TO_READ &&
+      !is_request_active_ &&
+      request_->status().is_success())
+    ReadNextChunk();
+}
+
+void UrlDownloader::CancelRequest() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  request_->Cancel();
+}
+
+void UrlDownloader::ReadNextChunk() {
+  net::IOBuffer* buffer = NULL;
+  int buf_size = 0;
+  int bytes_read = 0;
+  bool read_succeeded = false;
+
+  if (!is_request_active_)
+    return;
+
+  do {
+    request_model_->OnWillRead(&buffer, &buf_size, -1);
+    DCHECK_LT(0, buf_size);
+
+    // TODO(asanka): Check for re-entrancy issues. Can Read() result in a call
+    // into OnReadCompleted()?
+    read_succeeded = request_->Read(buffer, buf_size, &bytes_read);
+
+    // Read returns false if IO is pending or if the read failed.
+    if (read_succeeded || !request_->status().is_success())
+      HandleCompletedRead(bytes_read);
+  } while(read_succeeded && is_request_active_);
+}
+
+void UrlDownloader::HandleCompletedRead(int bytes_read) {
+  DownloadRequestModel::ReadState read_state =
+      request_model_->OnReadCompleted(bytes_read);
+  is_request_active_ = (read_state == DownloadRequestModel::READY_TO_READ);
+  if (bytes_read == 0 || !request_->status().is_success()) {
+    request_model_->OnResponseCompleted();
+    is_request_active_ = false;
+  }
+}
+
+}  // namespace content