Separate BufferedDataSource and BufferedResourceLoader into two files.

webkit/glue/media/buffered_resource_loader.cc

+// Copyright (c) 2010 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 "webkit/glue/media/buffered_resource_loader.h"
+
+#include "base/format_macros.h"
+#include "base/string_util.h"
+#include "net/base/net_errors.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebKit.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebKitClient.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebString.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebURLError.h"
+#include "webkit/glue/multipart_response_delegate.h"
+#include "webkit/glue/webkit_glue.h"
+
+using WebKit::WebFrame;
+using WebKit::WebString;
+using WebKit::WebURLError;
+using WebKit::WebURLLoader;
+using WebKit::WebURLRequest;
+using WebKit::WebURLResponse;
+using webkit_glue::MultipartResponseDelegate;
+
+namespace {
+
+const int kHttpOK = 200;
+const int kHttpPartialContent = 206;
+
+// Define the number of bytes in a megabyte.
+const size_t kMegabyte = 1024 * 1024;
+
+// Backward capacity of the buffer, by default 2MB.
+const size_t kBackwardCapcity = 2 * kMegabyte;
+
+// Forward capacity of the buffer, by default 10MB.
+const size_t kForwardCapacity = 10 * kMegabyte;
+
+// The threshold of bytes that we should wait until the data arrives in the
+// future instead of restarting a new connection. This number is defined in the
+// number of bytes, we should determine this value from typical connection speed
+// and amount of time for a suitable wait. Now I just make a guess for this
+// number to be 2MB.
+// TODO(hclam): determine a better value for this.
+const int kForwardWaitThreshold = 2 * kMegabyte;
+
+} // namespace
+
+namespace webkit_glue {
+
+BufferedResourceLoader::BufferedResourceLoader(
+    const GURL& url,
+    int64 first_byte_position,
+    int64 last_byte_position)
+    : buffer_(new media::SeekableBuffer(kBackwardCapcity, kForwardCapacity)),
+      deferred_(false),
+      defer_allowed_(true),
+      completed_(false),
+      range_requested_(false),
+      partial_response_(false),
+      url_(url),
+      first_byte_position_(first_byte_position),
+      last_byte_position_(last_byte_position),
+      start_callback_(NULL),
+      offset_(0),
+      content_length_(kPositionNotSpecified),
+      instance_size_(kPositionNotSpecified),
+      read_callback_(NULL),
+      read_position_(0),
+      read_size_(0),
+      read_buffer_(NULL),
+      first_offset_(0),
+      last_offset_(0),
+      keep_test_loader_(false) {
+}
+
+BufferedResourceLoader::~BufferedResourceLoader() {
+  if (!completed_ && url_loader_.get())
+    url_loader_->cancel();
+}
+
+void BufferedResourceLoader::Start(net::CompletionCallback* start_callback,
+                                   NetworkEventCallback* event_callback,
+                                   WebFrame* frame) {
+  // Make sure we have not started.
+  DCHECK(!start_callback_.get());
+  DCHECK(!event_callback_.get());
+  DCHECK(start_callback);
+  DCHECK(event_callback);
+  CHECK(frame);
+
+  start_callback_.reset(start_callback);
+  event_callback_.reset(event_callback);
+
+  if (first_byte_position_ != kPositionNotSpecified) {
+    range_requested_ = true;
+    // TODO(hclam): server may not support range request so |offset_| may not
+    // equal to |first_byte_position_|.
+    offset_ = first_byte_position_;
+  }
+
+  // Increment the reference count right before we start the request. This
+  // reference will be release when this request has ended.
+  AddRef();
+
+  // Prepare the request.
+  WebURLRequest request(url_);
+  request.setHTTPHeaderField(WebString::fromUTF8("Range"),
+                             WebString::fromUTF8(GenerateHeaders(
+                                                 first_byte_position_,
+                                                 last_byte_position_)));
+  frame->setReferrerForRequest(request, WebKit::WebURL());
+
+  // This flag is for unittests as we don't want to reset |url_loader|
+  if (!keep_test_loader_)
+    url_loader_.reset(frame->createAssociatedURLLoader());
+
+  // Start the resource loading.
+  url_loader_->loadAsynchronously(request, this);
+}
+
+void BufferedResourceLoader::Stop() {
+  // Reset callbacks.
+  start_callback_.reset();
+  event_callback_.reset();
+  read_callback_.reset();
+
+  // Use the internal buffer to signal that we have been stopped.
+  // TODO(hclam): Not so pretty to do this.
+  if (!buffer_.get())
+    return;
+
+  // Destroy internal buffer.
+  buffer_.reset();
+
+  if (url_loader_.get()) {
+    if (deferred_)
+      url_loader_->setDefersLoading(false);
+    deferred_ = false;
+
+    if (!completed_) {
+      url_loader_->cancel();
+      completed_ = true;
+    }
+  }
+}
+
+void BufferedResourceLoader::Read(int64 position,
+                                  int read_size,
+                                  uint8* buffer,
+                                  net::CompletionCallback* read_callback) {
+  DCHECK(!read_callback_.get());
+  DCHECK(buffer_.get());
+  DCHECK(read_callback);
+  DCHECK(buffer);
+
+  // Save the parameter of reading.
+  read_callback_.reset(read_callback);
+  read_position_ = position;
+  read_size_ = read_size;
+  read_buffer_ = buffer;
+
+  // If read position is beyond the instance size, we cannot read there.
+  if (instance_size_ != kPositionNotSpecified &&
+      instance_size_ <= read_position_) {
+    DoneRead(0);
+    return;
+  }
+
+  // Make sure |offset_| and |read_position_| does not differ by a large
+  // amount.
+  if (read_position_ > offset_ + kint32max ||
+      read_position_ < offset_ + kint32min) {
+    DoneRead(net::ERR_CACHE_MISS);
+    return;
+  }
+
+  // Prepare the parameters.
+  first_offset_ = static_cast<int>(read_position_ - offset_);
+  last_offset_ = first_offset_ + read_size_;
+
+  // If we can serve the request now, do the actual read.
+  if (CanFulfillRead()) {
+    ReadInternal();
+    DisableDeferIfNeeded();
+    return;
+  }
+
+  // If we expected the read request to be fulfilled later, returns
+  // immediately and let more data to flow in.
+  if (WillFulfillRead())
+    return;
+
+  // Make a callback to report failure.
+  DoneRead(net::ERR_CACHE_MISS);
+}
+
+int64 BufferedResourceLoader::GetBufferedPosition() {
+  if (buffer_.get())
+    return offset_ + static_cast<int>(buffer_->forward_bytes()) - 1;
+  return kPositionNotSpecified;
+}
+
+void BufferedResourceLoader::SetAllowDefer(bool is_allowed) {
+  defer_allowed_ = is_allowed;
+  DisableDeferIfNeeded();
+}
+
+int64 BufferedResourceLoader::content_length() {
+  return content_length_;
+}
+
+int64 BufferedResourceLoader::instance_size() {
+  return instance_size_;
+}
+
+bool BufferedResourceLoader::partial_response() {
+  return partial_response_;
+}
+
+bool BufferedResourceLoader::network_activity() {
+  return !completed_ && !deferred_;
+}
+
+const GURL& BufferedResourceLoader::url() {
+  return url_;
+}
+
+void BufferedResourceLoader::SetURLLoaderForTest(WebURLLoader* mock_loader) {
+  url_loader_.reset(mock_loader);
+  keep_test_loader_ = true;
+}
+
+// WebKit::WebURLLoaderClient implementations.
+void BufferedResourceLoader::willSendRequest(
+    WebURLLoader* loader,
+    WebURLRequest& newRequest,
+    const WebURLResponse& redirectResponse) {
+
+  // The load may have been stopped and |start_callback| is destroyed.
+  // In this case we shouldn't do anything.
+  if (!start_callback_.get()) {
+    // Set the url in the request to an invalid value (empty url).
+    newRequest.setURL(WebKit::WebURL());
+    return;
+  }
+
+  if (!IsProtocolSupportedForMedia(newRequest.url())) {
+    // Set the url in the request to an invalid value (empty url).
+    newRequest.setURL(WebKit::WebURL());
+    DoneStart(net::ERR_ADDRESS_INVALID);
+    Stop();
+    return;
+  }
+
+  url_ = newRequest.url();
+}
+
+void BufferedResourceLoader::didSendData(
+    WebURLLoader* loader,
+    unsigned long long bytes_sent,
+    unsigned long long total_bytes_to_be_sent) {
+  NOTIMPLEMENTED();
+}
+
+void BufferedResourceLoader::didReceiveResponse(
+    WebURLLoader* loader,
+    const WebURLResponse& response) {
+
+  // The loader may have been stopped and |start_callback| is destroyed.
+  // In this case we shouldn't do anything.
+  if (!start_callback_.get())
+    return;
+
+  // We make a strong assumption that when we reach here we have either
+  // received a response from HTTP/HTTPS protocol or the request was
+  // successful (in particular range request). So we only verify the partial
+  // response for HTTP and HTTPS protocol.
+  if (url_.SchemeIs(kHttpScheme) || url_.SchemeIs(kHttpsScheme)) {
+    int error = net::OK;
+
+    if (response.httpStatusCode() == kHttpPartialContent)
+      partial_response_ = true;
+
+    if (range_requested_ && partial_response_) {
+      // If we have verified the partial response and it is correct, we will
+      // return net::OK.
+      if (!VerifyPartialResponse(response))
+        error = net::ERR_INVALID_RESPONSE;
+    } else if (response.httpStatusCode() != kHttpOK) {
+      // We didn't request a range but server didn't reply with "200 OK".
+      error = net::ERR_FAILED;
+    }
+
+    if (error != net::OK) {
+      DoneStart(error);
+      Stop();
+      return;
+    }
+  } else {
+    // For any protocol other than HTTP and HTTPS, assume range request is
+    // always fulfilled.
+    partial_response_ = range_requested_;
+  }
+
+  // Expected content length can be |kPositionNotSpecified|, in that case
+  // |content_length_| is not specified and this is a streaming response.
+  content_length_ = response.expectedContentLength();
+
+  // If we have not requested a range, then the size of the instance is equal
+  // to the content length.
+  if (!partial_response_)
+    instance_size_ = content_length_;
+
+  // Calls with a successful response.
+  DoneStart(net::OK);
+}
+
+void BufferedResourceLoader::didReceiveData(
+    WebURLLoader* loader,
+    const char* data,
+    int data_length) {
+  DCHECK(!completed_);
+  DCHECK_GT(data_length, 0);
+
+  // If this loader has been stopped, |buffer_| would be destroyed.
+  // In this case we shouldn't do anything.
+  if (!buffer_.get())
+    return;
+
+  // Writes more data to |buffer_|.
+  buffer_->Append(reinterpret_cast<const uint8*>(data), data_length);
+
+  // If there is an active read request, try to fulfill the request.
+  if (HasPendingRead() && CanFulfillRead()) {
+    ReadInternal();
+  } else if (!defer_allowed_) {
+    // If we're not allowed to defer, slide the buffer window forward instead
+    // of deferring.
+    if (buffer_->forward_bytes() > buffer_->forward_capacity()) {
+      size_t excess = buffer_->forward_bytes() - buffer_->forward_capacity();
+      bool success = buffer_->Seek(excess);
+      DCHECK(success);
+      offset_ += first_offset_ + excess;
+    }
+  }
+
+  // At last see if the buffer is full and we need to defer the downloading.
+  EnableDeferIfNeeded();
+
+  // Notify that we have received some data.
+  NotifyNetworkEvent();
+}
+
+void BufferedResourceLoader::didDownloadData(
+    WebKit::WebURLLoader* loader,
+    int dataLength) {
+  NOTIMPLEMENTED();
+}
+
+void BufferedResourceLoader::didReceiveCachedMetadata(
+    WebURLLoader* loader,
+    const char* data,
+    int data_length) {
+  NOTIMPLEMENTED();
+}
+
+void BufferedResourceLoader::didFinishLoading(
+    WebURLLoader* loader,
+    double finishTime) {
+  DCHECK(!completed_);
+  completed_ = true;
+
+  // If there is a start callback, calls it.
+  if (start_callback_.get()) {
+    DoneStart(net::OK);
+  }
+
+  // If there is a pending read but the request has ended, returns with what
+  // we have.
+  if (HasPendingRead()) {
+    // Make sure we have a valid buffer before we satisfy a read request.
+    DCHECK(buffer_.get());
+
+    // Try to fulfill with what is in the buffer.
+    if (CanFulfillRead())
+      ReadInternal();
+    else
+      DoneRead(net::ERR_CACHE_MISS);
+  }
+
+  // There must not be any outstanding read request.
+  DCHECK(!HasPendingRead());
+
+  // Notify that network response is completed.
+  NotifyNetworkEvent();
+
+  url_loader_.reset();
+  Release();
+}
+
+void BufferedResourceLoader::didFail(
+    WebURLLoader* loader,
+    const WebURLError& error) {
+  DCHECK(!completed_);
+  completed_ = true;
+
+  // If there is a start callback, calls it.
+  if (start_callback_.get()) {
+    DoneStart(error.reason);
+  }
+
+  // If there is a pending read but the request failed, return with the
+  // reason for the error.
+  if (HasPendingRead()) {
+    DoneRead(error.reason);
+  }
+
+  // Notify that network response is completed.
+  NotifyNetworkEvent();
+
+  url_loader_.reset();
+  Release();
+}
+
+void BufferedResourceLoader::EnableDeferIfNeeded() {
+  if (!defer_allowed_)
+    return;
+
+  if (!deferred_ &&
+      buffer_->forward_bytes() >= buffer_->forward_capacity()) {
+    deferred_ = true;
+
+  if (url_loader_.get())
+    url_loader_->setDefersLoading(true);
+
+    NotifyNetworkEvent();
+  }
+}
+
+void BufferedResourceLoader::DisableDeferIfNeeded() {
+  if (deferred_ &&
+      (!defer_allowed_ ||
+       buffer_->forward_bytes() < buffer_->forward_capacity() / 2)) {
+    deferred_ = false;
+
+    if (url_loader_.get())
+      url_loader_->setDefersLoading(false);
+
+    NotifyNetworkEvent();
+  }
+}
+
+bool BufferedResourceLoader::CanFulfillRead() {
+  // If we are reading too far in the backward direction.
+  if (first_offset_ < 0 &&
+      first_offset_ + static_cast<int>(buffer_->backward_bytes()) < 0)
+    return false;
+
+  // If the start offset is too far ahead.
+  if (first_offset_ >= static_cast<int>(buffer_->forward_bytes()))
+    return false;
+
+  // At the point, we verified that first byte requested is within the buffer.
+  // If the request has completed, then just returns with what we have now.
+  if (completed_)
+    return true;
+
+  // If the resource request is still active, make sure the whole requested
+  // range is covered.
+  if (last_offset_ > static_cast<int>(buffer_->forward_bytes()))
+    return false;
+
+  return true;
+}
+
+bool BufferedResourceLoader::WillFulfillRead() {
+  // Reading too far in the backward direction.
+  if (first_offset_ < 0 &&
+      first_offset_ + static_cast<int>(buffer_->backward_bytes()) < 0)
+    return false;
+
+  // Try to read too far ahead.
+  if (last_offset_ > kForwardWaitThreshold)
+    return false;
+
+  // The resource request has completed, there's no way we can fulfill the
+  // read request.
+  if (completed_)
+    return false;
+
+  return true;
+}
+
+void BufferedResourceLoader::ReadInternal() {
+  // Seek to the first byte requested.
+  bool ret = buffer_->Seek(first_offset_);
+  DCHECK(ret);
+
+  // Then do the read.
+  int read = static_cast<int>(buffer_->Read(read_buffer_, read_size_));
+  offset_ += first_offset_ + read;
+
+  // And report with what we have read.
+  DoneRead(read);
+}
+
+bool BufferedResourceLoader::VerifyPartialResponse(
+    const WebURLResponse& response) {
+  int first_byte_position, last_byte_position, instance_size;
+
+  if (!MultipartResponseDelegate::ReadContentRanges(response,
+                         &first_byte_position,
+                         &last_byte_position,
+                         &instance_size)) {
+    return false;
+  }
+
+  if (instance_size != kPositionNotSpecified) {
+    instance_size_ = instance_size;
+  }
+
+  if (first_byte_position_ != kPositionNotSpecified &&
+      first_byte_position_ != first_byte_position) {
+    return false;
+  }
+
+  // TODO(hclam): I should also check |last_byte_position|, but since
+  // we will never make such a request that it is ok to leave it unimplemented.
+  return true;
+}
+
+std::string BufferedResourceLoader::GenerateHeaders(
+    int64 first_byte_position,
+    int64 last_byte_position) {
+  // Construct the value for the range header.
+  std::string header;
+  if (first_byte_position > kPositionNotSpecified &&
+      last_byte_position > kPositionNotSpecified) {
+    if (first_byte_position <= last_byte_position) {
+      header = base::StringPrintf("bytes=%" PRId64 "-%" PRId64,
+                                  first_byte_position,
+                                  last_byte_position);
+    }
+  } else if (first_byte_position > kPositionNotSpecified) {
+    header = base::StringPrintf("bytes=%" PRId64 "-",
+                                first_byte_position);
+  } else if (last_byte_position > kPositionNotSpecified) {
+    NOTIMPLEMENTED() << "Suffix range not implemented";
+  }
+  return header;
+}
+
+void BufferedResourceLoader::DoneRead(int error) {
+  read_callback_->RunWithParams(Tuple1<int>(error));
+  read_callback_.reset();
+  read_position_ = 0;
+  read_size_ = 0;
+  read_buffer_ = NULL;
+  first_offset_ = 0;
+  last_offset_ = 0;
+}
+
+void BufferedResourceLoader::DoneStart(int error) {
+  start_callback_->RunWithParams(Tuple1<int>(error));
+  start_callback_.reset();
+}
+
+void BufferedResourceLoader::NotifyNetworkEvent() {
+  if (event_callback_.get())
+    event_callback_->Run();
+}
+
+}  // namespace webkit_glue