[iOS] Upstream WebP network client

components/webp_transcode/webp_network_client.mm

+// 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.
+
+#import "components/webp_transcode/webp_network_client.h"
+
+#include "base/bind.h"
+#include "base/compiler_specific.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/mac/bind_objc_block.h"
+#include "base/mac/scoped_nsobject.h"
+#include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
+#include "base/strings/string_util.h"
+#include "base/strings/sys_string_conversions.h"
+#include "base/thread_task_runner_handle.h"
+#include "components/webp_transcode/webp_decoder.h"
+#include "net/base/net_errors.h"
+#include "net/http/http_request_headers.h"
+#include "net/url_request/url_request.h"
+
+namespace net {
+class URLRequest;
+}  // namespace net

[sdefresne, 2015/03/19 17:06:34]

nit: no need for the "//  namespace net" for single-line namespaces

+
+using namespace webp_transcode;
+
+namespace {
+
+// MIME type for WebP images.
+const char kWebPMimeType[] = "image/webp";
+
+NSURLResponse* NewImageResponse(NSURLResponse* webp_response,
+                                size_t content_length,
+                                WebpDecoder::DecodedImageFormat format) {
+  DCHECK(webp_response);
+
+  NSString* mime_type = nil;
+  switch (format) {
+    case WebpDecoder::JPEG:
+      mime_type = @"image/jpeg";
+      break;
+    case WebpDecoder::PNG:
+      mime_type = @"image/png";
+      break;
+    case WebpDecoder::TIFF:
+      mime_type = @"image/tiff";
+      break;
+    case WebpDecoder::DECODED_FORMAT_COUNT:
+      NOTREACHED();
+      break;
+  }
+  DCHECK(mime_type);
+
+  if ([webp_response isKindOfClass:[NSHTTPURLResponse class]]) {
+    NSHTTPURLResponse* http_response =
+        static_cast<NSHTTPURLResponse*>(webp_response);
+    NSMutableDictionary* header_fields = [NSMutableDictionary
+        dictionaryWithDictionary:[http_response allHeaderFields]];
+    [header_fields setObject:[NSString stringWithFormat:@"%zu", content_length]
+                      forKey:@"Content-Length"];
+    [header_fields setObject:mime_type forKey:@"Content-Type"];
+    return [[NSHTTPURLResponse alloc] initWithURL:[http_response URL]
+                                       statusCode:[http_response statusCode]
+                                      HTTPVersion:@"HTTP/1.1"
+                                     headerFields:header_fields];
+  } else {
+    return [[NSURLResponse alloc] initWithURL:[webp_response URL]
+                                     MIMEType:mime_type
+                        expectedContentLength:content_length
+                             textEncodingName:[webp_response textEncodingName]];
+  }
+}
+
+class WebpDecoderDelegate : public WebpDecoder::Delegate {
+ public:
+  WebpDecoderDelegate(id<CRNNetworkClientProtocol> client,
+                      const base::Time& request_creation_time,
+                      const scoped_refptr<base::TaskRunner>& callback_runner)
+      : underlying_client_([client retain]),
+        callback_task_runner_(callback_runner),
+        request_creation_time_(request_creation_time) {
+    DCHECK(underlying_client_.get());
+  }
+
+  void SetOriginalResponse(
+      const base::scoped_nsobject<NSURLResponse>& response) {
+    original_response_.reset([response retain]);
+  }
+
+  // WebpDecoder::Delegate methods.
+  void OnFinishedDecoding(bool success) override {
+    base::scoped_nsprotocol<id<CRNNetworkClientProtocol>> block_client(
+        [underlying_client_ retain]);
+    if (success) {
+      callback_task_runner_->PostTask(FROM_HERE, base::BindBlock(^{
+        [block_client didFinishLoading];
+      }));
+    } else {
+      DLOG(WARNING) << "WebP decoding failed "
+                    << base::SysNSStringToUTF8(
+                           [[original_response_ URL] absoluteString]);
+      void (^errorBlock)(void) = ^{
+        [block_client didFailWithNSErrorCode:NSURLErrorCannotDecodeContentData
+                                netErrorCode:net::ERR_CONTENT_DECODING_FAILED];
+      };
+      callback_task_runner_->PostTask(FROM_HERE, base::BindBlock(errorBlock));
+    }
+  }
+
+  void SetImageFeatures(size_t total_size,
+                        WebpDecoder::DecodedImageFormat format) override {
+    base::scoped_nsobject<NSURLResponse> imageResponse(
+        NewImageResponse(original_response_, total_size, format));
+    DCHECK(imageResponse);
+    base::scoped_nsprotocol<id<CRNNetworkClientProtocol>> block_client(
+        [underlying_client_ retain]);
+    callback_task_runner_->PostTask(FROM_HERE, base::BindBlock(^{
+      [block_client didReceiveResponse:imageResponse];
+    }));
+  }
+
+  void OnDataDecoded(NSData* data) override {
+    base::scoped_nsprotocol<id<CRNNetworkClientProtocol>> block_client(
+        [underlying_client_ retain]);
+    callback_task_runner_->PostTask(FROM_HERE, base::BindBlock(^{
+      [block_client didLoadData:data];
+    }));
+  }
+
+ private:
+  ~WebpDecoderDelegate() override {}
+
+  base::scoped_nsprotocol<id<CRNNetworkClientProtocol>> underlying_client_;
+  base::scoped_nsobject<NSURLResponse> original_response_;
+  scoped_refptr<base::TaskRunner> callback_task_runner_;
+  base::Time request_creation_time_;
+};
+
+}  // namespace
+
+@interface WebPNetworkClient () {
+  scoped_refptr<webp_transcode::WebpDecoder> _webpDecoder;
+  scoped_refptr<WebpDecoderDelegate> _webpDecoderDelegate;
+  scoped_refptr<base::SequencedTaskRunner> _taskRunner;
+  base::Time _requestCreationTime;
+}
+@end
+
+@implementation WebPNetworkClient
+
+- (instancetype)init {
+  NOTREACHED() << "Use |-initWithTaskRunner:| instead";
+  return nil;
+}
+
+- (instancetype)initWithTaskRunner:
+        (const scoped_refptr<base::SequencedTaskRunner>&)runner {

[sdefresne, 2015/03/19 17:06:34]

style: should be 4 space indentation, not 8

+  if (self = [super init]) {
+    DCHECK(runner);
+    _taskRunner = runner;
+  }
+  return self;
+}
+
+- (void)didCreateNativeRequest:(net::URLRequest*)nativeRequest {
+  // Append 'image/webp' to the outgoing 'Accept' header.
+  const net::HttpRequestHeaders& headers =
+      nativeRequest->extra_request_headers();
+  std::string acceptHeader;
+  if (headers.GetHeader("Accept", &acceptHeader)) {
+    // Add 'image/webp' if it isn't in the Accept header yet.
+    std::string mimePattern = std::string("*") + kWebPMimeType + "*";

[sdefresne, 2015/03/19 17:06:34]

All those allocations for every native requests make me sad (there are at least
three gratuitious allocation on just this line). Moreover, the "*Constant*"
pattern matching is terrible (look at implementation
https://code.google.com/p/chromium/codesearch#chromium/src/base/strings/strin...)
as it must match all Constant pattern against all possible substrings.

What about using std::string::find() instead?

if (acceptHeader.find(kWebPMimeType) != std::string::npos) {
  acceptHeader += std::string(",") + kWebPMimeType;

+    if (!MatchPattern(acceptHeader, mimePattern)) {
+      acceptHeader += std::string(",") + kWebPMimeType;
+      nativeRequest->SetExtraRequestHeaderByName("Accept", acceptHeader, true);
+    }
+  } else {
+    // All requests should already have an Accept: header, so this case
+    // should never happen outside of unit tests.
+    nativeRequest->SetExtraRequestHeaderByName("Accept", kWebPMimeType, false);
+  }
+  [super didCreateNativeRequest:nativeRequest];
+}
+
+- (void)didLoadData:(NSData*)data {
+  if (_webpDecoder.get()) {
+    // |data| is assumed to be immutable.
+    base::scoped_nsobject<NSData> scopedData([data retain]);
+    _taskRunner->PostTask(FROM_HERE, base::Bind(&WebpDecoder::OnDataReceived,
+                                                _webpDecoder, scopedData));
+  } else {
+    [super didLoadData:data];
+  }
+}
+
+- (void)didReceiveResponse:(NSURLResponse*)response {
+  DCHECK(self.underlyingClient);
+  NSString* responseMimeType = [response MIMEType];
+  NSString* webPMimeType =
+      [NSString stringWithCString:kWebPMimeType encoding:NSASCIIStringEncoding];
+  if (responseMimeType &&
+      [responseMimeType caseInsensitiveCompare:webPMimeType] == NSOrderedSame) {
+    _webpDecoderDelegate =
+        new WebpDecoderDelegate(self.underlyingClient, _requestCreationTime,
+                                base::ThreadTaskRunnerHandle::Get());
+    _webpDecoder = new webp_transcode::WebpDecoder(_webpDecoderDelegate.get());
+    base::scoped_nsobject<NSURLResponse> scoped_response([response copy]);
+    _taskRunner->PostTask(FROM_HERE,
+                          base::Bind(&WebpDecoderDelegate::SetOriginalResponse,
+                                     _webpDecoderDelegate, scoped_response));
+    // Do not call super here, the WebpDecoderDelegate will update the mime type
+    // and call |-didReceiveResponse:|.
+  } else {
+    // If this isn't a WebP, pass the call up the chain.
+    // TODO(marq): It would be nice if at this point the client could remove
+    // itself from the client stack.
+    [super didReceiveResponse:response];
+  }
+}
+
+- (void)didFinishLoading {
+  if (_webpDecoder.get()) {
+    _taskRunner->PostTask(FROM_HERE,
+                          base::Bind(&WebpDecoder::Stop, _webpDecoder));
+  } else {
+    [super didFinishLoading];
+  }
+}
+
+@end