src/net/instaweb/util/public/http_dump_url_fetcher.h

/**
 * Copyright 2010 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// Author: sligocki@google.com (Shawn Ligocki)

#ifndef NET_INSTAWEB_UTIL_PUBLIC_HTTP_DUMP_URL_FETCHER_H_
#define NET_INSTAWEB_UTIL_PUBLIC_HTTP_DUMP_URL_FETCHER_H_

#include "base/basictypes.h"
#include "net/instaweb/util/public/file_system.h"
#include <string>
#include "net/instaweb/util/public/string_util.h"
#include "net/instaweb/util/public/url_fetcher.h"

class GURL;

namespace net_instaweb {

class Timer;

// TODO(sligocki): Can we forward declare these somehow?
// class FileSystem;
// class FileSystem::InputFile;

// HttpDumpFetcher fetches raw HTTP dumps from the filesystem.
// These dumps could be compressed or chunked, the fetcher does not
// decompress or de-chunk them.
class HttpDumpUrlFetcher : public UrlFetcher {
 public:

  // When the slurped data is gzipped, but request headers are made
  // that don't include 'gzip' in an Accept-Encodings header, then
  // this fetcher inflates the gzipped output as it streams.  It
  // also captures the original gzipped size in this attribute in
  // the response headers.
  static const char kGzipContentLengthAttribute[];

  HttpDumpUrlFetcher(const StringPiece& root_dir, FileSystem* file_system,
                     Timer* timer);
  virtual ~HttpDumpUrlFetcher();

  // Converts URL into filename the way that Latency Lab does.
  // Note: root_dir_ must be standardized to have a / at end already.
  static bool GetFilenameFromUrl(const StringPiece& root_dir,
                                 const GURL& url,
                                 std::string* filename,
                                 MessageHandler* message_handler);

  // Non-static version that uses the fetcher's root dir.
  bool GetFilename(const GURL& url,
                   std::string* filename,
                   MessageHandler* message_handler) {
    return GetFilenameFromUrl(root_dir_, url, filename, message_handler);
  }

  // Converts URL into filename prefix the way that Latency Lab does.
  // Note: root_dir_ must be standardized to have a / at end already.
  static bool GetFilenamePrefixFromUrl(const StringPiece& root_dir,
                                       const GURL& url,
                                       std::string* filename,
                                       MessageHandler* message_handler);

  // This is a synchronous/blocking implementation.
  virtual bool StreamingFetchUrl(const std::string& url,
                                 const MetaData& request_headers,
                                 MetaData* response_headers,
                                 Writer* fetched_content_writer,
                                 MessageHandler* message_handler);

  // Parse file into response_headers and response_writer as if it were bytes
  // off the wire.
  bool ParseFile(FileSystem::InputFile* file,
                 MetaData* response_headers,
                 Writer* response_writer,
                 MessageHandler* handler);

  // Helper function to return a generic error response.
  void RespondError(MetaData* response_headers, Writer* response_writer,
                    MessageHandler* handler);

 private:
  std::string root_dir_;  // Root directory of the HTTP dumps.
  FileSystem* file_system_;
  Timer* timer_;

  // Response to use if something goes wrong.
  std::string error_body_;

  DISALLOW_COPY_AND_ASSIGN(HttpDumpUrlFetcher);
};

}  // namespace net_instaweb

#endif  // NET_INSTAWEB_UTIL_PUBLIC_HTTP_DUMP_URL_FETCHER_H_