Revert of ServiceWorkerWriteToCacheJob: refactor

content/browser/service_worker/service_worker_cache_writer.h

-// Copyright 2015 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_SERVICE_WORKER_SERVICE_WORKER_CACHE_WRITER_H_
-#define CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CACHE_WRITER_H_
-
-#include <map>
-#include <set>
-
-#include "base/callback.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "content/common/content_export.h"
-#include "net/base/io_buffer.h"
-#include "net/base/net_errors.h"
-
-namespace content {
-
-struct HttpResponseInfoIOBuffer;
-class ServiceWorkerCacheWriterCore;
-class ServiceWorkerResponseReader;
-class ServiceWorkerResponseWriter;
-class ServiceWorkerStorage;
-
-// This class is responsible for possibly updating the ServiceWorker script
-// cache for an installed ServiceWorker main script. If there is no existing
-// cache entry, this class always writes supplied data back to the cache; if
-// there is an existing cache entry, this class only writes supplied data back
-// if there is a cache mismatch.
-//
-// Note that writes done by this class cannot be "short" - ie, if they succeed,
-// they always write all the supplied data back. Therefore completions are
-// signalled with net::Error without a count of bytes written.
-//
-// This class's behavior is modelled as a state machine; see the DoLoop function
-// for comments about this.
-class CONTENT_EXPORT ServiceWorkerCacheWriter {
- public:
-  using OnWriteCompleteCallback = base::Callback<void(net::Error)>;
-
-  // The types for the factory functions passed into the constructor. These are
-  // responsible for creating readers from the existing cache entry and writers
-  // to the new cache entry when called. These are passed in as factories
-  // instead of passing readers and writers in directly to avoid creating
-  // writers to entries that won't be updated, and because this class may need
-  // multiple readers internally.
-  using ResponseReaderCreator =
-      base::Callback<scoped_ptr<ServiceWorkerResponseReader>(void)>;
-  using ResponseWriterCreator =
-      base::Callback<scoped_ptr<ServiceWorkerResponseWriter>(void)>;
-
-  // The existing reader may be null, in which case this instance will
-  // unconditionally write back data supplied to |MaybeWriteHeaders| and
-  // |MaybeWriteData|.
-  ServiceWorkerCacheWriter(const ResponseReaderCreator& reader_creator,
-                           const ResponseWriterCreator& writer_creator);
-
-  virtual ~ServiceWorkerCacheWriter();
-
-  // Writes the supplied |headers| back to the cache. Returns ERR_IO_PENDING if
-  // the write will complete asynchronously, in which case |callback| will be
-  // called when it completes. Otherwise, returns a code other than
-  // ERR_IO_PENDING and does not invoke |callback|. Note that this method will
-  // not necessarily write data back to the cache if the incoming data is
-  // equivalent to the existing cached data. See the source of this function for
-  // details about how this function drives the state machine.
-  net::Error MaybeWriteHeaders(HttpResponseInfoIOBuffer* headers,
-                               const OnWriteCompleteCallback& callback);
-
-  // Writes the supplied body data |data| back to the cache. Returns
-  // ERR_IO_PENDING if the write will complete asynchronously, in which case
-  // |callback| will be called when it completes. Otherwise, returns a code
-  // other than ERR_IO_PENDING and does not invoke |callback|. Note that this
-  // method will not necessarily write data back to the cache if the incoming
-  // data is equivalent to the existing cached data. See the source of this
-  // function for details about how this function drives the state machine.
-  net::Error MaybeWriteData(net::IOBuffer* buf,
-                            size_t buf_size,
-                            const OnWriteCompleteCallback& callback);
-
-  // Returns a count of bytes written back to the cache.
-  size_t bytes_written() const { return bytes_written_; }
-  bool did_replace() const { return did_replace_; }
-
- private:
-  // States for the state machine.
-  //
-  // The state machine flows roughly like this: if there is no existing cache
-  // entry, incoming headers and data are written directly back to the cache
-  // ("passthrough mode", the PASSTHROUGH states). If there is an existing cache
-  // entry, incoming headers and data are compared to the existing cache entry
-  // ("compare mode", the COMPARE states); if at any point the incoming
-  // headers/data are not equal to the cached headers/data, this class copies
-  // the cached data up to the point where the incoming data and the cached data
-  // diverged ("copy mode", the COPY states), then switches to "passthrough
-  // mode" to write the remainder of the incoming data. The overall effect is to
-  // avoid rewriting the cache entry if the incoming data is identical to the
-  // cached data.
-  //
-  // Note that after a call to MaybeWriteHeaders or MaybeWriteData completes,
-  // the machine is always in STATE_DONE, indicating that the call is finished;
-  // those methods are responsible for setting a new initial state.
-  enum State {
-    STATE_START,
-    // Control flows linearly through these four states, then loops from
-    // READ_DATA_FOR_COMPARE_DONE to READ_DATA_FOR_COMPARE, or exits to
-    // READ_HEADERS_FOR_COPY.
-    STATE_READ_HEADERS_FOR_COMPARE,
-    STATE_READ_HEADERS_FOR_COMPARE_DONE,
-    STATE_READ_DATA_FOR_COMPARE,
-    STATE_READ_DATA_FOR_COMPARE_DONE,
-
-    // Control flows linearly through these states, with each pass from
-    // READ_DATA_FOR_COPY to WRITE_DATA_FOR_COPY_DONE copying one block of data
-    // at a time. Control loops from WRITE_DATA_FOR_COPY_DONE back to
-    // READ_DATA_FOR_COPY if there is more data to copy, or exits to
-    // WRITE_DATA_FOR_PASSTHROUGH.
-    STATE_READ_HEADERS_FOR_COPY,
-    STATE_READ_HEADERS_FOR_COPY_DONE,
-    STATE_WRITE_HEADERS_FOR_COPY,
-    STATE_WRITE_HEADERS_FOR_COPY_DONE,
-    STATE_READ_DATA_FOR_COPY,
-    STATE_READ_DATA_FOR_COPY_DONE,
-    STATE_WRITE_DATA_FOR_COPY,
-    STATE_WRITE_DATA_FOR_COPY_DONE,
-
-    // Control flows linearly through these states, with a loop between
-    // WRITE_DATA_FOR_PASSTHROUGH and WRITE_DATA_FOR_PASSTHROUGH_DONE.
-    STATE_WRITE_HEADERS_FOR_PASSTHROUGH,
-    STATE_WRITE_HEADERS_FOR_PASSTHROUGH_DONE,
-    STATE_WRITE_DATA_FOR_PASSTHROUGH,
-    STATE_WRITE_DATA_FOR_PASSTHROUGH_DONE,
-
-    // This state means "done with the current call; ready for another one."
-    STATE_DONE,
-  };
-
-  // Drives this class's state machine. This function steps the state machine
-  // until one of:
-  //   a) One of the state functions returns an error
-  //   b) The state machine reaches STATE_DONE
-  // A successful value (net::OK or greater) indicates that the requested
-  // operation completed synchronously. A return value of ERR_IO_PENDING
-  // indicates that some step had to submit asynchronous IO for later
-  // completion, and the state machine will resume running (via AsyncDoLoop)
-  // when that asynchronous IO completes. Any other return value indicates that
-  // the requested operation failed synchronously.
-  int DoLoop(int result);
-
-  // State handlers. See function comments in the corresponding source file for
-  // details on these.
-  int DoStart(int result);
-  int DoReadHeadersForCompare(int result);
-  int DoReadHeadersForCompareDone(int result);
-  int DoReadDataForCompare(int result);
-  int DoReadDataForCompareDone(int result);
-  int DoReadHeadersForCopy(int result);
-  int DoReadHeadersForCopyDone(int result);
-  int DoWriteHeadersForCopy(int result);
-  int DoWriteHeadersForCopyDone(int result);
-  int DoReadDataForCopy(int result);
-  int DoReadDataForCopyDone(int result);
-  int DoWriteDataForCopy(int result);
-  int DoWriteDataForCopyDone(int result);
-  int DoWriteHeadersForPassthrough(int result);
-  int DoWriteHeadersForPassthroughDone(int result);
-  int DoWriteDataForPassthrough(int result);
-  int DoWriteDataForPassthroughDone(int result);
-  int DoDone(int result);
-
-  // Wrappers for asynchronous calls. These are responsible for scheduling a
-  // callback to drive the state machine if needed. These either:
-  //   a) Return ERR_IO_PENDING, and schedule a callback to run the state
-  //      machine's Run() later, or
-  //   b) Return some other value and do not schedule a callback.
-  int ReadInfoHelper(const scoped_ptr<ServiceWorkerResponseReader>& reader,
-                     HttpResponseInfoIOBuffer* buf);
-  int ReadDataHelper(const scoped_ptr<ServiceWorkerResponseReader>& reader,
-                     net::IOBuffer* buf,
-                     int buf_len);
-  int WriteInfoHelper(const scoped_ptr<ServiceWorkerResponseWriter>& writer,
-                      HttpResponseInfoIOBuffer* buf);
-  int WriteDataHelper(const scoped_ptr<ServiceWorkerResponseWriter>& writer,
-                      net::IOBuffer* buf,
-                      int buf_len);
-
-  // Callback used by the above helpers for their IO operations. This is only
-  // run when those IO operations complete asynchronously, in which case it
-  // invokes the synchronous DoLoop function and runs the client callback (the
-  // one passed into MaybeWriteData/MaybeWriteHeaders) if that invocation
-  // of DoLoop completes synchronously.
-  void AsyncDoLoop(int result);
-
-  State state_;
-  // Note that this variable is only used for assertions; it reflects "state !=
-  // DONE && not in synchronous DoLoop".
-  bool io_pending_;
-  bool comparing_;
-
-  scoped_refptr<HttpResponseInfoIOBuffer> headers_to_read_;
-  scoped_refptr<HttpResponseInfoIOBuffer> headers_to_write_;
-  scoped_refptr<net::IOBuffer> data_to_read_;
-  int len_to_read_;
-  scoped_refptr<net::IOBuffer> data_to_copy_;
-  scoped_refptr<net::IOBuffer> data_to_write_;
-  int len_to_write_;
-  OnWriteCompleteCallback pending_callback_;
-
-  size_t cached_length_;
-
-  size_t bytes_compared_;
-  size_t bytes_copied_;
-  size_t bytes_written_;
-
-  bool did_replace_;
-
-  size_t compare_offset_;
-
-  ResponseReaderCreator reader_creator_;
-  ResponseWriterCreator writer_creator_;
-  scoped_ptr<ServiceWorkerResponseReader> compare_reader_;
-  scoped_ptr<ServiceWorkerResponseReader> copy_reader_;
-  scoped_ptr<ServiceWorkerResponseWriter> writer_;
-  base::WeakPtrFactory<ServiceWorkerCacheWriter> weak_factory_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_SERVICE_WORKER_SERVICE_WORKER_CACHE_WRITER_H_