ServiceWorkerWriteToCacheJob: refactor

content/browser/service_worker/service_worker_cache_writer.h

Index: content/browser/service_worker/service_worker_cache_writer.h
diff --git a/content/browser/service_worker/service_worker_cache_writer.h b/content/browser/service_worker/service_worker_cache_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..20c36af420575addc5c5e41dacdf8803efa6acf0
--- /dev/null
+++ b/content/browser/service_worker/service_worker_cache_writer.h
@@ -0,0 +1,162 @@
+// 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 "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 cache for

[falken, 2015/09/01 08:06:37]

I'd write this out as "service worker script cache". The "service worker cache"
used to mean the "Cache Storage API", and there's still confusion when saying
"cache" when talking about service workers.

[Elly Fong-Jones, 2015/09/01 13:17:48]

Done.

+// 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 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|.
+  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|.
+  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 BytesWritten() const;
+
+ private:
+  // 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) One of the state functions pauses the machine
+  //   c) 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 Start(int* next_state, bool* pause, int result);
+  int ReadHeadersForCompare(int* next_state, bool* pause, int result);
+  int ReadHeadersForCompareDone(int* next_state, bool* pause, int result);
+  int ReadDataForCompare(int* next_state, bool* pause, int result);
+  int ReadDataForCompareDone(int* next_state, bool* pause, int result);
+  int ReadHeadersForCopy(int* next_state, bool* pause, int result);
+  int ReadHeadersForCopyDone(int* next_state, bool* pause, int result);
+  int WriteHeadersForCopy(int* next_state, bool* pause, int result);
+  int WriteHeadersForCopyDone(int* next_state, bool* pause, int result);
+  int ReadDataForCopy(int* next_state, bool* pause, int result);
+  int ReadDataForCopyDone(int* next_state, bool* pause, int result);
+  int WriteDataForCopy(int* next_state, bool* pause, int result);
+  int WriteDataForCopyDone(int* next_state, bool* pause, int result);
+  int WriteHeadersForPassthrough(int* next_state, bool* pause, int result);
+  int WriteHeadersForPassthroughDone(int* next_state, bool* pause, int result);
+  int WriteDataForPassthrough(int* next_state, bool* pause, int result);
+  int WriteDataForPassthroughDone(int* next_state, bool* pause, int result);
+  int Done(int* next_state, bool* pause, 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.
+  void AsyncDoLoop(int result);
+
+  int state_;
+
+  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 net_length_;
+
+  size_t bytes_compared_;
+  size_t bytes_copied_;
+  size_t bytes_written_;
+
+  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_