[ON HOLD] Implement pull-based design for content decoding

net/url_request/url_request_job.h

Index: net/url_request/url_request_job.h
diff --git a/net/url_request/url_request_job.h b/net/url_request/url_request_job.h
index 29c330f063154a9dce1e8751bdc07495b1d7bf09..a36ddbec6d7136de6690fbb86a52101e67657131 100644
--- a/net/url_request/url_request_job.h
+++ b/net/url_request/url_request_job.h
@@ -22,6 +22,7 @@
 #include "net/base/request_priority.h"
 #include "net/base/upload_progress.h"
 #include "net/cookies/canonical_cookie.h"
+#include "net/filter/stream_source.h"
 #include "net/socket/connection_attempts.h"
 #include "net/url_request/redirect_info.h"
 #include "net/url_request/url_request.h"
@@ -47,6 +48,7 @@ class X509Certificate;
 
 class NET_EXPORT URLRequestJob : public base::PowerObserver {
  public:
+  typedef base::Callback<void(net::Error, size_t)> ReadRawCompleteCallback;
   explicit URLRequestJob(URLRequest* request,
                          NetworkDelegate* network_delegate);
   ~URLRequestJob() override;
@@ -149,13 +151,11 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
   // network stack makes the request to.
   virtual void PopulateNetErrorDetails(NetErrorDetails* details) const;
 
-  // Called to setup a stream filter for this request. An example of filter is
-  // content encoding/decoding.
-  // Subclasses should return the appropriate Filter, or NULL for no Filter.
-  // This class takes ownership of the returned Filter.
-  //
-  // The default implementation returns NULL.
-  virtual Filter* SetupFilter() const;
+  // Called to set up a StreamSource chain for this request.
+  // Subclasses should return the appropriate first StreamSource of the chain,
+  // or nullptr if no StreamSource should be used. This class takes ownership of
+  // the returned StreamSource.
+  virtual std::unique_ptr<StreamSource> SetupSource();
 
   // Called to determine if this response is a redirect.  Only makes sense
   // for some types of requests.  This method returns true if the response
@@ -252,6 +252,10 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
                                          const GURL& redirect_destination);
 
  protected:
+  // Callback for asynchronous reads from |source_|. See the documentation for
+  // |Read| above for the contract of this method.
+  void SourceReadComplete(Error error, size_t bytes_read);
+
   // Notifies the job that a certificate is requested.
   void NotifyCertificateRequested(SSLCertRequestInfo* cert_request_info);
 
@@ -312,25 +316,6 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
   // bodies are never read.
   virtual void DoneReadingRedirectResponse();
 
-  // Reads filtered data from the request. Returns OK if immediately successful,
-  // ERR_IO_PENDING if the request couldn't complete synchronously, and some
-  // other error code if the request failed synchronously. Note that this
-  // function can issue new asynchronous requests if needed, in which case it
-  // returns ERR_IO_PENDING. If this method completes synchronously,
-  // |*bytes_read| is the number of bytes output by the filter chain if this
-  // method returns OK, or zero if this method returns an error.
-  Error ReadFilteredData(int* bytes_read);
-
-  // Whether the response is being filtered in this job.
-  // Only valid after NotifyHeadersComplete() has been called.
-  bool HasFilter() { return filter_ != NULL; }
-
-  // At or near destruction time, a derived class may request that the filters
-  // be destroyed so that statistics can be gathered while the derived class is
-  // still present to assist in calculations.  This is used by URLRequestHttpJob
-  // to get SDCH to emit stats.
-  void DestroyFilters();
-
   // Provides derived classes with access to the request's network delegate.
   NetworkDelegate* network_delegate() { return network_delegate_; }
 
@@ -342,11 +327,11 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
 
   // The number of bytes read before passing to the filter. This value reflects
   // bytes read even when there is no filter.
-  int64_t prefilter_bytes_read() const { return prefilter_bytes_read_; }
+  int64_t prefilter_bytes_read() const;
 
   // The number of bytes read after passing through the filter. This value
   // reflects bytes read even when there is no filter.
-  int64_t postfilter_bytes_read() const { return postfilter_bytes_read_; }
+  int64_t postfilter_bytes_read() const;
 
   // Turns an integer result code into an Error and a count of bytes read.
   // The semantics are:
@@ -363,21 +348,17 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
   URLRequest* request_;
 
  private:
+  class URLRequestJobStreamSource;

[Randy Smith (Not in Mondays), 2016/04/26 21:54:02]

I don't see this class referred to in the header file; is there any need to
declare it here?

[xunjieli, 2016/07/20 21:00:48]

The declaration here is needed because this class needs to access the private
method (ReadRawDataHelper) of the enclosing class. 

   // Set the status of the associated URLRequest.
   // TODO(mmenke): Make the URLRequest manage its own status.
   void SetStatus(const URLRequestStatus& status);
 
-  // When data filtering is enabled, this function is used to read data
-  // for the filter. Returns a net error code to indicate if raw data was
-  // successfully read,  an error happened, or the IO is pending.
-  Error ReadRawDataForFilter(int* bytes_read);
-
-  // Informs the filter chain that data has been read into its buffer.
-  void PushInputToFilter(int bytes_read);
-
   // Invokes ReadRawData and records bytes read if the read completes
   // synchronously.
-  Error ReadRawDataHelper(IOBuffer* buf, int buf_size, int* bytes_read);
+  Error ReadRawDataHelper(IOBuffer* buf,
+                          int buf_size,
+                          int* bytes_read,
+                          const StreamSource::OnReadCompleteCallback& callback);
 
   // Called in response to a redirect that was not canceled to follow the
   // redirect. The current job will be replaced with a new job loading the
@@ -394,10 +375,6 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
   // |bytes_read| unfiltered bytes have been read for this job.
   void RecordBytesRead(int bytes_read);
 
-  // Called to query whether there is data available in the filter to be read
-  // out.
-  bool FilterHasData();
-
   // NotifyDone marks that request is done. It is really a glorified
   // set_status, but also does internal state checking and job tracking. It
   // should be called once per request, when the job is finished doing all IO.
@@ -427,23 +404,13 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
   // NotifyDone so that it is kept in sync with the request.
   bool done_;
 
-  int64_t prefilter_bytes_read_;
-  int64_t postfilter_bytes_read_;
-
-  // The data stream filter which is enabled on demand.
-  std::unique_ptr<Filter> filter_;
+  // The first StreamSource of the StreamSource chain used.
+  std::unique_ptr<StreamSource> source_;
 
   // If the filter filled its output buffer, then there is a change that it
   // still has internal data to emit, and this flag is set.
   bool filter_needs_more_output_space_;
 
-  // When we filter data, we receive data into the filter buffers.  After
-  // processing the filtered data, we return the data in the caller's buffer.
-  // While the async IO is in progress, we save the user buffer here, and
-  // when the IO completes, we fill this in.
-  scoped_refptr<IOBuffer> filtered_read_buffer_;
-  int filtered_read_buffer_len_;
-
   // We keep a pointer to the read buffer while asynchronous reads are
   // in progress, so we are able to pass those bytes to job observers.
   scoped_refptr<IOBuffer> raw_read_buffer_;
@@ -471,6 +438,13 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
   // notification.
   int64_t last_notified_total_sent_bytes_;
 
+  ReadRawCompleteCallback read_raw_callback_;
+
+  // Raw network bytes read from job subclass.
+  size_t raw_bytes_read_;
+
+  size_t postfilter_bytes_read_;
+
   base::WeakPtrFactory<URLRequestJob> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(URLRequestJob);