Exposing CacheEntryStatus (former TransactionPattern) via UrlRequest

net/http/http_response_info.h

 // Copyright (c) 2011 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 NET_HTTP_HTTP_RESPONSE_INFO_H_
 #define NET_HTTP_HTTP_RESPONSE_INFO_H_
 
 #include <string>
 
 #include "base/time/time.h"
@@ skipping 26 matching lines @@
     CONNECTION_INFO_HTTP1 = 1,
     CONNECTION_INFO_DEPRECATED_SPDY2 = 2,
     CONNECTION_INFO_SPDY3 = 3,
     CONNECTION_INFO_HTTP2 = 4,  // HTTP/2.
     CONNECTION_INFO_QUIC1_SPDY3 = 5,
     CONNECTION_INFO_HTTP2_14 = 6,  // HTTP/2 draft-14.
     CONNECTION_INFO_HTTP2_15 = 7,  // HTTP/2 draft-15.
     NUM_OF_CONNECTION_INFOS,
   };
 
+  // Used for categorizing transactions for reporting in histograms.
+  // CacheEntryStatus covers relatively common use cases being measured and
+  // considered for optimization. Many use cases that are more complex or
+  // uncommon are binned as OTHER, and details are not reported.
+  // NOTE: This enumeration is used in histograms, so please do not add entries
+  // in the middle.
+  enum CacheEntryStatus {
+    UNDEFINED,

[jkarlin, 2016/07/06 17:09:41]

Please prefix the names with ENTRY_

e.g., ENTRY_UNDEFINED, ENTRY_OTHER, ENTRY_NOT_IN_CACHE, ENTRY_USED,
ENTRY_VALIDATED, ENTRY_UPDATED, ENTRY_CANT_CONDITIONALIZE, ENTRY_MAX

[jamartin, 2016/07/07 21:36:38]

Done.

Why? if I may ask. I considered the ENTRY_ prefix very much redundant given the
CacheEntryStatus:: qualification.

+    // Complex or uncommon case (e.g., partial responses - 206).
+    OTHER,
+    // The response was not in the cache. Implies !was_cached &&
+    // network_accessed.
+    NOT_IN_CACHE,
+    // The response was served from the cache and no validation was needed.
+    // Implies was_cached && !network_accessed.
+    USED,
+    // The response was validated and served from the cache. Implies was_cached
+    // && network_accessed.
+    VALIDATED,
+    // There was a stale entry in the cache that was updated. Implies
+    // !was_cached && network_accessed.
+    UPDATED,
+    // The HTTP request didn't allow a conditional request. Implies !was_cached
+    // && network_accessed.
+    CANT_CONDITIONALIZE,
+    MAX,
+  };
+
   HttpResponseInfo();
   HttpResponseInfo(const HttpResponseInfo& rhs);
   ~HttpResponseInfo();
   HttpResponseInfo& operator=(const HttpResponseInfo& rhs);
   // Even though we could get away with the copy ctor and default operator=,
   // that would prevent us from doing a bunch of forward declaration.
 
   // Initializes from the representation stored in the given pickle.
   bool InitFromPickle(const base::Pickle& pickle, bool* response_truncated);
 
@@ skipping 11 matching lines @@
   // If this resource was found in the cache, then this bool is set, and
   // request_time may corresponds to a time "far" in the past.  Note that
   // stale content (perhaps un-cacheable) may be fetched from cache subject to
   // the load flags specified on the request info.  For example, this is done
   // when a user presses the back button to re-render pages, or at startup,
   // when reloading previously visited pages (without going over the network).
   // Note also that under normal circumstances, was_cached is set to the correct
   // value even if the request fails.
   bool was_cached;
 
+  // How this response was handled by the HTTP cache.
+  CacheEntryStatus cache_entry_status;
+
   // True if the request was fetched from cache rather than the network
   // because of a LOAD_FROM_CACHE_IF_OFFLINE flag when the system
   // was unable to contact the server.
   bool server_data_unavailable;
 
   // True if the request accessed the network in the process of retrieving
   // data.
   bool network_accessed;
 
   // True if the request was fetched over a SPDY channel.
@@ skipping 69 matching lines @@
   scoped_refptr<IOBufferWithSize> metadata;
 
   static ConnectionInfo ConnectionInfoFromNextProto(NextProto next_proto);
 
   static std::string ConnectionInfoToString(ConnectionInfo connection_info);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_RESPONSE_INFO_H_