Add HttpCache histograms focussed on blocking and transaction type.

net/http/http_cache_transaction.h

 // Copyright (c) 2012 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.
 
 // This file declares HttpCache::Transaction, a private class of HttpCache so
 // it should only be included by http_cache.cc
 
 #ifndef NET_HTTP_HTTP_CACHE_TRANSACTION_H_
 #define NET_HTTP_HTTP_CACHE_TRANSACTION_H_
 
@@ skipping 157 matching lines @@
     STATE_CACHE_READ_METADATA,
     STATE_CACHE_READ_METADATA_COMPLETE,
     STATE_CACHE_QUERY_DATA,
     STATE_CACHE_QUERY_DATA_COMPLETE,
     STATE_CACHE_READ_DATA,
     STATE_CACHE_READ_DATA_COMPLETE,
     STATE_CACHE_WRITE_DATA,
     STATE_CACHE_WRITE_DATA_COMPLETE
   };
 
+  // Used for categorizing transactions for reporting in histograms. Patterns
+  // cover relatively common use cases being measured and considered for
+  // optimization. Many use cases that are more complex or uncommon are binned
+  // as PATTERN_NOT_COVERED, and details are not reported.
+  enum TransactionPattern {
+    PATTERN_UNDEFINED,
+    PATTERN_NOT_COVERED,
+    PATTERN_ENTRY_NOT_CACHED,
+    PATTERN_ENTRY_USED,
+    PATTERN_ENTRY_VALIDATED,
+    PATTERN_ENTRY_UPDATED,
+  };
+
   // This is a helper function used to trigger a completion callback.  It may
   // only be called if callback_ is non-null.
   void DoCallback(int rv);
 
   // This will trigger the completion callback if appropriate.
   int HandleResult(int rv);
 
   // Runs the state transition loop.
   int DoLoop(int result);
 
@@ skipping 147 matching lines @@
   // Returns true if we should bother attempting to resume this request if it
   // is aborted while in progress. If |has_data| is true, the size of the stored
   // data is considered for the result.
   bool CanResume(bool has_data);
 
   // Called to signal completion of asynchronous IO.
   void OnIOComplete(int result);
 
   void ReportCacheActionStart();
   void ReportCacheActionFinish();
+  void UpdateTransactionPattern(TransactionPattern new_transaction_pattern);
+  void RecordHistograms();
 
   State next_state_;
   const HttpRequestInfo* request_;
   BoundNetLog net_log_;
   scoped_ptr<HttpRequestInfo> custom_request_;
   HttpRequestHeaders request_headers_copy_;
   // If extra_headers specified a "if-modified-since" or "if-none-match",
   // |external_validation_| contains the value of those headers.
   ValidationHeaders external_validation_;
   base::WeakPtr<HttpCache> cache_;
   HttpCache::ActiveEntry* entry_;
-  base::TimeTicks entry_lock_waiting_since_;
   HttpCache::ActiveEntry* new_entry_;
   scoped_ptr<HttpTransaction> network_trans_;
   CompletionCallback callback_;  // Consumer's callback.
   HttpResponseInfo response_;
   HttpResponseInfo auth_response_;
   const HttpResponseInfo* new_response_;
   std::string cache_key_;
   Mode mode_;
   State target_state_;
   bool reading_;  // We are already reading.
   bool invalid_range_;  // We may bypass the cache for this request.
   bool truncated_;  // We don't have all the response data.
   bool is_sparse_;  // The data is stored in sparse byte ranges.
   bool range_requested_;  // The user requested a byte range.
   bool handling_206_;  // We must deal with this 206 response.
   bool cache_pending_;  // We are waiting for the HttpCache.
   bool done_reading_;
   scoped_refptr<IOBuffer> read_buf_;
   int io_buf_len_;
   int read_offset_;
   int effective_load_flags_;
   int write_len_;
   scoped_ptr<PartialData> partial_;  // We are dealing with range requests.
   uint64 final_upload_progress_;
   base::WeakPtrFactory<Transaction> weak_factory_;
   CompletionCallback io_callback_;
+
+  // Members used to track data for histograms.
+  TransactionPattern transaction_pattern_;
+  int bytes_read_from_cache_;
+  int bytes_read_from_network_;
+  base::TimeTicks entry_lock_waiting_since_;
+  base::TimeTicks first_cache_access_since_;
+  base::TimeTicks send_request_since_;
+
   HttpTransactionDelegate* transaction_delegate_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_TRANSACTION_H_