[net] Better StopCaching() handling for HttpCache::Transaction.

net/http/http_cache_transaction.h

Index: net/http/http_cache_transaction.h
diff --git a/net/http/http_cache_transaction.h b/net/http/http_cache_transaction.h
index ec88da37e1416febc51c03d538ea5a0af79d2d0a..a094d93f93650b7607cae5cadea23d4adbba4075 100644
--- a/net/http/http_cache_transaction.h
+++ b/net/http/http_cache_transaction.h
@@ -210,15 +210,17 @@ class HttpCache::Transaction : public HttpTransaction {
     STATE_CACHE_READ_METADATA,
     STATE_CACHE_READ_METADATA_COMPLETE,
 
-    // These states are entered from Read/AddTruncatedFlag.
+    // These states are entered from Read

[rvargas (doing something else), 2015/08/19 23:46:39]

nit: period at the end.

[asanka, 2015/09/04 19:09:04]

Done.

+    STATE_RELEASE_CACHE_ENTRY_AND_CONTINUE_USING_NETWORK,
     STATE_NETWORK_READ,
     STATE_NETWORK_READ_COMPLETE,
     STATE_CACHE_READ_DATA,
     STATE_CACHE_READ_DATA_COMPLETE,
     STATE_CACHE_WRITE_DATA,
     STATE_CACHE_WRITE_DATA_COMPLETE,
+
     STATE_CACHE_WRITE_TRUNCATED_RESPONSE,
-    STATE_CACHE_WRITE_TRUNCATED_RESPONSE_COMPLETE
+    STATE_CACHE_WRITE_TRUNCATED_RESPONSE_COMPLETE,
   };
 
   // Used for categorizing transactions for reporting in histograms. Patterns
@@ -290,6 +292,7 @@ class HttpCache::Transaction : public HttpTransaction {
   int DoCacheWriteDataComplete(int result);
   int DoCacheWriteTruncatedResponse();
   int DoCacheWriteTruncatedResponseComplete(int result);
+  int DoReleaseCacheEntryAndContinueUsingNetwork();

[rvargas (doing something else), 2015/08/19 23:46:39]

nit: keep the same order of the enum.

[asanka, 2015/09/04 19:09:04]

Done.

 
   // These functions are involved in a field trial testing storing certificates
   // in seperate entries from the HttpResponseInfo.
@@ -375,6 +378,42 @@ class HttpCache::Transaction : public HttpTransaction {
   // is always "OK".
   int OnWriteResponseInfoToEntryComplete(int result);
 
+  // Requested state of the cache entry after a call to
+  // ReleaseCacheEntry().
+  enum CacheEntryDisposition {
+    // Preserve the cache entry if it already existed prior to this cache
+    // transaction.
+    CACHE_ENTRY_PRESERVE_PREEXISTING,
+
+    // Try to preserve the existing cache entry. It will be marked as truncated
+    // if necessary.
+    CACHE_ENTRY_PRESERVE,
+
+    // Doom the cache entry.
+    CACHE_ENTRY_DOOM
+  };
+
+  // Called when the client has finished with the cache entry. May start the
+  // state machine again. Hence should only be called when there are no more
+  // pending operations.
+  //
+  // If |entry_disposition| is CACHE_ENTRY_PRESERVE_PREEXISTING:
+  //   If the cache entry is sparse or was not created by this transaction, then
+  //   acts as if |entry_disposition| was CACHE_ENTRY_PRESERVE. Otherwise acts
+  //   as if it was CACHE_ENTRY_DOOM.
+  //
+  // If |entry_disposition| is CACHE_ENTRY_PRESERVE:
+  //   If the cache entry was written completely or if the entry is resumable or
+  //   sparse, then preserves the cache entry. If a non-sparse entry wasn't
+  //   written completely, it will be marked as truncated.
+  //
+  // If |entry_disposition| is CACHE_ENTRY_DOOM:
+  //   Marks the cache entry as doomed.

[rvargas (doing something else), 2015/08/19 23:46:39]

nit: Dooms the entry (there's no really a doom mark).

[asanka, 2015/09/04 19:09:04]

Done.

+  //
+  // In all cases other than the case where the entry needs to be marked as
+  // truncated, this call will completely synchronously.
+  int ReleaseCacheEntry(CacheEntryDisposition entry_disposition);
+
   // Called when we are done writing to the cache entry.
   void DoneWritingToEntry(bool success);
 
@@ -403,6 +442,8 @@ class HttpCache::Transaction : public HttpTransaction {
   // between the byte range request and the cached entry.
   int DoRestartPartialRequest();
 
+  void OnCacheReleaseComplete(const base::Closure& closure, int result);
+
   // Resets the relavant internal state to remove traces of internal processing
   // related to range requests. Deletes |partial_| if |delete_object| is true.
   void ResetPartialState(bool delete_object);
@@ -442,15 +483,16 @@ class HttpCache::Transaction : public HttpTransaction {
   std::string cache_key_;
   Mode mode_;
   bool reading_;  // We are already reading. Never reverts to false once set.
-  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 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_;  // All available data was read.
-  bool vary_mismatch_;  // The request doesn't match the stored vary data.
+  bool handling_206_;     // We must deal with this 206 response.
+  bool cache_pending_;    // We are waiting for the HttpCache.
+  bool done_reading_;     // All available data was written to the cache entry.
+  bool vary_mismatch_;    // The request doesn't match the stored vary data.
   bool couldnt_conditionalize_request_;
+  bool stopped_caching_;       // Avoid further writes to the cache.
   bool bypass_lock_for_test_;  // A test is exercising the cache lock.
   bool fail_conditionalization_for_test_;  // Fail ConditionalizeRequest.
   scoped_refptr<IOBuffer> read_buf_;