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

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 192 matching lines @@
     STATE_CACHE_WRITE_RESPONSE,
     STATE_CACHE_WRITE_RESPONSE_COMPLETE,
     STATE_TRUNCATE_CACHED_DATA,
     STATE_TRUNCATE_CACHED_DATA_COMPLETE,
     STATE_TRUNCATE_CACHED_METADATA,
     STATE_TRUNCATE_CACHED_METADATA_COMPLETE,
     STATE_PARTIAL_HEADERS_RECEIVED,
     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
   // 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.
   // NOTE: This enumeration is used in histograms, so please do not add entries
   // in the middle.
   enum TransactionPattern {
     PATTERN_UNDEFINED,
@@ skipping 51 matching lines @@
   int DoCacheReadMetadata();
   int DoCacheReadMetadataComplete(int result);
   int DoNetworkRead();
   int DoNetworkReadComplete(int result);
   int DoCacheReadData();
   int DoCacheReadDataComplete(int result);
   int DoCacheWriteData(int num_bytes);
   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.
   void ReadCertChain();
   void WriteCertChain();
 
   // Sets request_ and fields derived from it.
   void SetRequest(const BoundNetLog& net_log, const HttpRequestInfo* request);
 
   // Returns true if the request should be handled exclusively by the network
@@ skipping 65 matching lines @@
   int WriteResponseInfoToEntry(bool truncated);
 
   // Helper function, should be called with result of WriteResponseInfoToEntry
   // (or the result of the callback, when WriteResponseInfoToEntry returns
   // ERR_IO_PENDING). Calls DoneWritingToEntry if |result| is not the right
   // number of bytes. It is expected that the state that calls this will
   // return whatever net error code this function returns, which currently
   // 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);
 
   // Returns an error to signal the caller that the current read failed. The
   // current operation |result| is also logged. If |restart| is true, the
   // transaction should be restarted.
   int OnCacheReadError(int result, bool restart);
 
   // Called when the cache lock timeout fires.
   void OnAddToEntryTimeout(base::TimeTicks start_time);
 
   // Deletes the current partial cache entry (sparse), and optionally removes
   // the control object (partial_).
   void DoomPartialEntry(bool delete_object);
 
   // Performs the needed work after receiving data from the network, when
   // working with range requests.
   int DoPartialNetworkReadCompleted(int result);
 
   // Performs the needed work after receiving data from the cache, when
   // working with range requests.
   int DoPartialCacheReadCompleted(int result);
 
   // Restarts this transaction after deleting the cached data. It is meant to
   // be used when the current request cannot be fulfilled due to conflicts
   // 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);
 
   // Resets |network_trans_|, which must be non-NULL.  Also updates
   // |old_network_trans_load_timing_|, which must be NULL when this is called.
   void ResetNetworkTransaction();
 
   // 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
@@ skipping 19 matching lines @@
   HttpCache::ActiveEntry* entry_;
   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_;
   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_;
   int io_buf_len_;
   int read_offset_;
   int effective_load_flags_;
   int write_len_;
   scoped_ptr<PartialData> partial_;  // We are dealing with range requests.
   UploadProgress final_upload_progress_;
   CompletionCallback io_callback_;
@@ skipping 24 matching lines @@
   BeforeProxyHeadersSentCallback before_proxy_headers_sent_callback_;
 
   base::WeakPtrFactory<Transaction> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Transaction);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_TRANSACTION_H_