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

net/http/http_cache.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 a HttpTransactionFactory implementation that can be
 // layered on top of another HttpTransactionFactory to add HTTP caching.  The
 // caching logic follows RFC 7234 (any exceptions are called out in the code).
 //
 // The HttpCache takes a disk_cache::Backend as a parameter, and uses that for
 // the cache storage.
@@ skipping 329 matching lines @@
   // Destroys an ActiveEntry (active or doomed).
   void DestroyEntry(ActiveEntry* entry);
 
   // Adds a transaction to an ActiveEntry. If this method returns ERR_IO_PENDING
   // the transaction will be notified about completion via its IO callback. This
   // method returns ERR_CACHE_RACE to signal the transaction that it cannot be
   // added to the provided entry, and it should retry the process with another
   // one (in this case, the entry is no longer valid).
   int AddTransactionToEntry(ActiveEntry* entry, Transaction* trans);
 
-  // Called when the transaction has finished working with this entry. |cancel|
-  // is true if the operation was cancelled by the caller instead of running
-  // to completion.
-  void DoneWithEntry(ActiveEntry* entry, Transaction* trans, bool cancel);
+  // Used with DoneWithEntry() to indicate the state of the entry.
+  enum class EntryState { SUCCEEDED, DOOMED };

[rvargas (doing something else), 2015/09/11 23:56:17]

nit: types go before methods.

[asanka, 2015/09/17 21:59:40]

Done.

 
-  // Called when the transaction has finished writing to this entry. |success|
-  // is false if the cache entry should be deleted.
-  void DoneWritingToEntry(ActiveEntry* entry, bool success);
-
-  // Called when the transaction has finished reading from this entry.
-  void DoneReadingFromEntry(ActiveEntry* entry, Transaction* trans);
+  // Removes |trans| from |entry|. |trans| is required to be a reader or writer
+  // that was added to |trans| by AddTransactionToEntry(). For writers,
+  // |entry_state| indicates the state of the entry after releasing.

[rvargas (doing something else), 2015/09/11 23:56:17]

nit: what is "after releasing"?

[asanka, 2015/09/17 21:59:40]

Clarified.

+  //
+  // If |entry_state| is DOOMED, then the cache entry is destroyed and any

[rvargas (doing something else), 2015/09/11 23:56:17]

nit: Can we change this to a command like word instead of past-tense status?. As
in, the caller wants to doom the entry, it's not saying that the entry was
doomed (which it can do by itself).

(succeed - doom) is a little weird because they don't seem to be on the same
axis.

[asanka, 2015/09/17 21:59:40]

Changed to KEEP/DOOM

+  // pending transactions that were formerly waiting to be added to |entry| will
+  // receive ERR_CACHE_RACE.
+  //
+  // If |entry_state| is SUCCEEDED, then |entry| is assumed to be safe for
+  // further consumption and pending transaction will be permitted to use it.
+  void DoneWithEntry(ActiveEntry* entry,
+                     Transaction* trans,
+                     EntryState entry_state);
 
   // Converts the active writer transaction to a reader so that other
   // transactions can start reading from this entry.
   void ConvertWriterToReader(ActiveEntry* entry);
 
   // Returns the LoadState of the provided pending transaction.
   LoadState GetLoadStateForPendingTransaction(const Transaction* trans);
 
   // Removes the transaction |trans|, from the pending list of an entry
   // (PendingOp, active or doomed entry).
@@ skipping 70 matching lines @@
   scoped_ptr<base::Clock> clock_;
 
   base::WeakPtrFactory<HttpCache> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpCache);
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_CACHE_H_