IndexedDBFactory now ForceCloses databases.

content/browser/indexed_db/indexed_db_database.cc

 // Copyright (c) 2013 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.
 
 #include "content/browser/indexed_db/indexed_db_database.h"
 
 #include <math.h>
 #include <set>
 
 #include "base/auto_reset.h"
@@ skipping 1628 matching lines @@
   }
   metadata_.version = kNoStringVersion;
   metadata_.id = kInvalidId;
   metadata_.int_version = IndexedDBDatabaseMetadata::NO_INT_VERSION;
   metadata_.object_stores.clear();
   callbacks->OnSuccess();
   if (factory_)
     factory_->DatabaseDeleted(identifier_);
 }
 
+void IndexedDBDatabase::ForceClose() {
+  ConnectionSet conns(connections_);

[jsbell, 2013/12/20 00:24:42]

Is this copy necessary?

[cmumford, 2013/12/20 18:09:26]

I can't see an alternative. listset has no front method, so I can't do a while
(!empty) type of loop. Nor does it have a reverse_iterator. And ForceClose
modifies connections_ which invalidates the iterator and causes a crash. Let me
know if I'm missing something.

[jsbell, 2013/12/20 18:22:56]

A few possibilities:

* list_set does have begin() - should be equivalent to front()

* unless there's a bug, the iterator shouldn't be invalidated during
modification if it's incremented before the removal, similar to the STL
erase(it++) idiom:

it = set.begin();
while (it != set.end()) {
  con = *it;
  ++it;
  con->ForceClose();
}

* a common pattern in these cases is to do a swap rather than a copy. However,
that would empty out the "master" set, and there may be things that rely on
things being in the set. I'd avoid this if possible.

* Finally, if a copy is necessary, document it with a comment (since it's
unusual)

+  for (ConnectionSet::iterator i = conns.begin(); i != conns.end(); ++i)

[jsbell, 2013/12/20 00:24:42]

Nit: We try not to use single-character variables. Prefer "it" or "iter" here.

[cmumford, 2013/12/20 18:09:26]

Done.

+    (*i)->ForceClose();
+}
+
 void IndexedDBDatabase::Close(IndexedDBConnection* connection, bool forced) {
   DCHECK(connections_.count(connection));
   DCHECK(connection->IsConnected());
   DCHECK(connection->database() == this);
 
   // Abort outstanding transactions from the closing connection. This
   // can not happen if the close is requested by the connection itself
   // as the front-end defers the close until all transactions are
   // complete, but can occur on process termination or forced close.
   {
@@ skipping 58 matching lines @@
     const base::string16& previous_version,
     int64 previous_int_version,
     IndexedDBTransaction* transaction) {
   IDB_TRACE("IndexedDBDatabase::VersionChangeAbortOperation");
   DCHECK(!transaction);
   metadata_.version = previous_version;
   metadata_.int_version = previous_int_version;
 }
 
 }  // namespace content