Security-55163.44.tar.gz

[apple/security.git] / libsecurity_utilities / lib / transactions.h

diff --git a/libsecurity_utilities/lib/transactions.h b/libsecurity_utilities/lib/transactions.h
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+/*
+ * Copyright (c) 2004 Apple Computer, Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// transactions - generic transaction frame support
+//
+#ifndef _H_TRANSACTIONS
+#define _H_TRANSACTIONS
+
+#include <security_utilities/utilities.h>
+#include <security_utilities/debugging.h>
+
+
+namespace Security {
+
+
+//
+// Implementation base class. Do not use directly.
+//
+class TransactionBase {
+public:
+       // what happens if this object gets destroyed?
+       enum Outcome {
+               successful,                                             // succeeds as set
+               cancelled,                                              // cancelled (rolled back)
+               conditional                                             // succeeds normally, cancelled on exception
+       };
+       
+public:
+    virtual ~TransactionBase();
+       
+       void outcome(Outcome oc)        { mOutcome = oc; }
+       Outcome outcome() const         { return mOutcome; }
+
+protected:
+       TransactionBase(Outcome outcome) : mOutcome(outcome) { }
+
+       Outcome finalOutcome() const;
+
+private:
+       Outcome mOutcome;                                       // current outcome setting
+};
+
+
+//
+// A ManagedTransaction will call methods begin() and end() on the Carrier object
+// it belongs to, and manage the "outcome" state and semantics automatically.
+// You would usually subclass this, though the class is complete in itself if you
+// need nothing else out of your transaction objects.
+//
+template <class Carrier>
+class ManagedTransaction : public TransactionBase {
+public:
+       ManagedTransaction(Carrier &carrier, Outcome outcome = conditional)
+               : TransactionBase(outcome), mCarrier(carrier)
+       {
+               carrier.begin();
+       }
+       
+       ~ManagedTransaction()
+       {
+               switch (finalOutcome()) {
+               case successful:
+                       this->commitAction();
+                       break;
+               case cancelled:
+                       this->cancelAction();
+                       break;
+               default:
+                       assert(false);
+                       break;
+               }
+       }
+
+protected:
+       virtual void commitAction()             { mCarrier.end(); }
+       virtual void cancelAction()             { mCarrier.cancel(); }
+
+       Carrier &mCarrier;
+};
+
+
+}      // end namespace Security
+
+
+#endif //_H_TRANSACTIONS