.NET Binding for Messaging classes need a test to check that binding is still
in effect
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Key: QPID-3193
URL: https://issues.apache.org/jira/browse/QPID-3193
Project: Qpid
Issue Type: Improvement
Affects Versions: 0.11
Reporter: Chuck Rolke
Assignee: Chuck Rolke
The .NET Binding for Messaging could be made more user-friendly with the
addition of a property that indicates whether or not the underlying binding is
still available. A C# coder may innocently write:
(1) Message mA = new Message("a");
(2) Message mB = mA;
...
(N) mB.Dispose();
After disposing of message mB then message mA is clobbered. 'Message' is a 'ref
class' type and messages mA and mB refer to the same object on managed heap.
When message mB is disposed then the bound C++ Messaging object is deleted [1].
Any reference to the bound message part of mA will result in an illegal memory
reference (to 0) and a process exit. The .NET runtime can't catch this fault.
The obvious answer is not to do that. If the second line of code was 'Message
mB = new Message(mA)' then mA and mB would have been completely separate and
disposing of either would have no effect on the other.
Another answer is to have the binding check for a null binding reference on
each and every access and then to throw if the underlying binding is gone. This
is not very appealing from a performance standpoint.
As a compromise I would like to add a property isBound to each class. Users
then have a fighting chance to check that the binding is still in effect and
that function calls on the object shouldn't blow up. This property would be
useful in Assert statements or in debugging.
[1] If anyone knows how to have my binding library intercept example code line
(2) and create reference counts, please let me know.
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