MuxMessageDispatcher mutates RequestOptions leading ultimately to potential
StackOverflowError
----------------------------------------------------------------------------------------------
Key: JGRP-1271
URL:
https://issues.jboss.org/browse/JGRP-1271
Project: JGroups
Issue Type: Bug
Affects Versions: 2.11
Environment: All
Reporter: Eric Sirianni
Assignee: Bela Ban
The presence of 'public static final' RequestOptions SYNC and ASYNC implies
strongly that RequestOptions are immutable. Otherwise, clients could be changing the
meaning of these shared constants.
However, MuxMessageDispatcher.cast() mutates the passed-in RequestOptions to set the
RspFilter. It chains the existing RspFilter in the RequestOptions to a new one:
options.setRspFilter((filter != null) ? new NoMuxHandlerRspFilter(filter) : new
NoMuxHandlerRspFilter())
The result of this is that the following innocent looking code code will quickly lead to a
stack overflow as the RspFilter chain in the RequestOptions.ASYNC object grows without
bound:
while (true) {
muxMessageDispatcher.cast(dests, msg, RequestOptions.ASYNC, false);
}
The workaround is to create a new RequestOptions object per call to cast() :
while (true) {
muxMessageDispatcher.cast(dests, msg, new RequestOptions(...), false);
}
I recommend either:
A. Deprecating the public static final RequestOptions ASYNC and SYNC fields and heavily
JavaDoc'ing that clients must use a fresh RequestOptions for each send() or cast()
invocation.
-or-
B. JavaDoc'ing the RequestOptions class as *immutable* and fixing MuxMessageDispatcher
and other such JGroups blocks that mutate RequestOptions. You may wish to add a
"copy constructor" to RequestOptions to facilitate this. The fix for
MuxMessageDispatcher is fairly easy - just "clone" the passed-in RequestOptions
and set the NoMuxHandlerRspFilter on the new RequestOptions object:
< return super.cast(dests, msg, options.setRspFilter((filter != null) ? new
NoMuxHandlerRspFilter(filter) : new NoMuxHandlerRspFilter()), blockForResults);
---
RequestOptions newOptions = new
RequestOptions(options.getMode(), options.getTimeout(), options.getAnycasting(), options,
(filter != null) ? new NoMuxHandlerRspFilter(filter) : new NoMuxHandlerRspFilter(),
options.getFlags());
return super.cast(dests, msg, newOptions), blockForResults);
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