Patch to enable short-circuiting for AND conditions

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Problem: Use of a urlrewrite rule that has a condition that consumes request 
input stream makes it impossible for any other downstream filter/servlet to 
consume it as a stream. 

For instance when jruby/rack servlet passes the request on to rails, and rails 
doesn't understand java HttpServletRequest and doesn't read parameters 
directly. In such cases the framework(in this case rails) tries to read the 
request input stream and parse out the payload from it, but this fails because 
urlrewrite condition consumes the stream while reading parameters. There 
appears to be no way to avoid this stream dereferencing either, because 'and' 
is not short-circuited.

What steps will reproduce the problem?
Add following url rewrite rules
    <rule>
        <name>Initialize _method translation</name>
        <from>.*</from>
        <set name="do_not_set_method">false</set>
    </rule>

    <rule>
        <name>Special request that does not require method setting</name>
        <from>^/((foo)|(bar))$</from>
        <to last="true">/special_req/$1</to>
        <set name="do_not_set_method">true</set>
    </rule>

    <rule>
        <name>Reset _method attribute if _method parameter is passed in</name>
        <condition type="attribute" name="do_not_set_method">false</condition>
        <condition type="parameter" name="_method">.+</condition>
        <from>.+</from>
        <set name="_method">%{parameter:_method}</set>
    </rule>

What is the expected output? What do you see instead?
When its a 'special request'(matched by second rule), condition evaluation for 
'reset _method' should not dereference stream contents in an attempt to read 
parameters, as the first condition for 'reset _method' is not met. But since 
'and' doesn't short-circuit, it dereferences it anyway, which means 
dereferencing of input stream can not be avoided.

What version of the product are you using? On what operating system?
3.2.0/Gentoo

Please provide any additional information below.
This patch short-circuits AND conditions, which means in the example above, the 
first condition failing will prevent the evaluation of second condition, hence 
making it possible to avoid dereferencing of input stream.

NOTE: this is a 'git format-patch' generated patch. Please use 'patch -p1 -i 
0001-AND-conditions-now-shortcircuit.patch'

This cleanly applies on 3.2.0 branch as well.

Original issue reported on code.google.com by singh.janmejay on 10 Aug 2010 at 11:09

Attachments:

• 0001-AND-conditions-now-shortcircuit.patch