XQDB: Assertion `str.size() == length' failed.

[David Graf]

I am able to produce an assertion in xqdb on ubuntu 10.04 64bit.

Query:
for $x in (1,2,3)
let $y := $x+1
return $y

Protocol:
./bin/xqdb -f -q debugger.xq
Communication port: 28028
Zorba executable: ./bin/zorba
Zorba arguments: -d -f -q debugger.xq
Zorba XQuery Debugger Server
Copyright 2006-2009 The FLWOR Foundation.
License: Apache License 2.0: <http://www.apache.org/licenses/LICENSE-2.0>

Established connection with XQuery client zorba
(xqdb) break -f debugger.xq -l 2

set breakpoint with id 1 and state enabled
(xqdb) run
<?xml version="1.0" encoding="UTF-8"?>

break in query body at /home/dagraf/zorba/build/debugger.xq:2

2 o| let $y := $x+1
(xqdb) print -c x

Error: Error while evaluating expression.
(xqdb) print -c $x
Segmentation fault
xqdb: /home/dagraf/zorba/sandbox/src/debugger/debugger_clientimpl.cpp:60: virtual void zorba::DebuggerListener::run(): Assertion `str.size() == length' failed.
Aborted

[Gabriel Petrovay (gabipetrovay)]

The error generated by the command:
print -c x

will cause a second evaluation command to fail whatever that is (even if a correct expression), for example:
print -c $x

[Gabriel Petrovay (gabipetrovay)]

I have tracked this down to a point where I don't know what to do.

The problem is that the debug iterator calls consumeNext on it's theChildren[1], which is an eval iterator. (debug_iterator_impl.cpp:169). If this eval iterator raises a runtime exception (for example, an invalid expression like the one shown in the comment above) in eval.cpp:198, while calling: state->thePlanWrapper->next(result), the execution jump out of EvalIterator::nextImpl without calling state->thePlanWrapper = NULL; in eval.cpp:203.

Therefore a second call to the same eval iterator will fail in eval.cpp:187 at "=" (something that has to do with an RCObject that calls ~PlanWrapper.

What I don't know is how to simulate
state->thePlanWrapper = NULL;
from a catch outside the caller of the eval iterator's nextImpl

Assigning to Markos.