teemperor created this revision.
teemperor added a reviewer: jingham.
Herald added a subscriber: abidh.
https://reviews.llvm.org/D48465 is currently blocked by the fact that
tab-completing the first expression is deadlocking LLDB.
The reason for this deadlock is that when we push the ProcessIO handler for
reading the Objective-C runtime
information from the executable (which is triggerd when we parse the an
expression for the first time_,
the IOHandler can't be pushed as the Editline::Cancel method is deadlocking.
The deadlock in Editline is coming from the m_output_mutex, which is locked
before we go into tab completion.
Even without this lock, calling Cancel on Editline will mean that Editline
cleans up behind itself and deletes the
current user-input, which is screws up the console when we are tab-completing
at the same time.
I think for now the most reasonable way of fixing this is to just not call
Cancel on the current IOHandler when we
push the ProcessIO handler. The ProcessIO handler is anyway always temporary,
so not cleaning up for the current
IOHandler for the short duration while the non-interactive ProcessIO handler is
in charge doesn't sound too bad.
As we can't really write unit tests for IOHandler itself (due to the hard
dependency on an initialized Debugger including
all its global state) and Editline completion is currently also not really
testable in an automatic fashion, the test for this has to be that the
expression command completion in https://reviews.llvm.org/D48465 doesn't fail
the first time.
I'll provide a proper unit test for this once I got around and made the
IOHandler code testable, but for now unblocking
https://reviews.llvm.org/D48465 is more critical.
Repository:
rLLDB LLDB
https://reviews.llvm.org/D50912
Files:
source/Core/Debugger.cpp
Index: source/Core/Debugger.cpp
===================================================================
--- source/Core/Debugger.cpp
+++ source/Core/Debugger.cpp
@@ -1098,7 +1098,11 @@
// this new input reader take over
if (top_reader_sp) {
top_reader_sp->Deactivate();
- top_reader_sp->Cancel();
+ // For the ProcessIO handler we don't cancel the current IOHandler. The
+ // current IOHandler shouldn't be influenced by the fact that the temporary
+ // ProcessIO handler has hijacked the IO.
+ if (reader_sp->GetType() != IOHandler::Type::ProcessIO)
+ top_reader_sp->Cancel();
}
}
Index: source/Core/Debugger.cpp
===================================================================
--- source/Core/Debugger.cpp
+++ source/Core/Debugger.cpp
@@ -1098,7 +1098,11 @@
// this new input reader take over
if (top_reader_sp) {
top_reader_sp->Deactivate();
- top_reader_sp->Cancel();
+ // For the ProcessIO handler we don't cancel the current IOHandler. The
+ // current IOHandler shouldn't be influenced by the fact that the temporary
+ // ProcessIO handler has hijacked the IO.
+ if (reader_sp->GetType() != IOHandler::Type::ProcessIO)
+ top_reader_sp->Cancel();
}
}
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