[Dexter] Temporarily print DAP logs on specific exception (llvm#157130)

Buildbot cross-project-tests-sie-ubuntu sees sporadic test failures due to
missing "stackTrace" "source" "path". The "path" field is optional for
"source" according to DAP, so it's well formed. It works most of the time,
and doesn't consistently fail for any one test which is all strangely
inconsistent.

The failures couldn't be reproduced locally after running the feature_tests
in a loop for 3 hours. I haven't been able to work out why the "source" is
sometimes missing by just looking at LLDB code.

This patch prints the DAP log to stderr when the specific error condition is
hit, to help us understand why LLDB is sometimes getting into this state.

Dump additional context from FileCheck so this can be seen on the bots (on
a failure).

This patch will be reverted once we've collected some logs.

Author: OCHyams

cross-project-tests/debuginfo-tests/dexter/dex/debugger/DAP.py

@@ -10,6 +10,7 @@
 import abc
 from collections import defaultdict
 import copy
+import io
 import json
 import os
 import shlex
@@ -50,6 +51,7 @@ def __init__(self, context):
         self.prefix_recv: str = "<-"
         self.out_handle = None
         self.open = False
+        self.text = io.StringIO() # In-process copy of the message log.
         self.lock = threading.Lock()
 
     def _custom_enter(self):
@@ -91,6 +93,8 @@ def write_message(self, message: dict, incoming: bool):
         message_str = json.dumps(
             self._colorize_dap_message(message), indent=self.indent
         ).replace("\\u001b", "\033")
+
+        self.text.write(f"{prefix} {message_str}\n")
         if self.out_handle is not None and self.open:
             with self.lock:
                 self.out_handle.write(f"{prefix} {message_str}\n")

cross-project-tests/debuginfo-tests/dexter/dex/debugger/lldb/LLDB.py

@@ -430,9 +430,16 @@ def _post_step_hook(self):
             trace_response = self._await_response(trace_req_id)
             if not trace_response["success"]:
                 raise DebuggerException("failed to get stack frames")
-            stackframes = trace_response["body"]["stackFrames"]
-            path = stackframes[0]["source"]["path"]
-            addr = stackframes[0]["instructionPointerReference"]
+            try:
+                stackframes = trace_response["body"]["stackFrames"]
+                path = stackframes[0]["source"]["path"]
+                addr = stackframes[0]["instructionPointerReference"]
+            except KeyError as e:
+                # Temporarily print the DAP log if this fails to aid debugging
+                # a buildbot failure that doesn't reproduce easily.
+                print(self.message_logger.text.getvalue(), file=sys.stderr)
+                raise e
+
             if any(
                 self._debugger_state.bp_addr_map.get(self.dex_id_to_dap_id[dex_bp_id])
                 == addr

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/control/dex-continue.cpp

@@ -9,7 +9,7 @@
 // UNSUPPORTED: system-windows
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: %dexter_regression_test_run -v --binary %t -- %s 2>&1 | FileCheck %s
+// RUN: %dexter_regression_test_run -v --binary %t -- %s 2>&1 | FileCheck --dump-input-context=999999999 %s
 
 int g = 0;
 int c(int) {

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/control/dex_step_function.cpp

@@ -5,7 +5,7 @@
 // UNSUPPORTED: system-windows
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: %dexter_regression_test_run -v --binary %t -- %s 2>&1 | FileCheck %s
+// RUN: %dexter_regression_test_run -v --binary %t -- %s 2>&1 | FileCheck --dump-input-context=999999999 %s
 
 int g = 0;
 int c(int) {

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/dex_declare_file.cpp

@@ -6,7 +6,7 @@
 //
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck %s
+// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck --dump-input-context=999999999 %s
 // CHECK: dex_declare_file.cpp
 
 int main() {

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/expect_program_state.cpp

@@ -5,7 +5,7 @@
 // UNSUPPORTED: system-darwin
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck %s
+// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck --dump-input-context=999999999 %s
 // CHECK: expect_program_state.cpp:
 
 int GCD(int lhs, int rhs)

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/expect_step_kinds.cpp

@@ -5,7 +5,7 @@
 // UNSUPPORTED: system-darwin
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck %s
+// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck --dump-input-context=999999999 %s
 // CHECK: expect_step_kinds.cpp:
 
 int abs(int i){

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/expect_step_order.cpp

@@ -5,7 +5,7 @@
 // UNSUPPORTED: system-darwin
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck %s
+// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck --dump-input-context=999999999 %s
 // CHECK: expect_step_order.cpp:
 
 int main()

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/expect_watch_type.cpp

@@ -10,7 +10,7 @@
 // expected behaviour.
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck %s
+// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck --dump-input-context=999999999 %s
 // CHECK: expect_watch_type.cpp:
 
 template<class T>

cross-project-tests/debuginfo-tests/dexter/feature_tests/commands/penalty/expect_watch_value.cpp

@@ -6,7 +6,7 @@
 //
 //
 // RUN: %dexter_regression_test_cxx_build %s -o %t
-// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck %s
+// RUN: not %dexter_regression_test_run --binary %t -- %s | FileCheck --dump-input-context=999999999 %s
 // CHECK: expect_watch_value.cpp:
 
 int main()