[Dexter] Add timeout options

Adds a pair of options for Dexter that allow the user to specify a
timeout duration. These options are:

* --timeout-total: Times out if the total run-time of the debugger session
  exceeds <timeout-total> seconds.
* --timeout-breakpoint: Times out if the time without hitting a
  breakpoint exceeds <timeout-breakpoint> seconds.

Reviewed By: Orlando

Differential Revision: https://reviews.llvm.org/D145063

cross-project-tests/debuginfo-tests/dexter/dex/debugger/DebuggerControllers/ConditionalController.py

@@ -16,6 +16,7 @@ from dex.debugger.DebuggerControllers.ControllerHelpers import in_source_file, u
 from dex.debugger.DebuggerControllers.DebuggerControllerBase import DebuggerControllerBase
 from dex.debugger.DebuggerBase import DebuggerBase
 from dex.utils.Exceptions import DebuggerException
+from dex.utils.Timeout import Timeout
 
 
 class BreakpointRange:
@@ -140,10 +141,26 @@ class ConditionalController(DebuggerControllerBase):
         time.sleep(self._pause_between_steps)
 
         exit_desired = False
+        timed_out = False
+        total_timeout = Timeout(self.context.options.timeout_total)
 
         while not self.debugger.is_finished:
-            while self.debugger.is_running:
-                pass
+
+            breakpoint_timeout = Timeout(self.context.options.timeout_breakpoint)
+            while self.debugger.is_running and not timed_out:
+                # Check to see whether we've timed out while we're waiting.
+                if total_timeout.timed_out():
+                    self.context.logger.error('Debugger session has been '
+                        f'running for {total_timeout.elapsed}s, timeout reached!')
+                    timed_out = True
+                if breakpoint_timeout.timed_out():
+                    self.context.logger.error(f'Debugger session has not '
+                        f'hit a breakpoint for {breakpoint_timeout.elapsed}s, timeout '
+                        'reached!')
+                    timed_out = True
+
+            if timed_out:
+                break
 
             step_info = self.debugger.get_step_info(self._watches, self._step_index)
             if step_info.current_frame:

cross-project-tests/debuginfo-tests/dexter/dex/debugger/DebuggerControllers/DefaultController.py

@@ -13,6 +13,7 @@ import time
 from dex.debugger.DebuggerControllers.DebuggerControllerBase import DebuggerControllerBase
 from dex.debugger.DebuggerControllers.ControllerHelpers import in_source_file, update_step_watches
 from dex.utils.Exceptions import DebuggerException, LoadDebuggerException
+from dex.utils.Timeout import Timeout
 
 class EarlyExitCondition(object):
     def __init__(self, on_line, hit_count, expression, values):
@@ -81,12 +82,25 @@ class DefaultController(DebuggerControllerBase):
             self.watches.update(command_obj.get_watches())
         early_exit_conditions = self._get_early_exit_conditions()
 
+        timed_out = False
+        total_timeout = Timeout(self.context.options.timeout_total)
         max_steps = self.context.options.max_steps
         for _ in range(max_steps):
-            while self.debugger.is_running:
-                pass
 
-            if self.debugger.is_finished:
+            breakpoint_timeout = Timeout(self.context.options.timeout_breakpoint)
+            while self.debugger.is_running and not timed_out:
+                # Check to see whether we've timed out while we're waiting.
+                if total_timeout.timed_out():
+                    self.context.logger.error('Debugger session has been '
+                        f'running for {total_timeout.elapsed}s, timeout reached!')
+                    timed_out = True
+                if breakpoint_timeout.timed_out():
+                    self.context.logger.error(f'Debugger session has not '
+                        f'hit a breakpoint for {breakpoint_timeout.elapsed}s, timeout '
+                        'reached!')
+                    timed_out = True
+
+            if timed_out or self.debugger.is_finished:
                 break
 
             self.step_index += 1

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

@@ -121,7 +121,21 @@ def add_debugger_tool_arguments(parser, context, defaults):
         default='',
         help='command line arguments for the test program, in addition to any '
              'provided by DexCommandLine')
-
+    parser.add_argument(
+        '--timeout-total',
+        metavar='<seconds>',
+        type=float,
+        default=0.0,
+        help='if >0, debugger session will automatically exit after '
+             'running for <timeout-total> seconds')
+    parser.add_argument(
+        '--timeout-breakpoint',
+        metavar='<seconds>',
+        type=float,
+        default=0.0,
+        help='if >0, debugger session will automatically exit after '
+             'waiting <timeout-breakpoint> seconds without hitting a '
+             'breakpoint')
 
 def handle_debugger_tool_base_options(context, defaults):  # noqa
     options = context.options

cross-project-tests/debuginfo-tests/dexter/dex/utils/Timeout.py

@@ -0,0 +1,31 @@
+# DExTer : Debugging Experience Tester
+# ~~~~~~   ~         ~~         ~   ~~
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+"""Utility class to check for timeouts. Timer starts when the object is initialized,
+and can be checked by calling timed_out(). Passing a timeout value of 0.0 or less
+means a timeout will never be triggered, i.e. timed_out() will always return False.
+"""
+
+import time
+
+class Timeout(object):
+
+    def __init__(self, duration: float):
+        self.start = self.now
+        self.duration = duration
+
+    def timed_out(self):
+        if self.duration <= 0.0:
+            return False
+        return self.elapsed > self.duration
+
+    @property
+    def elapsed(self):
+        return self.now - self.start
+
+    @property
+    def now(self):
+        return time.time()