[lldb/test] Add events listener helper class to lldbtest

This patch introduces a generic helper class that will listen for
event in a background thread and match it against a source broadcaster.

If the event received matches the source broadcaster, the event is
queued up in a list that the user can access later on.

The motivation behind this is to easily test new kinds of events
(i.e. Swift type-system progress events). However, this patch also
updates `TestProgressReporting.py` and `TestDiagnosticReporting.py`
to make use of this new helper class.

Differential Revision: https://reviews.llvm.org/D121977

Signed-off-by: Med Ismail Bennani <[email protected]>

Author: medismailben

lldb/packages/Python/lldbsuite/test/eventlistener.py

@@ -0,0 +1,72 @@
+import threading
+
+import lldb
+from lldbsuite.test.lldbtest import *
+
+class EventListenerTestBase(TestBase):
+
+    """
+    Base class for lldb event listener tests.
+
+    This class will setup and start an event listener for the test to use.
+
+    If the event received matches the source broadcaster, the event is
+    queued up in a list that the user can access later on.
+    """
+    NO_DEBUG_INFO_TESTCASE = True
+
+    eBroadcastBitStopListenerThread = (1 << 0)
+    events = []
+    event_mask = None
+    event_data_extractor = None
+
+    def setUp(self):
+        TestBase.setUp(self)
+
+        self.src_broadcaster = self.dbg.GetBroadcaster()
+        self.broadcaster = lldb.SBBroadcaster('lldb.test.broadcaster')
+        self.listener = lldb.SBListener("lldb.test.listener")
+        self.listener.StartListeningForEvents(self.broadcaster,
+                                              self.eBroadcastBitStopListenerThread)
+
+        self.src_broadcaster.AddListener(self.listener, self.event_mask)
+
+        self.listener_thread = threading.Thread(target=self._fetch_events)
+        self.listener_thread.start()
+
+    def tearDown(self):
+        # Broadcast a eBroadcastBitStopListenerThread` event so the background
+        # thread stops listening to events, then join the background thread.
+        self.broadcaster.BroadcastEventByType(self.eBroadcastBitStopListenerThread)
+        self.listener_thread.join()
+        TestBase.tearDown(self)
+
+    def _fetch_events(self):
+        event = lldb.SBEvent()
+
+        done = False
+        while not done:
+            if self.listener.GetNextEvent(event):
+                event_mask = event.GetType();
+                if event.BroadcasterMatchesRef(self.broadcaster):
+                    if event_mask & self.eBroadcastBitStopListenerThread:
+                        done = True;
+                elif event.BroadcasterMatchesRef(self.src_broadcaster):
+                    # NOTE: https://wiki.python.org/moin/FromFunctionToMethod
+                    #
+                    # When assigning the `event_data_extractor` function pointer
+                    # to the `EventListenerTestBase` instance, it turns the
+                    # function object into an instance method which subsequently
+                    # passes `self` as an extra argument.
+
+                    # However, because most of the event data extractor
+                    # functions are static, passing the `self` argument makes
+                    # the number of passed arguments exceeds the function definition
+
+                    # This is why we unwrap the function from the instance
+                    # method object calling `__func__` instead.
+                    ret_args = self.event_data_extractor.__func__(event);
+                    if not ret_args:
+                        continue
+
+                    self.events.append(ret_args)

lldb/test/API/functionalities/diagnostic_reporting/TestDiagnosticReporting.py

@@ -2,51 +2,20 @@
 Test that we are able to broadcast and receive diagnostic events from lldb
 """
 import lldb
-from lldbsuite.test.lldbtest import *
-from lldbsuite.test.decorators import *
+
 import lldbsuite.test.lldbutil as lldbutil
-import threading
 
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.eventlistener import EventListenerTestBase
 
-class TestDiagnosticReporting(TestBase):
+class TestDiagnosticReporting(EventListenerTestBase):
 
     mydir = TestBase.compute_mydir(__file__)
-
-    eBroadcastBitStopDiagnosticThread = (1 << 0)
-
-    def setUp(self):
-        TestBase.setUp(self)
-        self.diagnostic_events = []
-
-    def fetch_events(self):
-        event = lldb.SBEvent()
-
-        done = False
-        while not done:
-            if self.listener.WaitForEvent(1, event):
-                event_mask = event.GetType()
-                if event.BroadcasterMatchesRef(self.test_broadcaster):
-                    if event_mask & self.eBroadcastBitStopDiagnosticThread:
-                        done = True
-                elif event.BroadcasterMatchesRef(self.diagnostic_broadcaster):
-                    self.diagnostic_events.append(
-                        lldb.SBDebugger.GetDiagnosticFromEvent(event))
+    event_mask = lldb.SBDebugger.eBroadcastBitWarning | lldb.SBDebugger.eBroadcastBitError
+    event_data_extractor = lldb.SBDebugger.GetDiagnosticFromEvent
 
     def test_dwarf_symbol_loading_diagnostic_report(self):
         """Test that we are able to fetch diagnostic events"""
-        self.listener = lldb.SBListener("lldb.diagnostic.listener")
-        self.test_broadcaster = lldb.SBBroadcaster('lldb.broadcaster.test')
-        self.listener.StartListeningForEvents(
-            self.test_broadcaster, self.eBroadcastBitStopDiagnosticThread)
-
-        self.diagnostic_broadcaster = self.dbg.GetBroadcaster()
-        self.diagnostic_broadcaster.AddListener(
-            self.listener, lldb.SBDebugger.eBroadcastBitWarning)
-        self.diagnostic_broadcaster.AddListener(
-            self.listener, lldb.SBDebugger.eBroadcastBitError)
-
-        listener_thread = threading.Thread(target=self.fetch_events)
-        listener_thread.start()
 
         self.yaml2obj("minidump.yaml", self.getBuildArtifact("minidump.core"))
 
@@ -55,13 +24,9 @@ def test_dwarf_symbol_loading_diagnostic_report(self):
         self.process = self.target.LoadCore(
             self.getBuildArtifact("minidump.core"))
 
-        self.test_broadcaster.BroadcastEventByType(
-            self.eBroadcastBitStopDiagnosticThread)
-        listener_thread.join()
-
-        self.assertEquals(len(self.diagnostic_events), 1)
+        self.assertEquals(len(self.events), 1)
 
-        diagnostic_event = self.diagnostic_events[0]
+        diagnostic_event = self.events[0]
         self.assertEquals(
             diagnostic_event.GetValueForKey("type").GetStringValue(100),
             "warning")

lldb/test/API/functionalities/progress_reporting/TestProgressReporting.py

@@ -2,57 +2,22 @@
 Test that we are able to broadcast and receive progress events from lldb
 """
 import lldb
-from lldbsuite.test.lldbtest import *
-from lldbsuite.test.decorators import *
-import lldbsuite.test.lldbutil as lldbutil
-import threading
 
-class TestProgressReporting(TestBase):
-
-    mydir = TestBase.compute_mydir(__file__)
-
-    eBroadcastBitStopProgressThread = (1 << 0)
+import lldbsuite.test.lldbutil as lldbutil
 
-    def setUp(self):
-        TestBase.setUp(self)
-        self.progress_events = []
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.eventlistener import EventListenerTestBase
 
-    def fetch_events(self):
-        event = lldb.SBEvent()
 
-        done = False
-        while not done:
-            if self.listener.WaitForEvent(1, event):
-                event_mask = event.GetType();
-                if event.BroadcasterMatchesRef(self.test_broadcaster):
-                    if event_mask & self.eBroadcastBitStopProgressThread:
-                        done = True;
-                elif event.BroadcasterMatchesRef(self.progress_broadcaster):
-                    ret_args = lldb.SBDebugger().GetProgressFromEvent(event);
-                    self.assertGreater(len(ret_args), 1)
+class TestProgressReporting(EventListenerTestBase):
 
-                    message = ret_args[0]
-                    if message:
-                        self.progress_events.append((message, event))
+    mydir = TestBase.compute_mydir(__file__)
+    event_mask = lldb.SBDebugger.eBroadcastBitProgress
+    event_data_extractor = lldb.SBDebugger.GetProgressFromEvent
 
     def test_dwarf_symbol_loading_progress_report(self):
         """Test that we are able to fetch dwarf symbol loading progress events"""
         self.build()
 
-        self.listener = lldb.SBListener("lldb.progress.listener")
-        self.test_broadcaster = lldb.SBBroadcaster('lldb.broadcaster.test')
-        self.listener.StartListeningForEvents(self.test_broadcaster,
-                                              self.eBroadcastBitStopProgressThread)
-
-        self.progress_broadcaster = self.dbg.GetBroadcaster()
-        self.progress_broadcaster.AddListener(self.listener, lldb.SBDebugger.eBroadcastBitProgress)
-
-        listener_thread = threading.Thread(target=self.fetch_events)
-        listener_thread.start()
-
         lldbutil.run_to_source_breakpoint(self, 'break here', lldb.SBFileSpec('main.c'))
-
-        self.test_broadcaster.BroadcastEventByType(self.eBroadcastBitStopProgressThread)
-        listener_thread.join()
-
-        self.assertGreater(len(self.progress_events), 0)
+        self.assertGreater(len(self.events), 0)