add custom sampling errors

Signed-off-by: Keming <kemingy94@gmail.com>

Author: kemingy

Lib/profiling/sampling/__main__.py

@@ -46,6 +46,7 @@
 """
 
 from .cli import main
+from .errors import SamplingUnknownProcessError, SamplingModuleNotFoundError, SamplingScriptNotFoundError
 
 def handle_permission_error():
     """Handle PermissionError by displaying appropriate error message."""
@@ -64,3 +65,9 @@ def handle_permission_error():
         main()
     except PermissionError:
         handle_permission_error()
+    except SamplingUnknownProcessError as err:
+        print(f"Tachyon cannot find the process: {err}", file=sys.stderr)
+        sys.exit(1)
+    except (SamplingModuleNotFoundError, SamplingScriptNotFoundError) as err:
+        print(f"Tachyon cannot find the target: {err}", file=sys.stderr)
+        sys.exit(1)

Lib/profiling/sampling/cli.py

@@ -10,6 +10,7 @@
 import time
 from contextlib import nullcontext
 
+from .errors import SamplingUnknownProcessError, SamplingModuleNotFoundError, SamplingScriptNotFoundError
 from .sample import sample, sample_live, _is_process_running
 from .pstats_collector import PstatsCollector
 from .stack_collector import CollapsedStackCollector, FlamegraphCollector
@@ -744,7 +745,7 @@ def main():
 def _handle_attach(args):
     """Handle the 'attach' command."""
     if not _is_process_running(args.pid):
-        raise sys.exit(f"Process with PID {args.pid} is not running.")
+        raise SamplingUnknownProcessError(args.pid)
     # Check if live mode is requested
     if args.live:
         _handle_live_attach(args, args.pid)
@@ -794,13 +795,13 @@ def _handle_run(args):
             added_cwd = True
         try:
             if importlib.util.find_spec(args.target) is None:
-                sys.exit(f"Error: Module not found: {args.target}")
+                raise SamplingModuleNotFoundError(args.target)
         finally:
             if added_cwd:
                 sys.path.remove(cwd)
     else:
         if not os.path.exists(args.target):
-            sys.exit(f"Error: Script not found: {args.target}")
+            raise SamplingScriptNotFoundError(args.target)
 
     # Check if live mode is requested
     if args.live:

Lib/profiling/sampling/errors.py

@@ -0,0 +1,23 @@
+"""Custom exceptions for the sampling profiler."""
+
+class SamplingProfilerError(Exception):
+    """Base exception for sampling profiler errors."""
+
+class SamplingPermissionError(SamplingProfilerError):
+    def __init__(self):
+        super().__init__(f"Insufficient permission to access process.")
+
+class SamplingUnknownProcessError(SamplingProfilerError):
+    def __init__(self, pid):
+        self.pid = pid
+        super().__init__(f"Process with PID '{pid}' does not exist.")
+
+class SamplingScriptNotFoundError(SamplingProfilerError):
+    def __init__(self, script_path):
+        self.script_path = script_path
+        super().__init__(f"Script '{script_path}' not found.")
+
+class SamplingModuleNotFoundError(SamplingProfilerError):
+    def __init__(self, module_name):
+        self.module_name = module_name
+        super().__init__(f"Module '{module_name}' not found.")

Lib/profiling/sampling/sample.py

@@ -35,26 +35,29 @@ def __init__(self, pid, sample_interval_usec, all_threads, *, mode=PROFILING_MOD
         self.mode = mode  # Store mode for later use
         self.collect_stats = collect_stats
         try:
-            if _FREE_THREADED_BUILD:
-                self.unwinder = _remote_debugging.RemoteUnwinder(
-                    self.pid, all_threads=self.all_threads, mode=mode, native=native, gc=gc,
-                    opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
-                    cache_frames=True, stats=collect_stats
-                )
-            else:
-                only_active_threads = bool(self.all_threads)
-                self.unwinder = _remote_debugging.RemoteUnwinder(
-                    self.pid, only_active_thread=only_active_threads, mode=mode, native=native, gc=gc,
-                    opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
-                    cache_frames=True, stats=collect_stats
-                )
+            self.unwinder = self._new_unwinder(native, gc, opcodes, skip_non_matching_threads)
         except RuntimeError as err:
             raise SystemExit(err)
         # Track sample intervals and total sample count
         self.sample_intervals = deque(maxlen=100)
         self.total_samples = 0
         self.realtime_stats = False
 
+    def _new_unwinder(self, native, gc, opcodes, skip_non_matching_threads):
+        if _FREE_THREADED_BUILD:
+            unwinder = _remote_debugging.RemoteUnwinder(
+                self.pid, all_threads=self.all_threads, mode=self.mode, native=native, gc=gc,
+                opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
+                cache_frames=True, stats=self.collect_stats
+            )
+        else:
+            unwinder = _remote_debugging.RemoteUnwinder(
+                self.pid, only_active_thread=bool(self.all_threads), mode=self.mode, native=native, gc=gc,
+                opcodes=opcodes, skip_non_matching_threads=skip_non_matching_threads,
+                cache_frames=True, stats=self.collect_stats
+            )
+        return unwinder
+
     def sample(self, collector, duration_sec=10, *, async_aware=False):
         sample_interval_sec = self.sample_interval_usec / 1_000_000
         running_time = 0

Lib/test/test_profiling/test_sampling_profiler/test_cli.py

@@ -16,6 +16,7 @@
 from test.support import is_emscripten, requires_remote_subprocess_debugging
 
 from profiling.sampling.cli import main
+from profiling.sampling.errors import SamplingScriptNotFoundError, SamplingModuleNotFoundError, SamplingUnknownProcessError
 
 
 class TestSampleProfilerCLI(unittest.TestCase):
@@ -203,12 +204,12 @@ def test_cli_mutually_exclusive_pid_script(self):
         with (
             mock.patch("sys.argv", test_args),
             mock.patch("sys.stderr", io.StringIO()) as mock_stderr,
-            self.assertRaises(SystemExit) as cm,
+            self.assertRaises(SamplingScriptNotFoundError) as cm,
         ):
             main()
 
         # Verify the error is about the non-existent script
-        self.assertIn("12345", str(cm.exception.code))
+        self.assertIn("12345", str(cm.exception))
 
     def test_cli_no_target_specified(self):
         # In new CLI, must specify a subcommand
@@ -704,14 +705,20 @@ def test_async_aware_incompatible_with_all_threads(self):
     def test_run_nonexistent_script_exits_cleanly(self):
         """Test that running a non-existent script exits with a clean error."""
         with mock.patch("sys.argv", ["profiling.sampling.cli", "run", "/nonexistent/script.py"]):
-            with self.assertRaises(SystemExit) as cm:
+            with self.assertRaisesRegex(SamplingScriptNotFoundError, "Script '[\\w/.]+' not found."):
                 main()
-        self.assertIn("Script not found", str(cm.exception.code))
 
     @unittest.skipIf(is_emscripten, "subprocess not available")
     def test_run_nonexistent_module_exits_cleanly(self):
         """Test that running a non-existent module exits with a clean error."""
         with mock.patch("sys.argv", ["profiling.sampling.cli", "run", "-m", "nonexistent_module_xyz"]):
-            with self.assertRaises(SystemExit) as cm:
+            with self.assertRaisesRegex(SamplingModuleNotFoundError, "Module '[\\w/.]+' not found."):
+                main()
+
+    def test_cli_attach_nonexistent_pid(self):
+        fake_pid = "99999"
+        with mock.patch("sys.argv", ["profiling.sampling.cli", "attach", fake_pid]):
+            with self.assertRaises(SamplingUnknownProcessError) as cm:
                 main()
-        self.assertIn("Module not found", str(cm.exception.code))
+
+            self.assertIn(fake_pid, str(cm.exception))