[telemetry] Consolidate global hooks.

tools/telemetry/telemetry/util/global_hooks.py

Index: tools/telemetry/telemetry/util/global_hooks.py
diff --git a/tools/telemetry/telemetry/util/global_hooks.py b/tools/telemetry/telemetry/util/global_hooks.py
new file mode 100644
index 0000000000000000000000000000000000000000..50ed5b5f3b4d4831c8c20e0bf45bacc9bf942d2f
--- /dev/null
+++ b/tools/telemetry/telemetry/util/global_hooks.py
@@ -0,0 +1,75 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Hooks that apply globally to all scripts that import or use Telemetry."""
+
+import os
+import signal
+import sys
+import traceback
+
+from telemetry.core import util
+from telemetry.util import exception_formatter
+
+
+def InstallHooks():
+  RemoveAllStalePycFiles(util.GetTelemetryDir())
+  RemoveAllStalePycFiles(util.GetBaseDir())
+  InstallUnhandledExceptionFormatter()
+  InstallStackDumpOnSigusr1()
+  InstallTerminationHook()
+
+
+def RemoveAllStalePycFiles(base_dir):
+  """Scan directories for old .pyc files without a .py file and delete them."""
+  for dirname, _, filenames in os.walk(base_dir):
+    if '.svn' in dirname or '.git' in dirname:
+      continue
+    for filename in filenames:
+      root, ext = os.path.splitext(filename)
+      if ext != '.pyc':
+        continue
+
+      pyc_path = os.path.join(dirname, filename)
+      py_path = os.path.join(dirname, root + '.py')
+
+      try:
+        if not os.path.exists(py_path):
+          os.remove(pyc_path)
+      except OSError:
+        # Wrap OS calls in try/except in case another process touched this file.
+        pass
+
+    try:
+      os.removedirs(dirname)
+    except OSError:
+      # Wrap OS calls in try/except in case another process touched this dir.
+      pass
+
+
+def InstallUnhandledExceptionFormatter():
+  """Print prettier exceptions that also contain the stack frame's locals."""
+  sys.excepthook = exception_formatter.PrintFormattedException
+
+
+def InstallStackDumpOnSigusr1():
+  """Catch SIGUSR1 and print a stack trace."""
+  # Windows doesn't define SIGUSR1.
+  if not hasattr(signal, 'SIGUSR1'):
+    return
+
+  def PrintDiagnostics(_, stack_frame):
+    print >> sys.stderr, 'SIGUSR1 received, printing stack trace:'
+    traceback.print_stack(stack_frame)
+  signal.signal(signal.SIGUSR1, PrintDiagnostics)
+
+
+def InstallTerminationHook():
+  """Catch SIGTERM, print a stack trace, and exit."""
+  def PrintStackAndExit(sig, stack_frame):
+    print >> sys.stderr, 'Traceback (most recent call last):'
+    traceback.print_stack(stack_frame)
+    print >> sys.stderr, 'Received signal %s, exiting' % sig
+    sys.exit(-1)
+  signal.signal(signal.SIGTERM, PrintStackAndExit)