Trie repr.

[python_utils.git] / bootstrap.py

diff --git a/bootstrap.py b/bootstrap.py
index 3b03b3a691b5bb823a3f0548a616358eff93ee96..bf5d91f9eb3a42cd2432d493b74aba436e85e640 100644 (file)
--- a/bootstrap.py
+++ b/bootstrap.py
@@ -3,9 +3,7 @@
 import functools
 import logging
 import os
-import pdb
 import sys
-import traceback
 
 # This module is commonly used by others in here and should avoid
 # taking any unnecessary dependencies back on them.
@@ -25,29 +23,72 @@ args.add_argument(
     default=False,
     help='Break into pdb on top level unhandled exceptions.'
 )
+args.add_argument(
+    '--show_random_seed',
+    action=ActionNoYes,
+    default=False,
+    help='Should we display (and log.debug) the global random seed?'
+)
+args.add_argument(
+    '--set_random_seed',
+    type=int,
+    nargs=1,
+    default=None,
+    metavar='SEED_INT',
+    help='Override the global random seed with a particular number.'
+)
+
+original_hook = sys.excepthook
 
 
-def handle_uncaught_exception(
-        exc_type,
-        exc_value,
-        exc_traceback):
+def handle_uncaught_exception(exc_type, exc_value, exc_tb):
+    """
+    Top-level exception handler for exceptions that make it past any exception
+    handlers in the python code being run.  Logs the error and stacktrace then
+    maybe attaches a debugger.
+    """
+    global original_hook
+    msg = f'Unhandled top level exception {exc_type}'
+    logger.exception(msg)
+    print(msg, file=sys.stderr)
     if issubclass(exc_type, KeyboardInterrupt):
-        sys.__excepthook__(exc_type, exc_value, exc_traceback)
+        sys.__excepthook__(exc_type, exc_value, exc_tb)
         return
-    logger.exception(f'Unhandled top level {exc_type}',
-                     exc_info=(exc_type, exc_value, exc_traceback))
-    traceback.print_exception(exc_type, exc_value, exc_traceback)
-    if config.config['debug_unhandled_exceptions']:
-        logger.info("Invoking the debugger...")
-        pdb.pm()
+    else:
+        if (
+                not sys.stderr.isatty() or
+                not sys.stdin.isatty()
+        ):
+            # stdin or stderr is redirected, just do the normal thing
+            original_hook(exc_type, exc_value, exc_tb)
+        else:
+            # a terminal is attached and stderr is not redirected, maybe debug.
+            import traceback
+            traceback.print_exception(exc_type, exc_value, exc_tb)
+            if config.config['debug_unhandled_exceptions']:
+                import pdb
+                logger.info("Invoking the debugger...")
+                pdb.pm()
+            else:
+                original_hook(exc_type, exc_value, exc_tb)
 
 
 def initialize(entry_point):
+    """
+    Remember to initialize config, initialize logging, set/log a random
+    seed, etc... before running main.
 
-    """Remember to initialize config and logging before running main."""
+    """
     @functools.wraps(entry_point)
     def initialize_wrapper(*args, **kwargs):
-        sys.excepthook = handle_uncaught_exception
+
+        # Hook top level unhandled exceptions, maybe invoke debugger.
+        if sys.excepthook == sys.__excepthook__:
+            sys.excepthook = handle_uncaught_exception
+
+        # Try to figure out the name of the program entry point.  Then
+        # parse configuration (based on cmdline flags, environment vars
+        # etc...)
         if (
                 '__globals__' in entry_point.__dict__ and
                 '__file__' in entry_point.__globals__
@@ -56,12 +97,28 @@ def initialize(entry_point):
         else:
             config.parse(None)
 
+        # Initialize logging... and log some remembered messages from
+        # config module.
         logging_utils.initialize_logging(logging.getLogger())
-
         config.late_logging()
 
-        logger.debug(f'Starting {entry_point.__name__} (program entry point)')
+        # Allow programs that don't bother to override the random seed
+        # to be replayed via the commandline.
+        import random
+        random_seed = config.config['set_random_seed']
+        if random_seed is not None:
+            random_seed = random_seed[0]
+        else:
+            random_seed = int.from_bytes(os.urandom(4), 'little')
+
+        if config.config['show_random_seed']:
+            msg = f'Global random seed is: {random_seed}'
+            print(msg)
+            logger.debug(msg)
+        random.seed(random_seed)
 
+        # Do it, invoke the user's code.  Pay attention to how long it takes.
+        logger.debug(f'Starting {entry_point.__name__} (program entry point)')
         ret = None
         import stopwatch
         with stopwatch.Timer() as t:
@@ -79,8 +136,10 @@ def initialize(entry_point):
                      f'child system: {cstime}s\n'
                      f'machine uptime: {elapsed_time}s\n'
                      f'walltime: {walltime}s')
-        if ret != 0:
-            logger.info(f'Exit {ret}')
+
+        # If it doesn't return cleanly, call attention to the return value.
+        if ret is not None and ret != 0:
+            logger.error(f'Exit {ret}')
         else:
             logger.debug(f'Exit {ret}')
         sys.exit(ret)