Change executable_linenos_cache to global variable and add check cache mechanism

Author: aisk

Lib/bdb.py

@@ -189,6 +189,51 @@ def _get_executable_linenos(code):
     return linenos
 
 
+# filename: (size, mtime, executable_linenos, fullname)
+_executable_linenos_cache = {}
+
+
+def _check_executable_linenos_cache(filename=None):
+    if filename is None:
+        filenames = tuple(_executable_linenos_cache)
+    else:
+        filenames = tuple(filename)
+
+    for filename in filenames:
+        if (entry := _executable_linenos_cache.get(filename)) is None:
+            continue
+        size, mtime, _, fullname = entry
+        if mtime is None:
+            continue
+        try:
+            stat = os.stat(fullname)
+        except (OSError, ValueError):
+            _executable_linenos_cache.pop(filename, None)
+            continue
+        if size != stat.st_size or mtime != stat.st_mtime:
+            _executable_linenos_cache.pop(filename, None)
+
+
+def _set_executable_linenos_cache_entry(
+    filename, executable_linenos, source, linecache_entry
+):
+    if linecache_entry is not None and len(linecache_entry) != 1:
+        size, mtime, _, fullname = linecache_entry
+    else:
+        fullname = filename
+        try:
+            stat = os.stat(filename)
+        except (OSError, ValueError):
+            size = len(source)
+            mtime = None
+        else:
+            size = stat.st_size
+            mtime = stat.st_mtime
+    _executable_linenos_cache[filename] = (
+        size, mtime, executable_linenos, fullname
+    )
+
+
 class Bdb:
     """Generic Python debugger base class.
 
@@ -207,7 +252,6 @@ def __init__(self, skip=None, backend='settrace'):
         self.skip = set(skip) if skip else None
         self.breaks = {}
         self.fncache = {}
-        self.executable_linenos_cache = {}
         self.frame_trace_lines_opcodes = {}
         self.frame_returning = None
         self.trace_opcodes = False
@@ -258,6 +302,7 @@ def reset(self):
         """Set values of attributes as ready to start debugging."""
         import linecache
         linecache.checkcache()
+        _check_executable_linenos_cache()
         self.botframe = None
         self._set_stopinfo(None, None)
 
@@ -681,16 +726,25 @@ def set_break(self, filename, lineno, temporary=False, cond=None,
         """
         filename = self.canonic(filename)
         import linecache # Import as late as possible
+        linecache.checkcache(filename)
+        _check_executable_linenos_cache(filename)
         line = linecache.getline(filename, lineno)
         if not line:
             return 'Line %s:%d does not exist' % (filename, lineno)
-        if filename not in self.executable_linenos_cache:
+        if filename not in _executable_linenos_cache:
             source = ''.join(linecache.getlines(filename))
             if source:
                 with suppress(SyntaxError):
                     code = compile(source, filename, 'exec')
-                    self.executable_linenos_cache[filename] = _get_executable_linenos(code)
-        executable_lines = self.executable_linenos_cache.get(filename)
+                    executable_lines = _get_executable_linenos(code)
+                    _set_executable_linenos_cache_entry(
+                        filename,
+                        executable_lines,
+                        source,
+                        linecache.cache.get(filename),
+                    )
+        cache_entry = _executable_linenos_cache.get(filename)
+        executable_lines = cache_entry[2] if cache_entry else None
         if executable_lines and lineno not in executable_lines:
             return 'Line %d has no code associated with it' % lineno
         self._add_to_breaks(filename, lineno)