move Perf to its own module

babi/main.py

@@ -1,7 +1,6 @@
 import argparse
 import collections
 import contextlib
-import cProfile
 import curses
 import enum
 import functools
@@ -12,7 +11,6 @@ import os
 import re
 import signal
 import sys
-import time
 from typing import Any
 from typing import Callable
 from typing import cast
@@ -34,6 +32,7 @@ from babi.horizontal_scrolling import scrolled_line
 from babi.list_spy import ListSpy
 from babi.list_spy import MutableSequenceNoSlice
 from babi.margin import Margin
+from babi.perf import Perf
 from babi.prompt import Prompt
 from babi.prompt import PromptResult
 from babi.status import Status
@@ -105,46 +104,6 @@ class History:
                         f.write('\n'.join(new_history) + '\n')
 
 
-class Perf:
-    def __init__(self) -> None:
-        self._prof: Optional[cProfile.Profile] = None
-        self._records: List[Tuple[str, float]] = []
-        self._name: Optional[str] = None
-        self._time: Optional[float] = None
-
-    def start(self, name: str) -> None:
-        if self._prof:
-            assert self._name is None, self._name
-            self._name = name
-            self._time = time.monotonic()
-            self._prof.enable()
-
-    def end(self) -> None:
-        if self._prof:
-            assert self._name is not None
-            assert self._time is not None
-            self._prof.disable()
-            self._records.append((self._name, time.monotonic() - self._time))
-            self._name = self._time = None
-
-    @contextlib.contextmanager
-    def log(self, filename: Optional[str]) -> Generator[None, None, None]:
-        if filename is None:
-            yield
-        else:
-            self._prof = cProfile.Profile()
-            self.start('startup')
-            try:
-                yield
-            finally:
-                self.end()
-                self._prof.dump_stats(f'{filename}.pstats')
-                with open(filename, 'w') as f:
-                    f.write('μs\tevent\n')
-                    for name, duration in self._records:
-                        f.write(f'{int(duration * 1000 * 1000)}\t{name}\n')
-
-
 def _restore_lines_eof_invariant(lines: MutableSequenceNoSlice) -> None:
     """The file lines will always contain a blank empty string at the end to
     simplify rendering.  This should be called whenever the end of the file

babi/perf.py

@@ -0,0 +1,47 @@
+import contextlib
+import cProfile
+import time
+from typing import Generator
+from typing import List
+from typing import Optional
+from typing import Tuple
+
+
+class Perf:
+    def __init__(self) -> None:
+        self._prof: Optional[cProfile.Profile] = None
+        self._records: List[Tuple[str, float]] = []
+        self._name: Optional[str] = None
+        self._time: Optional[float] = None
+
+    def start(self, name: str) -> None:
+        if self._prof:
+            assert self._name is None, self._name
+            self._name = name
+            self._time = time.monotonic()
+            self._prof.enable()
+
+    def end(self) -> None:
+        if self._prof:
+            assert self._name is not None
+            assert self._time is not None
+            self._prof.disable()
+            self._records.append((self._name, time.monotonic() - self._time))
+            self._name = self._time = None
+
+    @contextlib.contextmanager
+    def log(self, filename: Optional[str]) -> Generator[None, None, None]:
+        if filename is None:
+            yield
+        else:
+            self._prof = cProfile.Profile()
+            self.start('startup')
+            try:
+                yield
+            finally:
+                self.end()
+                self._prof.dump_stats(f'{filename}.pstats')
+                with open(filename, 'w') as f:
+                    f.write('μs\tevent\n')
+                    for name, duration in self._records:
+                        f.write(f'{int(duration * 1000 * 1000)}\t{name}\n')