Rework linecache handling (#828)

* Rework linecache handling

* lint

* Add changelog

changelog.d/828.changes.rst

@@ -0,0 +1 @@
+Generated source code is now cached more efficiently for identical classes.

src/attr/_make.py

@@ -5,7 +5,6 @@
 import linecache
 import sys
 import threading
-import uuid
 import warnings
 
 from operator import itemgetter
@@ -329,16 +328,25 @@ def _make_method(name, script, filename, globs=None):
  if globs is None:
  globs = {}
 
- _compile_and_eval(script, globs, locs, filename)
-
  # In order of debuggers like PDB being able to step through the code,
  # we add a fake linecache entry.
- linecache.cache[filename] = (
- len(script),
- None,
- script.splitlines(True),
- filename,
- )
+ count = 1
+ base_filename = filename
+ while True:
+ linecache_tuple = (
+ len(script),
+ None,
+ script.splitlines(True),
+ filename,
+ )
+ old_val = linecache.cache.setdefault(filename, linecache_tuple)
+ if old_val == linecache_tuple:
+ break
+ else:
+ filename = "{}-{}>".format(base_filename[:-1], count)
+ count += 1
+
+ _compile_and_eval(script, globs, locs, filename)
 
  return locs[name]
 
@@ -1632,30 +1640,12 @@ def _generate_unique_filename(cls, func_name):
  """
  Create a "filename" suitable for a function being generated.
  """
- unique_id = uuid.uuid4()
- extra = ""
- count = 1
-
- while True:
- unique_filename = "<attrs generated {0} {1}.{2}{3}>".format(
- func_name,
- cls.__module__,
- getattr(cls, "__qualname__", cls.__name__),
- extra,
- )
- # To handle concurrency we essentially "reserve" our spot in
- # the linecache with a dummy line. The caller can then
- # set this value correctly.
- cache_line = (1, None, (str(unique_id),), unique_filename)
- if (
- linecache.cache.setdefault(unique_filename, cache_line)
- == cache_line
- ):
- return unique_filename
-
- # Looks like this spot is taken. Try again.
- count += 1
- extra = "-{0}".format(count)
+ unique_filename = "<attrs generated {0} {1}.{2}>".format(
+ func_name,
+ cls.__module__,
+ getattr(cls, "__qualname__", cls.__name__),
+ )
+ return unique_filename
 
 
 def _make_hash(cls, attrs, frozen, cache_hash):

tests/test_dunders.py

@@ -936,6 +936,16 @@ class C(object):
  pass
 
 
+CopyC = C
+
+
+@attr.s(hash=True, order=True)
+class C(object):
+ """A different class, to generate different methods."""
+
+ a = attr.ib()
+
+
 class TestFilenames(object):
  def test_filenames(self):
  """
@@ -953,15 +963,27 @@ def test_filenames(self):
  OriginalC.__hash__.__code__.co_filename
  == "<attrs generated hash tests.test_dunders.C>"
  )
+ assert (
+ CopyC.__init__.__code__.co_filename
+ == "<attrs generated init tests.test_dunders.C>"
+ )
+ assert (
+ CopyC.__eq__.__code__.co_filename
+ == "<attrs generated eq tests.test_dunders.C>"
+ )
+ assert (
+ CopyC.__hash__.__code__.co_filename
+ == "<attrs generated hash tests.test_dunders.C>"
+ )
  assert (
  C.__init__.__code__.co_filename
- == "<attrs generated init tests.test_dunders.C-2>"
+ == "<attrs generated init tests.test_dunders.C-1>"
  )
  assert (
  C.__eq__.__code__.co_filename
- == "<attrs generated eq tests.test_dunders.C-2>"
+ == "<attrs generated eq tests.test_dunders.C-1>"
  )
  assert (
  C.__hash__.__code__.co_filename
- == "<attrs generated hash tests.test_dunders.C-2>"
+ == "<attrs generated hash tests.test_dunders.C-1>"
  )