Fix pex3 cache prune handling of cached Pips. (#2589)

Previously, performing a `pex3 cache prune` would bump the last access
time of all un-pruned cached Pips artificially. If you ran
`pex3 cache prune` in a daily or weekly cron job, this would mean Pips
would never be pruned.

CHANGES.md

@@ -1,5 +1,15 @@
 # Release Notes
 
+## 2.24.1
+
+This release fixes `pex3 cache prune` handling of cached Pips.
+Previously, performing a `pex3 cache prune` would bump the last access
+time of all un-pruned cached Pips artificially. If you ran
+`pex3 cache prune` in a daily or weekly cron job, this would mean Pips
+would never be pruned.
+
+* Fix `pex3 cache prune` handling of cached Pips. (#2589)
+
 ## 2.24.0
 
 This release adds `pex3 cache prune` as a likely more useful Pex cache

pex/cache/access.py

@@ -6,17 +6,16 @@
 import fcntl
 import itertools
 import os
-import time
 from contextlib import contextmanager
 
-from pex.common import safe_mkdir
+from pex.common import safe_mkdir, touch
 from pex.typing import TYPE_CHECKING
 from pex.variables import ENV
 
 if TYPE_CHECKING:
     from typing import Iterator, Optional, Tuple, Union
 
-    from pex.cache.dirs import AtomicCacheDir, UnzipDir, VenvDirs  # noqa
+    from pex.cache.dirs import UnzipDir, VenvDir, VenvDirs  # noqa
 
 
 # N.B.: The lock file path is last in the lock state tuple to allow for a simple encoding scheme in
@@ -105,18 +104,21 @@ def await_delete_lock():
     _lock(exclusive=True)
 
 
+LAST_ACCESS_FILE = ".last-access"
+
+
+def _last_access_file(pex_dir):
+    # type: (Union[UnzipDir, VenvDir, VenvDirs]) -> str
+    return os.path.join(pex_dir.path, LAST_ACCESS_FILE)
+
+
 def record_access(
-    atomic_cache_dir,  # type: AtomicCacheDir
+    pex_dir,  # type: Union[UnzipDir, VenvDir]
     last_access=None,  # type: Optional[float]
 ):
     # type: (...) -> None
 
-    # N.B.: We explicitly set atime and do not rely on the filesystem implicitly setting it when the
-    # directory is read since filesystems may be mounted noatime, nodiratime or relatime on Linux
-    # and similar toggles exist, at least in part, for some macOS file systems.
-    atime = last_access or time.time()
-    mtime = os.stat(atomic_cache_dir.path).st_mtime
-    os.utime(atomic_cache_dir.path, (atime, mtime))
+    touch(_last_access_file(pex_dir), last_access)
 
 
 def iter_all_cached_pex_dirs():
@@ -128,5 +130,5 @@ def iter_all_cached_pex_dirs():
         UnzipDir.iter_all(), VenvDirs.iter_all()
     )  # type: Iterator[Union[UnzipDir, VenvDirs]]
     for pex_dir in pex_dirs:
-        last_access = os.stat(pex_dir.path).st_atime
+        last_access = os.stat(_last_access_file(pex_dir)).st_mtime
         yield pex_dir, last_access

pex/cache/dirs.py

@@ -189,15 +189,15 @@ def iter_transitive_dependents(self):
 
     UNZIPPED_PEXES = Value(
         "unzipped_pexes",
-        version=0,
+        version=1,
         name="Unzipped PEXes",
         description="The unzipped PEX files executed on this machine.",
         dependencies=[BOOTSTRAPS, USER_CODE, INSTALLED_WHEELS],
     )
 
     VENVS = Value(
         "venvs",
-        version=0,
+        version=1,
         name="Virtual Environments",
         description="Virtual environments generated at runtime for `--venv` mode PEXes.",
         dependencies=[INSTALLED_WHEELS],

pex/cache/prunable.py

@@ -41,31 +41,24 @@
     from pex.third_party import attr
 
 
-@attr.s(frozen=True)
-class PrunablePipCache(object):
-    pip = attr.ib()  # type: Pip
-    pex_dir = attr.ib()  # type: Union[UnzipDir, VenvDirs]
-    last_access = attr.ib()  # type: float
-
-
 @attr.s(frozen=True)
 class Pips(object):
     @classmethod
     def scan(cls, pex_dirs_by_hash):
-        # type: (Mapping[str, Tuple[Union[UnzipDir, VenvDirs], float, bool]]) -> Pips
+        # type: (Mapping[str, Tuple[Union[UnzipDir, VenvDirs], bool]]) -> Pips
 
         # True to prune the Pip version completely, False to just prune the Pip PEX.
         pips_to_prune = OrderedDict()  # type: OrderedDict[Pip, bool]
 
         # N.B.: We just need 1 Pip per version (really per paired cache). Whether a Pip has
         # extra requirements installed does not affect cache management.
-        pip_caches_to_prune = OrderedDict()  # type: OrderedDict[PipVersionValue, PrunablePipCache]
-        for pip in iter_all_pips():
-            pex_dir, last_access, prunable = pex_dirs_by_hash[pip.pex_hash]
+        pip_caches_to_prune = OrderedDict()  # type: OrderedDict[PipVersionValue, Pip]
+        for pip in iter_all_pips(record_access=False):
+            pex_dir, prunable = pex_dirs_by_hash[pip.pex_hash]
             if prunable:
                 pips_to_prune[pip] = False
             else:
-                pip_caches_to_prune[pip.version] = PrunablePipCache(pip, pex_dir, last_access)
+                pip_caches_to_prune[pip.version] = pip
         for pip in pips_to_prune:
             if pip.version not in pip_caches_to_prune:
                 pips_to_prune[pip] = True
@@ -74,10 +67,10 @@ def scan(cls, pex_dirs_by_hash):
             (pip.pex_dir.base_dir if prune_version else pip.pex_dir.path)
             for pip, prune_version in pips_to_prune.items()
         )
-        return cls(paths=pip_paths_to_prune, caches=tuple(pip_caches_to_prune.values()))
+        return cls(paths=pip_paths_to_prune, pips=tuple(pip_caches_to_prune.values()))
 
     paths = attr.ib()  # type: Tuple[str, ...]
-    caches = attr.ib()  # type: Tuple[PrunablePipCache, ...]
+    pips = attr.ib()  # type: Tuple[Pip, ...]
 
 
 @attr.s(frozen=True)
@@ -107,15 +100,15 @@ def scan(cls, cutoff):
             OrderedSet()
         )  # type: OrderedSet[Union[BootstrapDir, UserCodeDir, InstalledWheelDir]]
         unprunable_deps = []  # type: List[Union[BootstrapDir, UserCodeDir, InstalledWheelDir]]
-        pex_dirs_by_hash = {}  # type: Dict[str, Tuple[Union[UnzipDir, VenvDirs], float, bool]]
+        pex_dirs_by_hash = {}  # type: Dict[str, Tuple[Union[UnzipDir, VenvDirs], bool]]
         for pex_dir, last_access in access.iter_all_cached_pex_dirs():
             prunable = pex_dir in prunable_pex_dirs
             if prunable:
                 pex_dirs.append(pex_dir)
                 pex_deps.update(pex_dir.iter_deps())
             else:
                 unprunable_deps.extend(pex_dir.iter_deps())
-            pex_dirs_by_hash[pex_dir.pex_hash] = pex_dir, last_access, prunable
+            pex_dirs_by_hash[pex_dir.pex_hash] = pex_dir, prunable
         pips = Pips.scan(pex_dirs_by_hash)
 
         return cls(

pex/cli/commands/cache/command.py

@@ -21,7 +21,7 @@
     InstalledWheelDir,
     VenvDirs,
 )
-from pex.cache.prunable import Prunable, PrunablePipCache
+from pex.cache.prunable import Prunable
 from pex.cli.command import BuildTimeCommand
 from pex.cli.commands.cache.bytes import ByteAmount, ByteUnits
 from pex.cli.commands.cache.du import DiskUsage
@@ -33,6 +33,7 @@
 from pex.orderedset import OrderedSet
 from pex.pep_440 import Version
 from pex.pep_503 import ProjectName
+from pex.pip.tool import Pip
 from pex.result import Error, Ok, Result
 from pex.typing import TYPE_CHECKING
 from pex.variables import ENV
@@ -629,21 +630,21 @@ def prune_pip_caches():
             if not prunable_wheels:
                 return
 
-            def spawn_list(prunable_pip_cache):
-                # type: (PrunablePipCache) -> SpawnedJob[Tuple[ProjectNameAndVersion, ...]]
+            def spawn_list(pip):
+                # type: (Pip) -> SpawnedJob[Tuple[ProjectNameAndVersion, ...]]
                 return SpawnedJob.stdout(
-                    job=prunable_pip_cache.pip.spawn_cache_list(),
+                    job=pip.spawn_cache_list(),
                     result_func=lambda stdout: tuple(
                         ProjectNameAndVersion.from_filename(wheel_file)
                         for wheel_file in stdout.decode("utf-8").splitlines()
                         if wheel_file
                     ),
                 )
 
-            pip_removes = []  # type: List[Tuple[PrunablePipCache, str]]
-            for prunable_pip_cache, project_name_and_versions in zip(
-                prunable.pips.caches,
-                execute_parallel(inputs=prunable.pips.caches, spawn_func=spawn_list),
+            pip_removes = []  # type: List[Tuple[Pip, str]]
+            for pip, project_name_and_versions in zip(
+                prunable.pips.pips,
+                execute_parallel(inputs=prunable.pips.pips, spawn_func=spawn_list),
             ):
                 for pnav in project_name_and_versions:
                     if (
@@ -652,7 +653,7 @@ def spawn_list(prunable_pip_cache):
                     ) in prunable_wheels:
                         pip_removes.append(
                             (
-                                prunable_pip_cache,
+                                pip,
                                 "{project_name}-{version}*".format(
                                     project_name=pnav.project_name, version=pnav.version
                                 ),
@@ -673,22 +674,19 @@ def parse_remove(stdout):
                     return 0
 
             def spawn_remove(args):
-                # type: (Tuple[PrunablePipCache, str]) -> SpawnedJob[int]
-                prunable_pip_cache, wheel_name_glob = args
+                # type: (Tuple[Pip, str]) -> SpawnedJob[int]
+                pip, wheel_name_glob = args
                 return SpawnedJob.stdout(
-                    job=prunable_pip_cache.pip.spawn_cache_remove(wheel_name_glob),
+                    job=pip.spawn_cache_remove(wheel_name_glob),
                     result_func=parse_remove,
                 )
 
             removes_by_pip = Counter()  # type: typing.Counter[str]
-            for prunable_pip_cache, remove_count in zip(
-                [prunable_pip_cache for prunable_pip_cache, _ in pip_removes],
+            for pip, remove_count in zip(
+                [pip for pip, _ in pip_removes],
                 execute_parallel(inputs=pip_removes, spawn_func=spawn_remove),
             ):
-                removes_by_pip[prunable_pip_cache.pip.version.value] += remove_count
-                cache_access.record_access(
-                    prunable_pip_cache.pex_dir, last_access=prunable_pip_cache.last_access
-                )
+                removes_by_pip[pip.version.value] += remove_count
             if removes_by_pip:
                 total = sum(removes_by_pip.values())
                 print(

pex/common.py

@@ -532,11 +532,19 @@ def can_write_dir(path):
     return os.path.isdir(path) and os.access(path, os.R_OK | os.W_OK | os.X_OK)
 
 
-def touch(file):
-    # type: (_Text) -> _Text
-    """Equivalent of unix `touch path`."""
+def touch(
+    file,  # type: _Text
+    times=None,  # type: Optional[Union[int, float, Tuple[int, int], Tuple[float, float]]]
+):
+    # type: (...) -> _Text
+    """Equivalent of unix `touch path`.
+
+    If no times is passed, the current time is used to set atime and mtime. If a single int or float
+    is passed for times, it is used for both atime and mtime. If a 2-tuple of ints or floats is
+    passed, the 1st slot is the atime and the 2nd the mtime, just as for `os.utime`.
+    """
     with safe_open(file, "a"):
-        os.utime(file, None)
+        os.utime(file, (times, times) if isinstance(times, (int, float)) else times)
     return file
 
 

pex/layout.py

@@ -320,8 +320,6 @@ def _ensure_installed(
         if not os.path.exists(install_to):
             with ENV.patch(PEX_ROOT=pex_root):
                 cache_access.read_write()
-        else:
-            cache_access.record_access(install_to)
         with atomic_directory(install_to) as chroot:
             if not chroot.is_finalized():
                 with ENV.patch(PEX_ROOT=pex_root), TRACER.timed(
@@ -374,6 +372,7 @@ def _ensure_installed(
                     layout.extract_pex_info(chroot.work_dir)
                     layout.extract_main(chroot.work_dir)
                     layout.record(chroot.work_dir)
+        cache_access.record_access(install_to)
         return install_to
 
 

pex/pex_bootstrapper.py

@@ -507,6 +507,7 @@ def ensure_venv(
     pex,  # type: PEX
     collisions_ok=True,  # type: bool
     copy_mode=None,  # type: Optional[CopyMode.Value]
+    record_access=True,  # type: bool
 ):
     # type: (...) -> VenvPex
     pex_info = pex.pex_info()
@@ -524,8 +525,6 @@ def ensure_venv(
     if not os.path.exists(venv_dir):
         with ENV.patch(PEX_ROOT=pex_info.pex_root):
             cache_access.read_write()
-    else:
-        cache_access.record_access(venv_dir)
     with atomic_directory(venv_dir) as venv:
         if not venv.is_finalized():
             from pex.venv.virtualenv import Virtualenv
@@ -626,7 +625,8 @@ def ensure_venv(
                                 )
 
                             break
-
+    if record_access:
+        cache_access.record_access(venv_dir)
     return VenvPex(venv_dir, hermetic_scripts=pex_info.venv_hermetic_scripts)
 
 

pex/pip/installation.py

@@ -45,14 +45,15 @@ def _create_pip(
     pip_pex,  # type: PipPexDir
     interpreter=None,  # type: Optional[PythonInterpreter]
     use_system_time=False,  # type: bool
+    record_access=True,  # type: bool
 ):
     # type: (...) -> Pip
 
     production_assert(os.path.exists(pip_pex.path))
 
     pip_interpreter = interpreter or PythonInterpreter.get()
     pex = PEX(pip_pex.path, interpreter=pip_interpreter)
-    venv_pex = ensure_venv(pex, copy_mode=CopyMode.SYMLINK)
+    venv_pex = ensure_venv(pex, copy_mode=CopyMode.SYMLINK, record_access=record_access)
     pex_hash = pex.pex_info().pex_hash
     production_assert(pex_hash is not None)
     pip_venv = PipVenv(
@@ -512,8 +513,14 @@ def iter_all(
     interpreter=None,  # type: Optional[PythonInterpreter]
     use_system_time=False,  # type: bool
     pex_root=ENV,  # type: Union[str, Variables]
+    record_access=True,  # type: bool
 ):
     # type: (...) -> Iterator[Pip]
 
     for pip_pex in PipPexDir.iter_all(pex_root=pex_root):
-        yield _create_pip(pip_pex, interpreter=interpreter, use_system_time=use_system_time)
+        yield _create_pip(
+            pip_pex,
+            interpreter=interpreter,
+            use_system_time=use_system_time,
+            record_access=record_access,
+        )

pex/venv/installer.py

@@ -10,6 +10,7 @@
 from textwrap import dedent
 
 from pex import layout, pex_warnings, repl
+from pex.cache import access as cache_access
 from pex.common import CopyMode, chmod_plus_x, iter_copytree, pluralize
 from pex.compatibility import is_valid_python_identifier
 from pex.dist_metadata import Distribution
@@ -534,6 +535,7 @@ def mount(cls, pex):
                 "__main__.py",
                 "__pex__",
                 "__pycache__",
+                cache_access.LAST_ACCESS_FILE,
                 layout.BOOTSTRAP_DIR,
                 layout.DEPS_DIR,
                 layout.PEX_INFO_PATH,

pex/version.py

@@ -1,4 +1,4 @@
 # Copyright 2015 Pex project contributors.
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
-__version__ = "2.24.0"
+__version__ = "2.24.1"