From ce933c3a77cf12b7745e9caa75dec2cddc362ddb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Piotr=20Ma=C5=9Blanka?= <piotr.maslanka@henrietta.com.pl>
Date: Tue, 31 Dec 2019 01:22:34 +0100
Subject: [PATCH] Pidlock (#36)
---
.gitignore | 2 +-
CHANGELOG.md | 4 +-
MANIFEST.in | 1 -
README.md | 4 +-
docs/posix.rst | 10 ++
requirements.txt | 1 +
satella/__init__.py | 2 +-
satella/configuration/__init__.py | 4 +
satella/posix/__init__.py | 4 +-
satella/posix/pidlock.py | 94 ++++++++-----------
setup.py | 3 +-
.../test_sources/test_envvars.py | 3 +-
tests/test_posix/__init__.py | 27 +++++-
13 files changed, 93 insertions(+), 66 deletions(-)
diff --git a/.gitignore b/.gitignore
index 062e6445..3acd50de 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,7 +3,7 @@
#################
satella.sublime*
-
+hs_err_pid*.log
*.pydevproject
.project
.metadata
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1ac80439..16a700b4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,8 @@
# v2.2.3
-* _TBA_
+* renamed `AcquirePIDLock` to `PIDFileLock`
+* more unit tests for `PIDFileLock`
+ * it finally works
# v2.2.2
diff --git a/MANIFEST.in b/MANIFEST.in
index cfabbb68..373701c7 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,4 +1,3 @@
include LICENSE
include README.md
-include requirements.txt
include CHANGELOG.md
diff --git a/README.md b/README.md
index 91dc6379..f591be91 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,9 @@ _satella.posix_ in unavailable on non-POSIX systems, but the rest should work OK
Full [documentation](http://satella.readthedocs.io/en/latest/?badge=latest)
is available for the brave souls that do decide to use this library.
-Satella is a Python 3.5+ library for writing server applications, especially those dealing with mundane but useful things.
+Satella is a zero-requirements Python 3.5+ library for writing
+server applications, especially those dealing with mundane but
+useful things. It also runs on PyPy.
See [LICENSE](LICENSE) for text of the license.
diff --git a/docs/posix.rst b/docs/posix.rst
index 7e9e789f..e8f0dd49 100644
--- a/docs/posix.rst
+++ b/docs/posix.rst
@@ -23,3 +23,13 @@ Return if running as root
.. autofunction:: satella.posix.is_running_as_root
+
+PIDFileLock
+--------------
+
+This is meant to acquire a lock on a file.
+
+.. autoclass:: satella.posix.PIDFileLock
+ :members:
+
+.. autoclass:: satella.posix.LockIsHeld
diff --git a/requirements.txt b/requirements.txt
index e69de29b..a4d92cc0 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -0,0 +1 @@
+psutil
diff --git a/satella/__init__.py b/satella/__init__.py
index 94657e46..9749a659 100644
--- a/satella/__init__.py
+++ b/satella/__init__.py
@@ -1,2 +1,2 @@
# coding=UTF-8
-__version__ = '2.2.3a1'
+__version__ = '2.2.3'
diff --git a/satella/configuration/__init__.py b/satella/configuration/__init__.py
index e69de29b..5d2c95b5 100644
--- a/satella/configuration/__init__.py
+++ b/satella/configuration/__init__.py
@@ -0,0 +1,4 @@
+from . import schema
+from . import sources
+
+__all__ = ['schema', 'sources']
diff --git a/satella/posix/__init__.py b/satella/posix/__init__.py
index cf61df57..b38c9099 100644
--- a/satella/posix/__init__.py
+++ b/satella/posix/__init__.py
@@ -5,12 +5,12 @@ POSIX things
import os
from .daemon import daemonize
-from .pidlock import AcquirePIDLock
+from .pidlock import PIDFileLock, LockIsHeld
from .signals import hang_until_sig
__all__ = [
'daemonize',
- 'AcquirePIDLock',
+ 'PIDFileLock', 'LockIsHeld',
'hang_until_sig',
'is_running_as_root',
'suicide'
diff --git a/satella/posix/pidlock.py b/satella/posix/pidlock.py
index 30ded11a..39e1d0d3 100644
--- a/satella/posix/pidlock.py
+++ b/satella/posix/pidlock.py
@@ -1,109 +1,95 @@
import logging
import os
-logger = logging.getLogger(__name__)
-
+import psutil
-class FailedToAcquire(Exception):
- """Failed to acquire the process lock file"""
+logger = logging.getLogger(__name__)
-class LockIsHeld(FailedToAcquire):
+class LockIsHeld(Exception):
"""
Lock is held by someone
- Has two attributes:
- pid - integer - PID of the holder
- is_alive - bool - whether the holder is an alive process
+ pid -- PID of the holder, who is alive
"""
+ def __init__(self, pid):
+ self.pid = pid
+
-class AcquirePIDLock:
+class PIDFileLock:
"""
Acquire a PID lock file.
+ Usable also on Windows
+
Usage:
- >>> with AcquirePIDLock('myservice.pid'):
+ >>> with PIDFileLock('myservice.pid'):
>>> ... rest of code ..
Or alternatively
- >>> pid_lock = AcquirePIDLock('myservice.pid')
+ >>> pid_lock = PIDFileLock('myservice.pid')
>>> pid_lock.acquire()
>>> ...
>>> pid_lock.release()
The constructor doesn't throw, __enter__ or acquire() does, one of:
- * AcquirePIDLock.FailedToAcquire - base class for errors. Thrown if can't read the file
- * AcquirePIDLock.LockIsHeld - lock is already held. This has two attributes - pid (int), the PID of holder,
+ * LockIsHeld - lock is already held. This has two attributes - pid (int), the PID of holder,
and is_alive (bool) - whether the holder is an alive process
"""
- def __init__(self, pid, is_alive):
- self.pid = pid
- self.is_alive = is_alive
-
- def __init__(self, pid_file, base_dir=u'/var/run', delete_on_dead=False):
+ def __init__(self, pid_file, base_dir=u'/var/run'):
"""
Initialize a PID lock file object
:param pid_file: rest of path
:param base_dir: base lock directory
- :param delete_on_dead: delete the lock file if holder is dead, and retry
"""
- self.delete_on_dead = delete_on_dead
-
self.path = os.path.join(base_dir, pid_file)
-
- self.fileno = None
+ self.file_no = None
def release(self):
- if self.fileno is not None:
- os.close(self.fileno)
+ """
+ Free the lock
+ """
+ if self.file_no is not None:
os.unlink(self.path)
+ self.file_no = None
def acquire(self):
"""
Acquire the PID lock
:raises LockIsHeld: if lock if held
- :raises FailedToAcquire: if for example a directory exists in that place
"""
try:
- self.fileno = os.open(self.path, os.O_CREAT | os.O_EXCL)
- except (IOError, OSError):
- try:
- with open(self.path, 'rb') as flock:
- try:
- pid = int(flock.read())
- except ValueError:
- logger.warning(
- 'PID file found but doesn''t have an int, skipping')
- return
- except IOError as e:
- raise FailedToAcquire(repr(e))
-
- # Is this process alive?
- try:
- os.kill(pid, 0)
- except OSError: # dead
- raise LockIsHeld(pid, False)
- else:
- raise LockIsHeld(pid, True)
+ self.file_no = os.open(self.path, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
+ except (OSError, FileExistsError):
+ with open(self.path, 'r') as fin:
+ data = fin.read().strip()
- def __enter__(self):
- try:
- self.acquire()
- except LockIsHeld as e:
- if self.delete_on_dead and (not e.is_alive):
+ try:
+ pid = int(data)
+ except ValueError:
os.unlink(self.path)
- self.acquire()
+ return self.acquire()
+
+ if pid in {x.pid for x in psutil.process_iter()}:
+ raise LockIsHeld(pid)
else:
- raise
+ # does not exist
+ os.unlink(self.path)
+ return self.acquire()
- self.success = True
+ fd = os.fdopen(self.file_no, 'w')
+ fd.write(str(os.getpid()) + '\n')
+ fd.close()
+
+ def __enter__(self):
+ self.acquire()
def __exit__(self, exc_type, exc_val, exc_tb):
self.release()
diff --git a/setup.py b/setup.py
index 594a2324..620a3d4b 100644
--- a/setup.py
+++ b/setup.py
@@ -7,10 +7,11 @@ setup(keywords=['ha', 'high availability', 'scalable', 'scalability', 'server'],
packages=find_packages(include=['satella', 'satella.*']),
version=__version__,
install_requires=[
+ 'psutil'
],
tests_require=[
"nose", "mock", "coverage"
],
test_suite='nose.collector',
- python_requires='!=2.7.*,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*'
+ python_requires='!=2.7.*,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*',
)
diff --git a/tests/test_configuration/test_sources/test_envvars.py b/tests/test_configuration/test_sources/test_envvars.py
index 66a22444..37a40f06 100644
--- a/tests/test_configuration/test_sources/test_envvars.py
+++ b/tests/test_configuration/test_sources/test_envvars.py
@@ -1,3 +1,4 @@
+from satella.configuration import sources
from satella.configuration.sources import EnvVarsSource, OptionalSource, AlternativeSource, EnvironmentSource, \
StaticSource, MergingSource
from .utils import SourceTestCase, mock_env
@@ -6,7 +7,7 @@ from .utils import SourceTestCase, mock_env
class TestEnvVarsSource(SourceTestCase):
@mock_env('satella', '{"a":2}')
def test_ok(self):
- self.assertSourceHas(EnvVarsSource('satella'), {u"a": 2})
+ self.assertSourceHas(sources.EnvVarsSource('satella'), {u"a": 2})
def test_none(self):
self.assertSourceEmpty(OptionalSource(EnvVarsSource('satella')))
diff --git a/tests/test_posix/__init__.py b/tests/test_posix/__init__.py
index 6864cbaa..b7f2695c 100644
--- a/tests/test_posix/__init__.py
+++ b/tests/test_posix/__init__.py
@@ -1,18 +1,26 @@
# coding=UTF-8
from __future__ import print_function, absolute_import, division
+import multiprocessing
import os
import sys
import unittest
from mock import patch, Mock
+from satella.posix import PIDFileLock, LockIsHeld
+
+
+def acquire_lock_file_and_wait_for_signal(q, p):
+ with PIDFileLock('lock', '.'):
+ p.put(None)
+ q.get()
+
class TestPidlock(unittest.TestCase):
- def test_pidlock(self):
- from satella.posix.pidlock import AcquirePIDLock
- with AcquirePIDLock('lock', '.', delete_on_dead=True):
+ def test_pidlock(self):
+ with PIDFileLock('lock', '.'):
self.assertTrue(os.path.exists('./lock'))
r = open('./lock', 'rb').read()
try:
@@ -23,6 +31,19 @@ class TestPidlock(unittest.TestCase):
self.assertTrue(not os.path.exists('./lock'))
+ def test_pidlock_multiacquire(self):
+ q, p = multiprocessing.Queue(), multiprocessing.Queue()
+ process = multiprocessing.Process(target=acquire_lock_file_and_wait_for_signal, args=(q, p))
+ process.start()
+ p.get()
+ n = PIDFileLock('lock', '.')
+ try:
+ self.assertRaises(LockIsHeld, lambda: n.acquire())
+ finally:
+ q.put(None)
+ process.terminate()
+ process.join()
+
class TestDaemon(unittest.TestCase):
@unittest.skipIf('win' in sys.platform, 'Running on Windows')
--
GitLab