From 2bea6fc523f0cf58dacab21c723f105c3652ecff Mon Sep 17 00:00:00 2001 From: Jean-Christophe Fillion-Robin Date: Wed, 19 Apr 2017 16:57:22 -0400 Subject: [PATCH] Add support for support parallel build This was adapted from sage.git: * http://git.sagemath.org/sage.git/log/build/pkgs/setuptools/patches/easy_install_lock.patch * http://trac.sagemath.org/ticket/17268#comment:7 * http://trac.sagemath.org/ticket/13201 And generalized to all platforms integrating openstack/pylockfile@99870bf --- setuptools/command/easy_install.py | 14 +- setuptools/command/lockfile/__init__.py | 347 ++++++++++++++++++ setuptools/command/lockfile/linklockfile.py | 73 ++++ setuptools/command/lockfile/mkdirlockfile.py | 84 +++++ setuptools/command/lockfile/pidlockfile.py | 190 ++++++++++ setuptools/command/lockfile/sqlitelockfile.py | 156 ++++++++ .../command/lockfile/symlinklockfile.py | 70 ++++ 7 files changed, 933 insertions(+), 1 deletion(-) create mode 100644 setuptools/command/lockfile/__init__.py create mode 100644 setuptools/command/lockfile/linklockfile.py create mode 100644 setuptools/command/lockfile/mkdirlockfile.py create mode 100644 setuptools/command/lockfile/pidlockfile.py create mode 100644 setuptools/command/lockfile/sqlitelockfile.py create mode 100644 setuptools/command/lockfile/symlinklockfile.py diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py index e30ca3ac16..447567b421 100755 --- a/setuptools/command/easy_install.py +++ b/setuptools/command/easy_install.py @@ -1553,6 +1553,10 @@ def __init__(self, filename, sitedirs=()): list(map(self.add, find_distributions(path, True))) def _load(self): + # Lock self.filename until save() is called + from lockfile import LockFile + self.lockfile = LockFile(self.filename) + self.lockfile.acquire() self.paths = [] saw_import = False seen = dict.fromkeys(self.sitedirs) @@ -1585,7 +1589,12 @@ def _load(self): def save(self): """Write changed .pth file back to disk""" + from lockfile import NotLocked if not self.dirty: + try: + self.lockfile.release() + except NotLocked: + pass return rel_paths = list(map(self.make_relative, self.paths)) @@ -1602,7 +1611,10 @@ def save(self): elif os.path.exists(self.filename): log.debug("Deleting empty %s", self.filename) os.unlink(self.filename) - + try: + self.lockfile.release() + except NotLocked: + pass self.dirty = False @staticmethod diff --git a/setuptools/command/lockfile/__init__.py b/setuptools/command/lockfile/__init__.py new file mode 100644 index 0000000000..a6f44a55c6 --- /dev/null +++ b/setuptools/command/lockfile/__init__.py @@ -0,0 +1,347 @@ +# -*- coding: utf-8 -*- + +""" +lockfile.py - Platform-independent advisory file locks. + +Requires Python 2.5 unless you apply 2.4.diff +Locking is done on a per-thread basis instead of a per-process basis. + +Usage: + +>>> lock = LockFile('somefile') +>>> try: +... lock.acquire() +... except AlreadyLocked: +... print 'somefile', 'is locked already.' +... except LockFailed: +... print 'somefile', 'can\\'t be locked.' +... else: +... print 'got lock' +got lock +>>> print lock.is_locked() +True +>>> lock.release() + +>>> lock = LockFile('somefile') +>>> print lock.is_locked() +False +>>> with lock: +... print lock.is_locked() +True +>>> print lock.is_locked() +False + +>>> lock = LockFile('somefile') +>>> # It is okay to lock twice from the same thread... +>>> with lock: +... lock.acquire() +... +>>> # Though no counter is kept, so you can't unlock multiple times... +>>> print lock.is_locked() +False + +Exceptions: + + Error - base class for other exceptions + LockError - base class for all locking exceptions + AlreadyLocked - Another thread or process already holds the lock + LockFailed - Lock failed for some other reason + UnlockError - base class for all unlocking exceptions + AlreadyUnlocked - File was not locked. + NotMyLock - File was locked but not by the current thread/process +""" + +from __future__ import absolute_import + +import functools +import os +import socket +import threading +import warnings + +# Work with PEP8 and non-PEP8 versions of threading module. +if not hasattr(threading, "current_thread"): + threading.current_thread = threading.currentThread +if not hasattr(threading.Thread, "get_name"): + threading.Thread.get_name = threading.Thread.getName + +__all__ = ['Error', 'LockError', 'LockTimeout', 'AlreadyLocked', + 'LockFailed', 'UnlockError', 'NotLocked', 'NotMyLock', + 'LinkFileLock', 'MkdirFileLock', 'SQLiteFileLock', + 'LockBase', 'locked'] + + +class Error(Exception): + """ + Base class for other exceptions. + + >>> try: + ... raise Error + ... except Exception: + ... pass + """ + pass + + +class LockError(Error): + """ + Base class for error arising from attempts to acquire the lock. + + >>> try: + ... raise LockError + ... except Error: + ... pass + """ + pass + + +class LockTimeout(LockError): + """Raised when lock creation fails within a user-defined period of time. + + >>> try: + ... raise LockTimeout + ... except LockError: + ... pass + """ + pass + + +class AlreadyLocked(LockError): + """Some other thread/process is locking the file. + + >>> try: + ... raise AlreadyLocked + ... except LockError: + ... pass + """ + pass + + +class LockFailed(LockError): + """Lock file creation failed for some other reason. + + >>> try: + ... raise LockFailed + ... except LockError: + ... pass + """ + pass + + +class UnlockError(Error): + """ + Base class for errors arising from attempts to release the lock. + + >>> try: + ... raise UnlockError + ... except Error: + ... pass + """ + pass + + +class NotLocked(UnlockError): + """Raised when an attempt is made to unlock an unlocked file. + + >>> try: + ... raise NotLocked + ... except UnlockError: + ... pass + """ + pass + + +class NotMyLock(UnlockError): + """Raised when an attempt is made to unlock a file someone else locked. + + >>> try: + ... raise NotMyLock + ... except UnlockError: + ... pass + """ + pass + + +class _SharedBase(object): + def __init__(self, path): + self.path = path + + def acquire(self, timeout=None): + """ + Acquire the lock. + + * If timeout is omitted (or None), wait forever trying to lock the + file. + + * If timeout > 0, try to acquire the lock for that many seconds. If + the lock period expires and the file is still locked, raise + LockTimeout. + + * If timeout <= 0, raise AlreadyLocked immediately if the file is + already locked. + """ + raise NotImplemented("implement in subclass") + + def release(self): + """ + Release the lock. + + If the file is not locked, raise NotLocked. + """ + raise NotImplemented("implement in subclass") + + def __enter__(self): + """ + Context manager support. + """ + self.acquire() + return self + + def __exit__(self, *_exc): + """ + Context manager support. + """ + self.release() + + def __repr__(self): + return "<%s: %r>" % (self.__class__.__name__, self.path) + + +class LockBase(_SharedBase): + """Base class for platform-specific lock classes.""" + def __init__(self, path, threaded=True, timeout=None): + """ + >>> lock = LockBase('somefile') + >>> lock = LockBase('somefile', threaded=False) + """ + super(LockBase, self).__init__(path) + self.lock_file = os.path.abspath(path) + ".lock" + self.hostname = socket.gethostname() + self.pid = os.getpid() + if threaded: + t = threading.current_thread() + # Thread objects in Python 2.4 and earlier do not have ident + # attrs. Worm around that. + ident = getattr(t, "ident", hash(t)) + self.tname = "-%x" % (ident & 0xffffffff) + else: + self.tname = "" + dirname = os.path.dirname(self.lock_file) + + # unique name is mostly about the current process, but must + # also contain the path -- otherwise, two adjacent locked + # files conflict (one file gets locked, creating lock-file and + # unique file, the other one gets locked, creating lock-file + # and overwriting the already existing lock-file, then one + # gets unlocked, deleting both lock-file and unique file, + # finally the last lock errors out upon releasing. + self.unique_name = os.path.join(dirname, + "%s%s.%s%s" % (self.hostname, + self.tname, + self.pid, + hash(self.path))) + self.timeout = timeout + + def is_locked(self): + """ + Tell whether or not the file is locked. + """ + raise NotImplemented("implement in subclass") + + def i_am_locking(self): + """ + Return True if this object is locking the file. + """ + raise NotImplemented("implement in subclass") + + def break_lock(self): + """ + Remove a lock. Useful if a locking thread failed to unlock. + """ + raise NotImplemented("implement in subclass") + + def __repr__(self): + return "<%s: %r -- %r>" % (self.__class__.__name__, self.unique_name, + self.path) + + +def _fl_helper(cls, mod, *args, **kwds): + warnings.warn("Import from %s module instead of lockfile package" % mod, + DeprecationWarning, stacklevel=2) + # This is a bit funky, but it's only for awhile. The way the unit tests + # are constructed this function winds up as an unbound method, so it + # actually takes three args, not two. We want to toss out self. + if not isinstance(args[0], str): + # We are testing, avoid the first arg + args = args[1:] + if len(args) == 1 and not kwds: + kwds["threaded"] = True + return cls(*args, **kwds) + + +def LinkFileLock(*args, **kwds): + """Factory function provided for backwards compatibility. + + Do not use in new code. Instead, import LinkLockFile from the + lockfile.linklockfile module. + """ + from . import linklockfile + return _fl_helper(linklockfile.LinkLockFile, "lockfile.linklockfile", + *args, **kwds) + + +def MkdirFileLock(*args, **kwds): + """Factory function provided for backwards compatibility. + + Do not use in new code. Instead, import MkdirLockFile from the + lockfile.mkdirlockfile module. + """ + from . import mkdirlockfile + return _fl_helper(mkdirlockfile.MkdirLockFile, "lockfile.mkdirlockfile", + *args, **kwds) + + +def SQLiteFileLock(*args, **kwds): + """Factory function provided for backwards compatibility. + + Do not use in new code. Instead, import SQLiteLockFile from the + lockfile.mkdirlockfile module. + """ + from . import sqlitelockfile + return _fl_helper(sqlitelockfile.SQLiteLockFile, "lockfile.sqlitelockfile", + *args, **kwds) + + +def locked(path, timeout=None): + """Decorator which enables locks for decorated function. + + Arguments: + - path: path for lockfile. + - timeout (optional): Timeout for acquiring lock. + + Usage: + @locked('/var/run/myname', timeout=0) + def myname(...): + ... + """ + def decor(func): + @functools.wraps(func) + def wrapper(*args, **kwargs): + lock = FileLock(path, timeout=timeout) + lock.acquire() + try: + return func(*args, **kwargs) + finally: + lock.release() + return wrapper + return decor + + +if hasattr(os, "link"): + from . import linklockfile as _llf + LockFile = _llf.LinkLockFile +else: + from . import mkdirlockfile as _mlf + LockFile = _mlf.MkdirLockFile + +FileLock = LockFile diff --git a/setuptools/command/lockfile/linklockfile.py b/setuptools/command/lockfile/linklockfile.py new file mode 100644 index 0000000000..2ca9be0423 --- /dev/null +++ b/setuptools/command/lockfile/linklockfile.py @@ -0,0 +1,73 @@ +from __future__ import absolute_import + +import time +import os + +from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout, + AlreadyLocked) + + +class LinkLockFile(LockBase): + """Lock access to a file using atomic property of link(2). + + >>> lock = LinkLockFile('somefile') + >>> lock = LinkLockFile('somefile', threaded=False) + """ + + def acquire(self, timeout=None): + try: + open(self.unique_name, "wb").close() + except IOError: + raise LockFailed("failed to create %s" % self.unique_name) + + timeout = timeout if timeout is not None else self.timeout + end_time = time.time() + if timeout is not None and timeout > 0: + end_time += timeout + + while True: + # Try and create a hard link to it. + try: + os.link(self.unique_name, self.lock_file) + except OSError: + # Link creation failed. Maybe we've double-locked? + nlinks = os.stat(self.unique_name).st_nlink + if nlinks == 2: + # The original link plus the one I created == 2. We're + # good to go. + return + else: + # Otherwise the lock creation failed. + if timeout is not None and time.time() > end_time: + os.unlink(self.unique_name) + if timeout > 0: + raise LockTimeout("Timeout waiting to acquire" + " lock for %s" % + self.path) + else: + raise AlreadyLocked("%s is already locked" % + self.path) + time.sleep(timeout is not None and timeout / 10 or 0.1) + else: + # Link creation succeeded. We're good to go. + return + + def release(self): + if not self.is_locked(): + raise NotLocked("%s is not locked" % self.path) + elif not os.path.exists(self.unique_name): + raise NotMyLock("%s is locked, but not by me" % self.path) + os.unlink(self.unique_name) + os.unlink(self.lock_file) + + def is_locked(self): + return os.path.exists(self.lock_file) + + def i_am_locking(self): + return (self.is_locked() and + os.path.exists(self.unique_name) and + os.stat(self.unique_name).st_nlink == 2) + + def break_lock(self): + if os.path.exists(self.lock_file): + os.unlink(self.lock_file) diff --git a/setuptools/command/lockfile/mkdirlockfile.py b/setuptools/command/lockfile/mkdirlockfile.py new file mode 100644 index 0000000000..05a8c96ca5 --- /dev/null +++ b/setuptools/command/lockfile/mkdirlockfile.py @@ -0,0 +1,84 @@ +from __future__ import absolute_import, division + +import time +import os +import sys +import errno + +from . import (LockBase, LockFailed, NotLocked, NotMyLock, LockTimeout, + AlreadyLocked) + + +class MkdirLockFile(LockBase): + """Lock file by creating a directory.""" + def __init__(self, path, threaded=True, timeout=None): + """ + >>> lock = MkdirLockFile('somefile') + >>> lock = MkdirLockFile('somefile', threaded=False) + """ + LockBase.__init__(self, path, threaded, timeout) + # Lock file itself is a directory. Place the unique file name into + # it. + self.unique_name = os.path.join(self.lock_file, + "%s.%s%s" % (self.hostname, + self.tname, + self.pid)) + + def acquire(self, timeout=None): + timeout = timeout if timeout is not None else self.timeout + end_time = time.time() + if timeout is not None and timeout > 0: + end_time += timeout + + if timeout is None: + wait = 0.1 + else: + wait = max(0, timeout / 10) + + while True: + try: + os.mkdir(self.lock_file) + except OSError: + err = sys.exc_info()[1] + if err.errno == errno.EEXIST: + # Already locked. + if os.path.exists(self.unique_name): + # Already locked by me. + return + if timeout is not None and time.time() > end_time: + if timeout > 0: + raise LockTimeout("Timeout waiting to acquire" + " lock for %s" % + self.path) + else: + # Someone else has the lock. + raise AlreadyLocked("%s is already locked" % + self.path) + time.sleep(wait) + else: + # Couldn't create the lock for some other reason + raise LockFailed("failed to create %s" % self.lock_file) + else: + open(self.unique_name, "wb").close() + return + + def release(self): + if not self.is_locked(): + raise NotLocked("%s is not locked" % self.path) + elif not os.path.exists(self.unique_name): + raise NotMyLock("%s is locked, but not by me" % self.path) + os.unlink(self.unique_name) + os.rmdir(self.lock_file) + + def is_locked(self): + return os.path.exists(self.lock_file) + + def i_am_locking(self): + return (self.is_locked() and + os.path.exists(self.unique_name)) + + def break_lock(self): + if os.path.exists(self.lock_file): + for name in os.listdir(self.lock_file): + os.unlink(os.path.join(self.lock_file, name)) + os.rmdir(self.lock_file) diff --git a/setuptools/command/lockfile/pidlockfile.py b/setuptools/command/lockfile/pidlockfile.py new file mode 100644 index 0000000000..069e85b15b --- /dev/null +++ b/setuptools/command/lockfile/pidlockfile.py @@ -0,0 +1,190 @@ +# -*- coding: utf-8 -*- + +# pidlockfile.py +# +# Copyright © 2008–2009 Ben Finney +# +# This is free software: you may copy, modify, and/or distribute this work +# under the terms of the Python Software Foundation License, version 2 or +# later as published by the Python Software Foundation. +# No warranty expressed or implied. See the file LICENSE.PSF-2 for details. + +""" Lockfile behaviour implemented via Unix PID files. + """ + +from __future__ import absolute_import + +import errno +import os +import time + +from . import (LockBase, AlreadyLocked, LockFailed, NotLocked, NotMyLock, + LockTimeout) + + +class PIDLockFile(LockBase): + """ Lockfile implemented as a Unix PID file. + + The lock file is a normal file named by the attribute `path`. + A lock's PID file contains a single line of text, containing + the process ID (PID) of the process that acquired the lock. + + >>> lock = PIDLockFile('somefile') + >>> lock = PIDLockFile('somefile') + """ + + def __init__(self, path, threaded=False, timeout=None): + # pid lockfiles don't support threaded operation, so always force + # False as the threaded arg. + LockBase.__init__(self, path, False, timeout) + self.unique_name = self.path + + def read_pid(self): + """ Get the PID from the lock file. + """ + return read_pid_from_pidfile(self.path) + + def is_locked(self): + """ Test if the lock is currently held. + + The lock is held if the PID file for this lock exists. + + """ + return os.path.exists(self.path) + + def i_am_locking(self): + """ Test if the lock is held by the current process. + + Returns ``True`` if the current process ID matches the + number stored in the PID file. + """ + return self.is_locked() and os.getpid() == self.read_pid() + + def acquire(self, timeout=None): + """ Acquire the lock. + + Creates the PID file for this lock, or raises an error if + the lock could not be acquired. + """ + + timeout = timeout if timeout is not None else self.timeout + end_time = time.time() + if timeout is not None and timeout > 0: + end_time += timeout + + while True: + try: + write_pid_to_pidfile(self.path) + except OSError as exc: + if exc.errno == errno.EEXIST: + # The lock creation failed. Maybe sleep a bit. + if time.time() > end_time: + if timeout is not None and timeout > 0: + raise LockTimeout("Timeout waiting to acquire" + " lock for %s" % + self.path) + else: + raise AlreadyLocked("%s is already locked" % + self.path) + time.sleep(timeout is not None and timeout / 10 or 0.1) + else: + raise LockFailed("failed to create %s" % self.path) + else: + return + + def release(self): + """ Release the lock. + + Removes the PID file to release the lock, or raises an + error if the current process does not hold the lock. + + """ + if not self.is_locked(): + raise NotLocked("%s is not locked" % self.path) + if not self.i_am_locking(): + raise NotMyLock("%s is locked, but not by me" % self.path) + remove_existing_pidfile(self.path) + + def break_lock(self): + """ Break an existing lock. + + Removes the PID file if it already exists, otherwise does + nothing. + + """ + remove_existing_pidfile(self.path) + + +def read_pid_from_pidfile(pidfile_path): + """ Read the PID recorded in the named PID file. + + Read and return the numeric PID recorded as text in the named + PID file. If the PID file cannot be read, or if the content is + not a valid PID, return ``None``. + + """ + pid = None + try: + pidfile = open(pidfile_path, 'r') + except IOError: + pass + else: + # According to the FHS 2.3 section on PID files in /var/run: + # + # The file must consist of the process identifier in + # ASCII-encoded decimal, followed by a newline character. + # + # Programs that read PID files should be somewhat flexible + # in what they accept; i.e., they should ignore extra + # whitespace, leading zeroes, absence of the trailing + # newline, or additional lines in the PID file. + + line = pidfile.readline().strip() + try: + pid = int(line) + except ValueError: + pass + pidfile.close() + + return pid + + +def write_pid_to_pidfile(pidfile_path): + """ Write the PID in the named PID file. + + Get the numeric process ID (“PID”) of the current process + and write it to the named file as a line of text. + + """ + open_flags = (os.O_CREAT | os.O_EXCL | os.O_WRONLY) + open_mode = 0o644 + pidfile_fd = os.open(pidfile_path, open_flags, open_mode) + pidfile = os.fdopen(pidfile_fd, 'w') + + # According to the FHS 2.3 section on PID files in /var/run: + # + # The file must consist of the process identifier in + # ASCII-encoded decimal, followed by a newline character. For + # example, if crond was process number 25, /var/run/crond.pid + # would contain three characters: two, five, and newline. + + pid = os.getpid() + pidfile.write("%s\n" % pid) + pidfile.close() + + +def remove_existing_pidfile(pidfile_path): + """ Remove the named PID file if it exists. + + Removing a PID file that doesn't already exist puts us in the + desired state, so we ignore the condition if the file does not + exist. + + """ + try: + os.remove(pidfile_path) + except OSError as exc: + if exc.errno == errno.ENOENT: + pass + else: + raise diff --git a/setuptools/command/lockfile/sqlitelockfile.py b/setuptools/command/lockfile/sqlitelockfile.py new file mode 100644 index 0000000000..f997e2444e --- /dev/null +++ b/setuptools/command/lockfile/sqlitelockfile.py @@ -0,0 +1,156 @@ +from __future__ import absolute_import, division + +import time +import os + +try: + unicode +except NameError: + unicode = str + +from . import LockBase, NotLocked, NotMyLock, LockTimeout, AlreadyLocked + + +class SQLiteLockFile(LockBase): + "Demonstrate SQL-based locking." + + testdb = None + + def __init__(self, path, threaded=True, timeout=None): + """ + >>> lock = SQLiteLockFile('somefile') + >>> lock = SQLiteLockFile('somefile', threaded=False) + """ + LockBase.__init__(self, path, threaded, timeout) + self.lock_file = unicode(self.lock_file) + self.unique_name = unicode(self.unique_name) + + if SQLiteLockFile.testdb is None: + import tempfile + _fd, testdb = tempfile.mkstemp() + os.close(_fd) + os.unlink(testdb) + del _fd, tempfile + SQLiteLockFile.testdb = testdb + + import sqlite3 + self.connection = sqlite3.connect(SQLiteLockFile.testdb) + + c = self.connection.cursor() + try: + c.execute("create table locks" + "(" + " lock_file varchar(32)," + " unique_name varchar(32)" + ")") + except sqlite3.OperationalError: + pass + else: + self.connection.commit() + import atexit + atexit.register(os.unlink, SQLiteLockFile.testdb) + + def acquire(self, timeout=None): + timeout = timeout if timeout is not None else self.timeout + end_time = time.time() + if timeout is not None and timeout > 0: + end_time += timeout + + if timeout is None: + wait = 0.1 + elif timeout <= 0: + wait = 0 + else: + wait = timeout / 10 + + cursor = self.connection.cursor() + + while True: + if not self.is_locked(): + # Not locked. Try to lock it. + cursor.execute("insert into locks" + " (lock_file, unique_name)" + " values" + " (?, ?)", + (self.lock_file, self.unique_name)) + self.connection.commit() + + # Check to see if we are the only lock holder. + cursor.execute("select * from locks" + " where unique_name = ?", + (self.unique_name,)) + rows = cursor.fetchall() + if len(rows) > 1: + # Nope. Someone else got there. Remove our lock. + cursor.execute("delete from locks" + " where unique_name = ?", + (self.unique_name,)) + self.connection.commit() + else: + # Yup. We're done, so go home. + return + else: + # Check to see if we are the only lock holder. + cursor.execute("select * from locks" + " where unique_name = ?", + (self.unique_name,)) + rows = cursor.fetchall() + if len(rows) == 1: + # We're the locker, so go home. + return + + # Maybe we should wait a bit longer. + if timeout is not None and time.time() > end_time: + if timeout > 0: + # No more waiting. + raise LockTimeout("Timeout waiting to acquire" + " lock for %s" % + self.path) + else: + # Someone else has the lock and we are impatient.. + raise AlreadyLocked("%s is already locked" % self.path) + + # Well, okay. We'll give it a bit longer. + time.sleep(wait) + + def release(self): + if not self.is_locked(): + raise NotLocked("%s is not locked" % self.path) + if not self.i_am_locking(): + raise NotMyLock("%s is locked, but not by me (by %s)" % + (self.unique_name, self._who_is_locking())) + cursor = self.connection.cursor() + cursor.execute("delete from locks" + " where unique_name = ?", + (self.unique_name,)) + self.connection.commit() + + def _who_is_locking(self): + cursor = self.connection.cursor() + cursor.execute("select unique_name from locks" + " where lock_file = ?", + (self.lock_file,)) + return cursor.fetchone()[0] + + def is_locked(self): + cursor = self.connection.cursor() + cursor.execute("select * from locks" + " where lock_file = ?", + (self.lock_file,)) + rows = cursor.fetchall() + return not not rows + + def i_am_locking(self): + cursor = self.connection.cursor() + cursor.execute("select * from locks" + " where lock_file = ?" + " and unique_name = ?", + (self.lock_file, self.unique_name)) + return not not cursor.fetchall() + + def break_lock(self): + cursor = self.connection.cursor() + cursor.execute("delete from locks" + " where lock_file = ?", + (self.lock_file,)) + self.connection.commit() diff --git a/setuptools/command/lockfile/symlinklockfile.py b/setuptools/command/lockfile/symlinklockfile.py new file mode 100644 index 0000000000..915cf19f03 --- /dev/null +++ b/setuptools/command/lockfile/symlinklockfile.py @@ -0,0 +1,70 @@ +from __future__ import absolute_import + +import os +import time + +from . import (LockBase, NotLocked, NotMyLock, LockTimeout, + AlreadyLocked) + + +class SymlinkLockFile(LockBase): + """Lock access to a file using symlink(2).""" + + def __init__(self, path, threaded=True, timeout=None): + # super(SymlinkLockFile).__init(...) + LockBase.__init__(self, path, threaded, timeout) + # split it back! + self.unique_name = os.path.split(self.unique_name)[1] + + def acquire(self, timeout=None): + # Hopefully unnecessary for symlink. + # try: + # open(self.unique_name, "wb").close() + # except IOError: + # raise LockFailed("failed to create %s" % self.unique_name) + timeout = timeout if timeout is not None else self.timeout + end_time = time.time() + if timeout is not None and timeout > 0: + end_time += timeout + + while True: + # Try and create a symbolic link to it. + try: + os.symlink(self.unique_name, self.lock_file) + except OSError: + # Link creation failed. Maybe we've double-locked? + if self.i_am_locking(): + # Linked to out unique name. Proceed. + return + else: + # Otherwise the lock creation failed. + if timeout is not None and time.time() > end_time: + if timeout > 0: + raise LockTimeout("Timeout waiting to acquire" + " lock for %s" % + self.path) + else: + raise AlreadyLocked("%s is already locked" % + self.path) + time.sleep(timeout / 10 if timeout is not None else 0.1) + else: + # Link creation succeeded. We're good to go. + return + + def release(self): + if not self.is_locked(): + raise NotLocked("%s is not locked" % self.path) + elif not self.i_am_locking(): + raise NotMyLock("%s is locked, but not by me" % self.path) + os.unlink(self.lock_file) + + def is_locked(self): + return os.path.islink(self.lock_file) + + def i_am_locking(self): + return (os.path.islink(self.lock_file) and + os.readlink(self.lock_file) == self.unique_name) + + def break_lock(self): + if os.path.islink(self.lock_file): # exists && link + os.unlink(self.lock_file)