mercurial/lock.py
author mpm@selenic.com
Sat, 04 Jun 2005 23:37:11 -0800
changeset 259 45c293b71341
parent 161 0b4c5cb953d9
child 422 10c43444a38e
child 429 688d03d6997a
permissions -rw-r--r--
fix addremove -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 fix addremove manifest hash: 15a37c156e2186e89ef086ef974541bf1c695280 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCoqunywK+sNU5EO8RAuICAJ9x7W0xz1ZBJ7nFYiiQEBljyYwqhACfVE7R oiP0nigB4SzQMMmifrQ7UkA= =/c5l -----END PGP SIGNATURE-----
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
161
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     1
# lock.py - simple locking scheme for mercurial
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     2
#
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     3
# Copyright 2005 Matt Mackall <mpm@selenic.com>
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     4
#
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     5
# This software may be used and distributed according to the terms
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     6
# of the GNU General Public License, incorporated herein by reference.
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     7
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     8
import os, time
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
     9
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    10
class LockHeld(Exception):
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    11
    pass
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    12
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    13
class lock:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    14
    def __init__(self, file, wait = 1):
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    15
        self.f = file
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    16
        self.held = 0
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    17
        self.wait = wait
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    18
        self.lock()
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    19
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    20
    def __del__(self):
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    21
        self.release()
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    22
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    23
    def lock(self):
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    24
        while 1:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    25
            try:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    26
                self.trylock()
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    27
                return 1
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    28
            except LockHeld, inst:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    29
                if self.wait:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    30
                    time.sleep(1)
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    31
                    continue
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    32
                raise inst
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    33
        
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    34
    def trylock(self):
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    35
        pid = os.getpid()
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    36
        try:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    37
            os.symlink(str(pid), self.f)
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    38
            self.held = 1
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    39
        except:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    40
            raise LockHeld(os.readlink(self.f))
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    41
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    42
    def release(self):
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    43
        if self.held:
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    44
            self.held = 0
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    45
            os.unlink(self.f)
0b4c5cb953d9 Simply repository locking
mpm@selenic.com
parents:
diff changeset
    46