1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
#
# Author:: Daniel DeLeo (<dan@opscode.com>)
# Copyright:: Copyright (c) 2012 Opscode, Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
require 'chef/mixin/create_path'
require 'fcntl'
if Chef::Platform.windows?
require 'chef/win32/mutex'
end
class Chef
# == Chef::RunLock
# Provides an interface for acquiring and releasing a system-wide exclusive
# lock.
#
# Used by Chef::Client to ensure only one instance of chef-client (or solo)
# is modifying the system at a time.
class RunLock
include Chef::Mixin::CreatePath
attr_reader :runlock
attr_reader :mutex
attr_reader :runlock_file
# Create a new instance of RunLock
# === Arguments
# * :lockfile::: the full path to the lockfile.
def initialize(lockfile)
@runlock_file = lockfile
@runlock = nil
@mutex = nil
end
# Acquire the system-wide lock. Will block indefinitely if another process
# already has the lock.
#
# Each call to acquire should have a corresponding call to #release.
#
# The implementation is based on File#flock (see also: flock(2)).
#
# Either acquire() or test() methods should be called in order to
# get the ownership of run_lock.
def acquire
wait unless test
end
#
# Tests and if successful acquires the system-wide lock.
# Returns true if the lock is acquired, false otherwise.
#
# Either acquire() or test() methods should be called in order to
# get the ownership of run_lock.
def test
# ensure the runlock_file path exists
create_path(File.dirname(runlock_file))
@runlock = File.open(runlock_file,'a+')
if Chef::Platform.windows?
acquire_win32_mutex
else
# If we support FD_CLOEXEC, then use it.
# NB: ruby-2.0.0-p195 sets FD_CLOEXEC by default, but not
# ruby-1.8.7/1.9.3
if Fcntl.const_defined?('F_SETFD') && Fcntl.const_defined?('FD_CLOEXEC')
runlock.fcntl(Fcntl::F_SETFD, runlock.fcntl(Fcntl::F_GETFD, 0) | Fcntl::FD_CLOEXEC)
end
# Flock will return 0 if it can acquire the lock otherwise it
# will return false
if runlock.flock(File::LOCK_NB|File::LOCK_EX) == 0
true
else
false
end
end
end
#
# Waits until acquiring the system-wide lock.
#
def wait
runpid = runlock.read.strip.chomp
Chef::Log.warn("Chef client #{runpid} is running, will wait for it to finish and then run.")
if Chef::Platform.windows?
mutex.wait
else
runlock.flock(File::LOCK_EX)
end
end
def save_pid
runlock.truncate(0)
runlock.rewind # truncate doesn't reset position to 0.
runlock.write(Process.pid.to_s)
# flush the file fsync flushes the system buffers
# in addition to ruby buffers
runlock.fsync
end
# Release the system-wide lock.
def release
if runlock
if Chef::Platform.windows?
mutex.release
else
runlock.flock(File::LOCK_UN)
end
runlock.close
# Don't unlink the pid file, if another chef-client was waiting, it
# won't be recreated. Better to leave a "dead" pid file than not have
# it available if you need to break the lock.
reset
end
end
private
def reset
@runlock = nil
@mutex = nil
end
# Since flock mechanism doesn't exist on windows we are using
# platform Mutex.
# We are creating a "Global" mutex here so that non-admin
# users can not DoS chef-client by creating the same named
# mutex we are using locally.
# Mutex name is case-sensitive contrary to other things in
# windows. "\" is the only invalid character.
def acquire_win32_mutex
@mutex = Chef::ReservedNames::Win32::Mutex.new("Global\\#{runlock_file.gsub(/[\\]/, "/").downcase}")
mutex.test
end
end
end
|
