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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
require 'byteback/utils'
module Byteback
# Represents a particular timestamped backup directory
class Snapshot
include Byteback::Util
class << self
# What order to remove snapshots in to regain disk space?
#
# Order backups by their closeness to defined backup times, which are
# listed in a set order (i.e. today's backup is more important than yesterday's).
#
BACKUP_IMPORTANCE = [1, 2, 7, 14, 21, 28, 56, 112]
def sort_by_importance(snapshots_unsorted, now = Time.now)
return snapshots_unsorted if snapshots_unsorted.size < 1
#
# Keep the last 7 days backups
#
snapshots_sorted = []
snapshots_unsorted = snapshots_unsorted.sort_by(&:time).reverse
#
# Group snapshots by host
#
snapshots_by_host = Hash.new { |h, k| h[k] = [] }
snapshots_unsorted.each do |snapshot|
snapshots_by_host[snapshot.host] << snapshot
end
#
# We want the snapshot nearest to the middle of the day each day.
#
today_midday = Time.mktime(*([0, 0, 12] + now.utc.to_a.last(7)))
#
# We want today, and the previous seven days
#
targets = [today_midday]
targets += 6.times.map { today_midday -= 86_400 }
#
# Now the previous four Sundays (we should bump on a week if today is a Sunday!)
#
today_midday -= (today_midday.wday == 0 ? 7 : today_midday.wday) * 86_400
targets << today_midday
targets += 3.times.map { today_midday -= 7 * 86_400 }
#
# Our 28 day periods are anchored on Time.at(0). However this was a
# Thursday, so we have to add 3 days to get it to Sunday.
#
targets << (today_midday -= ((today_midday.to_i / 86_400.0).floor % 28 - 3) * 86_400)
#
# Continue removing 28 day periods until we get beyond the oldest backup time.
#
targets << (today_midday -= 28 * 86_400) while today_midday > snapshots_unsorted.last.time
#
# This has records the last nearest snapshot for each host
#
last_nearest = {}
#
# For each target, and for each host, find the nearest snapshot
#
targets.each do |target|
snapshots_by_host.each do |host, snapshots|
next if snapshots.empty?
nearest = snapshots.sort { |a, b| (a.time - target).abs <=> (b.time - target).abs }.first
#
# Don't process any more if the last snapshot for this for this
# host was more recent, i.e. we've reached the oldest, and are
# bouncing back again.
#
if last_nearest[host].nil? || last_nearest[host].time > nearest.time
last_nearest[host] = nearest
snapshots_by_host[host] -= [nearest]
snapshots_sorted << nearest
end
end
end
#
# Remove any snapshots we've already sorted and add in the remaining snapshots
#
snapshots_unsorted -= snapshots_sorted
snapshots_sorted += snapshots_unsorted
snapshots_sorted
end
end
attr_reader :backup_directory, :path
def initialize(backup_directory, snapshot_path)
@backup_directory = backup_directory
@path = snapshot_path
@time = Time.parse(File.basename(path)) # throws ArgumentError if it can't parse
nil
end
attr_reader :time
def host
File.basename(File.dirname(path))
end
def <=>(b)
time <=> b.time
end
def create!(from)
system_no_error("#{btrfs_bin} subvolume snapshot #{from} #{path}")
end
def delete!
system_no_error("#{btrfs_bin} subvolume delete #{path}")
end
# Returns the size of the given snapshot (runs du, may be slow)
#
# Would much prefer to take advantage of this feature:
# http://dustymabe.com/2013/09/22/btrfs-how-big-are-my-snapshots/
# but it's not currently in Debian/wheezy.
#
def du
`du -s -b #{path}`.to_i
end
protected
def system_no_error(*args)
args[-1] += ' > /dev/null' unless @verbose
fail RuntimeError.new('Command failed: ' + args.join(' ')) unless
system(*args)
end
end
# Represent a directory full of backups where "current" is a subvolume
# which is snapshotted to frozen backup directories called e.g.
# "yyyy-mm-ddThh:mm+zzzz".
#
class BackupDirectory
class << self
# Return all backup directories
#
def all
Dir.new(ENV['HOME']).entries.map do |entry|
next if entry[0] == '.'
name = File.expand_path(ENV['HOME'] + '/' + entry)
File.directory?(name + '/current') ? BackupDirectory.new(name) : nil
end
.compact
end
# Returns every snapshot in every backup directory
#
def all_snapshots
all.map(&:snapshots).flatten
end
end
attr_reader :dir
def initialize(dir)
@dir = Dir.new(dir)
fail Errno::ENOENT unless File.directory?(dir)
current
end
# Return total amount of free space in backup directory (bytes)
#
def free
df = DiskFree.new(@dir.path)
df.total - df.used
end
# Return an array of Times representing the current list of
# snapshots.
#
def snapshots
@dir.entries.map do |entry|
next if entry[0] == '.' || entry == 'current'
snapshot_path = File.expand_path(@dir.path + '/' + entry)
next unless File.directory?(snapshot_path)
begin
Snapshot.new(self, snapshot_path)
rescue ArgumentError => ae
# directory name must represent a parseable Time
nil
end
end
.compact
end
# Create a new snapshot of 'current'
#
def new_snapshot!(time = Time.now)
snapshot_path = time.strftime(dir.path + '/%Y-%m-%dT%H:%M%z')
Snapshot.new(self, snapshot_path).create!(current.path)
end
def current
Dir.new("#{dir.path}/current")
end
end
end
|
