blob: 969ba8e79da3b87d15b798c982ce1f65be506a5b (
plain)
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
|
#
# Attempt to load the Redis-library.
#
# Without this we cannot connect to our queue.
#
%w( redis ).each do |library|
begin
require library
rescue LoadError
puts("Failed to load the #{library} library - queue access will fail!")
end
end
module Custodian
#
# An abstraction layer for our queue.
#
class QueueType
#
# Retrieve a job from the queue.
#
def fetch(_timeout)
raise 'Subclasses must implement this method!'
end
#
# Add a new job to the queue.
#
def add(_job_string)
raise 'Subclasses must implement this method!'
end
#
# Get the size of the queue
#
def size?
raise 'Subclasses must implement this method!'
end
#
# Empty the queue
#
def flush!
raise 'Subclasses must implement this method!'
end
end
#
# This is a simple queue which uses Redis for storage.
#
class RedisQueueType < QueueType
#
# Connect to the server on localhost, unless QUEUE_ADDRESS is set.
#
def initialize
host = ENV['QUEUE_ADDRESS'] || '127.0.0.1'
@redis = Redis.new(:host => host)
end
#
# Fetch a job from the queue.
#
# The timeout is used to specify the period we wait for a new job, and
# we pause that same period between fetches.
#
def fetch(timeout = 1)
job = nil
loop do
# Get the next job from the queue.
#
# NOTE: This returns an array - but the array will have only
# one element because we're picking from element 0 with a range
# of 0 - which really means 1,1.
#
job = @redis.ZREVRANGE('custodian_queue', '0', '0')
if ! job.empty?
# We only have one entry in our array
job = job[0]
# Remove from the queue
@redis.zrem('custodian_queue', job );
return job
else
sleep(timeout)
end
end
end
#
# Add a new job to the queue.
#
def add(job_string)
#
# We need to build a "score" for this job - the score
# will be used for ordering by Redis.
#
# We don't care what order the jobs are running in, however
# we do care that this the order is always the same.
#
# On that basis we need to create a score for the string which
# will always be the same, and will always be a number.
#
# We'll sum up the ASCII values of each character in the test
# which gives us a "number" which that should be consistent for
# each distinct-test.
#
#
score = Time.now.to_i
@redis.zadd('custodian_queue', score, job_string)
end
#
# How many jobs in the queue?
#
def size?
@redis.zcard('custodian_queue')
end
#
# Empty the queue, discarding all pending jobs.
#
def flush!
@redis.del('custodian_queue')
end
end
end
|
