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
|
begin
require 'memcache'
rescue LoadError => e
$stderr.puts "You don't have memcache-client installed in your application. Please add it to your Gemfile and run bundle install"
raise e
end
require 'digest/md5'
require 'active_support/core_ext/string/encoding'
module ActiveSupport
module Cache
# A cache store implementation which stores data in Memcached:
# http://www.danga.com/memcached/
#
# This is currently the most popular cache store for production websites.
#
# Special features:
# - Clustering and load balancing. One can specify multiple memcached servers,
# and MemCacheStore will load balance between all available servers. If a
# server goes down, then MemCacheStore will ignore it until it comes back up.
#
# MemCacheStore implements the Strategy::LocalCache strategy which implements
# an in memory cache inside of a block.
class MemCacheStore < Store
module Response # :nodoc:
STORED = "STORED\r\n"
NOT_STORED = "NOT_STORED\r\n"
EXISTS = "EXISTS\r\n"
NOT_FOUND = "NOT_FOUND\r\n"
DELETED = "DELETED\r\n"
end
ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n
def self.build_mem_cache(*addresses)
addresses = addresses.flatten
options = addresses.extract_options!
addresses = ["localhost:11211"] if addresses.empty?
MemCache.new(addresses, options)
end
# Creates a new MemCacheStore object, with the given memcached server
# addresses. Each address is either a host name, or a host-with-port string
# in the form of "host_name:port". For example:
#
# ActiveSupport::Cache::MemCacheStore.new("localhost", "server-downstairs.localnetwork:8229")
#
# If no addresses are specified, then MemCacheStore will connect to
# localhost port 11211 (the default memcached port).
#
# Instead of addresses one can pass in a MemCache-like object. For example:
#
# require 'memcached' # gem install memcached; uses C bindings to libmemcached
# ActiveSupport::Cache::MemCacheStore.new(Memcached::Rails.new("localhost:11211"))
def initialize(*addresses)
addresses = addresses.flatten
options = addresses.extract_options!
super(options)
if addresses.first.respond_to?(:get)
@data = addresses.first
else
mem_cache_options = options.dup
UNIVERSAL_OPTIONS.each{|name| mem_cache_options.delete(name)}
@data = self.class.build_mem_cache(*(addresses + [mem_cache_options]))
end
extend Strategy::LocalCache
extend LocalCacheWithRaw
end
# Reads multiple values from the cache using a single call to the
# servers for all keys. Options can be passed in the last argument.
def read_multi(*names)
options = names.extract_options!
options = merged_options(options)
keys_to_names = Hash[names.map{|name| [escape_key(namespaced_key(name, options)), name]}]
raw_values = @data.get_multi(keys_to_names.keys, :raw => true)
values = {}
raw_values.each do |key, value|
entry = deserialize_entry(value)
values[keys_to_names[key]] = entry.value unless entry.expired?
end
values
end
# Increment a cached value. This method uses the memcached incr atomic
# operator and can only be used on values written with the :raw option.
# Calling it on a value not stored with :raw will initialize that value
# to zero.
def increment(name, amount = 1, options = nil) # :nodoc:
options = merged_options(options)
response = instrument(:increment, name, :amount => amount) do
@data.incr(escape_key(namespaced_key(name, options)), amount)
end
response == Response::NOT_FOUND ? nil : response.to_i
rescue MemCache::MemCacheError
nil
end
# Decrement a cached value. This method uses the memcached decr atomic
# operator and can only be used on values written with the :raw option.
# Calling it on a value not stored with :raw will initialize that value
# to zero.
def decrement(name, amount = 1, options = nil) # :nodoc:
options = merged_options(options)
response = instrument(:decrement, name, :amount => amount) do
@data.decr(escape_key(namespaced_key(name, options)), amount)
end
response == Response::NOT_FOUND ? nil : response.to_i
rescue MemCache::MemCacheError
nil
end
# Clear the entire cache on all memcached servers. This method should
# be used with care when shared cache is being used.
def clear(options = nil)
@data.flush_all
end
# Get the statistics from the memcached servers.
def stats
@data.stats
end
protected
# Read an entry from the cache.
def read_entry(key, options) # :nodoc:
deserialize_entry(@data.get(escape_key(key), true))
rescue MemCache::MemCacheError => e
logger.error("MemCacheError (#{e}): #{e.message}") if logger
nil
end
# Write an entry to the cache.
def write_entry(key, entry, options) # :nodoc:
method = options && options[:unless_exist] ? :add : :set
value = options[:raw] ? entry.value.to_s : entry
expires_in = options[:expires_in].to_i
if expires_in > 0 && !options[:raw]
# Set the memcache expire a few minutes in the future to support race condition ttls on read
expires_in += 5.minutes
end
response = @data.send(method, escape_key(key), value, expires_in, options[:raw])
response == Response::STORED
rescue MemCache::MemCacheError => e
logger.error("MemCacheError (#{e}): #{e.message}") if logger
false
end
# Delete an entry from the cache.
def delete_entry(key, options) # :nodoc:
response = @data.delete(escape_key(key))
response == Response::DELETED
rescue MemCache::MemCacheError => e
logger.error("MemCacheError (#{e}): #{e.message}") if logger
false
end
private
# Memcache keys are binaries. So we need to force their encoding to binary
# before applying the regular expression to ensure we are escaping all
# characters properly.
def escape_key(key)
key = key.to_s.dup
key = key.force_encoding("BINARY") if key.encoding_aware?
key = key.gsub(ESCAPE_KEY_CHARS){ |match| "%#{match.getbyte(0).to_s(16).upcase}" }
key = "#{key[0, 213]}:md5:#{Digest::MD5.hexdigest(key)}" if key.size > 250
key
end
def deserialize_entry(raw_value)
if raw_value
entry = Marshal.load(raw_value) rescue raw_value
entry.is_a?(Entry) ? entry : Entry.new(entry)
else
nil
end
end
# Provide support for raw values in the local cache strategy.
module LocalCacheWithRaw # :nodoc:
protected
def write_entry(key, entry, options) # :nodoc:
retval = super
if options[:raw] && local_cache && retval
raw_entry = Entry.new(entry.value.to_s)
raw_entry.expires_at = entry.expires_at
local_cache.write_entry(key, raw_entry, options)
end
retval
end
end
end
end
end
|