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
|
module ActiveRecord
# = Active Record Identity Map
#
# Ensures that each object gets loaded only once by keeping every loaded
# object in a map. Looks up objects using the map when referring to them.
#
# More information on Identity Map pattern:
# http://www.martinfowler.com/eaaCatalog/identityMap.html
#
# == Configuration
#
# In order to enable IdentityMap, set <tt>config.active_record.identity_map = true</tt>
# in your <tt>config/application.rb</tt> file.
#
# IdentityMap is disabled by default.
#
module IdentityMap
class << self
def enabled=(flag)
Thread.current[:identity_map_enabled] = flag
end
def enabled
Thread.current[:identity_map_enabled]
end
alias enabled? enabled
def repository
Thread.current[:identity_map] ||= Hash.new { |h,k| h[k] = {} }
end
def use
old, self.enabled = enabled, true
yield if block_given?
ensure
self.enabled = old
clear
end
def without
old, self.enabled = enabled, false
yield if block_given?
ensure
self.enabled = old
end
def get(klass, primary_key)
record = repository[klass.symbolized_sti_name][primary_key]
if record.is_a?(klass)
ActiveSupport::Notifications.instrument("identity.active_record",
:line => "From Identity Map (id: #{primary_key})",
:name => "#{klass} Loaded",
:connection_id => object_id)
record
else
nil
end
end
def add(record)
repository[record.class.symbolized_sti_name][record.id] = record
end
def remove(record)
repository[record.class.symbolized_sti_name].delete(record.id)
end
def remove_by_id(symbolized_sti_name, id)
repository[symbolized_sti_name].delete(id)
end
def clear
repository.clear
end
end
# Reinitialize an Identity Map model object from +coder+.
# +coder+ must contain the attributes necessary for initializing an empty
# model object.
def reinit_with(coder)
@attributes_cache = {}
dirty = @changed_attributes.keys
@attributes.update(coder['attributes'].except(*dirty))
@changed_attributes.update(coder['attributes'].slice(*dirty))
@changed_attributes.delete_if{|k,v| v.eql? @attributes[k]}
set_serialized_attributes
run_callbacks :find
self
end
class Middleware
class Body #:nodoc:
def initialize(target, original)
@target = target
@original = original
end
def each(&block)
@target.each(&block)
end
def close
@target.close if @target.respond_to?(:close)
ensure
IdentityMap.enabled = @original
IdentityMap.clear
end
end
def initialize(app)
@app = app
end
def call(env)
enabled = IdentityMap.enabled
IdentityMap.enabled = true
status, headers, body = @app.call(env)
[status, headers, Body.new(body, enabled)]
end
end
end
end
|