Class: FluidFeatures::AppState

Inherits:
Object
  • Object
show all
Defined in:
lib/fluidfeatures/app/state.rb

Constant Summary collapse

USER_ID_NUMERIC = 
/^\d+$/
ETAG_WAIT =

Request to FluidFeatures API to long-poll for max 30 seconds. The API may choose a different duration. If not change in this time, API will return HTTP 304.

ENV["FF_DEV"] ? 5 : 30
WAIT_BETWEEN_FETCH_SUCCESS =

Hard max of 2 req/sec

0.5
WAIT_BETWEEN_SEND_SUCCESS_NEXT_WAITING =

Hard max of 10 req/sec

0.1
WAIT_BETWEEN_FETCH_FAILURES =

If we are failing to communicate with the FluidFeautres API then wait for this long between requests.

5

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ AppState

seconds



31
32
33
34
35
 
# File 'lib/fluidfeatures/app/state.rb', line 31

def initialize(app)
  raise "app invalid : #{app}" unless app.is_a? ::FluidFeatures::App
  @receiving = false
  configure(app)
end

Instance Attribute Details

#app ⇒ Object

Returns the value of attribute app.



12
13
14
 
# File 'lib/fluidfeatures/app/state.rb', line 12

def app
  @app
end

Instance Method Details

#configure(app) ⇒ Object 



37
38
39
40
41
 
# File 'lib/fluidfeatures/app/state.rb', line 37

def configure(app)
  @app = app
  @features = nil
  @features_lock = ::Mutex.new
end

#feature_version_enabled_for_user(feature_name, version_name, user_id, user_attributes = {}) ⇒ Object 



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
 
# File 'lib/fluidfeatures/app/state.rb', line 159

def feature_version_enabled_for_user(feature_name, version_name, user_id, user_attributes={})
  raise "feature_name invalid : #{feature_name}" unless feature_name.is_a? String
  version_name ||= ::FluidFeatures::DEFAULT_VERSION_NAME
  raise "version_name invalid : #{version_name}" unless version_name.is_a? String

  user_attributes ||= {}
  user_attributes["user"] = user_id.to_s
  if user_id.is_a? Integer
    user_id_hash = user_id
  elsif USER_ID_NUMERIC.match(user_id)
    user_id_hash = user_id.to_i
  else
    user_id_hash = Digest::SHA1.hexdigest(user_id)[-10, 10].to_i(16)
  end
  enabled = false

  feature = features[feature_name]
  return false unless feature
  version = feature["versions"][version_name]
  return false unless version

  modulus = ((user_id_hash - 1) % feature["num_parts"]) + 1
  enabled = version["parts"].include? modulus

  feature["versions"].each_pair do |other_version_name, other_version|
    if other_version
      version_attributes = (other_version["enabled"] || {})["attributes"]
      if version_attributes
        user_attributes.each_pair do |attr_key, attr_id|
          version_attribute = version_attributes[attr_key.to_s]
          if version_attribute and version_attribute.include? attr_id.to_s
            if other_version_name == version_name
              # explicitly enabled for this version
              return true
            else
              # explicitly enabled for another version
              return false
            end
          end
        end
      end
    end
  end

  enabled
end

#features ⇒ Object 



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
 
# File 'lib/fluidfeatures/app/state.rb', line 60

def features
  f = nil
  if @receiving
    # use features loaded in background
    features_lock_synchronize do
      f = @features
    end
  end
  unless f
    # we have not loaded features yet.
    # load in foreground but do not use caching (etags)
    success, state = load_state(use_cache=false)
    if success
      unless state
        # Since we did not use etag caching, state should never
        # be nil if success was true.
        raise FFeaturesAppStateLoadFailure.new("Unexpected nil state returned from successful load_state(use_cache=false).")
      end
      self.features = f = state
    else
      # fluidfeatures API must be down.
      # load persisted features from disk.
      self.features = f = features_storage.list
    end
  end
  # we should never return nil
  unless f
    # If we still could not load state then croak
    raise FFeaturesAppStateLoadFailure.new("Could not load features state from API: #{state}")
  end
  unless @receiving
    # start background receiver loop
    start_receiving
  end
  f
end

#features=(f) ⇒ Object 



97
98
99
100
101
102
103
104
 
# File 'lib/fluidfeatures/app/state.rb', line 97

def features= f
  return unless f.is_a? Hash
  features_lock_synchronize do
    features_storage.replace(f)
    @features = f
  end
  f
end

#features_lock_synchronize ⇒ Object 



207
208
209
210
211
 
# File 'lib/fluidfeatures/app/state.rb', line 207

def features_lock_synchronize
  @features_lock.synchronize do
    yield
  end
end

#features_storage ⇒ Object 



56
57
58
 
# File 'lib/fluidfeatures/app/state.rb', line 56

def features_storage
  @features_storage ||= FluidFeatures::Persistence::Features.create(FluidFeatures.config["cache"])
end

#load_state(use_cache = true) ⇒ Object 



146
147
148
149
150
151
152
153
154
155
156
157
 
# File 'lib/fluidfeatures/app/state.rb', line 146

def load_state(use_cache=true)
  success, state = app.get("/features", { :verbose => true, :etag_wait => ETAG_WAIT }, use_cache)
  if success and state
    state.each_pair do |feature_name, feature|
      feature["versions"].each_pair do |version_name, version|
        # convert parts to a Set for quick lookup
        version["parts"] = Set.new(version["parts"] || [])
      end
    end
  end
  return success, state
end

#run_loop ⇒ Object 



106
107
108
109
110
111
112
113
114
115
116
 
# File 'lib/fluidfeatures/app/state.rb', line 106

def run_loop

  return unless @receiving
  return if @loop_thread and @loop_thread.alive?

  @loop_thread = Thread.new do
    while @receiving
      run_loop_iteration(WAIT_BETWEEN_FETCH_SUCCESS, WAIT_BETWEEN_FETCH_FAILURES)
    end
  end
end

#run_loop_iteration(wait_between_fetch_success, wait_between_fetch_failures) ⇒ Object 



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
 
# File 'lib/fluidfeatures/app/state.rb', line 118

def run_loop_iteration(wait_between_fetch_success, wait_between_fetch_failures)
  begin

    success, state = load_state

    # Note, success could be true, but state might be nil.
    # This occurs with 304 (no change)
    if success and state
      # switch out current state with new one
      self.features = state
    elsif not success
      # If service is down, then slow our requests
      # within this thread
      sleep wait_between_fetch_failures
    end

    # What ever happens never make more than N requests
    # per second
    sleep wait_between_fetch_success

  rescue Exception => err
    # catch errors, so that we do not affect the rest of the application
    app.logger.error "load_state failed : #{err.message}\n#{err.backtrace.join("\n")}"
    # hold off for a little while and try again
    sleep wait_between_fetch_failures
  end
end

#start_receiving ⇒ Object 



43
44
45
46
47
 
# File 'lib/fluidfeatures/app/state.rb', line 43

def start_receiving
  return if @receiving
  @receiving = true
  run_loop
end

#stop_receiving(wait = false) ⇒ Object 



49
50
51
52
53
54
 
# File 'lib/fluidfeatures/app/state.rb', line 49

def stop_receiving(wait=false)
  @receiving = false
  if wait
    @loop_thread.join if @loop_thread and @loop_thread.alive?
  end
end