Class: Sfn::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/sfn/cache.rb

Overview

Data caching helper

Defined Under Namespace

Classes: LocalLock, LocalValue, Stamped

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key) ⇒ Cache

Create new instance

Parameters:

  • key (String, Array) 


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# File 'lib/sfn/cache.rb', line 79

def initialize(key)
  if key.respond_to?(:sort)
    key = key.flatten if key.respond_to?(:flatten)
    key = key.map(&:to_s).sort
  end
  @key = Digest::SHA256.hexdigest(key.to_s)
  @apply_limit = self.class.default_limits
end

Instance Attribute Details

#key ⇒ String (readonly)

Returns custom key for this cache.

Returns:

  • (String) —

    custom key for this cache



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# File 'lib/sfn/cache.rb', line 74

def key
  @key
end

Class Method Details

.apply_limit(kind, seconds = nil) ⇒ Object

Set/get time limit on data type

return [Integer] seconds

Parameters:

  • kind (String, Symbol) —

    data type

  • seconds (Integer) (defaults to: nil) 


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# File 'lib/sfn/cache.rb', line 51

def apply_limit(kind, seconds = nil)
  @apply_limit ||= {}
  if seconds
    @apply_limit[kind.to_sym] = seconds.to_i
  end
  @apply_limit[kind.to_sym].to_i
end

.configure(type, args = {}) ⇒ Object

Configure the caching approach to use

Parameters:

  • type (Symbol) —

    :redis or :local

  • args (Hash) (defaults to: {}) —

    redis connection arguments if used



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# File 'lib/sfn/cache.rb', line 14

def configure(type, args = {})
  type = type.to_sym
  case type
  when :redis
    begin
      require "redis-objects"
    rescue LoadError
      $stderr.puts "The `redis-objects` gem is required for Cache support!"
      raise
    end
    @_pid = Process.pid
    Redis::Objects.redis = Redis.new(args)
  when :local
  else
    raise TypeError.new("Unsupported caching type: #{type}")
  end
  enable(type)
end

.default_limits ⇒ Hash

Returns default limits.

Returns:

  • (Hash) —

    default limits



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# File 'lib/sfn/cache.rb', line 60

def default_limits
  (@apply_limit || {}).dup
end

.enable(type) ⇒ Symbol

Set enabled caching type

Parameters:

  • type (Symbol)

Returns:

  • (Symbol) 


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# File 'lib/sfn/cache.rb', line 37

def enable(type)
  @type = type.to_sym
end

.redis_ping! ⇒ Object

Ping the redis connection and reconnect if dead



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# File 'lib/sfn/cache.rb', line 65

def redis_ping!
  if (@_pid && @_pid != Process.pid) || !Redis::Objects.redis.connected?
    Redis::Objects.redis.client.reconnect
    @_pid = Process.pid
  end
end

.type ⇒ Symbol

Returns type of caching enabled.

Returns:

  • (Symbol) —

    type of caching enabled



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# File 'lib/sfn/cache.rb', line 42

def type
  @type || :local
end

Instance Method Details

#[](name) ⇒ Object, NilClass

Fetch data

Parameters:

  • name (String, Symbol)

Returns:

  • (Object, NilClass) 


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# File 'lib/sfn/cache.rb', line 216

def [](name)
  if kind = registry[name.to_s]
    get_storage(self.class.type, kind, name)
  else
    nil
  end
end

#[]=(key, val) ⇒ Object

Note:

this will never work, thus you should never use it

Set data

Parameters:

  • key (Object)
  • val (Object) 


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# File 'lib/sfn/cache.rb', line 229

def []=(key, val)
  raise "Setting backend data is not allowed"
end

#apply_limit(kind, seconds = nil) ⇒ Object

Apply time limit for data type

return [Integer]

Parameters:

  • kind (String, Symbol) —

    data type

  • seconds (Integer) (defaults to: nil) 


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# File 'lib/sfn/cache.rb', line 247

def apply_limit(kind, seconds = nil)
  @apply_limit ||= {}
  if seconds
    @apply_limit[kind.to_sym] = seconds.to_i
  end
  @apply_limit[kind.to_sym].to_i
end

#clear!(*args) ⇒ TrueClass

Note:

clears all data if no names provided

Clear data

Parameters:

  • args (Symbol) —

    list of names to delete

Returns:

  • (TrueClass) 


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# File 'lib/sfn/cache.rb', line 108

def clear!(*args)
  internal_lock do
    args = registry.keys if args.empty?
    args.each do |key|
      value = self[key]
      if value.respond_to?(:clear)
        value.clear
      elsif value.respond_to?(:value)
        value.value = nil
      end
      registry.delete(key)
    end
    yield if block_given?
  end
  true
end

#get_local_storage(data_type, full_name, args = {}) ⇒ Object

TODO:

make proper singleton for local storage

Fetch item from local storage

Parameters:

  • data_type (Symbol)
  • full_name (Symbol)
  • args (Hash) (defaults to: {})

Returns:

  • (Object) 


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# File 'lib/sfn/cache.rb', line 184

def get_local_storage(data_type, full_name, args = {})
  @storage ||= {}
  @storage[full_name] ||= case data_type.to_sym
                          when :array
                            []
                          when :hash
                            {}
                          when :value
                            LocalValue.new
                          when :lock
                            LocalLock.new(full_name, {:expiration => 60, :timeout => 0.1}.merge(args))
                          when :stamped
                            Stamped.new(full_name.sub("#{key}_", "").to_sym, get_local_storage(:value, full_name), self)
                          else
                            raise TypeError.new("Unsupported caching data type encountered: #{data_type}")
                          end
end

#get_redis_storage(data_type, full_name, args = {}) ⇒ Object

Fetch item from redis storage

Parameters:

  • data_type (Symbol)
  • full_name (Symbol)
  • args (Hash) (defaults to: {})

Returns:

  • (Object) 


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# File 'lib/sfn/cache.rb', line 159

def get_redis_storage(data_type, full_name, args = {})
  self.class.redis_ping!
  case data_type.to_sym
  when :array
    Redis::List.new(full_name, {:marshal => true}.merge(args))
  when :hash
    Redis::HashKey.new(full_name)
  when :value
    Redis::Value.new(full_name, {:marshal => true}.merge(args))
  when :lock
    Redis::Lock.new(full_name, {:expiration => 60, :timeout => 0.1}.merge(args))
  when :stamped
    Stamped.new(full_name.sub("#{key}_", "").to_sym, get_redis_storage(:value, full_name), self)
  else
    raise TypeError.new("Unsupported caching data type encountered: #{data_type}")
  end
end

#get_storage(store_type, data_type, name, args = {}) ⇒ Object

Fetch item from storage

Parameters:

  • store_type (Symbol)
  • data_type (Symbol)
  • name (Symbol) —

    name of data

  • args (Hash) (defaults to: {}) —

    options for underlying storage

Returns:

  • (Object) 


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# File 'lib/sfn/cache.rb', line 132

def get_storage(store_type, data_type, name, args = {})
  full_name = "#{key}_#{name}"
  result = nil
  case store_type.to_sym
  when :redis
    result = get_redis_storage(data_type, full_name.to_s, args)
  when :local
    @_local_cache ||= {}
    unless @_local_cache[full_name.to_s]
      @_local_cache[full_name.to_s] = get_local_storage(data_type, full_name.to_s, args)
    end
    result = @_local_cache[full_name.to_s]
  else
    raise TypeError.new("Unsupported caching storage type encountered: #{store_type}")
  end
  unless full_name == "#{key}_registry_#{key}"
    registry[name.to_s] = data_type
  end
  result
end

#init(name, kind, args = {}) ⇒ Object

Initialize a new data type

Parameters:

  • name (Symbol) —

    name of data

  • kind (Symbol) —

    data type

  • args (Hash) (defaults to: {}) —

    options for data type



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# File 'lib/sfn/cache.rb', line 93

def init(name, kind, args = {})
  get_storage(self.class.type, kind, name, args)
  true
end

#internal_lock ⇒ Object

Note:

for internal use

Execute block within internal lock

Returns:

  • (Object) —

    result of yield



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# File 'lib/sfn/cache.rb', line 206

def internal_lock
  get_storage(self.class.type, :lock, :internal_access, :timeout => 20, :expiration => 120).lock do
    yield
  end
end

#locked_action(lock_name, raise_on_locked = false) ⇒ Object

Perform action within lock

Parameters:

  • lock_name (String, Symbol) —

    name of lock

  • raise_on_locked (TrueClass, FalseClass) (defaults to: false) —

    raise execption if lock wait times out

Returns:

  • (Object) —

    result of yield



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# File 'lib/sfn/cache.rb', line 260

def locked_action(lock_name, raise_on_locked = false)
  begin
    self[lock_name].lock do
      yield
    end
  rescue => e
    if e.class.to_s.end_with?("Timeout")
      raise if raise_on_locked
    else
      raise
    end
  end
end

#registry ⇒ Hash

Returns data registry.

Returns:

  • (Hash) —

    data registry



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# File 'lib/sfn/cache.rb', line 99

def registry
  get_storage(self.class.type, :hash, "registry_#{key}")
end

#time_check_allow?(key, stamp) ⇒ TrueClass, FalseClass

Check if cache time has expired

Parameters:

  • key (String, Symbol) —

    value key

  • stamp (Time, Integer)

Returns:

  • (TrueClass, FalseClass) 


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# File 'lib/sfn/cache.rb', line 238

def time_check_allow?(key, stamp)
  Time.now.to_i - stamp.to_i > apply_limit(key)
end