Class: Moneta::Adapters::ActiveRecord

Inherits:
Object
  • Object
show all
Includes:
Defaults
Defined in:
lib/moneta/adapters/activerecord.rb

Overview

ActiveRecord as key/value stores

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Defaults

#[], #[]=, #decrement, #features, #fetch, included, #supports?, #update

Methods included from OptionSupport

#expires, #prefix, #raw, #with

Constructor Details

#initialize(options = {}) ⇒ ActiveRecord

Returns a new instance of ActiveRecord

Parameters:

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :backend (Object)

    A class object inheriting from ActiveRecord::Base to use as a table

  • :table (String) — default: 'moneta'

    Table name

  • :connection (Hash/String/Symbol)

    ActiveRecord connection configuration (`Hash` or `String`), or symbol giving the name of a Rails connection (e.g. :production)

  • :create_table (Proc, Boolean)

    Proc called with a connection if table needs to be created. Pass false to skip the create table check all together.

  • :key_column (Symbol) — default: :k

    The name of the column to use for keys

  • :value_column (Symbol) — default: :v

    The name of the column to use for values


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# File 'lib/moneta/adapters/activerecord.rb', line 48

def initialize(options = {})
  @key_column = options.delete(:key_column) || :k
  @value_column = options.delete(:value_column) || :v

  if backend = options.delete(:backend)
    @spec = backend.connection_pool.spec
    @table = ::Arel::Table.new(backend.table_name.to_sym)
  else
    # Feed the connection info into ActiveRecord and get back a name to use for getting the
    # connection pool
    connection = options.delete(:connection)
    @spec =
      case connection
      when Symbol
        connection
      when Hash, String
        # Normalize the connection specification to a hash
        resolver = ::ActiveRecord::ConnectionAdapters::ConnectionSpecification::Resolver.new \
          'dummy' => connection

        # Turn the config into a standardised hash, sans a couple of bits
        hash = resolver.resolve(:dummy)
        hash.delete('name')
        hash.delete(:password) # For security
        # Make a name unique to this config
        name = 'moneta?' + URI.encode_www_form(hash.to_a.sort)
        # Add into configurations unless its already there (initially done without locking for
        # speed)
        unless self.class.configurations.key? name
          self.class.connection_lock.synchronize do
            self.class.configurations[name] = connection \
              unless self.class.configurations.key? name
          end
        end

        name.to_sym
      else
        ::ActiveRecord::Base.connection_pool.spec.name.to_s
      end

    table_name = (options.delete(:table) || :moneta).to_sym
    create_table_proc = options.delete(:create_table)
    if create_table_proc.nil?
      create_table(table_name)
    elsif create_table_proc
      with_connection(&create_table_proc)
    end

    @table = ::Arel::Table.new(table_name)
  end
end

Class Attribute Details

.connection_lockObject (readonly)


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# File 'lib/moneta/adapters/activerecord.rb', line 18

def connection_lock
  @connection_lock
end

Instance Attribute Details

#key_columnObject (readonly)


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# File 'lib/moneta/adapters/activerecord.rb', line 13

def key_column
  @key_column
end

#tableObject (readonly)


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# File 'lib/moneta/adapters/activerecord.rb', line 13

def table
  @table
end

#value_columnObject (readonly)


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# File 'lib/moneta/adapters/activerecord.rb', line 13

def value_column
  @value_column
end

Class Method Details

.establish_connection(spec_name) ⇒ Object


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# File 'lib/moneta/adapters/activerecord.rb', line 25

def establish_connection(spec_name)
  connection_lock.synchronize do
    if connection_pool = retrieve_connection_pool(spec_name)
      connection_pool
    else
      connection_handler.establish_connection(spec_name.to_sym)
    end
  end
end

.retrieve_connection_pool(spec_name) ⇒ Object


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# File 'lib/moneta/adapters/activerecord.rb', line 21

def retrieve_connection_pool(spec_name)
  connection_handler.retrieve_connection_pool(spec_name.to_s)
end

.retrieve_or_establish_connection_pool(spec_name) ⇒ Object


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# File 'lib/moneta/adapters/activerecord.rb', line 35

def retrieve_or_establish_connection_pool(spec_name)
  retrieve_connection_pool(spec_name) || establish_connection(spec_name)
end

Instance Method Details

#clear(options = {}) ⇒ void

This method returns an undefined value.

Clear all keys in this store

Parameters:

  • options (Hash) (defaults to: {})

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# File 'lib/moneta/adapters/activerecord.rb', line 184

def clear(options = {})
  with_connection do |conn|
    conn.delete(arel_del)
  end
  self
end

#closeObject

Explicitly close the store

Returns:

  • nil


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# File 'lib/moneta/adapters/activerecord.rb', line 192

def close
  @table = nil
  @spec = nil
end

#create(key, value, options = {}) ⇒ Boolean

Note:

Not every Moneta store implements this method, a NotImplementedError is raised if it is not supported.

Atomically sets a key to value if it's not set.

Parameters:

  • key (Object)
  • value (Object)
  • options (Hash) (defaults to: {})

Options Hash (options):

  • :expires (Integer)

    Update expiration time (See Expires)

  • :raw (Boolean)

    Raw access without value transformation (See Transformer)

  • :prefix (String)

    Prefix key (See Transformer)

Returns:

  • (Boolean)

    key was set


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# File 'lib/moneta/adapters/activerecord.rb', line 174

def create(key, value, options = {})
  with_connection do |conn|
    conn_ins(conn, key, value)
    true
  end
rescue ::ActiveRecord::RecordNotUnique
  false
end

#delete(key, options = {}) ⇒ Object

Delete the key from the store and return the current value

Parameters:

  • key (Object)
  • options (Hash) (defaults to: {})

Options Hash (options):

  • :raw (Boolean)

    Raw access without value transformation (See Transformer)

  • :prefix (String)

    Prefix key (See Transformer)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • (Object)

    current value


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# File 'lib/moneta/adapters/activerecord.rb', line 135

def delete(key, options = {})
  with_connection do |conn|
    conn.transaction do
      sel = arel_sel_key(key).project(table[value_column]).lock
      value = decode(conn, conn.select_value(sel))

      del = arel_del.where(table[key_column].eq(key))
      conn.delete(del)

      value
    end
  end
end

#each_keyEnumerator #each_key {|key| ... } ⇒ self

Note:

Not every Moneta store implements this method, a NotImplementedError is raised if it is not supported.

Calls block once for each key in store, passing the key as a parameter. If no block is given, an enumerator is returned instead.

Overloads:

  • #each_keyEnumerator

    Returns An all-the-keys enumerator

    Returns:

    • (Enumerator)

      An all-the-keys enumerator

  • #each_key {|key| ... } ⇒ self

    Yield Parameters:

    • key (Object)

      Each key is yielded to the supplied block

    Returns:

    • (self)

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# File 'lib/moneta/adapters/activerecord.rb', line 110

def each_key(&block)
  with_connection do |conn|
    return enum_for(:each_key) { conn.select_value(arel_sel.project(table[key_column].count)) } unless block_given?
    conn.select_values(arel_sel.project(table[key_column])).each { |k| yield(k) }
  end
  self
end

#fetch_values(*keys, **options) ⇒ Object #fetch_values(*keys, **options) {|key| ... } ⇒ Array<Object, nil>

Note:

Some adapters may implement this method atomically. The default implmentation uses #values_at.

Behaves identically to #values_at except that it accepts an optional block. When supplied, the block will be called successively with each supplied key that is not present in the store. The return value of the block call will be used in place of nil in returned the array of values.

Overloads:

  • #fetch_values(*keys, **options) {|key| ... } ⇒ Array<Object, nil>

    Returns Array containing the values requested, or where keys are missing, the return values from the corresponding block calls

    Yield Parameters:

    • key (Object)

      Each key that is not found in the store

    Yield Returns:

    • (Object, nil)

      The value to substitute for the missing one

    Returns:

    • (Array<Object, nil>)

      Array containing the values requested, or where keys are missing, the return values from the corresponding block calls


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# File 'lib/moneta/adapters/activerecord.rb', line 219

def fetch_values(*keys, **options)
  return values_at(*keys, **options) unless block_given?
  hash = Hash[slice(*keys, **options)]
  keys.map do |key|
    if hash.key?(key)
      hash[key]
    else
      yield key
    end
  end
end

#increment(key, amount = 1, options = {}) ⇒ Object

Note:

Not every Moneta store implements this method, a NotImplementedError is raised if it is not supported.

Atomically increment integer value with key

This method also accepts negative amounts.

Parameters:

  • key (Object)
  • amount (Integer) (defaults to: 1)
  • options (Hash) (defaults to: {})

Options Hash (options):

  • :prefix (String)

    Prefix key (See Transformer)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • (Object)

    value from store


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# File 'lib/moneta/adapters/activerecord.rb', line 150

def increment(key, amount = 1, options = {})
  with_connection do |conn|
    begin
      conn_ins(conn, key, amount.to_s)
      amount
    rescue ::ActiveRecord::RecordNotUnique
      conn.transaction do
        sel = arel_sel_key(key).project(table[value_column]).lock
        value = decode(conn, conn.select_value(sel))
        value = (value ? Integer(value) : 0) + amount
        # Re-raise if the upate affects no rows (i.e. row deleted after attempted insert,
        # before select for update)
        raise unless conn_upd(conn, key, value.to_s) == 1
        value
      end
    end
  end
rescue ::ActiveRecord::RecordNotUnique
  # This handles the "no row updated" issue, above
  tries ||= 0
  if (tries += 1) <= 3; retry else raise end
end

#key?(key, options = {}) ⇒ Boolean

Exists the value with key

Parameters:

  • key (Object)
  • options (Hash) (defaults to: {})

Options Hash (options):

  • :expires (Integer)

    Update expiration time (See Expires)

  • :prefix (String)

    Prefix key (See Transformer)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • (Boolean)

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# File 'lib/moneta/adapters/activerecord.rb', line 101

def key?(key, options = {})
  with_connection do |conn|
    sel = arel_sel_key(key).project(::Arel.sql('1'))
    result = conn.select_all(sel)
    !result.empty?
  end
end

#load(key, options = {}) ⇒ Object

Fetch value with key. Return nil if the key doesn't exist

Parameters:

  • key (Object)
  • options (Hash) (defaults to: {})

Options Hash (options):

  • :expires (Integer)

    Update expiration time (See Expires)

  • :raw (Boolean)

    Raw access without value transformation (See Transformer)

  • :prefix (String)

    Prefix key (See Transformer)

  • :sync (Boolean)

    Synchronized load (Cache reloads from adapter, Daybreak syncs with file)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • (Object)

    value


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# File 'lib/moneta/adapters/activerecord.rb', line 119

def load(key, options = {})
  with_connection do |conn|
    conn_sel_value(conn, key)
  end
end

#merge!(pairs, options = {}) ⇒ self #merge!(pairs, options = {}) {|key, old_value, new_value| ... } ⇒ self

Note:

Some adapters may implement this method atomically, or in two passes when a block is provided. The default implmentation uses #key?, #load and #store.

Stores the pairs in the key-value store, and returns itself. When a block is provided, it will be called before overwriting any existing values with the key, old value and supplied value, and the return value of the block will be used in place of the supplied value.

Overloads:

  • #merge!(pairs, options = {}) ⇒ self

    Parameters:

    • pairs (<(Object, Object)>)

      A collection of key-value pairs to store

    • options (Hash) (defaults to: {})

    Returns:

    • (self)
  • #merge!(pairs, options = {}) {|key, old_value, new_value| ... } ⇒ self

    Parameters:

    • pairs (<(Object, Object)>)

      A collection of key-value pairs to store

    • options (Hash) (defaults to: {})

    Yield Parameters:

    • key (Object)

      A key that whose value is being overwritten

    • old_value (Object)

      The existing value which is being overwritten

    • new_value (Object)

      The value supplied in the method call

    Yield Returns:

    • (Object)

      The value to use for overwriting

    Returns:

    • (self)

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# File 'lib/moneta/adapters/activerecord.rb', line 232

def merge!(pairs, options = {})
  with_connection do |conn|
    conn.transaction do
      existing = Hash[slice(*pairs.map { |k, _| k }, lock: true, **options)]
      update_pairs, insert_pairs = pairs.partition { |k, _| existing.key?(k) }
      insert_pairs.each { |key, value| conn_ins(conn, key, encode(conn, value)) }

      if block_given?
        update_pairs.map! do |key, new_value|
          [key, yield(key, existing[key], new_value)]
        end
      end

      update_pairs.each { |key, value| conn_upd(conn, key, encode(conn, value)) }
    end
  end

  self
end

#slice(*keys, lock: false, **options) ⇒ <(Object, Object)>

Note:

The keys in the return value may be the same objects that were supplied (i.e. Object#equal?), or may simply be equal (i.e. Object#==).

Note:

Some adapters may implement this method atomically. The default implmentation uses #values_at.

Returns a collection of key-value pairs corresponding to those supplied keys which are present in the key-value store, and their associated values. Only those keys present in the store will have pairs in the return value. The return value can be any enumerable object that yields pairs, so it could be a hash, but needn't be.

Parameters:

  • keys (<Object>)

    The keys for the values to fetch

  • options (Hash)

Options Hash (**options):

  • :expires (Integer)

    Update expiration time (See Expires)

  • :raw (Boolean)

    Raw access without value transformation (See Transformer)

  • :prefix (String)

    Prefix key (See Transformer)

  • :sync (Boolean)

    Synchronized load (Cache reloads from adapter, Daybreak syncs with file)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • (<(Object, Object)>)

    A collection of key-value pairs


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# File 'lib/moneta/adapters/activerecord.rb', line 198

def slice(*keys, lock: false, **options)
  with_connection do |conn|
    sel = arel_slice(keys).project(table[key_column], table[value_column])
    sel = sel.lock if lock
    result = conn.select_all(sel)

    k = key_column.to_s
    v = value_column.to_s
    result.map do |row|
      [row[k], decode(conn, row[v])]
    end
  end
end

#store(key, value, options = {}) ⇒ Object

Store value with key

Parameters:

  • key (Object)
  • value (Object)
  • options (Hash) (defaults to: {})

Options Hash (options):

  • :expires (Integer)

    Set expiration time (See Expires)

  • :raw (Boolean)

    Raw access without value transformation (See Transformer)

  • :prefix (String)

    Prefix key (See Transformer)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • value


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# File 'lib/moneta/adapters/activerecord.rb', line 126

def store(key, value, options = {})
  with_connection do |conn|
    encoded = encode(conn, value)
    conn_ins(conn, key, encoded) unless conn_upd(conn, key, encoded) == 1
  end
  value
end

#values_at(*keys, **options) ⇒ Array<Object, nil>

Note:

Some adapters may implement this method atomically, but the default implementation simply makes repeated calls to #load.

Returns an array containing the values associated with the given keys, in the same order as the supplied keys. If a key is not present in the key-value-store, nil is returned in its place.

Parameters:

  • keys (<Object>)

    The keys for the values to fetch

  • options (Hash)

Options Hash (**options):

  • :expires (Integer)

    Update expiration time (See Expires)

  • :raw (Boolean)

    Raw access without value transformation (See Transformer)

  • :prefix (String)

    Prefix key (See Transformer)

  • :sync (Boolean)

    Synchronized load (Cache reloads from adapter, Daybreak syncs with file)

  • Other (Object)

    options as defined by the adapters or middleware

Returns:

  • (Array<Object, nil>)

    Array containing the values requested, with nil for missing values


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# File 'lib/moneta/adapters/activerecord.rb', line 213

def values_at(*keys, **options)
  hash = Hash[slice(*keys, **options)]
  keys.map { |key| hash[key] }
end