rf-web/vendor/bundle/gems/concurrent-ruby-1.1.5/lib/concurrent/map.rb
2019-10-21 10:18:17 +02:00

338 lines
11 KiB
Ruby

require 'thread'
require 'concurrent/constants'
require 'concurrent/synchronization'
require 'concurrent/utility/engine'
module Concurrent
# @!visibility private
module Collection
# @!visibility private
MapImplementation = case
when Concurrent.on_jruby?
# noinspection RubyResolve
JRubyMapBackend
when Concurrent.on_cruby?
require 'concurrent/collection/map/mri_map_backend'
MriMapBackend
when Concurrent.on_rbx? || Concurrent.on_truffleruby?
require 'concurrent/collection/map/atomic_reference_map_backend'
AtomicReferenceMapBackend
else
warn 'Concurrent::Map: unsupported Ruby engine, using a fully synchronized Concurrent::Map implementation'
require 'concurrent/collection/map/synchronized_map_backend'
SynchronizedMapBackend
end
end
# `Concurrent::Map` is a hash-like object and should have much better performance
# characteristics, especially under high concurrency, than `Concurrent::Hash`.
# However, `Concurrent::Map `is not strictly semantically equivalent to a ruby `Hash`
# -- for instance, it does not necessarily retain ordering by insertion time as `Hash`
# does. For most uses it should do fine though, and we recommend you consider
# `Concurrent::Map` instead of `Concurrent::Hash` for your concurrency-safe hash needs.
class Map < Collection::MapImplementation
# @!macro map.atomic_method
# This method is atomic.
# @!macro map.atomic_method_with_block
# This method is atomic.
# @note Atomic methods taking a block do not allow the `self` instance
# to be used within the block. Doing so will cause a deadlock.
# @!method compute_if_absent(key)
# Compute and store new value for key if the key is absent.
# @param [Object] key
# @yield new value
# @yieldreturn [Object] new value
# @return [Object] new value or current value
# @!macro map.atomic_method_with_block
# @!method compute_if_present(key)
# Compute and store new value for key if the key is present.
# @param [Object] key
# @yield new value
# @yieldparam old_value [Object]
# @yieldreturn [Object, nil] new value, when nil the key is removed
# @return [Object, nil] new value or nil
# @!macro map.atomic_method_with_block
# @!method compute(key)
# Compute and store new value for key.
# @param [Object] key
# @yield compute new value from old one
# @yieldparam old_value [Object, nil] old_value, or nil when key is absent
# @yieldreturn [Object, nil] new value, when nil the key is removed
# @return [Object, nil] new value or nil
# @!macro map.atomic_method_with_block
# @!method merge_pair(key, value)
# If the key is absent, the value is stored, otherwise new value is
# computed with a block.
# @param [Object] key
# @param [Object] value
# @yield compute new value from old one
# @yieldparam old_value [Object] old value
# @yieldreturn [Object, nil] new value, when nil the key is removed
# @return [Object, nil] new value or nil
# @!macro map.atomic_method_with_block
# @!method replace_pair(key, old_value, new_value)
# Replaces old_value with new_value if key exists and current value
# matches old_value
# @param [Object] key
# @param [Object] old_value
# @param [Object] new_value
# @return [true, false] true if replaced
# @!macro map.atomic_method
# @!method replace_if_exists(key, new_value)
# Replaces current value with new_value if key exists
# @param [Object] key
# @param [Object] new_value
# @return [Object, nil] old value or nil
# @!macro map.atomic_method
# @!method get_and_set(key, value)
# Get the current value under key and set new value.
# @param [Object] key
# @param [Object] value
# @return [Object, nil] old value or nil when the key was absent
# @!macro map.atomic_method
# @!method delete(key)
# Delete key and its value.
# @param [Object] key
# @return [Object, nil] old value or nil when the key was absent
# @!macro map.atomic_method
# @!method delete_pair(key, value)
# Delete pair and its value if current value equals the provided value.
# @param [Object] key
# @param [Object] value
# @return [true, false] true if deleted
# @!macro map.atomic_method
def initialize(options = nil, &block)
if options.kind_of?(::Hash)
validate_options_hash!(options)
else
options = nil
end
super(options)
@default_proc = block
end
# Get a value with key
# @param [Object] key
# @return [Object] the value
def [](key)
if value = super # non-falsy value is an existing mapping, return it right away
value
# re-check is done with get_or_default(key, NULL) instead of a simple !key?(key) in order to avoid a race condition, whereby by the time the current thread gets to the key?(key) call
# a key => value mapping might have already been created by a different thread (key?(key) would then return true, this elsif branch wouldn't be taken and an incorrent +nil+ value
# would be returned)
# note: nil == value check is not technically necessary
elsif @default_proc && nil == value && NULL == (value = get_or_default(key, NULL))
@default_proc.call(self, key)
else
value
end
end
alias_method :get, :[]
# TODO (pitr-ch 30-Oct-2018): doc
alias_method :put, :[]=
# Get a value with key, or default_value when key is absent,
# or fail when no default_value is given.
# @param [Object] key
# @param [Object] default_value
# @yield default value for a key
# @yieldparam key [Object]
# @yieldreturn [Object] default value
# @return [Object] the value or default value
# @raise [KeyError] when key is missing and no default_value is provided
# @!macro map_method_not_atomic
# @note The "fetch-then-act" methods of `Map` are not atomic. `Map` is intended
# to be use as a concurrency primitive with strong happens-before
# guarantees. It is not intended to be used as a high-level abstraction
# supporting complex operations. All read and write operations are
# thread safe, but no guarantees are made regarding race conditions
# between the fetch operation and yielding to the block. Additionally,
# this method does not support recursion. This is due to internal
# constraints that are very unlikely to change in the near future.
def fetch(key, default_value = NULL)
if NULL != (value = get_or_default(key, NULL))
value
elsif block_given?
yield key
elsif NULL != default_value
default_value
else
raise_fetch_no_key
end
end
# Fetch value with key, or store default value when key is absent,
# or fail when no default_value is given. This is a two step operation,
# therefore not atomic. The store can overwrite other concurrently
# stored value.
# @param [Object] key
# @param [Object] default_value
# @yield default value for a key
# @yieldparam key [Object]
# @yieldreturn [Object] default value
# @return [Object] the value or default value
# @!macro map.atomic_method_with_block
def fetch_or_store(key, default_value = NULL)
fetch(key) do
put(key, block_given? ? yield(key) : (NULL == default_value ? raise_fetch_no_key : default_value))
end
end
# Insert value into map with key if key is absent in one atomic step.
# @param [Object] key
# @param [Object] value
# @return [Object, nil] the value or nil when key was present
def put_if_absent(key, value)
computed = false
result = compute_if_absent(key) do
computed = true
value
end
computed ? nil : result
end unless method_defined?(:put_if_absent)
# Is the value stored in the map. Iterates over all values.
# @param [Object] value
# @return [true, false]
def value?(value)
each_value do |v|
return true if value.equal?(v)
end
false
end
# All keys
# @return [::Array<Object>] keys
def keys
arr = []
each_pair { |k, v| arr << k }
arr
end unless method_defined?(:keys)
# All values
# @return [::Array<Object>] values
def values
arr = []
each_pair { |k, v| arr << v }
arr
end unless method_defined?(:values)
# Iterates over each key.
# @yield for each key in the map
# @yieldparam key [Object]
# @return [self]
# @!macro map.atomic_method_with_block
def each_key
each_pair { |k, v| yield k }
end unless method_defined?(:each_key)
# Iterates over each value.
# @yield for each value in the map
# @yieldparam value [Object]
# @return [self]
# @!macro map.atomic_method_with_block
def each_value
each_pair { |k, v| yield v }
end unless method_defined?(:each_value)
# Iterates over each key value pair.
# @yield for each key value pair in the map
# @yieldparam key [Object]
# @yieldparam value [Object]
# @return [self]
# @!macro map.atomic_method_with_block
def each_pair
return enum_for :each_pair unless block_given?
super
end
alias_method :each, :each_pair unless method_defined?(:each)
# Find key of a value.
# @param [Object] value
# @return [Object, nil] key or nil when not found
def key(value)
each_pair { |k, v| return k if v == value }
nil
end unless method_defined?(:key)
alias_method :index, :key if RUBY_VERSION < '1.9'
# Is map empty?
# @return [true, false]
def empty?
each_pair { |k, v| return false }
true
end unless method_defined?(:empty?)
# The size of map.
# @return [Integer] size
def size
count = 0
each_pair { |k, v| count += 1 }
count
end unless method_defined?(:size)
# @!visibility private
def marshal_dump
raise TypeError, "can't dump hash with default proc" if @default_proc
h = {}
each_pair { |k, v| h[k] = v }
h
end
# @!visibility private
def marshal_load(hash)
initialize
populate_from(hash)
end
undef :freeze
# @!visibility private
def inspect
format '%s entries=%d default_proc=%s>', to_s[0..-2], size.to_s, @default_proc.inspect
end
private
def raise_fetch_no_key
raise KeyError, 'key not found'
end
def initialize_copy(other)
super
populate_from(other)
end
def populate_from(hash)
hash.each_pair { |k, v| self[k] = v }
self
end
def validate_options_hash!(options)
if (initial_capacity = options[:initial_capacity]) && (!initial_capacity.kind_of?(Integer) || initial_capacity < 0)
raise ArgumentError, ":initial_capacity must be a positive Integer"
end
if (load_factor = options[:load_factor]) && (!load_factor.kind_of?(Numeric) || load_factor <= 0 || load_factor > 1)
raise ArgumentError, ":load_factor must be a number between 0 and 1"
end
end
end
end