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require 'thread'
module ThreadSafe
autoload :JRubyCacheBackend, 'thread_safe/jruby_cache_backend'
autoload :MriCacheBackend, 'thread_safe/mri_cache_backend'
autoload :NonConcurrentCacheBackend, 'thread_safe/non_concurrent_cache_backend'
autoload :AtomicReferenceCacheBackend, 'thread_safe/atomic_reference_cache_backend'
autoload :SynchronizedCacheBackend, 'thread_safe/synchronized_cache_backend'
ConcurrentCacheBackend = if defined?(RUBY_ENGINE)
case RUBY_ENGINE
when 'jruby'; JRubyCacheBackend
when 'ruby'; MriCacheBackend
when 'rbx'; AtomicReferenceCacheBackend
else
warn 'ThreadSafe: unsupported Ruby engine, using a fully synchronized ThreadSafe::Cache implementation' if $VERBOSE
SynchronizedCacheBackend
end
else
MriCacheBackend
end
class Cache < ConcurrentCacheBackend
def initialize(options = nil, &block)
if options.kind_of?(::Hash)
validate_options_hash!(options)
else
options = nil
end
super(options)
@default_proc = block
end
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, :[]
alias_method :put, :[]=
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
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
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)
def value?(value)
each_value do |v|
return true if value.equal?(v)
end
false
end unless method_defined?(:value?)
def keys
arr = []
each_pair {|k, v| arr << k}
arr
end unless method_defined?(:keys)
def values
arr = []
each_pair {|k, v| arr << v}
arr
end unless method_defined?(:values)
def each_key
each_pair {|k, v| yield k}
end unless method_defined?(:each_key)
def each_value
each_pair {|k, v| yield v}
end unless method_defined?(:each_value)
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'
def empty?
each_pair {|k, v| return false}
true
end unless method_defined?(:empty?)
def size
count = 0
each_pair {|k, v| count += 1}
count
end unless method_defined?(:size)
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
def marshal_load(hash)
initialize
populate_from(hash)
end
undef :freeze
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?(0.class) || initial_capacity < 0)
raise ArgumentError, ":initial_capacity must be a positive #{0.class}"
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
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