/usr/lib/ruby/vendor_ruby/ramaze/cache/sequel.rb is in ruby-ramaze 2012.12.08-3.
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module Ramaze
class Cache
##
# The Sequel cache is a cache system that uses the Sequel database toolkit
# to store the data in a DBMS supported by Sequel. Examples of these
# databases are MySQL, SQLite3 and so on. In order to use this cache you'd
# have to do the following:
#
# Ramaze::Cache.options.view = Ramaze::Cache::Sequel.using(
# :connection => Sequel.mysql(
# :host => 'localhost',
# :user => 'user',
# :password => 'password',
# :database => 'blog'
# ),
# :table => :blog_sessions
# )
#
# If you already have an existing connection you can just pass the object to
# the :connection option instead of creating a new connection manually.
#
# Massive thanks to Lars Olsson for patching the original Sequel cache so
# that it supports multiple connections and other useful features.
#
# @example Setting a custom database connection
# Ramaze::Cache.options.names.push(:sequel)
# Ramaze::Cache.options.sequel = Ramaze::Cache::Sequel.using(
# :connection => Sequel.connect(
# :adapter => 'mysql2',
# :host => 'localhost',
# :username => 'cache',
# :password => 'cache123',
# :database => 'ramaze_cache'
# )
# )
#
# @author Lars Olsson
# @since 18-04-2011
#
class Sequel
include Cache::API
include Innate::Traited
# Hash containing the default options
trait :default => {
# The default Sequel connection to use
:connection => nil,
# Whether or not warnings should be displayed
:display_warnings => false,
# The name of the default database table to use
:table => 'ramaze_cache',
# The default TTL to use
:ttl => nil
}
# Hash containing all the default options merged with the user specified
# ones
attr_accessor :options
class << self
attr_accessor :options
##
# This method returns a subclass of Ramaze::Cache::Sequel with the
# provided options set. This is necessary because Ramaze expects a class
# and not an instance of a class for its cache option.
#
# You can provide any parameters you want, but those not used by the
# cache will not get stored. No parameters are mandatory. Any missing
# parameters will be replaced by default values.
#
# @example
# ##
# # This will create a mysql session cache in the blog
# # database in the table blog_sessions
# # Please note that the permissions on the database must
# # be set up correctly before you can just create a new table
# #
# Ramaze.options.cache.session = Ramaze::Cache::Sequel.using(
# :connection => Sequel.mysql(
# :host =>'localhost',
# :user =>'user',
# :password =>'password',
# :database =>'blog'
# ),
# :table => :blog_sessions
# )
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] options A hash containing the options to use
# @option options [Object] :connection a Sequel database object
# (Sequel::Database) You can use any parameters that Sequel supports for
# this object. If this option is left unset, a Sqlite memory database
# will be used.
# @option options [String] :table The table name you want to use for the
# cache. Can be either a String or a Symbol. If this option is left
# unset, a table called ramaze_cache will be used.
# @option options [Fixnum] :ttl Setting this value will override
# Ramaze's default setting for when a particular cache item will be
# invalidated. By default this setting is not used and the cache uses
# the values provided by Ramaze, but if you want to use this setting it
# should be set to an integer representing the number of seconds before
# a cache item becomes invalidated.
# @option options [TrueClass] :display_warnings When this option is set
# to true, failure to serialiaze or deserialize cache items will produce
# a warning in the Ramaze log. This option is set to false by default.
# Please note that certain objects (for instance Procs) cannot be
# serialized by ruby and therefore cannot be cached by this cache class.
# Setting this option to true is a good way to find out if the stuff you
# are trying to cache is affected by this. Failure to
# serialize/deserialize a cache item will never raise an exception, the
# item will just remain uncached.
# @return [Object]
#
def using(options = {})
merged = Ramaze::Cache::Sequel.trait[:default].merge(options)
Class.new(self) { @options = merged }
end
end
##
# Creates a new instance of the cache class.
#
# @author Michael Fellinger
# @since 04-05-2011
# @param [Hash] options A hash with custom options, see
# Ramaze::Cache::Sequel.using for all available options.
#
def initialize(options = {})
self.class.options ||= Ramaze::Cache::Sequel.trait[:default].merge(
options
)
@options = options.merge(self.class.options)
end
##
# Executed after #initialize and before any other method.
#
# Some parameters identifying the current process will be passed so caches
# that act in one global name-space can use them as a prefix.
#
# @author Lars Olsson
# @since 18-04-2011
# @param [String] hostname the hostname of the machine
# @param [String] username user executing the process
# @param [String] appname identifier for the application
# @param [String] cachename namespace, like 'session' or 'action'
#
def cache_setup(hostname, username, appname, cachename)
@namespace = [hostname, username, appname, cachename].compact.join(':')
# Create the table if it's not there yet
if !options[:connection].table_exists?(options[:table])
options[:connection].create_table(
options[:table]) do
primary_key :id
String :key , :null => false, :unique => true
String :value, :text => true
Time :expires
end
end
@dataset = options[:connection][options[:table].to_sym]
end
##
# Remove all key/value pairs from the cache. Should behave as if #delete
# had been called with all +keys+ as argument.
#
# @author Lars Olsson
# @since 18-04-2011
#
def cache_clear
@dataset.delete
end
##
# Remove the corresponding key/value pair for each key passed. If removing
# is not an option it should set the corresponding value to nil.
#
# If only one key was deleted, answer with the corresponding value. If
# multiple keys were deleted, answer with an Array containing the values.
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] key The key for the value to delete
# @param [Object] keys Any other keys to delete as well
# @return [Object/Array/nil]
#
def cache_delete(key, *keys)
# Remove a single key
if keys.empty?
nkey = namespaced(key)
result = @dataset.select(:value).filter(:key => nkey).limit(1)
# Ramaze expects nil values
if result.empty?
result = nil
else
result = deserialize(result.first[:value])
end
@dataset.filter(:key => nkey).delete
# Remove multiple keys
else
nkeys = [key, keys].flatten.map! { |n| namespaced(n) }
result = dataset.select(:value).filter(:key => nkeys)
result.map! do |row|
deserialize(row[:value])
end
@dataset.filter(:key => nkeys).delete
end
return result
end
##
# Answer with the value associated with the +key+, +nil+ if not found or
# expired.
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] key The key for which to fetch the value
# @param [Object] default Will return this if no value was found
# @return [Object]
#
def cache_fetch(key, default = nil)
nkey = namespaced(key)
# Delete expired rows
@dataset.select.filter(:key => nkey) do
expires < Time.now
end.delete
# Get remaining row (if any)
result = @dataset.select(:value).filter(:key => nkey).limit(1)
if result.empty?
return default
else
return deserialize(result.first[:value])
end
end
##
# Sets the given key to the given value.
#
# @example
# Cache.value.store(:num, 3, :ttl => 20)
# Cache.value.fetch(:num)
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] key The value is stored with this key
# @param [Object] value The key points to this value
# @param [Hash] options for now, only :ttl => Fixnum is used.
# @option options [Fixnum] :ttl The time in seconds after which the cache
# item should be expired.
#
def cache_store(key, value, options = {})
nkey = namespaced(key)
# Get the time after which the cache should be expired
if options[:ttl]
ttl = options[:ttl]
else
ttl = Ramaze::Cache::Sequel.options[:ttl]
end
expires = Time.now + ttl if ttl
# The row already exists, update it.
if @dataset.filter(:key => nkey).count == 1
serialized_value = serialize(value)
if serialized_value
@dataset.filter(:key => nkey) \
.update(:value => serialize(value), :expires => expires)
end
# The row doesn't exist yet.
else
serialized_value = serialize(value)
if serialized_value
@dataset.insert(
:key => nkey, :value => serialize(value), :expires => expires
)
end
end
# Try to deserialize the value. If this fails we'll return a different
# value
deserialized = deserialize(@dataset.select(:value) \
.filter(:key => nkey) \
.limit(1).first[:value])
if deserialized
return deserialized
else
return value
end
end
##
# Prefixes the given key with current namespace.
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] key Key without namespace.
# @return [Object]
#
def namespaced(key)
return [@namespace, key].join(':')
end
##
# Deserialize method, adapted from Sequels serialize plugin
# This method will try to deserialize a value using Marshal.load
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] value Value to be deserialized
# @return [Object nil]
#
def deserialize(value)
begin
::Marshal.load(value.unpack('m')[0])
rescue
begin
::Marshal.load(value)
rescue
# Log the error?
if options[:display_warnings] === true
Ramaze::Log::warn("Failed to deserialize #{value.inspect}")
end
return nil
end
end
end
##
# Serialize method, adapted from Sequels serialize plugin
# This method will try to serialize a value using Marshal.dump
#
# @author Lars Olsson
# @since 18-04-2011
# @param [Object] value Value to be serialized.
# @return [Object nil]
#
def serialize(value)
begin
[::Marshal.dump(value)].pack('m')
rescue
if options[:display_warnings] === true
Ramaze::Log::warn("Failed to serialize #{value.inspect}")
end
return nil
end
end
end # Sequel
end # Cache
end # Ramaze
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