Class: ActiveSupport::Cache::Entry

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

Overview

This class is used to represent cache entries. Cache entries have a value, an optional expiration time, and an optional version. The expiration time is used to support the :race_condition_ttl option on the cache. The version is used to support the :version option on the cache for rejecting mismatches.

Since cache entries in most instances will be serialized, the internals of this class are highly optimized using short instance variable names that are lazily defined.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(value, compressed: false, version: nil, expires_in: nil, expires_at: nil) ⇒ Entry

Creates a new cache entry for the specified value. Options supported are :compressed, :version, :expires_at and :expires_in.



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# File 'activesupport/lib/active_support/cache.rb', line 1025

def initialize(value, compressed: false, version: nil, expires_in: nil, expires_at: nil, **)
  @value      = value
  @version    = version
  @created_at = 0.0
  @expires_in = expires_at&.to_f || expires_in && (expires_in.to_f + Time.now.to_f)
  @compressed = true if compressed
end

Instance Attribute Details

#version ⇒ Object (readonly)

Returns the value of attribute version



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# File 'activesupport/lib/active_support/cache.rb', line 1021

def version
  @version
end

Class Method Details

.unpack(members) ⇒ Object 



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# File 'activesupport/lib/active_support/cache.rb', line 1016

def unpack(members)
  new(members[0], expires_at: members[1], version: members[2])
end

Instance Method Details

#bytesize ⇒ Object

Returns the size of the cached value. This could be less than value.bytesize if the data is compressed.



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# File 'activesupport/lib/active_support/cache.rb', line 1061

def bytesize
  case value
  when NilClass
    0
  when String
    @value.bytesize
  else
    @s ||= Marshal.dump(@value).bytesize
  end
end

#compressed(compress_threshold) ⇒ Object 



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# File 'activesupport/lib/active_support/cache.rb', line 1076

def compressed(compress_threshold)
  return self if compressed?

  case @value
  when nil, true, false, Numeric
    uncompressed_size = 0
  when String
    uncompressed_size = @value.bytesize
  else
    serialized = Marshal.dump(@value)
    uncompressed_size = serialized.bytesize
  end

  if uncompressed_size >= compress_threshold
    serialized ||= Marshal.dump(@value)
    compressed = Zlib::Deflate.deflate(serialized)

    if compressed.bytesize < uncompressed_size
      return Entry.new(compressed, compressed: true, expires_at: expires_at, version: version)
    end
  end
  self
end

#compressed? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'activesupport/lib/active_support/cache.rb', line 1072

def compressed? # :nodoc:
  defined?(@compressed)
end

#dup_value! ⇒ Object

Duplicates the value in a class. This is used by cache implementations that don’t natively serialize entries to protect against accidental cache modifications.



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# File 'activesupport/lib/active_support/cache.rb', line 1106

def dup_value!
  if @value && !compressed? && !(@value.is_a?(Numeric) || @value == true || @value == false)
    if @value.is_a?(String)
      @value = @value.dup
    else
      @value = Marshal.load(Marshal.dump(@value))
    end
  end
end

#expired? ⇒ Boolean

Checks if the entry is expired. The expires_in parameter can override the value set when the entry was created.

Returns:

  • (Boolean) 


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# File 'activesupport/lib/active_support/cache.rb', line 1043

def expired?
  @expires_in && @created_at + @expires_in <= Time.now.to_f
end

#expires_at ⇒ Object 



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# File 'activesupport/lib/active_support/cache.rb', line 1047

def expires_at
  @expires_in ? @created_at + @expires_in : nil
end

#expires_at=(value) ⇒ Object 



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# File 'activesupport/lib/active_support/cache.rb', line 1051

def expires_at=(value)
  if value
    @expires_in = value.to_f - @created_at
  else
    @expires_in = nil
  end
end

#local? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'activesupport/lib/active_support/cache.rb', line 1100

def local?
  false
end

#mismatched?(version) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'activesupport/lib/active_support/cache.rb', line 1037

def mismatched?(version)
  @version && version && @version != version
end

#pack ⇒ Object 



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# File 'activesupport/lib/active_support/cache.rb', line 1116

def pack
  members = [value, expires_at, version]
  members.pop while !members.empty? && members.last.nil?
  members
end

#value ⇒ Object 



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# File 'activesupport/lib/active_support/cache.rb', line 1033

def value
  compressed? ? uncompress(@value) : @value
end