Class: Readthis::Cache

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(url, options = {}) ⇒ Cache

Creates a new Readthis::Cache object with the given redis URL. The URL is parsed by the redis client directly.

Examples:

Create a new cache instance

Readthis::Cache.new('redis://localhost:6379/0', namespace: 'cache')

Create a compressed cache instance

Readthis::Cache.new('redis://localhost:6379/0', compress: true, compression_threshold: 2048)

Parameters:

  • url (String) —

    A redis compliant url with necessary connection details

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

    a customizable set of options

Options Hash (options):

  • :namespace (String) —

    Prefix used to namespace entries

  • :expires_in (Number) —

    The number of seconds until an entry expires

  • :compress (Boolean) —

    Enable or disable automatic compression

  • :compression_threshold (Number) —

    The size a string must be for compression



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# File 'lib/readthis/cache.rb', line 45

def initialize(url, options = {})
  @expires_in = options.fetch(:expires_in, nil)
  @namespace  = options.fetch(:namespace,  nil)
  @compress   = options.fetch(:compress,   false)
  @compression_threshold = options.fetch(:compression_threshold, 1024)

  @pool = ConnectionPool.new(pool_options(options)) do
    Redis.new(url: url, driver: :hiredis)
  end
end

Instance Attribute Details

#compress ⇒ Object (readonly) Also known as: compress?

Returns the value of attribute compress.



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# File 'lib/readthis/cache.rb', line 10

def compress
  @compress
end

#compression_threshold ⇒ Object (readonly)

Returns the value of attribute compression_threshold.



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# File 'lib/readthis/cache.rb', line 10

def compression_threshold
  @compression_threshold
end

#expires_in ⇒ Object (readonly)

Returns the value of attribute expires_in.



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# File 'lib/readthis/cache.rb', line 10

def expires_in
  @expires_in
end

#namespace ⇒ Object (readonly)

Returns the value of attribute namespace.



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# File 'lib/readthis/cache.rb', line 10

def namespace
  @namespace
end

#pool ⇒ Object (readonly)

Returns the value of attribute pool.



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# File 'lib/readthis/cache.rb', line 10

def pool
  @pool
end

Class Method Details

.notifications ⇒ Object

Provide a class level lookup of the proper notifications module. Instrumention is expected to occur within applications that have ActiveSupport::Notifications available, but needs to work even when it isn’t.



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# File 'lib/readthis/cache.rb', line 22

def self.notifications
  if Object.const_defined?('ActiveSupport::Notifications')
    ActiveSupport::Notifications
  else
    Readthis::Notifications
  end
end

Instance Method Details

#clear ⇒ Object 



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# File 'lib/readthis/cache.rb', line 149

def clear
  invoke(:clear, '*', &:flushdb)
end

#decrement(key, options = {}) ⇒ Object 



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# File 'lib/readthis/cache.rb', line 100

def decrement(key, options = {})
  invoke(:decrement, key) do |store|
    store.decr(namespaced_key(key, merged_options(options)))
  end
end

#delete(key, options = {}) ⇒ Object 



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# File 'lib/readthis/cache.rb', line 77

def delete(key, options = {})
  invoke(:delete, key) do |store|
    store.del(namespaced_key(key, merged_options(options)))
  end
end

#exist?(key, options = {}) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/readthis/cache.rb', line 143

def exist?(key, options = {})
  invoke(:exist?, key) do |store|
    store.exists(namespaced_key(key, merged_options(options)))
  end
end

#fetch(key, options = {}) ⇒ Object 



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# File 'lib/readthis/cache.rb', line 83

def fetch(key, options = {})
  value = read(key, options) unless options[:force]

  if value.nil? && block_given?
    value = yield(key)
    write(key, value, options)
  end

  value
end

#fetch_multi(*keys) ⇒ Object

Fetches multiple keys from the cache using a single call to the server and filling in any cache misses. All read and write operations are executed atomically.

cache.fetch_multi('alpha', 'beta') do |key|
  "#{key}-was-missing"
end



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# File 'lib/readthis/cache.rb', line 124

def fetch_multi(*keys)
  results = read_multi(*keys)
  options = merged_options(extract_options!(keys))

  invoke(:fetch_multi, keys) do |store|
    store.pipelined do
      results.each do |key, value|
        if value.nil?
          value = yield key
          write(key, value, options)
          results[key] = value
        end
      end
    end

    results
  end
end

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



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# File 'lib/readthis/cache.rb', line 94

def increment(key, options = {})
  invoke(:incremenet, key) do |store|
    store.incr(namespaced_key(key, merged_options(options)))
  end
end

#read(key, options = {}) ⇒ Object 



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# File 'lib/readthis/cache.rb', line 56

def read(key, options = {})
  invoke(:read, key) do |store|
    value = store.get(namespaced_key(key, merged_options(options)))

    decompressed(value)
  end
end

#read_multi(*keys) ⇒ Object 



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# File 'lib/readthis/cache.rb', line 106

def read_multi(*keys)
  options = merged_options(extract_options!(keys))
  mapping = keys.map { |key| namespaced_key(key, options) }

  invoke(:read_multi, keys) do |store|
    values = decompressed_multi(store.mget(mapping))

    keys.zip(values).to_h
  end
end

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



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# File 'lib/readthis/cache.rb', line 64

def write(key, value, options = {})
  options    = merged_options(options)
  namespaced = namespaced_key(key, options)

  invoke(:write, key) do |store|
    if expiration = options[:expires_in]
      store.setex(namespaced, expiration, compressed(value))
    else
      store.set(namespaced, compressed(value))
    end
  end
end