Class: Frivol::Backend::Multi

Inherits:
Object
  • Object
show all
Defined in:
lib/frivol/backend/multi.rb

Overview

Configuration

This backend is used to migrate from one backend to another (and another) (and another). Essentially, this backend will check for the existence of the key in the newest backend, and if not found check in the older backends in order. If it’s found in an older backend it will move the value to the new backend.

I have used this in production to move from Redis to RedisDistributed.

old_backend = Frivol::Backend::Redis.new(:db => 10)
new_backend = Frivol::Backend::RedisDistributed.new(["redis://127.0.0.1:6379/11", "redis://127.0.0.1:6379/12"])
Frivol::Config.backend = Frivol::Backend::Multi.new([ new_backend, old_backend ])

Constant Summary collapse

BackendsNotUniqueError =

:nodoc:

Class.new(StandardError)

Instance Method Summary collapse

Constructor Details

#initialize(backends) ⇒ Multi

Returns a new instance of Multi.



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# File 'lib/frivol/backend/multi.rb', line 17

def initialize(backends)
  unless backends.map(&:inspect).uniq.size == backends.size
    raise BackendsNotUniqueError, "Backends are not unique: #{backends.map(&:inspect).join(', ')}"
  end
  @primary_backend = backends.shift
  @other_backends = backends
end

Instance Method Details

#connection ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 125

def connection
  @primary_backend.connection
end

#decr(key, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 77

def decr(key, expiry = Frivol::NEVER_EXPIRE)
  if @primary_backend.existsc(key)
    @primary_backend.decr(key)
  else
    migratec(key, :decrby, 1, expiry)
  end
end

#decrby(key, amt, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 93

def decrby(key, amt, expiry = Frivol::NEVER_EXPIRE)
  if @primary_backend.existsc(key)
    @primary_backend.decrby(key, amt)
  else
    migratec(key, :decrby, amt, expiry)
  end
end

#del(key) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 37

def del(key)
  @primary_backend.del(key)
  @other_backends.each { |be| be.del(key) }
end

#delc(key) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 59

def delc(key)
  @primary_backend.delc(key)
  @other_backends.each { |be| be.delc(key) }
end

#exists(key) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 42

def exists(key)
  @primary_backend.exists(key) ||
    @other_backends.detect { |be| be.exists(key) }
end

#existsc(key) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 64

def existsc(key)
  @primary_backend.existsc(key) ||
    @other_backends.detect { |be| be.existsc(key) }
end

#expire(key, ttl) ⇒ Object

Expiry/TTL



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# File 'lib/frivol/backend/multi.rb', line 102

def expire(key, ttl)
  @primary_backend.expire(key, ttl)
end

#flushdb ⇒ Object

Connection



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# File 'lib/frivol/backend/multi.rb', line 120

def flushdb
  @primary_backend.flushdb
  @other_backends.each { |be| be.flushdb }
end

#get(key, expiry = Frivol::NEVER_EXPIRE) ⇒ Object

Hashes



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# File 'lib/frivol/backend/multi.rb', line 26

def get(key, expiry = Frivol::NEVER_EXPIRE)
  val = @primary_backend.get(key)
  val = migrate(key, expiry) if val.nil?
  val
end

#getc(key, expiry = Frivol::NEVER_EXPIRE) ⇒ Object

Counters



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# File 'lib/frivol/backend/multi.rb', line 48

def getc(key, expiry = Frivol::NEVER_EXPIRE)
  val = @primary_backend.getc(key)
  val = migratec(key, :getc, 0, expiry) if val.nil?
  val
end

#incr(key, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 69

def incr(key, expiry = Frivol::NEVER_EXPIRE)
  if @primary_backend.existsc(key)
    @primary_backend.incr(key)
  else
    migratec(key, :incrby, 1, expiry)
  end
end

#incrby(key, amt, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 85

def incrby(key, amt, expiry = Frivol::NEVER_EXPIRE)
  if @primary_backend.existsc(key)
    @primary_backend.incrby(key, amt)
  else
    migratec(key, :incrby, amt, expiry)
  end
end

#migrate(key, expiry = Frivol::NEVER_EXPIRE) ⇒ Object

Migration



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# File 'lib/frivol/backend/multi.rb', line 130

def migrate(key, expiry = Frivol::NEVER_EXPIRE)
  backend = @other_backends.detect { |be| be.exists(key) }
  if backend
    val = backend.get(key)
    ttl = backend.ttl(key)
    @primary_backend.set(key, val, ttl)
    @other_backends.each { |be| be.del key }
    val
  end
end

#migratec(key, method = :incrby, amt = 0, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 141

def migratec(key, method = :incrby, amt = 0, expiry = Frivol::NEVER_EXPIRE)
  backend = @other_backends.detect { |be| be.existsc(key) }
  if backend
    val = backend.getc(key).to_i
    ttl = backend.ttl(key)
    @primary_backend.incrby(key, val) unless val.zero?
    val = @primary_backend.send(method, key, amt) unless amt.zero? || method == :getc
    @primary_backend.expire(key, ttl) if ttl
    @other_backends.each { |be| be.delc key }
    val
  elsif method != :getc
    @primary_backend.send(method, key, amt, expiry)
  else
    nil
  end
end

#set(key, val, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 32

def set(key, val, expiry = Frivol::NEVER_EXPIRE)
  @other_backends.each { |be| be.del(key) }
  @primary_backend.set(key, val, expiry)
end

#setc(key, val, expiry = Frivol::NEVER_EXPIRE) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 54

def setc(key, val, expiry = Frivol::NEVER_EXPIRE)
  @other_backends.each { |be| be.delc(key) }
  @primary_backend.setc(key, val, expiry)
end

#ttl(key) ⇒ Object 



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# File 'lib/frivol/backend/multi.rb', line 106

def ttl(key)
  expiry = @primary_backend.ttl(key)
  if expiry.nil?
    @other_backends.each do |be|
      expiry = be.ttl(key)
      return expiry unless expiry.nil?
    end
    nil
  else
    expiry
  end
end