Class: ConnectionPool

Inherits:
Object
  • Object
show all
Defined in:
lib/connection_pool.rb,
lib/connection_pool/version.rb

Overview

Generic connection pool class for e.g. sharing a limited number of network connections among many threads. Note: Connections are eager created.

Example usage with block (faster):

@pool = ConnectionPool.new { Redis.new }

@pool.with do |redis|
  redis.lpop('my-list') if redis.llen('my-list') > 0
end

Example usage replacing an existing connection (slower):

$redis = ConnectionPool.wrap { Redis.new }

def do_work
  $redis.lpop('my-list') if $redis.llen('my-list') > 0
end

Accepts the following options:

  • :size - number of connections to pool, defaults to 5

  • :timeout - amount of time to wait for a connection if none currently available, defaults to 5 seconds

Defined Under Namespace

Classes: Wrapper

Constant Summary collapse

DEFAULTS = 
{ :size => 5, :timeout => 5 }
VERSION = 
"0.9.2"

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}, &block) ⇒ ConnectionPool

Returns a new instance of ConnectionPool.

Raises:

  • (ArgumentError) 


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# File 'lib/connection_pool.rb', line 34

def initialize(options={}, &block)
  raise ArgumentError, 'Connection pool requires a block' unless block

  options = DEFAULTS.merge(options)

  @size = options[:size]
  @timeout = options[:timeout]

  @available = ::TimedQueue.new(@size, &block)
  @key = :"current-#{@available.object_id}"
end

Class Method Details

.wrap(options, &block) ⇒ Object 



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# File 'lib/connection_pool.rb', line 30

def self.wrap(options, &block)
  Wrapper.new(options, &block)
end

Instance Method Details

#checkin ⇒ Object 



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# File 'lib/connection_pool.rb', line 69

def checkin
  stack = ::Thread.current[@key]
  conn = stack.pop
  if stack.empty?
    @available << conn
  end
  nil
end

#checkout ⇒ Object 



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# File 'lib/connection_pool.rb', line 56

def checkout
  stack = ::Thread.current[@key] ||= []

  if stack.empty?
    conn = @available.timed_pop(@timeout)
  else
    conn = stack.last
  end

  stack.push conn
  conn
end

#with ⇒ Object Also known as: with_connection 



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# File 'lib/connection_pool.rb', line 46

def with
  conn = checkout
  begin
    yield conn
  ensure
    checkin
  end
end