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Class: Bundler::ConnectionPool

Overview

Generic connection pool class for sharing a limited number of objects or network connections among many threads. Note: pool elements are lazily created.

Example usage with block (faster):

@pool = Bundler::ConnectionPool.new { Redis.new }
@pool.with do |redis|
  redis.lpop('my-list') if redis.llen('my-list') > 0
end

Using optional timeout override (for that single invocation)

@pool.with(timeout: 2.0) do |redis|
  redis.lpop('my-list') if redis.llen('my-list') > 0
end

Example usage replacing an existing connection (slower):

$redis = Bundler::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

Constant Summary

Class Method Summary

Instance Attribute Summary

  • #size readonly

    Size of this connection pool.

Instance Method Summary

Constructor Details

.new(options = {}, &block) ⇒ ConnectionPool

Raises:

  • (ArgumentError)
[ GitHub ] 

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 45



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

  options = DEFAULTS.merge(options)

  @size = Integer(options.fetch(:size))
  @timeout = options.fetch(:timeout)

  @available = TimedStack.new(@size, &block)
  @key = :"pool-#{@available.object_id}"
  @key_count = :"pool-#{@available.object_id}-count"
end


  







Class Method Details



  

    .wrap(options, &block)  
  

  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 41



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


  







Instance Attribute Details



  

    #size   (readonly)
  



  

    

Size of this connection pool


  



  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 117



attr_reader :size


  







Instance Method Details



  

    #available  
  



  

    

Number of pool entries available for checkout at this instant.


  



  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 120



def available
  @available.length
end


  








  

    #checkin  
  

  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 82



def checkin
  if ::Thread.current[@key]
    if ::Thread.current[@key_count] == 1
      @available.push(::Thread.current[@key])
      ::Thread.current[@key] = nil
      ::Thread.current[@key_count] = nil
    else
      ::Thread.current[@key_count] -= 1
    end
  else
    raise Bundler::ConnectionPool::Error, "no connections are checked out"
  end

  nil
end


  








  

    #checkout(options = {})  
  

  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 72



def checkout(options = {})
  if ::Thread.current[@key]
    ::Thread.current[@key_count] += 1
    ::Thread.current[@key]
  else
    ::Thread.current[@key_count] = 1
    ::Thread.current[@key] = @available.pop(options[:timeout] || @timeout)
  end
end


  








  

    #reload(&block)  
  



  

    

Reloads the ConnectionPool by passing each connection to block and then removing it the pool. Subsequent checkouts will create new connections as needed.


  



  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 112



def reload(&block)
  @available.shutdown(reload: true, &block)
end


  








  

    #shutdown(&block)  
  



  

    

Shuts down the ConnectionPool by passing each connection to block and then removing it from the pool. Attempting to checkout a connection after shutdown will raise ConnectionPool::PoolShuttingDownError.


  



  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 103



def shutdown(&block)
  @available.shutdown(&block)
end


  








  

    #then(options = {})  
  



  

    

Alias for #with.


  



  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 70



alias then with


  








  

    #with(options = {})  
    Also known as: #then
  

  [ GitHub ]


  

  


# File 'lib/bundler/vendor/connection_pool/lib/connection_pool.rb', line 58



def with(options = {})
  Thread.handle_interrupt(Exception => :never) do
    conn = checkout(options)
    begin
      Thread.handle_interrupt(Exception => :immediate) do
        yield conn
      end
    ensure
      checkin
    end
  end
end