Class: HealthyPools

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

Overview

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

Example usage with block (faster):

@pool = HealthyPools.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 = HealthyPools.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: Error, PoolShuttingDownError, TimedStack, Wrapper

Constant Summary collapse

DEFAULTS = 
{size: 5, timeout: 5, health_check: nil}
VERSION = 
"2.2.5"

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

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

Returns a new instance of HealthyPools.

Raises:

  • (ArgumentError) 


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# File 'lib/healthy_pools.rb', line 44

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

  options = DEFAULTS.merge(options)

  @size = options.fetch(:size)
  @timeout = options.fetch(:timeout)
  @health_check = options[:health_check]

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

Class Method Details

.monotonic_time ⇒ Float

Returns the current time a tracked by the application monotonic clock.



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# File 'lib/healthy_pools/monotonic_time.rb', line 62

def monotonic_time
  GLOBAL_MONOTONIC_CLOCK.get_time
end

.wrap(options, &block) ⇒ Object 



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# File 'lib/healthy_pools.rb', line 40

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

Instance Method Details

#available ⇒ Object

Number of pool entries available for checkout at this instant.



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# File 'lib/healthy_pools.rb', line 123

def available
  @available.length
end

#checkin ⇒ Object 



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# File 'lib/healthy_pools.rb', line 98

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

  nil
end

#checkout(options = {}) ⇒ Object 



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# File 'lib/healthy_pools.rb', line 88

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

#shutdown(&block) ⇒ Object 



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# File 'lib/healthy_pools.rb', line 113

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

#size ⇒ Object

Size of this connection pool



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# File 'lib/healthy_pools.rb', line 118

def size
  @size
end

#with(options = {}) ⇒ Object

jruby 1.7.x



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# File 'lib/healthy_pools.rb', line 61

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