CODESAMPLE

Object Pool - Ruby

Object Pool Ruby

The Object Pool pattern manages a group of reusable objects, reducing the overhead of frequent object creation and destruction. This is particularly useful for expensive-to-create objects. This Ruby implementation uses a simple array to store a pool of DatabaseConnection objects. checkout retrieves an available object (or creates one if the pool is empty). checkin returns an object to the pool for reuse. Using an array and pop/push efficiently manages object availability, fitting Ruby’s dynamic nature. The Mutex ensures thread safety when accessing the shared pool. It favors a pragmatic Ruby style, providing a basic reusable implementation.

require 'mutex'

class DatabaseConnection
  def initialize
    # Simulate expensive connection setup
    sleep(0.5)
    puts "Establishing database connection..."
    @connected = true
  end

  def query(sql)
    puts "Executing query: #{sql}"
    # Simulate query execution
    sleep(0.1)
    "Query results"
  end

  def close
    @connected = false
    puts "Closing database connection..."
  end

  def connected?
    @connected
  end
end

class DatabaseConnectionPool
  def initialize(size = 5)
    @size = size
    @pool = []
    @mutex = Mutex.new
  end

  def checkout
    @mutex.synchronize do
      if @pool.empty?
        puts "Pool empty, creating new connection..."
        return DatabaseConnection.new
      else
        puts "Reusing connection from pool..."
        return @pool.pop
      end
    end
  end

  def checkin(connection)
    @mutex.synchronize do
      if connection.connected? == false
        puts "Connection is already closed. Discarding."
        return
      end
      @pool.push(connection)
      puts "Connection returned to pool. Pool size: #{@pool.size}"
    end
  end
end

# Example Usage
pool = DatabaseConnectionPool.new(2)

connection1 = pool.checkout
connection1.query("SELECT * FROM users")
pool.checkin(connection1)

connection2 = pool.checkout
connection2.query("SELECT * FROM products")
pool.checkin(connection2)

connection3 = pool.checkout #Might create a new connection, or reuse if available
connection3.query("UPDATE order SET status = 'shipped'")
pool.checkin(connection3)