Eventmachine talk - Aug 2006 - database connection pool

I grabbed some code off the net and modified it to come up with a
connection pool that uses ruby-dbi.

Start the pool like this:

@@pool = Dbpool::ConnectionPool.get_instance(:Connections=>3)

Then you can do your database calls like this:

@pool.open {|conn|
  ## db operations here
}

Or like this:

conn = @@pool.get_connection
## db operations here
@@pool.release conn

----------------------------------------------------------------------------------
require ''thread''
require ''dbi''
module Dbpool
    :User         => ''username'',
    :Password     => ''password'',
    :ConnString   => ''dbi:Pg:dbname=test;host=localhost'',
    :Connections  => 3,

  class ConnectionPool
    @@instance       = nil
    @@instance_mutex = Mutex.new
        @@instance ||= self.new(config)
      }
    end

    def initialize(config=Database)
        @num_busy           = 0
        @max_allowed        = @config[:Connections]
        @monitor_mutex      = Mutex.new
        @free_mutex         = Mutex.new
          @free_connections.push create_connection
        }
    end


        @free_connections.size
      }
    end

      release connection
    end


    def get_connection
      @busy_mutex.synchronize {
        while @free_connections.empty?
          sleep(0.001)
        end
        @free_connections.pop
      }
    end


    def release(connection)
      @free_mutex.synchronize {
        @free_connections.push connection
      }
    end

    protected

    def create_connection
      DBI.connect(@config[:ConnString],
@config[:User], at config[:Password], ''AutoCommit'' =>
false)
    end
  end


  class LenientConnectionPool < ConnectionPool

    def get_connection
      @busy_mutex.synchronize {
        if @free_connections.empty?
          create_connection
        else
          @free_connections.pop
        end
      }
    end

  end
end

On 8/8/06, snacktime <snacktime at gmail.com>
wrote:
>
> I grabbed some code off the net and modified it to come up with a
> connection pool that uses ruby-dbi.
>
> Start the pool like this:
>
> @@pool = Dbpool::ConnectionPool.get_instance(:Connections=>3)
>
> Then you can do your database calls like this:
>
> @pool.open {|conn|
>   ## db operations here
> }
>
> Or like this:
>
> conn = @@pool.get_connection
> ## db operations here
> @@pool.release conn
>
>
>
----------------------------------------------------------------------------------
> require ''thread''
> require ''dbi''
> module Dbpool
>     :User         => ''username'',
>     :Password     => ''password'',
>     :ConnString   =>
''dbi:Pg:dbname=test;host=localhost'',
>     :Connections  => 3,
>
>   class ConnectionPool
>     @@instance       = nil
>     @@instance_mutex = Mutex.new
>         @@instance ||= self.new(config)
>       }
>     end
>
>     def initialize(config=Database)
>         @num_busy           = 0
>         @max_allowed        = @config[:Connections]
>         @monitor_mutex      = Mutex.new
>         @free_mutex         = Mutex.new
>           @free_connections.push create_connection
>         }
>     end
>
>
>         @free_connections.size
>       }
>     end
>
>       release connection
>     end
>
>
>     def get_connection
>       @busy_mutex.synchronize {
>         while @free_connections.empty?
>           sleep(0.001)
>         end
>         @free_connections.pop
>       }
>     end
>
>
>     def release(connection)
>       @free_mutex.synchronize {
>         @free_connections.push connection
>       }
>     end
>
>     protected
>
>     def create_connection
>       DBI.connect(@config[:ConnString],
> @config[:User], at config[:Password], ''AutoCommit'' =>
false)
>     end
>   end
>
>
>   class LenientConnectionPool < ConnectionPool
>
>     def get_connection
>       @busy_mutex.synchronize {
>         if @free_connections.empty?
>           create_connection
>         else
>           @free_connections.pop
>         end
>       }
>     end
>
>   end
> end
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>

Thanks, Snacktime. I''ll see if I can integrate this code with EM.
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