Class: EventMachine::MySQLConnection

Inherits:
Connection
  • Object
show all
Defined in:
lib/em-mysqlplus/connection.rb

Constant Summary collapse

MAX_RETRIES_ON_DEADLOCKS = 
10
DisconnectErrors = 
[
  'query: not connected',
  'MySQL server has gone away',
  'Lost connection to MySQL server during query'
]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(mysql, opts, conn) ⇒ MySQLConnection

Returns a new instance of MySQLConnection.



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# File 'lib/em-mysqlplus/connection.rb', line 22

def initialize(mysql, opts, conn)
  @conn = conn
  @mysql = mysql
  @fd = mysql.socket
  @opts = opts
  @current = nil
  @queue = []
  @processing = false
  @connected = true

  self.notify_readable = true
  EM.add_timer(0){ next_query }
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *args, &blk) ⇒ Object

mysql gem has syncronous methods such as list_dbs and others which require that we execute without callbacks



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# File 'lib/em-mysqlplus/connection.rb', line 126

def method_missing(method, *args, &blk)
  @mysql.send(method, *args, &blk) if @mysql.respond_to? method
end

Instance Attribute Details

#connected ⇒ Object (readonly)

Returns the value of attribute connected.



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# File 'lib/em-mysqlplus/connection.rb', line 11

def connected
  @connected
end

#opts ⇒ Object (readonly) Also known as: settings

Returns the value of attribute opts.



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# File 'lib/em-mysqlplus/connection.rb', line 11

def opts
  @opts
end

#processing ⇒ Object (readonly)

Returns the value of attribute processing.



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# File 'lib/em-mysqlplus/connection.rb', line 11

def processing
  @processing
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/em-mysqlplus/connection.rb', line 130

def close
  return unless @connected

  detach
  @mysql.close
  @connected = false
end

#execute(sql, cblk = nil, eblk = nil, retries = 0) ⇒ Object 



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# File 'lib/em-mysqlplus/connection.rb', line 102

def execute(sql, cblk = nil, eblk = nil, retries = 0)
  begin
    if not @processing or not @connected
      @processing = true
      @mysql.send_query(sql)
    else
      @queue << [sql, cblk, eblk, retries]
      return
    end

  rescue Mysql::Error => e
    if DisconnectErrors.include? e.message
      @queue << [sql, cblk, eblk, retries]
      return close
    else
      raise e
    end
  end

  @current = [sql, cblk, eblk, retries]
end

#notify_readable ⇒ Object 



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# File 'lib/em-mysqlplus/connection.rb', line 36

def notify_readable
  if item = @current
    sql, cblk, eblk, retries = item
    result = @mysql.get_result
    result = @mysql.affected_rows if result.nil?

    # kick off next query in the background
    # as we process the current results
    @current = nil
    @processing = false
    next_query

    cblk.call(result)
  else
    return close
  end

rescue Mysql::Error => e

  if e.message =~ /Deadlock/ and retries < MAX_RETRIES_ON_DEADLOCKS
    @queue << [sql, cblk, eblk, retries + 1]
    @processing = false
    next_query

  elsif DisconnectErrors.include? e.message
    @queue << [sql, cblk, eblk, retries + 1]
    return close

  elsif cb = (eblk || @opts[:on_error])
    cb.call(e)
    @processing = false
    next_query

  else
    raise e
  end
end

#reconnect ⇒ Object 



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# File 'lib/em-mysqlplus/connection.rb', line 87

def reconnect
  @processing = false
  @mysql = @conn.connect_socket(@opts)
  @fd = @mysql.socket

  @signature = EM.attach_fd(@mysql.socket, true)
  EM.set_notify_readable(@signature, true)
  EM.instance_variable_get('@conns')[@signature] = self
  @connected = true
  next_query

rescue Mysql::Error => e
  EM.add_timer(1) { reconnect }
end

#unbind ⇒ Object 



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# File 'lib/em-mysqlplus/connection.rb', line 74

def unbind
  # wait for the next tick until the current fd is removed completely from the reactor
  #
  # in certain cases the new FD# (@mysql.socket) is the same as the old, since FDs are re-used
  # without next_tick in these cases, unbind will get fired on the newly attached signature as well
  #
  # do _NOT_ use EM.next_tick here. if a bunch of sockets disconnect at the same time, we want
  # reconnects to happen after all the unbinds have been processed

  @connected = false
  EM.next_tick { reconnect }
end