Class: EventMachine::PostgresConnection

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

Constant Summary collapse

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(postgres, opts, conn) ⇒ PostgresConnection

Returns a new instance of PostgresConnection.



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

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

  self.notify_readable = true
  EM.add_timer(0){ next_query }
rescue => e
  puts e.inspect
end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

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

act like the pg driver



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# File 'lib/em-postgres/connection.rb', line 203

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

Instance Attribute Details

#connected ⇒ Object (readonly)

Returns the value of attribute connected.



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

def opts
  @opts
end

#processing ⇒ Object (readonly)

Returns the value of attribute processing.



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

def processing
  @processing
end

Class Method Details

.connect(opts) ⇒ Object 



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# File 'lib/em-postgres/connection.rb', line 42

def self.connect(opts)
  if conn = connect_socket(opts)
    #debug [:connect, conn.socket, opts]
    EM.watch(conn.socket, EventMachine::PostgresConnection,conn,opts)
  else
    # invokes :errback callback in opts before firing again
    debug [:reconnect]
    EM.add_timer(5) { connect opts }
  end
end

.connect_socket(opts) ⇒ Object

stolen from sequel



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# File 'lib/em-postgres/connection.rb', line 54

def self.connect_socket(opts)
begin
  conn = PGconn.connect(
    opts[:host],
    (opts[:port]), #TODO deal with host and port
    nil,nil,
    opts[:database],
    opts[:user],
    opts[:password]
  )
  # set encoding _before_ connecting
  if encoding = opts[:encoding] || opts[:charset]
    if conn.respond_to?(:set_client_encoding)
      conn.set_client_encoding(encoding)
    else
      conn.async_exec("set client_encoding to '#{encoding}'")
    end
  end
  conn
rescue Exception => e
  puts "#{e} exception"
  if cb = opts[:errback]
    cb.call(e)
    nil
  else
    raise e
  end
end
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/em-postgres/connection.rb', line 211

def close
  return unless @connected
  detach
  @postgres.finish
  @connected = false
end

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



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# File 'lib/em-postgres/connection.rb', line 174

def execute(sql,params=nil, cblk = nil, eblk = nil, retries = 0)
  begin
    if not @processing or not @connected
    #if !@processing || !@connected
      @processing = true
        
      if sql =~ /\s+/
        @postgres.send_query(sql,params)
      else
        @postgres.send_query_prepared(sql,params)
      end
    else          
      @queue << [sql,params, cblk, eblk, retries]
      return
    end

  rescue Exception => e
    puts "error in execute #{e}"
    if DisconnectErrors.include? e.message
      @queue << [sql,params, cblk, eblk, retries]
      return #close
    else
      raise e
    end
  end
  @current = [sql,params, cblk, eblk, retries]
end

#notify_readable ⇒ Object 



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# File 'lib/em-postgres/connection.rb', line 84

def notify_readable
  if item = @current
    sql,params, cblk, eblk, retries = item
    #results = []
    #result = nil
    #@postgres.get_result{|r| result = r}
    #@postgres.get_result #TODO remove this, I can't process anymore code without this.
    result = nil        
    loop do
      # Fetch the next result. If there isn't one, the query is 
      # finished
      item = @postgres.get_result
      if item
        result = item
      else
        break
      end
      #puts "\n\nQuery result:\n%p\n" % [ result.values ]
    end
    unless @postgres.error_message == ""
      #TODO this is wrong
      eb = (eblk || @opts[:on_error])
      eb.call(result) if eb
      result.clear
      #reconnect
      @processing = false
      #@current = nil
      return next_query
    end
    # kick off next query in the background
    # as we process the current results
    @current = nil
    @processing = false
    cblk.call(result) if cblk
    result.clear
    next_query
  else
    return close
  end

rescue Exception => e
  puts "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,params, 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-postgres/connection.rb', line 159

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

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

rescue Exception => e
  EM.add_timer(1) { reconnect }
end

#unbind ⇒ Object 



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# File 'lib/em-postgres/connection.rb', line 145

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