From: Josh Mccartt <sendmail@...>
Date: 2010-05-15T00:16:20+09:00
Subject: GServer Miultiple Clients - Collisions

I've got a small problem using gserver with multiple client connections.
Let me give some quick background on my problem:

I'm running a Ruby script on a dozen or so different machines, doing
some basic performance monitoring tasks.  The script writes its output
to a local file (for buffering), then connects to a server running on
the local network.  The server receives the lines from the file, writes
them to a local file for archiving, then uses dbi to write them to a
database.

Everything is working fine, unless more than one client connects at a
time.  When two clients connect at once, I get numerous database errors,
and the results don't write.

I was under the impression that gserver threaded incoming connections,
so each connection would have its own independent database connection,
but it looks like the single database handle is being shared by all
clients.  Obviously, this isn't working properly.  Here's some code to
show what I've tried.  Any help would be greatly appreciated:

Server:

class ScriptResultsServer < GServer

  def initialize(port,hostname,*args)
    super(port, hostname,*args)
  end

  def serve(io)
    test_results = []
    loop do
      # Check for incoming data
      if IO.select([io],nil,nil,1)
        line = io.gets
        # After tests completed, client responds with "done"
        if (line =~ /done/)
          # After receiving "success", client deletes buffer
          io.puts("success")
          break
        else
          test_result = []
          test_result = line.split(',')

          test_results << test_result

          app_dir = Dir.getwd
          logs_dir = app_dir + "/logs/"

          # results[1] contains the hostname of the connected client
          filename = logs_dir + results[1] + ".log"

          # Write the results to the archive file
          write_log(filename,line)

          # Clean the old entries from the log file
          clean_log(filename)
        end
      end
    end
    write_db(test_results)
  end

 def clean_log(filename)
  # Code snipped - this method opens a file, and deletes all lines
  # older than 30 days
 end

  def write_log(filename,line)
   # Code snipped - this method opens a file, and appends the data that
   # was sent to the server
  end

  def write_db(results)
   # Code snipped - this method creates a DB connection and writes
   # the data that was sent to the server
  end

  def close_db
   # Code snipped - this method commits changes and disconnects
  end

end


  # Create a new instance of the server, accessible at this host on port
8050
  server = ScriptResultsServer.new 8050,Socket.gethostname
  # Enable logging
  server.audit = true
  # Start the server
  server.start
  # Join the server thread to the main thread (prevent exit)
  server.join


Client:

class ScriptClient

  def initialize(filename)
    # Open a socket to the ******* host on port 8050
    @sr_server = TCPSocket.open("*********","8050")
    @results_filename = filename
    # Open the local buffer file
    @results_file = File.open(filename, "r")
  end

  def write
    # Read each line from the buffer and send to the server
    while (line = @results_file.gets)
      @sr_server.puts(line)
    end
  end

  def disconnect
    # Close the buffer file
    @results_file.close
    # After streaming the buffer, send "done" to the server
    # If "success" is received, delete the buffer file
    @sr_server.puts("done")
    # Wait up to 30 seconds for acknowledgment
    if (IO.select([@sr_server],nil,nil,30))
      line = @sr_server.gets
      if (line =~ /success/)
        File.delete(@results_filename)
      end
    end
  end

end

Thanks again for any help!
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