Object
GServer implements a generic server, featuring
thread pool management, simple logging, and multi-server management. See
HttpServer in xmlrpc/httpserver.rb
in the Ruby standard
library for an example of GServer in action.
Any kind of application-level server can be implemented using this class.
It accepts multiple simultaneous connections from clients, up to an
optional maximum number. Several services (i.e. one service per
TCP port) can be run simultaneously, and stopped at any time through the
class method GServer.stop(port)
. All the threading issues are
handled, saving you the effort. All events are optionally logged, but you
can provide your own event handlers if you wish.
Using GServer is simple. Below we implement a
simple time server, run it, query it, and shut it down. Try this code in
irb
:
require 'gserver' # # A server that returns the time in seconds since 1970. # class TimeServer < GServer def initialize(port=10001, *args) super(port, *args) end def serve(io) io.puts(Time.now.to_s) end end # Run the server with logging enabled (it's a separate thread). server = TimeServer.new server.audit = true # Turn logging on. server.start # *** Now point your browser to http://localhost:10001 to see it working *** # See if it's still running. GServer.in_service?(10001) # -> true server.stopped? # -> false # Shut the server down gracefully. server.shutdown # Alternatively, stop it immediately. GServer.stop(10001) # or, of course, "server.stop".
All the business of accepting connections and exception handling is taken care of. All we have to do is implement the method that actually serves the client.
As the example above shows, the way to use GServer is to subclass it to create a specific
server, overriding the serve
method. You can override other
methods as well if you wish, perhaps to collect statistics, or emit more
detailed logging.
connecting disconnecting starting stopping
The above methods are only called if auditing is enabled.
You can also override log
and error
if, for
example, you wish to use a more sophisticated logging system.
# File gserver.rb, line 102 def GServer.in_service?(port, host = DEFAULT_HOST) @@services.has_key?(host) and @@services[host].has_key?(port) end
# File gserver.rb, line 171 def initialize(port, host = DEFAULT_HOST, maxConnections = 4, stdlog = $stderr, audit = false, debug = false) @tcpServerThread = nil @port = port @host = host @maxConnections = maxConnections @connections = [] @connectionsMutex = Mutex.new @connectionsCV = ConditionVariable.new @stdlog = stdlog @audit = audit @debug = debug end
# File gserver.rb, line 123 def connections @connections.size end
# File gserver.rb, line 127 def join @tcpServerThread.join if @tcpServerThread end
# File gserver.rb, line 185 def start(maxConnections = -1) raise "running" if !stopped? @shutdown = false @maxConnections = maxConnections if maxConnections > 0 @@servicesMutex.synchronize { if GServer.in_service?(@port,@host) raise "Port already in use: #{host}:#{@port}!" end @tcpServer = TCPServer.new(@host,@port) @port = @tcpServer.addr[1] @@services[@host] = {} unless @@services.has_key?(@host) @@services[@host][@port] = self; } @tcpServerThread = Thread.new { begin starting if @audit while !@shutdown @connectionsMutex.synchronize { while @connections.size >= @maxConnections @connectionsCV.wait(@connectionsMutex) end } client = @tcpServer.accept @connections << Thread.new(client) { |myClient| begin myPort = myClient.peeraddr[1] serve(myClient) if !@audit or connecting(myClient) rescue => detail error(detail) if @debug ensure begin myClient.close rescue end @connectionsMutex.synchronize { @connections.delete(Thread.current) @connectionsCV.signal } disconnecting(myPort) if @audit end } end rescue => detail error(detail) if @debug ensure begin @tcpServer.close rescue end if @shutdown @connectionsMutex.synchronize { while @connections.size > 0 @connectionsCV.wait(@connectionsMutex) end } else @connections.each { |c| c.raise "stop" } end @tcpServerThread = nil @@servicesMutex.synchronize { @@services[@host].delete(@port) } stopping if @audit end } self end
# File gserver.rb, line 134 def connecting(client) addr = client.peeraddr log("#{self.class.to_s} #{@host}:#{@port} client:#{addr[1]} " + "#{addr[2]}<#{addr[3]}> connect") true end
# File gserver.rb, line 141 def disconnecting(clientPort) log("#{self.class.to_s} #{@host}:#{@port} " + "client:#{clientPort} disconnect") end
# File gserver.rb, line 158 def error(detail) log(detail.backtrace.join("\n")) end
# File gserver.rb, line 162 def log(msg) if @stdlog @stdlog.puts("[#{Time.new.ctime}] %s" % msg) @stdlog.flush end end