#
# Copyright (C) 2001 John W. Small All Rights Reserved
#
# Author:: John W. Small
# Documentation:: Gavin Sinclair
# Licence:: Ruby License
require "socket"
require "thread"
#
# GServer implements a generic server, featuring thread pool management,
# simple logging, and multi-server management. See HttpServer in
# <tt>xmlrpc/httpserver.rb</tt> 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
# <tt>GServer.stop(port)</tt>. 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.
#
# == Example
#
# 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.
#
# === Advanced
#
# 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, via #audit=.
#
# You can also override #log and #error if, for example, you wish to use a
# more sophisticated logging system.
#
class GServer
DEFAULT_HOST = "127.0.0.1"
def serve(io)
end
@@services = {} # Hash of opened ports, i.e. services
@@servicesMutex = Mutex.new
# Stop the server running on the given port, bound to the given host
#
# +port+:: port, as a FixNum, of the server to stop
# +host+:: host on which to find the server to stop
def GServer.stop(port, host = DEFAULT_HOST)
@@servicesMutex.synchronize {
@@services[host][port].stop
}
end
# Check if a server is running on the given port and host
#
# +port+:: port, as a FixNum, of the server to check
# +host+:: host on which to find the server to check
#
# Returns true if a server is running on that port and host.
def GServer.in_service?(port, host = DEFAULT_HOST)
@@services.has_key?(host) and
@@services[host].has_key?(port)
end
# Stop the server
def stop
@connectionsMutex.synchronize {
if @tcpServerThread
@tcpServerThread.raise "stop"
end
}
end
# Returns true if the server has stopped.
def stopped?
@tcpServerThread == nil
end
# Schedule a shutdown for the server
def shutdown
@shutdown = true
end
# Return the current number of connected clients
def connections
@connections.size
end
# Join with the server thread
def join
@tcpServerThread.join if @tcpServerThread
end
# Port on which to listen, as a FixNum
attr_reader :port
# Host on which to bind, as a String
attr_reader :host
# Maximum number of connections to accept at at ime, as a FixNum
attr_reader :maxConnections
# IO Device on which log messages should be written
attr_accessor :stdlog
# Set to true to cause the callbacks #connecting, #disconnecting, #starting,
# and #stopping to be called during the server's lifecycle
attr_accessor :audit
# Set to true to show more detailed logging
attr_accessor :debug
# Called when a client connects, if auditing is enabled.
#
# +client+:: a TCPSocket instances representing the client that connected
#
# Return true to allow this client to connect, false to prevent it.
def connecting(client)
addr = client.peeraddr
log("#{self.class.to_s} #{@host}:#{@port} client:#{addr[1]} " +
"#{addr[2]}<#{addr[3]}> connect")
true
end
# Called when a client disconnects, if audition is enabled.
#
# +clientPort+:: the port of the client that is connecting
def disconnecting(clientPort)
log("#{self.class.to_s} #{@host}:#{@port} " +
"client:#{clientPort} disconnect")
end
protected :connecting, :disconnecting
# Called when the server is starting up, if auditing is enabled.
def starting()
log("#{self.class.to_s} #{@host}:#{@port} start")
end
# Called when the server is shutting down, if auditing is enabled.
def stopping()
log("#{self.class.to_s} #{@host}:#{@port} stop")
end
protected :starting, :stopping
# Called if #debug is true whenever an unhandled exception is raised.
# This implementation simply logs the backtrace.
#
# +detail+:: The Exception that was caught
def error(detail)
log(detail.backtrace.join("\n"))
end
# Log a message to #stdlog, if it's defined. This implementation
# outputs the timestamp and message to the log.
#
# +msg+:: the message to log
def log(msg)
if @stdlog
@stdlog.puts("[#{Time.new.ctime}] %s" % msg)
@stdlog.flush
end
end
protected :error, :log
# Create a new server
#
# +port+:: the port, as a FixNum, on which to listen.
# +host+:: the host to bind to
# +maxConnections+:: The maximum number of simultaneous connections to
# accept
# +stdlog+:: IO device on which to log messages
# +audit+:: if true, lifecycle callbacks will be called. See #audit
# +debug+:: if true, error messages are logged. See #debug
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
# Start the server if it isn't already running
#
# +maxConnections+::
# override +maxConnections+ given to the constructor. A negative
# value indicates that the value from the constructor should be used.
def start(maxConnections = -1)
raise "server is already 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
end
