On Jan 2, 2007, at 22:25, Kevin Scaldeferri wrote:
I've been digging through the website and mailing list archives,
and I'm still puzzled about how to achieve a graceful server shutdown.
By this, I mean something similar to 'apachectl graceful', where
new requests are refused, but any existing requests are fully
processed before the server performs shutdown functions and
terminates.
My server is an HTTP server using PoCo::Server::TCP, which runs a
fairly simple state machine to gather up all the information
required for each request and then puts it together to construct
the reply. It seems to me like implementing the graceful shutdown
requires 3 parts:
1) a signal handler that sets a global "shutting down" flag
Good. It should also send a "shutdown" signal to the
POE::Component::Server::TCP instance's alias. This shuts down the
listener but leaves the children running.
2) in my ClientInput callback, to only start the state machine if
the flag is not set
Not necessary. New clients will not be accepted.
3) somehow determine that all current requests have finished, and
shutdown if the flag is set. This is the part that I'm stuck on.
Not necessary. If your server is doing nothing else, it will exit
after the last client disconnects. If you need to trigger a more
complex shutdown after the last client disconnects, then you will
need a shutdown flag and an active connection counter:
a. Send the Server::TCP instance a "shutdown" message.
b. Set the global shutdown flag.
c. If the active session count is 0, commence complex shutdown.
d. Otherwise, increment the active session count from the
ClientConnected callback, and decrement it from the
ClientDisconnected callback.
e. When the active session count reaches 0, and the shutdown flag is
set, begin complex shutdown.
--
Rocco Caputo - [EMAIL PROTECTED]
