Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!ames!ucsd!sdcsvax!ucsdhub!hp-sdd!hplabs!decwrl!labrea!polya!ali
From: ali@polya.STANFORD.EDU (Ali Ozer)
Newsgroups: comp.sys.amiga
Subject: Re: IPC - A proposal
Message-ID: <2123@polya.STANFORD.EDU>
Date: 9 Mar 88 02:51:48 GMT
References: <5375@well.UUCP> <739@nuchat.UUCP> <7455@agate.BERKELEY.EDU> <2116@polya.STANFORD.EDU> <44626@sun.uucp>
Reply-To: ali@polya.UUCP (Ali Ozer)
Organization: Stanford University
Lines: 23

In article <44626@sun.uucp> cmcmanis@sun.UUCP (Chuck McManis) writes:
>Hmmm, the problem everyone is complaining about is the speed of doing
>a FindPort() which takes to long. Maybe what we need instead is a 
>way of checking to see that a port we originally got was still valid ...
>Note that the NewDeletePort() would scribble on the port in some way to make
>it appear invalid (nulling out the memory would be sufficient) 
>... this rule then A) it is fast (IsValidPort could be as simple
>as port.mn_Type == NT_MESSAGE) and B) it is reasonably safe from race 
>conditions.

What if that same chunk of memory gets allocated as a port as soon as
it's closed? A low probability, but possible... Or some byte gets put in 
that makes the chunk look like a port? You might need to check that
the port type in NT_MESSAGE, and then also probably check that the name
is still the same. That'd still beat searching through all the ports.
You'd need IsStillValid (port, name).

Ali Ozer, ali@polya.stanford.edu

ps. BTW, got just got SDB, and it's neat! A bug that I spent half an hour
    the day before took 10 seconds to find after I started SDB. There
    it was: "Divide by zero error". Where I would never have found it.
    Wow!