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From: ekberg@asl.dl.nec.COM (Tom Ekberg)
Newsgroups: comp.windows.x
Subject: Re: resource ID allocation
Message-ID: <9102141652.AA06583@asl.dl.nec.com>
Date: 14 Feb 91 16:52:49 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 43


 >    Since there were no replies, I figure nobody knows. I checked Xlib and
 > could find nothing that does such a thing. I also discovered that there
 > is no mechanism for setting your own ID when making a request to create
 > a resource. The client just keeps sucking up valid ID's until there are
 > none left and them is completely helpless... If I am wrong about this,
 > please, PLEASE, somebody tell me before my next free Friday night, or
 > I might just create a support library to handle this.
 > 
 >    BTW: How does one go about suggesting to the powers that be that this
 > might be a good addition to Xlib. [for ex. XReCreateWindow(Display *, XID)]

Sorry I wasn't on xpert when you sent your original message.  As a former
server implementer, I know that the number of bits available to a particular
client are server-dependant.  During connection setup, the server tells the
client how many bits are available (see page 101 of the X11R4 protocol
specification) as well as other server specific information.  On the MIT sample
server running on a Sun, I see 22 bits for each client.  If the client
allocates 1 resource every second, it will run out of resource bits in 48.6
days.  I suppose you could create a specific server to give you more bits, to
work around the problem.  The following table, shows that 25 bits should be
enough, but you will only be able to have at most 128 clients.

	Power    2**Power Num clients   sec/day      Days     Years
	22        4194304        1024  86400.00     48.55    0.1329
	23        8388608         512               97.09    0.2658
	24       16777216         256              194.18    0.5316
	25       33554432         128              388.36    1.0633
	26       67108864          64              776.72    2.1266
	27      134217728          32             1553.45    4.2531
	28      268435456          16             3106.89    8.5062
	29      536870912           8             6213.78   17.0124
	30     1073741824           4            12427.57   34.0248
	31     2147483648           2            24855.13   68.0497

A better solution would be to have more smarts in the server to allocate
resource ids better.  A simple approach would be to have a bitmap which
indicates the allocated/free state of each resource.  With a 22 bit resource
id, this would be 512k bytes for each client.  The idea is that a long-running
client would request this feature so the server would need this table only for 
certain clients.

  -- tom, ekberg@aslss02.asl.dl.nec.com (x3503)