June 2001
Intermediate to advanced
320 pages
9h 18m
English
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Message Format
A Cache Digest message consists of a fixed 128-octet header (see Figure E-3 followed by a variable-sized Bloom filter. The header definitions are as follows:
Figure E-3. Cache Digest header
- CURRENT
This is the version number of the digest. The CURRENT version number is incremented whenever a significant feature is added to the Cache Digest protocol. When the digest recipient decodes a message, the CURRENT value indicates which protocol features are included.
- REQUIRED
This is the minimum version number required to correctly interpret the digest message. In other words, this specifies the last version this message is backward-compatible with. It can also be used to “eliminate” serious bugs. If a bug is found with the Version X implementation, a sender can set the REQUIRED value to X+1. Then, all buggy implementations that support only Version X are forced to ignore the cache digest message.
- CAPACITY
This is an estimate of the number of objects for which the digest was built. It is in the header for informational purposes only. A digest user does not need to know the CAPACITY to decode the digest.
- COUNT
This is the actual number of objects encoded by this digest. It may be larger or smaller than CAPACITY. This value also is not needed to decode the digest.
- DEL_COUNT
This is a counter that tracks the number of objects removed from the cache since the digest was last created. ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.