code review 114050043: ogle/program/server: do less I/O when printing maps

ogle/program/server: do less I/O when printing maps
The buckets are stored in contiguous blocks of memory preceded by a header.
Introduce a cache so the entire structure can be read once in the typical
case, with printValueAt using the cache to print values in the bucket.
If the structure is a map of maps, the code will still work but
only the innermost map will exploit the cache well.
That's a rare case anyway, and no worse than the current situation.

[r, 2014-07-17 19:26:38]

Hello nigeltao,

I'd like you to review this change to
https://code.google.com/p/ogle

[nigeltao, 2014-07-21 07:31:29]

LGTM.

https://codereview.appspot.com/114050043/diff/1/program/server/print.go
File program/server/print.go (right):

https://codereview.appspot.com/114050043/diff/1/program/server/print.go#newco...
program/server/print.go:91: p.cache = p.cache[0:0]
You can drop the first "0".

https://codereview.appspot.com/114050043/diff/1/program/server/print.go#newco...
program/server/print.go:396: copy(tophash[:], p.cache)
You could be defensive here and say

if copy(etc) != bucketCnt {
  return // or panic??
}

[r, 2014-07-29 16:50:48]

*** Submitted as https://code.google.com/p/ogle/source/detail?r=a875c179a54f ***

ogle/program/server: do less I/O when printing maps
The buckets are stored in contiguous blocks of memory preceded by a header.
Introduce a cache so the entire structure can be read once in the typical
case, with printValueAt using the cache to print values in the bucket.
If the structure is a map of maps, the code will still work but
only the innermost map will exploit the cache well.
That's a rare case anyway, and no worse than the current situation.

LGTM=nigeltao
R=nigeltao
https://codereview.appspot.com/114050043