[asterisk-dev] [Code Review] Optimizations to the stringfields API

[Kevin Fleming]

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http://reviewboard.digium.com/r/165/
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(Updated 2009-02-17 19:46:36.635940)


Review request for Asterisk Developers.


Changes
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Addressed Mark's comments, added some minor optimizations, and changed the way the constant 'empty' string is defined to make it more obvious how it is setup.


Summary
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This patch provides a number of optimizations to the stringfields API, focused around saving (not wasting) memory whenever possible. Thanks to Mark Michelson for inspiring this work and coming up with the first two optimizations that are represented here:

Changes:

- Cleanup of some code, fix incorrect doxygen comments

- When a field is emptied or replaced with a new allocation, decrease the amount of 'active' space in the pool it was held in; if that pool reaches zero active space, and is not the current pool, then free it as it is no longer in use

- When allocating a pool, try to allocate a size that will fit in a 'standard' malloc() allocation without wasting space

- When allocating space for a field, store the amount of space in the two bytes immediately preceding the field; this eliminates the need to call strlen() on the field when overwriting it, and more importantly it 'remembers' the amount of space the field has available, even if a shorter string has been stored in it since it was allocated

- Don't automatically double the size of each successive pool allocated; it's wasteful


Diffs (updated)
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  /trunk/include/asterisk/stringfields.h 176840 
  /trunk/main/utils.c 176840 

Diff: http://reviewboard.digium.com/r/165/diff


Testing
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Compile testing only, so far.


Thanks,

Kevin