Performance improvements for gearmand_ready and gearman_server_function_get

[Keyur]

This patch addresses 2 hotspots we've detected. We have ~2000 worker processes connecting a gearmand server and processing ~500 jobs/sec.

1) gearmand_ready: a very tight loop that burns CPU. The attached patch creates a new list (ready_con_list) on the connection_list object that is just for "ready" connections. I also changed the "con_list" to use the macros GEARMAN_LIST_ADD/DEL. Deprecated the use of GEARMAND_CON_READY as I didn't find any real use for it.

2) gearman_server_function_get: changed the function_list to a hash table. Increased the default hash table buckets to 991. In text.cc, the majority of 'changes' are just white-space.

Both of these combined dropped user CPU use by ~50%.

[Brian Aker (brianaker)]

Would you mind applying this to 1.0.3 instead of 1.0.2?

Thanks

[Keyur (keyurdg)]

Done. Attached.