Push ftruncate operations down through the diskmgr into the i/o pool.
Fixes a problem with conflict detection in the case of multiple resize operations being queued/active at the same time.
Merge branch 'next' into daniel_265
Merge branch 'next' into daniel_265
Changed resize conflict-resolution logic. I think it's more robust now.
Wrote unit tests for resizing conflict resolution.
Fix oversights after refactoring.
adding alt_cache_balancer_t to automatically balance cache sizes across tables and shards, not yet integrated
integrating cache rebalancing throughout the stack
fixing code review comments
Restart read-ahead if the cache size has been increased and the cache isn't full yet.
removing cache config, adding a dummy cache balancer, and making cache balancer mandatory
removing cache_size from drivers and polyglot tests
Merge branch 'next' into grey_issue_97
Merge branch 'daniel_issue_97_read_ahead' into grey_issue_97
code review fixed for cache balancer
code review fixed for cache balancer
Merge branch 'grey_issue_97' of github.com:rethinkdb/rethinkdb into grey_issue_97
tweaking cache rebalance algorithm, updated spin_up_cluster to specify cache-size
adding warning when cache is overcommitted