The storer interface isn't necessary if the init/Free logic is
removed, which is unnecessary in a world with only one shard.
Additionally, there were some cases where an init/Free call could
race and cause data loss in the cache. Not doing it at all fixes
all of those races.
This commit adds a new Cache option, via the
`tsm1.CacheConfig.SnapshotAgeDuration` field, which controls the maximum
age the cache can reach before it is snapshotted to a TSM file.
The default value for this option is `0`, which means that the cache
will never be snapshotted based only on age. Setting this value to, for
example, 10 seconds, would result in the cache snapshotting every 10
seconds.
Snapshotting the cache more frequently can provide better durability
guarantees in some circumstances, though more, smaller TSM files will
lead to more work needed to compact them down to larger, more dense
files.
When using InfluxDB with a WAL there isn't really a strong reason to
alter `tsm1.CacheConfig.SnapshotAgeDuration` from `0`.
Because the WAL relies on the tsm1.Value type, we move that into its own
tsm1/value package and set up some aliases forwarding them into tsm1. This
also required adding some methods and changing consumers to avoid the
unexported fields. I imagine this step will be useful one day when we make
the write path more efficient with respect to consuming points.
This commit additionally fixes some issues with generation. The iterator.tmpldata
and generation for array_cursor_* were removed accidentally when removing
iterators, making those generated files stale. Restore that and regenerate.
No change in functionality.
I did this with a dumb editor macro, so some comments changed too.
Also rename root package from platform to influxdb.
In interest of minimizing risk, anyone importing the root package has
now aliased it to "platform" so that no changes beyond imports were
necessary in those files.
Lastly, replace the old platform module to local path /dev/null so that
nobody can accidentally reintroduce a platform dependency while
migrating platform code to influxdb.
Jeff Wendling
Edd Robinson
Mark Rushakoff
Jeff Wendling
Chris Goller