This commit changes the backup format of a fragment from a
simple file stream to a tar archive which combines the data file
and the cache file.
Fixes#63
This commit refactors the profile and bitmap attribute stores so
that they share the same code. There is a new `AttrStore` which
associates key/value pairs with a `uint64` identifier.
The previous JSON encoding has been fixed to use protobufs which
fixes encoding issues for int64.
This commit adds the ability of the Fragment to flush the cache
bitmap IDs to disk periodically. They can then be reloaded when
the fragment is reopened.
This commit attaches the mmap-backed roaring bitmaps as storage
to the fragments. Currently snapshotting is not supported from
Pilosa so the WAL will grow indefinitely, however, it is not a
difficult change to make.
This commit refactors the pilosa codebase. It makes several major
changes:
* Removes bitmap handles
* Removes dispatch/hold/transport
* Removes etcd dependency
* Adds consistent hash ring for slice placement
* Refactors parser/lexer
* Adds strong typing to PQL AST
* Flattens package hierarchy
