This commit refactors the anti-entropy system to fetch data from
all replicated blocks and only set/clear bits which deviate from
the consensus between all blocks.
An example of this is if 3 nodes had the following bits set for
a single bitmap:
Node A: 1 2 3
Node B: 2 4
Node C: 1 2 4
Then only bits which are set on a majority will be set. In this
case bits 1, 2, & 4 are set but 3 only exists on a single node.
The node performing the merge would then determine the following
set/clear diffs for each node:
Node A: clear(3), set(4)
Node B: set(1)
Node C: none
Once the merge is performed and all nodes receive their diff
instructions then the nodes will be in sync:
Node A: 1 2 4
Node B: 1 2 4
Node C: 1 2 4
There still exists situations where bits can be reset. If Node A
is up and Node B & C are down then Node A's bits will be reset
once B & C come back online. We should add write consistency
settings for incoming writes so that we can ensure that a quorum
is written to before returning a success. This is outside the
scope of this commit though.
This commit changes the `pql.Query` so that it can accept one or more
top-level calls instead of only one.
The query request format change because a query with a single call is
still valid. However, the result format now returns a `results` field
that has one result for each top-level call. The `profiles` field is
still the same, however, it combines all profiles from all bitmap
responses into one return so that there's not duplicate attributes.
Fixes#59
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 adds the ability to set string, integer, and boolean
values on bitmaps and profiles within Pilosa. Bitmap attributes
are automatically returned when making a `Bitmap()` call. Profile
attributes must be requested by setting `profile=true` in the
URL.
The function names have also been renamed to initial caps so that
the PQL query language can support math operations in the future.
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
