This commit changes the fragment allocation algorithm in the cluster
to make use of the `DB` name. This allows each database to use a
different slice distribution.
Initially, the `frame` was going to be used for allocation, however,
this was problematic since queries can span multiple frames so it's
impossible to choose a single frame to use.
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 adds a simple benchmarking utility to the `pilosactl`
binary. It currently only supports individual `SetBit()` commands
but it's a good start towards making a generic benchmarking
framework at the integration level.
The subcommands and usage/help messages were also cleaned up to
output correctly.
This commit adds an endpoint to restore an entire frame from
another cluster. Multiple hosts can use this endpoint to copy
and rebalance a cluster to a new cluster.
This commit adds two commands:
pilosactl backup
pilosactl restore
The `Client` implementations have also been added to support these
commands:
func (c *Client) BackupTo(w io.Writer, db, frame string) error
func (c *Client) RestoreFrom(r io.Reader, db, frame string) error
Backups occur on a per-frame basis and all slices from the cluster
are packed into a single tar file. The backup tool attempts to
read from owner nodes in a random order and will retry against
the next owner if one fails.
During restore, the slices are restored to all owner nodes. This
allows users to backup a frame from one cluster and restore it
to a different one -- even if the topology of the new cluster is
different.
This commit fixes the `pilosactl import` command to import data files
across an entire cluster of machines.
A `pilosactl config` command is also added to provide a default config.
