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raft-boltdb

This repository provides the raftboltdb package. The package exports the BoltStore which is an implementation of both a LogStore and StableStore.

It is meant to be used as a backend for the raft package here.

This implementation uses BoltDB. BoltDB is a simple key/value store implemented in pure Go, and inspired by LMDB.

Metrics

The raft-boldb library emits a number of metrics utilizing github.com/armon/go-metrics. Those metrics are detailed in the following table. One note is that the application which pulls in this library may add its own prefix to the metric names. For example within Consul, the metrics will be prefixed with consul..

Metric	Unit	Type	Description
`raft.boltdb.freelistBytes`	bytes	gauge	Represents the number of bytes necessary to encode the freelist metadata. When `raft_boltdb.NoFreelistSync` is set to `false` these metadata bytes must also be written to disk for each committed log.
`raft.boltdb.freePageBytes`	bytes	gauge	Represents the number of bytes of free space within the raft.db file.
`raft.boltdb.getLog`	ms	timer	Measures the amount of time spent reading logs from the db.
`raft.boltdb.logBatchSize`	bytes	sample	Measures the total size in bytes of logs being written to the db in a single batch.
`raft.boltdb.logsPerBatch`	logs	sample	Measures the number of logs being written per batch to the db.
`raft.boltdb.logSize`	bytes	sample	Measures the size of logs being written to the db.
`raft.boltdb.numFreePages`	pages	gauge	Represents the number of free pages within the raft.db file.
`raft.boltdb.numPendingPages`	pages	gauge	Represents the number of pending pages within the raft.db that will soon become free.
`raft.boltdb.openReadTxn`	transactions	gauge	Represents the number of open read transactions against the db
`raft.boltdb.storeLogs`	ms	timer	Measures the amount of time spent writing logs to the db.
`raft.boltdb.totalReadTxn`	transactions	gauge	Represents the total number of started read transactions against the db
`raft.boltdb.txstats.cursorCount`	cursors	counter	Counts the number of cursors created since Consul was started.
`raft.boltdb.txstats.nodeCount`	allocations	counter	Counts the number of node allocations within the db since Consul was started.
`raft.boltdb.txstats.nodeDeref`	dereferences	counter	Counts the number of node dereferences in the db since Consul was started.
`raft.boltdb.txstats.pageAlloc`	bytes	gauge	Represents the number of bytes allocated within the db since Consul was started. Note that this does not take into account space having been freed and reused. In that case, the value of this metric will still increase.
`raft.boltdb.txstats.pageCount`	pages	gauge	Represents the number of pages allocated since Consul was started. Note that this does not take into account space having been freed and reused. In that case, the value of this metric will still increase.
`raft.boltdb.txstats.rebalance`	rebalances	counter	Counts the number of node rebalances performed in the db since Consul was started.
`raft.boltdb.txstats.rebalanceTime`	ms	timer	Measures the time spent rebalancing nodes in the db.
`raft.boltdb.txstats.spill`	spills	counter	Counts the number of nodes spilled in the db since Consul was started.
`raft.boltdb.txstats.spillTime`	ms	timer	Measures the time spent spilling nodes in the db.
`raft.boltdb.txstats.split`	splits	counter	Counts the number of nodes split in the db since Consul was started.
`raft.boltdb.txstats.write`	writes	counter	Counts the number of writes to the db since Consul was started.
`raft.boltdb.txstats.writeTime`	ms	timer	Measures the amount of time spent performing writes to the db.
`raft.boltdb.writeCapacity`	logs/second	sample	Theoretical write capacity in terms of the number of logs that can be written per second. Each sample outputs what the capacity would be if future batched log write operations were similar to this one. This similarity encompasses 4 things: batch size, byte size, disk performance and boltdb performance. While none of these will be static and its highly likely individual samples of this metric will vary, aggregating this metric over a larger time window should provide a decent picture into how this BoltDB store can perform