Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( IOBuckets = prometheus.ExponentialBucketsRange(float64(time.Millisecond*1), float64(10*time.Second), 50) ChannelWriteBuckets = prometheus.ExponentialBucketsRange(float64(time.Microsecond*1), float64(10*time.Second), 50) )
Exported to enable exporting from package pebble to enable exporting metrics with below buckets in CRDB.
Functions ¶
This section is empty.
Types ¶
type Cache ¶
type Cache struct {
// contains filtered or unexported fields
}
Cache is a persistent cache backed by a local filesystem. It is intended to cache data that is in slower shared storage (e.g. S3), hence the package name 'sharedcache'.
func Open ¶
func Open( fs vfs.FS, logger base.Logger, fsDir string, blockSize int, shardingBlockSize int64, sizeBytes int64, numShards int, ) (*Cache, error)
Open opens a cache. If there is no existing cache at fsDir, a new one is created.
func (*Cache) Close ¶
Close closes the cache. Methods such as ReadAt should not be called after Close is called.
type Metrics ¶
type Metrics struct {
// The number of sstable bytes stored in the cache.
Size int64
// The count of cache blocks in the cache (not sstable blocks).
Count int64
// The number of calls to ReadAt.
TotalReads int64
// The number of calls to ReadAt that require reading data from 2+ shards.
MultiShardReads int64
// The number of calls to ReadAt that require reading data from 2+ cache blocks.
MultiBlockReads int64
// The number of calls to ReadAt where all data returned was read from the cache.
ReadsWithFullHit int64
// The number of calls to ReadAt where some data returned was read from the cache.
ReadsWithPartialHit int64
// The number of calls to ReadAt where no data returned was read from the cache.
ReadsWithNoHit int64
// The number of times a cache block was evicted from the cache.
Evictions int64
// The number of times writing a cache block to the cache failed.
WriteBackFailures int64
// The latency of calls to get some data from the cache.
GetLatency prometheus.Histogram
// The latency of reads of a single cache block from disk.
DiskReadLatency prometheus.Histogram
// The latency of writing data to write back to the cache to a channel.
// Generally should be low, but if the channel is full, could be high.
QueuePutLatency prometheus.Histogram
// The latency of calls to put some data read from block storage into the cache.
PutLatency prometheus.Histogram
// The latency of writes of a single cache block to disk.
DiskWriteLatency prometheus.Histogram
}
Metrics is a struct containing metrics exported by the secondary cache. TODO(josh): Reconsider the set of metrics exported by the secondary cache before we release the secondary cache to users. We choose to export many metrics right now, so we learn a lot from the benchmarking we are doing over the 23.2 cycle.
Source Files