mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-11-27 02:46:47 +01:00
411 lines
9.5 KiB
Go
411 lines
9.5 KiB
Go
package blockcache
|
|
|
|
import (
|
|
"container/heap"
|
|
"sync"
|
|
"sync/atomic"
|
|
"time"
|
|
"unsafe"
|
|
|
|
"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
|
|
"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
|
|
"github.com/cespare/xxhash/v2"
|
|
)
|
|
|
|
// Cache caches Block entries.
|
|
//
|
|
// Call NewCache() for creating new Cache.
|
|
type Cache struct {
|
|
shards []*cache
|
|
|
|
cleanerMustStopCh chan struct{}
|
|
cleanerStoppedCh chan struct{}
|
|
}
|
|
|
|
// NewCache creates new cache.
|
|
//
|
|
// Cache size in bytes is limited by the value returned by getMaxSizeBytes() callback.
|
|
// Call MustStop() in order to free up resources occupied by Cache.
|
|
func NewCache(getMaxSizeBytes func() int) *Cache {
|
|
cpusCount := cgroup.AvailableCPUs()
|
|
shardsCount := cgroup.AvailableCPUs()
|
|
// Increase the number of shards with the increased number of available CPU cores.
|
|
// This should reduce contention on per-shard mutexes.
|
|
multiplier := cpusCount
|
|
if multiplier > 16 {
|
|
multiplier = 16
|
|
}
|
|
shardsCount *= multiplier
|
|
shards := make([]*cache, shardsCount)
|
|
getMaxShardBytes := func() int {
|
|
n := getMaxSizeBytes()
|
|
return n / shardsCount
|
|
}
|
|
for i := range shards {
|
|
shards[i] = newCache(getMaxShardBytes)
|
|
}
|
|
c := &Cache{
|
|
shards: shards,
|
|
cleanerMustStopCh: make(chan struct{}),
|
|
cleanerStoppedCh: make(chan struct{}),
|
|
}
|
|
go c.cleaner()
|
|
return c
|
|
}
|
|
|
|
// MustStop frees up resources occupied by c.
|
|
func (c *Cache) MustStop() {
|
|
close(c.cleanerMustStopCh)
|
|
<-c.cleanerStoppedCh
|
|
}
|
|
|
|
// RemoveBlocksForPart removes all the blocks for the given part from the cache.
|
|
func (c *Cache) RemoveBlocksForPart(p interface{}) {
|
|
for _, shard := range c.shards {
|
|
shard.RemoveBlocksForPart(p)
|
|
}
|
|
}
|
|
|
|
// GetBlock returns a block for the given key k from c.
|
|
func (c *Cache) GetBlock(k Key) Block {
|
|
idx := uint64(0)
|
|
if len(c.shards) > 1 {
|
|
h := k.hashUint64()
|
|
idx = h % uint64(len(c.shards))
|
|
}
|
|
shard := c.shards[idx]
|
|
return shard.GetBlock(k)
|
|
}
|
|
|
|
// PutBlock puts the given block b under the given key k into c.
|
|
func (c *Cache) PutBlock(k Key, b Block) {
|
|
idx := uint64(0)
|
|
if len(c.shards) > 1 {
|
|
h := k.hashUint64()
|
|
idx = h % uint64(len(c.shards))
|
|
}
|
|
shard := c.shards[idx]
|
|
shard.PutBlock(k, b)
|
|
}
|
|
|
|
// Len returns the number of blocks in the cache c.
|
|
func (c *Cache) Len() int {
|
|
n := 0
|
|
for _, shard := range c.shards {
|
|
n += shard.Len()
|
|
}
|
|
return n
|
|
}
|
|
|
|
// SizeBytes returns an approximate size in bytes of all the blocks stored in the cache c.
|
|
func (c *Cache) SizeBytes() int {
|
|
n := 0
|
|
for _, shard := range c.shards {
|
|
n += shard.SizeBytes()
|
|
}
|
|
return n
|
|
}
|
|
|
|
// SizeMaxBytes returns the max allowed size in bytes for c.
|
|
func (c *Cache) SizeMaxBytes() int {
|
|
n := 0
|
|
for _, shard := range c.shards {
|
|
n += shard.SizeMaxBytes()
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Requests returns the number of requests served by c.
|
|
func (c *Cache) Requests() uint64 {
|
|
n := uint64(0)
|
|
for _, shard := range c.shards {
|
|
n += shard.Requests()
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Misses returns the number of cache misses for c.
|
|
func (c *Cache) Misses() uint64 {
|
|
n := uint64(0)
|
|
for _, shard := range c.shards {
|
|
n += shard.Misses()
|
|
}
|
|
return n
|
|
}
|
|
|
|
func (c *Cache) cleaner() {
|
|
ticker := time.NewTicker(57 * time.Second)
|
|
defer ticker.Stop()
|
|
perKeyMissesTicker := time.NewTicker(3 * time.Minute)
|
|
defer perKeyMissesTicker.Stop()
|
|
for {
|
|
select {
|
|
case <-c.cleanerMustStopCh:
|
|
close(c.cleanerStoppedCh)
|
|
return
|
|
case <-ticker.C:
|
|
c.cleanByTimeout()
|
|
case <-perKeyMissesTicker.C:
|
|
c.cleanPerKeyMisses()
|
|
}
|
|
}
|
|
}
|
|
|
|
func (c *Cache) cleanByTimeout() {
|
|
for _, shard := range c.shards {
|
|
shard.cleanByTimeout()
|
|
}
|
|
}
|
|
|
|
func (c *Cache) cleanPerKeyMisses() {
|
|
for _, shard := range c.shards {
|
|
shard.cleanPerKeyMisses()
|
|
}
|
|
}
|
|
|
|
type cache struct {
|
|
// Atomically updated fields must go first in the struct, so they are properly
|
|
// aligned to 8 bytes on 32-bit architectures.
|
|
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/212
|
|
requests uint64
|
|
misses uint64
|
|
|
|
// sizeBytes contains an approximate size for all the blocks stored in the cache.
|
|
sizeBytes int64
|
|
|
|
// getMaxSizeBytes() is a callback, which returns the maximum allowed cache size in bytes.
|
|
getMaxSizeBytes func() int
|
|
|
|
// mu protects all the fields below.
|
|
mu sync.Mutex
|
|
|
|
// m contains cached blocks keyed by Key.Part and then by Key.Offset
|
|
m map[interface{}]map[uint64]*cacheEntry
|
|
|
|
// perKeyMisses contains per-block cache misses.
|
|
//
|
|
// Blocks with less than 2 cache misses aren't stored in the cache in order to prevent from eviction for frequently accessed items.
|
|
perKeyMisses map[Key]int
|
|
|
|
// The heap for removing the least recently used entries from m.
|
|
lah lastAccessHeap
|
|
}
|
|
|
|
// Key represents a key, which uniquely identifies the Block.
|
|
type Key struct {
|
|
// Part must contain a pointer to part structure where the block belongs to.
|
|
Part interface{}
|
|
|
|
// Offset is the offset of the block in the part.
|
|
Offset uint64
|
|
}
|
|
|
|
func (k *Key) hashUint64() uint64 {
|
|
buf := (*[unsafe.Sizeof(*k)]byte)(unsafe.Pointer(k))
|
|
return xxhash.Sum64(buf[:])
|
|
}
|
|
|
|
// Block is an item, which may be cached in the Cache.
|
|
type Block interface {
|
|
// SizeBytes must return the approximate size of the given block in bytes
|
|
SizeBytes() int
|
|
}
|
|
|
|
type cacheEntry struct {
|
|
// The timestamp in seconds for the last access to the given entry.
|
|
lastAccessTime uint64
|
|
|
|
// heapIdx is the index for the entry in lastAccessHeap.
|
|
heapIdx int
|
|
|
|
// k contains the associated key for the given block.
|
|
k Key
|
|
|
|
// b contains the cached block.
|
|
b Block
|
|
}
|
|
|
|
func newCache(getMaxSizeBytes func() int) *cache {
|
|
var c cache
|
|
c.getMaxSizeBytes = getMaxSizeBytes
|
|
c.m = make(map[interface{}]map[uint64]*cacheEntry)
|
|
c.perKeyMisses = make(map[Key]int)
|
|
return &c
|
|
}
|
|
|
|
func (c *cache) RemoveBlocksForPart(p interface{}) {
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
|
|
sizeBytes := 0
|
|
for _, e := range c.m[p] {
|
|
sizeBytes += e.b.SizeBytes()
|
|
heap.Remove(&c.lah, e.heapIdx)
|
|
// do not delete the entry from c.perKeyMisses, since it is removed by cache.cleaner later.
|
|
}
|
|
c.updateSizeBytes(-sizeBytes)
|
|
delete(c.m, p)
|
|
}
|
|
|
|
func (c *cache) updateSizeBytes(n int) {
|
|
atomic.AddInt64(&c.sizeBytes, int64(n))
|
|
}
|
|
|
|
func (c *cache) cleanPerKeyMisses() {
|
|
c.mu.Lock()
|
|
c.perKeyMisses = make(map[Key]int, len(c.perKeyMisses))
|
|
c.mu.Unlock()
|
|
}
|
|
|
|
func (c *cache) cleanByTimeout() {
|
|
// Delete items accessed more than three minutes ago.
|
|
// This time should be enough for repeated queries.
|
|
lastAccessTime := fasttime.UnixTimestamp() - 3*60
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
|
|
for len(c.lah) > 0 {
|
|
if lastAccessTime < c.lah[0].lastAccessTime {
|
|
break
|
|
}
|
|
c.removeLeastRecentlyAccessedItem()
|
|
}
|
|
}
|
|
|
|
func (c *cache) GetBlock(k Key) Block {
|
|
atomic.AddUint64(&c.requests, 1)
|
|
var e *cacheEntry
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
|
|
pes := c.m[k.Part]
|
|
if pes != nil {
|
|
e = pes[k.Offset]
|
|
if e != nil {
|
|
// Fast path - the block already exists in the cache, so return it to the caller.
|
|
currentTime := fasttime.UnixTimestamp()
|
|
if e.lastAccessTime != currentTime {
|
|
e.lastAccessTime = currentTime
|
|
heap.Fix(&c.lah, e.heapIdx)
|
|
}
|
|
return e.b
|
|
}
|
|
}
|
|
// Slow path - the entry is missing in the cache.
|
|
c.perKeyMisses[k]++
|
|
atomic.AddUint64(&c.misses, 1)
|
|
return nil
|
|
}
|
|
|
|
func (c *cache) PutBlock(k Key, b Block) {
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
// If the entry wasn't accessed yet (e.g. c.perKeyMisses[k] == 0), then cache it, since it is likely it will be accessed soon.
|
|
// Do not cache the entry only if there was only a single unsuccessful attempt to access it.
|
|
// This may be one-time-wonders entry, which won't be accessed more, so there is no need in caching it.
|
|
doNotCache := c.perKeyMisses[k] == 1
|
|
if doNotCache {
|
|
// Do not cache b if it has been requested only once (aka one-time-wonders items).
|
|
// This should reduce memory usage for the cache.
|
|
return
|
|
}
|
|
|
|
// Store b in the cache.
|
|
pes := c.m[k.Part]
|
|
if pes == nil {
|
|
pes = make(map[uint64]*cacheEntry)
|
|
c.m[k.Part] = pes
|
|
} else if pes[k.Offset] != nil {
|
|
// The block has been already registered by concurrent goroutine.
|
|
return
|
|
}
|
|
e := &cacheEntry{
|
|
lastAccessTime: fasttime.UnixTimestamp(),
|
|
k: k,
|
|
b: b,
|
|
}
|
|
heap.Push(&c.lah, e)
|
|
pes[k.Offset] = e
|
|
c.updateSizeBytes(e.b.SizeBytes())
|
|
maxSizeBytes := c.getMaxSizeBytes()
|
|
for c.SizeBytes() > maxSizeBytes && len(c.lah) > 0 {
|
|
c.removeLeastRecentlyAccessedItem()
|
|
}
|
|
}
|
|
|
|
func (c *cache) removeLeastRecentlyAccessedItem() {
|
|
e := c.lah[0]
|
|
c.updateSizeBytes(-e.b.SizeBytes())
|
|
p := e.k.Part
|
|
pes := c.m[p]
|
|
delete(pes, e.k.Offset)
|
|
if len(pes) == 0 {
|
|
// Remove reference to p from c.m in order to free up memory occupied by p.
|
|
delete(c.m, p)
|
|
}
|
|
heap.Pop(&c.lah)
|
|
}
|
|
|
|
func (c *cache) Len() int {
|
|
c.mu.Lock()
|
|
defer c.mu.Unlock()
|
|
|
|
n := 0
|
|
for _, m := range c.m {
|
|
n += len(m)
|
|
}
|
|
return n
|
|
}
|
|
|
|
func (c *cache) SizeBytes() int {
|
|
return int(atomic.LoadInt64(&c.sizeBytes))
|
|
}
|
|
|
|
func (c *cache) SizeMaxBytes() int {
|
|
return c.getMaxSizeBytes()
|
|
}
|
|
|
|
func (c *cache) Requests() uint64 {
|
|
return atomic.LoadUint64(&c.requests)
|
|
}
|
|
|
|
func (c *cache) Misses() uint64 {
|
|
return atomic.LoadUint64(&c.misses)
|
|
}
|
|
|
|
// lastAccessHeap implements heap.Interface
|
|
type lastAccessHeap []*cacheEntry
|
|
|
|
func (lah *lastAccessHeap) Len() int {
|
|
return len(*lah)
|
|
}
|
|
func (lah *lastAccessHeap) Swap(i, j int) {
|
|
h := *lah
|
|
a := h[i]
|
|
b := h[j]
|
|
a.heapIdx = j
|
|
b.heapIdx = i
|
|
h[i] = b
|
|
h[j] = a
|
|
}
|
|
func (lah *lastAccessHeap) Less(i, j int) bool {
|
|
h := *lah
|
|
return h[i].lastAccessTime < h[j].lastAccessTime
|
|
}
|
|
func (lah *lastAccessHeap) Push(x interface{}) {
|
|
e := x.(*cacheEntry)
|
|
h := *lah
|
|
e.heapIdx = len(h)
|
|
*lah = append(h, e)
|
|
}
|
|
func (lah *lastAccessHeap) Pop() interface{} {
|
|
h := *lah
|
|
e := h[len(h)-1]
|
|
|
|
// Remove the reference to deleted entry, so Go GC could free up memory occupied by the deleted entry.
|
|
h[len(h)-1] = nil
|
|
|
|
*lah = h[:len(h)-1]
|
|
return e
|
|
}
|