prometheus/storage/metric/watermark.go
2013-06-25 15:52:42 +02:00

165 lines
3.5 KiB
Go

// Copyright 2013 Prometheus Team
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package metric
import (
"container/list"
"sync"
"time"
"code.google.com/p/goprotobuf/proto"
clientmodel "github.com/prometheus/client_golang/model"
dto "github.com/prometheus/prometheus/model/generated"
)
// unsafe.Sizeof(watermarks{})
const elementSize = 24
type Bytes uint64
// WatermarkCache is a thread-safe LRU cache for fingerprint watermark
// state.
type WatermarkCache struct {
mu sync.Mutex
list *list.List
table map[clientmodel.Fingerprint]*list.Element
size Bytes
allowance Bytes
}
type watermarks struct {
High time.Time
}
func (w *watermarks) load(d *dto.MetricHighWatermark) {
w.High = time.Unix(d.GetTimestamp(), 0).UTC()
}
func (w *watermarks) dump(d *dto.MetricHighWatermark) {
d.Reset()
d.Timestamp = proto.Int64(w.High.Unix())
}
type entry struct {
fingerprint *clientmodel.Fingerprint
watermarks *watermarks
accessed time.Time
}
func NewWatermarkCache(allowance Bytes) *WatermarkCache {
return &WatermarkCache{
list: list.New(),
table: map[clientmodel.Fingerprint]*list.Element{},
allowance: allowance,
}
}
func (lru *WatermarkCache) Get(f *clientmodel.Fingerprint) (v *watermarks, ok bool) {
lru.mu.Lock()
defer lru.mu.Unlock()
element, ok := lru.table[*f]
if !ok {
return nil, false
}
lru.moveToFront(element)
return element.Value.(*entry).watermarks, true
}
func (lru *WatermarkCache) Set(f *clientmodel.Fingerprint, w *watermarks) {
lru.mu.Lock()
defer lru.mu.Unlock()
if element, ok := lru.table[*f]; ok {
lru.updateInplace(element, w)
} else {
lru.addNew(f, w)
}
}
func (lru *WatermarkCache) SetIfAbsent(f *clientmodel.Fingerprint, w *watermarks) {
lru.mu.Lock()
defer lru.mu.Unlock()
if element, ok := lru.table[*f]; ok {
lru.moveToFront(element)
} else {
lru.addNew(f, w)
}
}
func (lru *WatermarkCache) Delete(f *clientmodel.Fingerprint) bool {
lru.mu.Lock()
defer lru.mu.Unlock()
element, ok := lru.table[*f]
if !ok {
return false
}
lru.list.Remove(element)
delete(lru.table, *f)
lru.size -= elementSize
return true
}
func (lru *WatermarkCache) Clear() {
lru.mu.Lock()
defer lru.mu.Unlock()
lru.list.Init()
lru.table = map[clientmodel.Fingerprint]*list.Element{}
lru.size = 0
}
func (lru *WatermarkCache) updateInplace(e *list.Element, w *watermarks) {
e.Value.(*entry).watermarks = w
lru.moveToFront(e)
lru.checkCapacity()
}
func (lru *WatermarkCache) moveToFront(e *list.Element) {
lru.list.MoveToFront(e)
e.Value.(*entry).accessed = time.Now()
}
func (lru *WatermarkCache) addNew(f *clientmodel.Fingerprint, w *watermarks) {
lru.table[*f] = lru.list.PushFront(&entry{
fingerprint: f,
watermarks: w,
accessed: time.Now(),
})
lru.size += elementSize
lru.checkCapacity()
}
func (lru *WatermarkCache) checkCapacity() {
for lru.size > lru.allowance {
delElem := lru.list.Back()
delWatermarks := delElem.Value.(*entry)
lru.list.Remove(delElem)
delete(lru.table, *delWatermarks.fingerprint)
lru.size -= elementSize
}
}