mirror of
https://github.com/ClusterCockpit/cc-metric-store.git
synced 2025-09-17 22:14:31 +02:00
New unfinished MemoryStore implementation
This commit is contained in:
Lou Knauer
275
memstore.go
Normal file
275
memstore.go
Normal file
@@ -0,0 +1,275 @@
|
||||
package main
|
||||
|
||||
import (
|
||||
"errors"
|
||||
"sync"
|
||||
)
|
||||
|
||||
// Default buffer capacity.
|
||||
// `buffer.data` will only ever grow up to it's capacity and a new link
|
||||
// in the buffer chain will be created if needed so that no copying
|
||||
// of needs to happen on writes.
|
||||
const (
|
||||
BUFFER_CAP int = 1024
|
||||
)
|
||||
|
||||
// So that we can reuse allocations
|
||||
var bufferPool sync.Pool = sync.Pool{
|
||||
New: func() interface{} {
|
||||
return make([]Float, 0, BUFFER_CAP)
|
||||
},
|
||||
}
|
||||
|
||||
// Each metric on each level has it's own buffer.
|
||||
// This is where the actual values go.
|
||||
type buffer struct {
|
||||
frequency int64 // Time between two "slots"
|
||||
start int64 // Timestamp of when `data[0]` was written.
|
||||
data []Float // The slice should never reallocacte as `cap(data)` is respected.
|
||||
prev, next *buffer // `prev` contains older data, `next` newer data.
|
||||
}
|
||||
|
||||
func newBuffer(ts, freq int64) *buffer {
|
||||
return &buffer{
|
||||
frequency: freq,
|
||||
start: ts,
|
||||
data: bufferPool.Get().([]Float)[:0],
|
||||
prev: nil,
|
||||
next: nil,
|
||||
}
|
||||
}
|
||||
|
||||
// If a new buffer was created, the new head is returnd.
|
||||
// Otherwise, the existing buffer is returnd.
|
||||
func (b *buffer) write(ts int64, value Float) (*buffer, error) {
|
||||
if ts < b.start {
|
||||
return nil, errors.New("cannot write value to buffer from past")
|
||||
}
|
||||
|
||||
idx := int((ts - b.start) / b.frequency)
|
||||
if idx >= cap(b.data) {
|
||||
newbuf := newBuffer(ts, b.frequency)
|
||||
newbuf.prev = b
|
||||
b.next = newbuf
|
||||
b = newbuf
|
||||
idx = 0
|
||||
}
|
||||
|
||||
// Overwriting value or writing value from past
|
||||
if idx < len(b.data) {
|
||||
b.data[idx] = value
|
||||
return b, nil
|
||||
}
|
||||
|
||||
// Fill up unwritten slots with NaN
|
||||
for i := len(b.data); i < idx; i++ {
|
||||
b.data = append(b.data, NaN)
|
||||
}
|
||||
|
||||
b.data = append(b.data, value)
|
||||
return b, nil
|
||||
}
|
||||
|
||||
// Return all known values from `from` to `to`. Gaps of information are
|
||||
// represented by NaN. If values at the start or end are missing,
|
||||
// instead of NaN values, the second and thrid return values contain
|
||||
// the actual `from`/`to`.
|
||||
func (b *buffer) read(from, to int64) ([]Float, int64, int64, error) {
|
||||
if from < b.start {
|
||||
if b.prev != nil {
|
||||
return b.prev.read(from, to)
|
||||
}
|
||||
from = b.start
|
||||
}
|
||||
|
||||
data := make([]Float, 0, (to-from)/b.frequency+1)
|
||||
|
||||
var t int64
|
||||
for t = from; t < to; t += b.frequency {
|
||||
idx := int((t - b.start) / b.frequency)
|
||||
if idx >= cap(b.data) {
|
||||
b = b.next
|
||||
if b == nil {
|
||||
return data, from, t, nil
|
||||
}
|
||||
idx = 0
|
||||
}
|
||||
|
||||
if t < b.start || idx >= len(b.data) {
|
||||
data = append(data, NaN)
|
||||
} else {
|
||||
data = append(data, b.data[idx])
|
||||
}
|
||||
}
|
||||
|
||||
return data, from, t, nil
|
||||
}
|
||||
|
||||
// Could also be called "node" as this forms a node in a tree structure.
|
||||
// Called level because "node" might be confusing here.
|
||||
// Can be both a leaf or a inner node. In this structue, inner nodes can
|
||||
// also hold data (in `metrics`).
|
||||
type level struct {
|
||||
lock sync.Mutex // There is performance to be gained by having different locks for `metrics` and `children` (Spinlock?).
|
||||
metrics map[string]*buffer // Every level can store metrics.
|
||||
children map[string]*level // Sub-granularities/nodes. Use `sync.Map`?
|
||||
}
|
||||
|
||||
// Caution: the lock of the returned level will be LOCKED.
|
||||
// Find the correct level for the given selector, creating it if
|
||||
// it does not exist. Example selector in the context of the
|
||||
// ClusterCockpit could be: []string{ "emmy", "host123", "cpu", "0" }
|
||||
// This function would probably benefit a lot from `level.children` beeing a `sync.Map`?
|
||||
func (l *level) findLevelOrCreate(selector []string) *level {
|
||||
l.lock.Lock()
|
||||
if len(selector) == 0 {
|
||||
return l
|
||||
}
|
||||
|
||||
child, ok := l.children[selector[0]]
|
||||
if !ok {
|
||||
child = &level{
|
||||
metrics: make(map[string]*buffer),
|
||||
children: make(map[string]*level),
|
||||
}
|
||||
l.children[selector[0]] = child
|
||||
}
|
||||
|
||||
l.lock.Unlock()
|
||||
return child.findLevelOrCreate(selector[1:])
|
||||
}
|
||||
|
||||
// This function assmumes that `l.lock` is LOCKED!
|
||||
// Read `buffer.read` for context. This function does
|
||||
// a lot of short-lived allocations and copies if this is
|
||||
// not the "native" level for the requested metric. There
|
||||
// is a lot of optimization potential here!
|
||||
// Optimization suggestion: Pass a buffer as argument onto which the values should be added.
|
||||
func (l *level) read(metric string, from, to int64, accumulation string) ([]Float, int64, int64, error) {
|
||||
if b, ok := l.metrics[metric]; ok {
|
||||
// Whoo, this is the "native" level of this metric:
|
||||
return b.read(from, to)
|
||||
}
|
||||
|
||||
if len(l.children) == 0 {
|
||||
return nil, 0, 0, errors.New("no data for that metric/level")
|
||||
}
|
||||
|
||||
if len(l.children) == 1 {
|
||||
for _, child := range l.children {
|
||||
child.lock.Lock()
|
||||
data, from, to, err := child.read(metric, from, to, accumulation)
|
||||
child.lock.Unlock()
|
||||
return data, from, to, err
|
||||
}
|
||||
}
|
||||
|
||||
// "slow" case: We need to accumulate metrics accross levels/scopes/tags/whatever.
|
||||
var data []Float = nil
|
||||
for _, child := range l.children {
|
||||
child.lock.Lock()
|
||||
cdata, cfrom, cto, err := child.read(metric, from, to, accumulation)
|
||||
child.lock.Unlock()
|
||||
|
||||
if err != nil {
|
||||
return nil, 0, 0, err
|
||||
}
|
||||
|
||||
if data == nil {
|
||||
data = cdata
|
||||
from = cfrom
|
||||
to = cto
|
||||
continue
|
||||
}
|
||||
|
||||
if cfrom != from || cto != to {
|
||||
// TODO: Here, we could take the max of cfrom and from and the min of cto and to instead.
|
||||
// This would mean that we also have to resize data.
|
||||
return nil, 0, 0, errors.New("data for metrics at child levels does not align")
|
||||
}
|
||||
|
||||
if len(data) != len(cdata) {
|
||||
panic("WTF? Different freq. at different levels?")
|
||||
}
|
||||
|
||||
for i := 0; i < len(data); i++ {
|
||||
data[i] += cdata[i]
|
||||
}
|
||||
}
|
||||
|
||||
switch accumulation {
|
||||
case "sum":
|
||||
return data, from, to, nil
|
||||
case "avg":
|
||||
normalize := 1. / Float(len(l.children))
|
||||
for i := 0; i < len(data); i++ {
|
||||
data[i] *= normalize
|
||||
}
|
||||
return data, from, to, nil
|
||||
default:
|
||||
return nil, 0, 0, errors.New("invalid accumulation strategy: " + accumulation)
|
||||
}
|
||||
}
|
||||
|
||||
type MemoryStore struct {
|
||||
root level // root of the tree structure
|
||||
metrics map[string]MetricConfig
|
||||
}
|
||||
|
||||
func NewMemoryStore(metrics map[string]MetricConfig) *MemoryStore {
|
||||
return &MemoryStore{
|
||||
root: level{
|
||||
metrics: make(map[string]*buffer),
|
||||
children: make(map[string]*level),
|
||||
},
|
||||
metrics: metrics,
|
||||
}
|
||||
}
|
||||
|
||||
// Write all values in `metrics` to the level specified by `selector` for time `ts`.
|
||||
// Look at `findLevelOrCreate` for how selectors work.
|
||||
func (m *MemoryStore) Write(selector []string, ts int64, metrics []Metric) error {
|
||||
l := m.root.findLevelOrCreate(selector)
|
||||
defer l.lock.Unlock()
|
||||
|
||||
for _, metric := range metrics {
|
||||
b, ok := l.metrics[metric.Name]
|
||||
if !ok {
|
||||
minfo, ok := m.metrics[metric.Name]
|
||||
if !ok {
|
||||
return errors.New("unkown metric: " + metric.Name)
|
||||
}
|
||||
|
||||
// First write to this metric and level
|
||||
b = newBuffer(ts, minfo.Frequency)
|
||||
l.metrics[metric.Name] = b
|
||||
}
|
||||
|
||||
nb, err := b.write(ts, metric.Value)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
|
||||
// Last write created a new buffer...
|
||||
if b != nb {
|
||||
l.metrics[metric.Name] = nb
|
||||
}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func (m *MemoryStore) Read(selector []string, metric string, from, to int64) ([]Float, int64, int64, error) {
|
||||
l := m.root.findLevelOrCreate(selector)
|
||||
defer l.lock.Unlock()
|
||||
|
||||
if from > to {
|
||||
return nil, 0, 0, errors.New("invalid time range")
|
||||
}
|
||||
|
||||
minfo, ok := m.metrics[metric]
|
||||
if !ok {
|
||||
return nil, 0, 0, errors.New("unkown metric: " + metric)
|
||||
}
|
||||
|
||||
return l.read(metric, from, to, minfo.Aggregation)
|
||||
}
|
||||
Reference in New Issue
Block a user