cc-metric-store/memoryStore.go

251 lines
5.7 KiB
Go

package main
import (
"fmt"
"math"
"strings"
"sync"
"time"
"github.com/ClusterCockpit/cc-metric-store/lineprotocol"
)
type storeBuffer struct {
store []lineprotocol.Float
start int64
}
type buffer struct {
current *storeBuffer
next *storeBuffer
lock sync.Mutex
}
//MemoryStore holds the state for a metric memory store.
//It does not export any variable.
type MemoryStore struct {
containers map[string]*buffer
offsets map[string]int
frequency int
numSlots int
numMetrics int
lock sync.Mutex
}
func initBuffer(b *storeBuffer) {
for i := 0; i < len(b.store); i++ {
b.store[i] = lineprotocol.Float(math.NaN())
}
}
func allocateBuffer(ts int64, size int) *buffer {
b := new(buffer)
s := make([]lineprotocol.Float, size)
b.current = &storeBuffer{s, ts}
initBuffer(b.current)
s = make([]lineprotocol.Float, size)
b.next = &storeBuffer{s, 0}
initBuffer(b.next)
return b
}
func switchBuffers(m *MemoryStore, b *buffer) {
initBuffer(b.next)
b.current, b.next = b.next, b.current
b.current.start = b.next.start + int64(m.numSlots*m.frequency)
}
func newMemoryStore(o []string, n int, f int) *MemoryStore {
var m MemoryStore
m.frequency = f
m.numSlots = n
m.containers = make(map[string]*buffer)
m.offsets = make(map[string]int)
for i, name := range o {
m.offsets[name] = i
}
m.numMetrics = len(o)
return &m
}
// AddMetrics writes metrics to the memoryStore for entity key
// at unix epoch time ts. The unit of ts is seconds.
// An error is returned if ts is out of bounds of MemoryStore.
func (m *MemoryStore) AddMetrics(
key string,
ts int64,
metrics []lineprotocol.Metric) error {
m.lock.Lock()
b, ok := m.containers[key]
if !ok {
//Key does not exist. Allocate new buffer.
m.containers[key] = allocateBuffer(ts, m.numMetrics*m.numSlots)
b = m.containers[key]
}
m.lock.Unlock()
b.lock.Lock()
defer b.lock.Unlock()
index := int(ts-b.current.start) / m.frequency
if index < 0 || index >= 2*m.numSlots {
return fmt.Errorf("ts %d out of bounds", ts)
}
if index >= m.numSlots {
//Index exceeds buffer length. Switch buffers.
switchBuffers(m, b)
index = int(ts-b.current.start) / m.frequency
}
s := b.current.store
for _, metric := range metrics {
s[m.offsets[metric.Name]*m.numSlots+index] = metric.Value
}
return nil
}
// GetMetric returns a slize with metric values for timerange
// and entity key. Returns an error if key does not exist,
// stop is before start or start is in the future.
func (m *MemoryStore) GetMetric(
key string,
metric string,
from int64,
to int64) ([]lineprotocol.Float, int64, error) {
m.lock.Lock()
b, ok := m.containers[key]
m.lock.Unlock()
if !ok {
return nil, 0, fmt.Errorf("key %s does not exist", key)
}
b.lock.Lock()
defer b.lock.Unlock()
if to <= from {
return nil, 0, fmt.Errorf("invalid duration %d - %d", from, to)
}
if from > b.current.start+int64(m.numSlots*m.frequency) {
return nil, 0, fmt.Errorf("from %d out of bounds", from)
}
if to < b.next.start {
return nil, 0, fmt.Errorf("to %d out of bounds", to)
}
var values1, values2 []lineprotocol.Float
offset := m.offsets[metric] * m.numSlots
valuesFrom := from
if from < b.current.start && b.next.start != 0 {
var start, stop = 0, m.numSlots
if from > b.next.start {
start = int(from-b.next.start) / m.frequency
} else {
valuesFrom = b.next.start
}
if to < b.current.start {
stop = int(to-b.next.start) / m.frequency
}
// fmt.Println("NEXT", start, stop)
values1 = b.next.store[offset+start : offset+stop]
}
if to >= b.current.start {
var start, stop = 0, m.numSlots
if from > b.current.start {
start = int(from-b.current.start) / m.frequency
}
if to <= b.current.start+int64(m.numSlots*m.frequency) {
stop = int(to-b.current.start) / m.frequency
}
// fmt.Println("CURRENT", start, stop, b.current.start)
values2 = b.current.store[offset+start : offset+stop]
}
return append(values1, values2...), valuesFrom, nil
}
// Call *f* once on every value which *GetMetric* would
// return for similar arguments. This operation might be known
// as fold in Ruby/Haskell/Scala. It can be used to implement
// the calculation of sums, averages, minimas and maximas.
// The advantage of using this over *GetMetric* for such calculations
// is that it can be implemented without copying data.
// TODO: Write Tests, implement without calling GetMetric!
func (m *MemoryStore) Reduce(
key string, metric string,
from int64, to int64,
f func(t int64, acc lineprotocol.Float, x lineprotocol.Float) lineprotocol.Float, initialX lineprotocol.Float) (lineprotocol.Float, error) {
values, valuesFrom, err := m.GetMetric(key, metric, from, to)
if err != nil {
return 0.0, err
}
acc := initialX
t := valuesFrom
for i := 0; i < len(values); i++ {
acc = f(t, acc, values[i])
t += int64(m.frequency)
}
return acc, nil
}
// Return a map of keys to a map of metrics to the most recent value writen to
// the store for that metric.
// TODO: Write Tests!
func (m *MemoryStore) Peak(prefix string) map[string]map[string]lineprotocol.Float {
m.lock.Lock()
defer m.lock.Unlock()
now := time.Now().Unix()
retval := make(map[string]map[string]lineprotocol.Float)
for key, b := range m.containers {
if !strings.HasPrefix(key, prefix) {
continue
}
b.lock.Lock()
index := int(now-b.current.start) / m.frequency
if index >= m.numSlots {
index = m.numSlots - 1
}
vals := make(map[string]lineprotocol.Float)
for metric, offset := range m.offsets {
val := lineprotocol.Float(math.NaN())
for i := index; i >= 0 && math.IsNaN(float64(val)); i -= 1 {
val = b.current.store[offset*m.numSlots+i]
}
vals[metric] = val
}
b.lock.Unlock()
retval[key[len(prefix):]] = vals
}
return retval
}