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|
package usage_metrics
import (
"fmt"
"sync"
"sync/atomic"
)
const (
ModuleName = "usage_metrics"
)
type UsageData struct {
Counters map[string]int64
UniqueCounters map[string][]int64
}
func (d *UsageData) IsEmpty() bool {
return len(d.Counters) == 0 && len(d.UniqueCounters) == 0
}
type UniqueCounter interface {
Add(int64)
}
type uniqueCounter struct {
mu sync.Mutex
set map[int64]struct{}
}
func (uc *uniqueCounter) Add(item int64) {
uc.mu.Lock()
uc.set[item] = struct{}{}
uc.mu.Unlock()
}
func (uc *uniqueCounter) subtract(items []int64) {
uc.mu.Lock()
for _, item := range items {
delete(uc.set, item)
}
uc.mu.Unlock()
}
type Counter interface {
// Inc increment the counter by 1.
Inc()
}
type counter struct {
// n is the first element in an allocated struct to ensure 64 bit alignment for atomic access.
n int64
}
func (c *counter) Inc() {
atomic.AddInt64(&c.n, 1)
}
func (c *counter) get() int64 {
return atomic.LoadInt64(&c.n)
}
func (c *counter) subtract(n int64) {
atomic.AddInt64(&c.n, -n)
}
type UsageTrackerRegisterer interface {
RegisterCounter(name string) Counter
RegisterUniqueCounter(name string) UniqueCounter
}
type UsageTrackerCollector interface {
// CloneUsageData returns collected usage data.
// Only non-zero counters are returned.
CloneUsageData() *UsageData
Subtract(data *UsageData)
}
type UsageTrackerInterface interface {
UsageTrackerRegisterer
UsageTrackerCollector
}
type UsageTracker struct {
counters map[string]*counter
uniqueCounters map[string]*uniqueCounter
}
func NewUsageTracker() *UsageTracker {
return &UsageTracker{
counters: map[string]*counter{},
uniqueCounters: map[string]*uniqueCounter{},
}
}
func (ut *UsageTracker) RegisterCounter(name string) Counter {
if _, exists := ut.counters[name]; exists {
panic(fmt.Errorf("counter with name %s already exists", name))
}
c := &counter{}
ut.counters[name] = c
return c
}
func (ut *UsageTracker) RegisterUniqueCounter(name string) UniqueCounter {
if _, exists := ut.uniqueCounters[name]; exists {
panic(fmt.Errorf("uniqueCounter with name %s already exists", name))
}
uc := &uniqueCounter{
set: make(map[int64]struct{}),
}
ut.uniqueCounters[name] = uc
return uc
}
func (ut *UsageTracker) CloneUsageData() *UsageData {
return &UsageData{
Counters: ut.cloneCounters(),
UniqueCounters: ut.cloneUniqueCounters(),
}
}
func (ut *UsageTracker) cloneUniqueCounters() map[string][]int64 {
c := make(map[string][]int64, len(ut.uniqueCounters))
for name, dataSet := range ut.uniqueCounters {
dataSet.mu.Lock()
if len(dataSet.set) == 0 {
dataSet.mu.Unlock()
continue
}
clone := make([]int64, 0, len(dataSet.set))
for i := range dataSet.set {
clone = append(clone, i)
}
dataSet.mu.Unlock()
c[name] = clone
}
return c
}
func (ut *UsageTracker) cloneCounters() map[string]int64 {
c := make(map[string]int64, len(ut.counters))
for name, counterItem := range ut.counters {
n := counterItem.get()
if n == 0 {
continue
}
c[name] = n
}
return c
}
func (ut *UsageTracker) Subtract(ud *UsageData) {
for name, dataSet := range ud.UniqueCounters {
s := ut.uniqueCounters[name]
s.subtract(dataSet)
}
for name, n := range ud.Counters {
ut.counters[name].subtract(n)
}
}
|
