frostfs-s3-gw/api/metrics/api.go

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package metrics
import (
"io"
"net/http"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/prometheus/client_golang/prometheus"
)
type (
// HTTPAPIStats holds statistics information about
// the API given in the requests.
HTTPAPIStats struct {
apiStats map[string]int
sync.RWMutex
}
// HTTPStats holds statistics information about
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// HTTP requests made by all clients.
HTTPStats struct {
currentS3Requests HTTPAPIStats
totalS3Requests HTTPAPIStats
totalS3Errors HTTPAPIStats
totalInputBytes uint64
totalOutputBytes uint64
}
readCounter struct {
io.ReadCloser
countBytes uint64
}
writeCounter struct {
http.ResponseWriter
countBytes uint64
}
responseWrapper struct {
sync.Once
http.ResponseWriter
statusCode int
startTime time.Time
}
)
const systemPath = "/system"
var (
httpStatsMetric = new(HTTPStats)
httpRequestsDuration = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Name: "frostfs_s3_request_seconds",
Help: "Time taken by requests served by current FrostFS S3 Gate instance",
Buckets: []float64{.05, .1, .25, .5, 1, 2.5, 5, 10},
},
[]string{"api"},
)
)
// Collects HTTP metrics for FrostFS S3 Gate in Prometheus specific format
// and sends to the given channel.
func collectHTTPMetrics(ch chan<- prometheus.Metric) {
for api, value := range httpStatsMetric.currentS3Requests.Load() {
ch <- prometheus.MustNewConstMetric(
prometheus.NewDesc(
prometheus.BuildFQName("frostfs_s3", "requests", "current"),
"Total number of running s3 requests in current FrostFS S3 Gate instance",
[]string{"api"}, nil),
prometheus.CounterValue,
float64(value),
api,
)
}
for api, value := range httpStatsMetric.totalS3Requests.Load() {
ch <- prometheus.MustNewConstMetric(
prometheus.NewDesc(
prometheus.BuildFQName("frostfs_s3", "requests", "total"),
"Total number of s3 requests in current FrostFS S3 Gate instance",
[]string{"api"}, nil),
prometheus.CounterValue,
float64(value),
api,
)
}
for api, value := range httpStatsMetric.totalS3Errors.Load() {
ch <- prometheus.MustNewConstMetric(
prometheus.NewDesc(
prometheus.BuildFQName("frostfs_s3", "errors", "total"),
"Total number of s3 errors in current FrostFS S3 Gate instance",
[]string{"api"}, nil),
prometheus.CounterValue,
float64(value),
api,
)
}
}
// APIStats wraps http handler for api with basic statistics collection.
func APIStats(api string, f http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
httpStatsMetric.currentS3Requests.Inc(api)
defer httpStatsMetric.currentS3Requests.Dec(api)
in := &readCounter{ReadCloser: r.Body}
out := &writeCounter{ResponseWriter: w}
r.Body = in
statsWriter := &responseWrapper{
ResponseWriter: out,
startTime: time.Now(),
}
f.ServeHTTP(statsWriter, r)
// Time duration in secs since the call started.
// We don't need to do nanosecond precision here
// simply for the fact that it is not human readable.
durationSecs := time.Since(statsWriter.startTime).Seconds()
httpStatsMetric.updateStats(api, statsWriter, r, durationSecs)
atomic.AddUint64(&httpStatsMetric.totalInputBytes, in.countBytes)
atomic.AddUint64(&httpStatsMetric.totalOutputBytes, out.countBytes)
}
}
// Inc increments the api stats counter.
func (stats *HTTPAPIStats) Inc(api string) {
if stats == nil {
return
}
stats.Lock()
defer stats.Unlock()
if stats.apiStats == nil {
stats.apiStats = make(map[string]int)
}
stats.apiStats[api]++
}
// Dec increments the api stats counter.
func (stats *HTTPAPIStats) Dec(api string) {
if stats == nil {
return
}
stats.Lock()
defer stats.Unlock()
if val, ok := stats.apiStats[api]; ok && val > 0 {
stats.apiStats[api]--
}
}
// Load returns the recorded stats.
func (stats *HTTPAPIStats) Load() map[string]int {
stats.Lock()
defer stats.Unlock()
var apiStats = make(map[string]int, len(stats.apiStats))
for k, v := range stats.apiStats {
apiStats[k] = v
}
return apiStats
}
func (st *HTTPStats) getInputBytes() uint64 {
return atomic.LoadUint64(&st.totalInputBytes)
}
func (st *HTTPStats) getOutputBytes() uint64 {
return atomic.LoadUint64(&st.totalOutputBytes)
}
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// Update statistics from http request and response data.
func (st *HTTPStats) updateStats(api string, w http.ResponseWriter, r *http.Request, durationSecs float64) {
var code int
if res, ok := w.(*responseWrapper); ok {
code = res.statusCode
}
// A successful request has a 2xx response code
successReq := code >= http.StatusOK && code < http.StatusMultipleChoices
if !strings.HasSuffix(r.URL.Path, systemPath) {
st.totalS3Requests.Inc(api)
if !successReq && code != 0 {
st.totalS3Errors.Inc(api)
}
}
if r.Method == http.MethodGet {
// Increment the prometheus http request response histogram with appropriate label
httpRequestsDuration.With(prometheus.Labels{"api": api}).Observe(durationSecs)
}
}
// WriteHeader -- writes http status code.
func (w *responseWrapper) WriteHeader(code int) {
w.Do(func() {
w.statusCode = code
w.ResponseWriter.WriteHeader(code)
})
}
// Flush -- calls the underlying Flush.
func (w *responseWrapper) Flush() {
if f, ok := w.ResponseWriter.(http.Flusher); ok {
f.Flush()
}
}
func (w *writeCounter) Write(p []byte) (int, error) {
n, err := w.ResponseWriter.Write(p)
atomic.AddUint64(&w.countBytes, uint64(n))
return n, err
}
func (r *readCounter) Read(p []byte) (int, error) {
n, err := r.ReadCloser.Read(p)
atomic.AddUint64(&r.countBytes, uint64(n))
return n, err
}