internal/frontend: add instrumentation for frontend fetch
Instrumentation for frontend fetch requests is added via the ochttp and
ocsql integrations.
Change-Id: I095ec224c24bdb7e341f2b620ddf020ed50f556e
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/765147
Reviewed-by: Jonathan Amsterdam <jba@google.com>
diff --git a/cmd/frontend/main.go b/cmd/frontend/main.go
index d3b29fd..1125f8b 100644
--- a/cmd/frontend/main.go
+++ b/cmd/frontend/main.go
@@ -115,6 +115,8 @@
views := append(dcensus.ServerViews,
postgres.SearchLatencyDistribution,
postgres.SearchResponseCount,
+ frontend.FrontendFetchLatencyDistribution,
+ frontend.FrontendFetchResponseCount,
middleware.CacheResultCount,
middleware.CacheErrorCount,
middleware.QuotaResultCount,
diff --git a/internal/frontend/fetch.go b/internal/frontend/fetch.go
index 2d212e6..99de031 100644
--- a/internal/frontend/fetch.go
+++ b/internal/frontend/fetch.go
@@ -9,17 +9,20 @@
"errors"
"fmt"
"net/http"
+ "strconv"
"strings"
"sync"
"time"
+ "go.opencensus.io/plugin/ochttp"
+ "go.opencensus.io/stats"
+ "go.opencensus.io/stats/view"
+ "go.opencensus.io/tag"
"golang.org/x/mod/semver"
"golang.org/x/pkgsite/internal"
"golang.org/x/pkgsite/internal/derrors"
- "golang.org/x/pkgsite/internal/fetch"
-
"golang.org/x/pkgsite/internal/experiment"
-
+ "golang.org/x/pkgsite/internal/fetch"
"golang.org/x/pkgsite/internal/log"
"golang.org/x/pkgsite/internal/postgres"
"golang.org/x/pkgsite/internal/proxy"
@@ -36,6 +39,33 @@
errPathDoesNotExistInModule = errors.New("path does not exist in module")
fetchTimeout = 30 * time.Second
pollEvery = 500 * time.Millisecond
+
+ // keyFrontendFetchStatus is a census tag for frontend fetch query types.
+ keyFrontendFetchStatus = tag.MustNewKey("frontend-fetch.status")
+ // keyFrontendFetchLatency holds observed latency in individual
+ // frontend fetch queries.
+ keyFrontendFetchLatency = stats.Float64(
+ "go-discovery/frontend-fetch/latency",
+ "Latency of a frontend fetch request.",
+ stats.UnitMilliseconds,
+ )
+ // FrontendFetchLatencyDistribution aggregates frontend fetch request
+ // latency by status code.
+ FrontendFetchLatencyDistribution = &view.View{
+ Name: "go-discovery/frontend-fetch/latency",
+ Measure: keyFrontendFetchLatency,
+ Aggregation: ochttp.DefaultLatencyDistribution,
+ Description: "FrontendFetch latency, by result source query type.",
+ TagKeys: []tag.Key{keyFrontendFetchStatus},
+ }
+ // FrontendFetchResponseCount counts frontend fetch responses by response type.
+ FrontendFetchResponseCount = &view.View{
+ Name: "go-discovery/frontend-fetch/count",
+ Measure: keyFrontendFetchLatency,
+ Aggregation: view.Count(),
+ Description: "Frontend fetch request count",
+ TagKeys: []tag.Key{keyFrontendFetchStatus},
+ }
)
// fetchHandler checks if a requested path and version exists in the database.
@@ -65,7 +95,9 @@
http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
return
}
+ start := time.Now()
status, responseText := s.fetchAndPoll(r.Context(), modulePath, fullPath, requestedVersion)
+ recordFrontendFetchMetric(status, time.Since(start))
if status != http.StatusOK {
http.Error(w, responseText, status)
return
@@ -427,3 +459,10 @@
return experiment.IsActive(ctx, internal.ExperimentFrontendFetch) &&
experiment.IsActive(ctx, internal.ExperimentInsertDirectories)
}
+
+func recordFrontendFetchMetric(status int, latency time.Duration) {
+ l := float64(latency) / float64(time.Millisecond)
+ stats.RecordWithTags(context.Background(), []tag.Mutator{
+ tag.Upsert(keyFrontendFetchStatus, strconv.Itoa(status)),
+ }, keyFrontendFetchLatency.M(l))
+}
