add resetable sync.Once for timed caching of ctags globs (#32082)

enterprise/cmd/frontend/internal/codeintel/resolvers/resolver.go

@@ -2,14 +2,10 @@ package resolvers
 
 import (
 	"context"
-	"path"
 	"time"
 
-	"github.com/gobwas/glob"
 	"github.com/opentracing/opentracing-go/log"
 
-	"github.com/sourcegraph/go-ctags"
-
 	gql "github.com/sourcegraph/sourcegraph/cmd/frontend/graphqlbackend"
 	"github.com/sourcegraph/sourcegraph/enterprise/internal/codeintel/policies"
 	store "github.com/sourcegraph/sourcegraph/enterprise/internal/codeintel/stores/dbstore"
@@ -304,15 +300,10 @@ func (r *resolver) SupportedByCtags(ctx context.Context, filepath string, repoNa
 		return false, "", err
 	}
 
-	for _, allowedLanguage := range ctags.SupportedLanguages {
-		for _, pattern := range mappings[allowedLanguage] {
-			compiled, err := glob.Compile(pattern)
-			if err != nil {
-				return false, "", err
-			}
-
-			if compiled.Match(path.Base(filepath)) {
-				return true, allowedLanguage, nil
+	for language, globs := range mappings {
+		for _, glob := range globs {
+			if glob.Match(filepath) {
+				return true, language, nil
 			}
 		}
 	}

internal/resetonce/resetable_once.go

@@ -0,0 +1,34 @@
+package resetonce
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+// Once is a copy of `sync.Once` with a `Reset` method, inspired by
+// https://github.com/matryer/resync/blob/master/once.go
+type Once struct {
+	done uint32
+	m    sync.Mutex
+}
+
+func (o *Once) Do(f func()) {
+	if atomic.LoadUint32(&o.done) == 0 {
+		o.doSlow(f)
+	}
+}
+
+func (o *Once) doSlow(f func()) {
+	o.m.Lock()
+	defer o.m.Unlock()
+	if o.done == 0 {
+		defer atomic.StoreUint32(&o.done, 1)
+		f()
+	}
+}
+
+func (o *Once) Reset() {
+	o.m.Lock()
+	defer o.m.Unlock()
+	atomic.StoreUint32(&o.done, 0)
+}

internal/symbols/client.go

@@ -8,18 +8,23 @@ import (
 	"net/http"
 	"strings"
 	"sync"
+	"time"
 
+	"github.com/gobwas/glob"
 	"github.com/neelance/parallel"
 	"github.com/opentracing-contrib/go-stdlib/nethttp"
 	"github.com/opentracing/opentracing-go/ext"
 	otlog "github.com/opentracing/opentracing-go/log"
 
+	"github.com/sourcegraph/go-ctags"
+
 	"github.com/sourcegraph/sourcegraph/internal/actor"
 	"github.com/sourcegraph/sourcegraph/internal/api"
 	"github.com/sourcegraph/sourcegraph/internal/authz"
 	"github.com/sourcegraph/sourcegraph/internal/endpoint"
 	"github.com/sourcegraph/sourcegraph/internal/env"
 	"github.com/sourcegraph/sourcegraph/internal/httpcli"
+	"github.com/sourcegraph/sourcegraph/internal/resetonce"
 	"github.com/sourcegraph/sourcegraph/internal/search"
 	"github.com/sourcegraph/sourcegraph/internal/search/result"
 	"github.com/sourcegraph/sourcegraph/internal/trace/ot"
@@ -61,12 +66,15 @@ type Client struct {
 	// database connection.
 	SubRepoPermsChecker func() authz.SubRepoPermissionChecker
 
-	once     sync.Once
-	endpoint *endpoint.Map
+	endpointOnce sync.Once
+	endpoint     *endpoint.Map
+
+	langMappingOnce  resetonce.Once
+	langMappingCache map[string][]glob.Glob
 }
 
 func (c *Client) url(repo api.RepoName) (string, error) {
-	c.once.Do(func() {
+	c.endpointOnce.Do(func() {
 		if len(strings.Fields(c.URL)) == 0 {
 			c.endpoint = endpoint.Empty(errors.New("a symbols service has not been configured"))
 		} else {
@@ -76,30 +84,48 @@ func (c *Client) url(repo api.RepoName) (string, error) {
 	return c.endpoint.Get(string(repo))
 }
 
-func (c *Client) ListLanguageMappings(ctx context.Context, repo api.RepoName) (_ map[string][]string, err error) {
-	mapping := make(map[string][]string)
+func (c *Client) ListLanguageMappings(ctx context.Context, repo api.RepoName) (_ map[string][]glob.Glob, err error) {
+	c.langMappingOnce.Do(func() {
+		var resp *http.Response
+		resp, err = c.httpPost(ctx, "list-languages", repo, nil)
+		if err != nil {
+			return
+		}
+		defer resp.Body.Close()
 
-	resp, err := c.httpPost(ctx, "list-languages", repo, nil)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
+		if resp.StatusCode != http.StatusOK {
+			// best-effort inclusion of body in error message
+			body, _ := io.ReadAll(io.LimitReader(resp.Body, 200))
+			err = errors.Errorf(
+				"Symbol.ListLanguageMappings http status %d: %s",
+				resp.StatusCode,
+				string(body),
+			)
+			return
+		}
 
-	if resp.StatusCode != http.StatusOK {
-		// best-effort inclusion of body in error message
-		body, _ := io.ReadAll(io.LimitReader(resp.Body, 200))
-		return nil, errors.Errorf(
-			"Symbol.ListLanguageMappings http status %d: %s",
-			resp.StatusCode,
-			string(body),
-		)
-	}
+		mapping := make(map[string][]string)
+		err = json.NewDecoder(resp.Body).Decode(&mapping)
 
-	if err = json.NewDecoder(resp.Body).Decode(&mapping); err != nil {
-		return nil, err
-	}
+		globs := make(map[string][]glob.Glob, len(ctags.SupportedLanguages))
 
-	return mapping, nil
+		for _, allowedLanguage := range ctags.SupportedLanguages {
+			for _, pattern := range mapping[allowedLanguage] {
+				var compiled glob.Glob
+				compiled, err = glob.Compile(pattern)
+				if err != nil {
+					return
+				}
+
+				globs[allowedLanguage] = append(globs[allowedLanguage], compiled)
+			}
+		}
+
+		c.langMappingCache = globs
+		time.AfterFunc(time.Minute*10, c.langMappingOnce.Reset)
+	})
+
+	return c.langMappingCache, nil
 }
 
 // Search performs a symbol search on the symbols service.