introduce last commit cache mode env var

cache/no_cache.go

@@ -0,0 +1,27 @@
+// Copyright 2022 Harness Inc. All rights reserved.
+// Use of this source code is governed by the Polyform Free Trial License
+// that can be found in the LICENSE.md file for this repository.
+
+package cache
+
+import (
+	"context"
+)
+
+type NoCache[K any, V any] struct {
+	getter Getter[K, V]
+}
+
+func NewNoCache[K any, V any](getter Getter[K, V]) NoCache[K, V] {
+	return NoCache[K, V]{
+		getter: getter,
+	}
+}
+
+func (c NoCache[K, V]) Stats() (int64, int64) {
+	return 0, 0
+}
+
+func (c NoCache[K, V]) Get(ctx context.Context, key K) (V, error) {
+	return c.getter.Find(ctx, key)
+}

gitrpc/internal/gitea/last_commit_cache.go

@@ -51,6 +51,12 @@ func NewRedisLastCommitCache(
 		cacheDuration)
 }
 
+func NoLastCommitCache(
+	repoCache cache.Cache[string, *RepoEntryValue],
+) cache.Cache[CommitEntryKey, *types.Commit] {
+	return cache.NewNoCache[CommitEntryKey, *types.Commit](commitEntryGetter{repoCache: repoCache})
+}
+
 type CommitEntryKey string
 
 const commitEntryKeySeparator = "\x00"

gitrpc/server/config.go

@@ -9,6 +9,12 @@ import (
 	"time"
 )
 
+const (
+	ModeInMemory = "inmemory"
+	ModeRedis    = "redis"
+	ModeNone     = "none"
+)
+
 // Config represents the configuration for the gitrpc server.
 type Config struct {
 	// Bind specifies the addr used to bind the grpc server.
@@ -26,8 +32,14 @@ type Config struct {
 	MaxConnAge      time.Duration `envconfig:"GITRPC_SERVER_MAX_CONN_AGE" default:"630720000s"`
 	MaxConnAgeGrace time.Duration `envconfig:"GITRPC_SERVER_MAX_CONN_AGE_GRACE" default:"630720000s"`
 
-	// LastCommitCacheSeconds defines cache duration in seconds of last commit, default=12h
-	LastCommitCacheSeconds int `envconfig:"GITRPC_LAST_COMMIT_CACHE_SECONDS" default:"43200"`
+	// LastCommitCache holds configuration options for the last commit cache.
+	LastCommitCache struct {
+		// Mode determines where the cache will be. Valid values are "inmemory" (default), "redis" or "none".
+		Mode string `envconfig:"GITRPC_LAST_COMMIT_CACHE_MODE" default:"inmemory"`
+
+		// DurationSeconds defines cache duration in seconds of last commit, default=12h.
+		DurationSeconds int `envconfig:"GITRPC_LAST_COMMIT_CACHE_SECONDS" default:"43200"`
+	}
 
 	Redis struct {
 		Endpoint           string `envconfig:"GITRPC_REDIS_ENDPOINT"             default:"localhost:6379"`
@@ -59,6 +71,9 @@ func (c *Config) Validate() error {
 	if c.MaxConnAgeGrace == 0 {
 		return errors.New("config.MaxConnAgeGrace is required")
 	}
+	if m := c.LastCommitCache.Mode; m != "" && m != ModeInMemory && m != ModeRedis && m != ModeNone {
+		return errors.New("config.LastCommitCache.Mode has unsupported value")
+	}
 
 	return nil
 }

gitrpc/server/wire.go

@@ -34,13 +34,17 @@ func ProvideLastCommitCache(
 	redisClient redis.UniversalClient,
 	repoCache cache.Cache[string, *gitea.RepoEntryValue],
 ) cache.Cache[gitea.CommitEntryKey, *types.Commit] {
-	cacheDuration := time.Duration(config.LastCommitCacheSeconds) * time.Second
+	cacheDuration := time.Duration(config.LastCommitCache.DurationSeconds) * time.Second
 
-	if redisClient == nil {
-		return gitea.NewInMemoryLastCommitCache(cacheDuration, repoCache)
+	if config.LastCommitCache.Mode == ModeNone || cacheDuration < time.Second {
+		return gitea.NoLastCommitCache(repoCache)
 	}
 
-	return gitea.NewRedisLastCommitCache(redisClient, cacheDuration, repoCache)
+	if config.LastCommitCache.Mode == ModeRedis && redisClient != nil {
+		return gitea.NewRedisLastCommitCache(redisClient, cacheDuration, repoCache)
+	}
+
+	return gitea.NewInMemoryLastCommitCache(cacheDuration, repoCache)
 }
 
 func ProvideGITAdapter(