Remove redundant caches

This commit removes the two extra caches (oidc, requested time) and uses
the new central registration cache instead. The requested time is
unified into the main machine object and the oidc key is just added to
the same cache, as a string with the state as a key instead of machine
key.

app.go

@@ -55,8 +55,8 @@ const (
 	HTTPReadTimeout    = 30 * time.Second
 	privateKeyFileMode = 0o600
 
-	requestedExpiryCacheExpiration      = time.Minute * 5
-	requestedExpiryCacheCleanupInterval = time.Minute * 10
+	registerCacheExpiration = time.Minute * 15
+	registerCacheCleanup    = time.Minute * 20
 
 	errUnsupportedDatabase                 = Error("unsupported DB")
 	errUnsupportedLetsEncryptChallengeType = Error(
@@ -148,11 +148,8 @@ type Headscale struct {
 
 	lastStateChange sync.Map
 
-	oidcProvider   *oidc.Provider
-	oauth2Config   *oauth2.Config
-	oidcStateCache *cache.Cache
-
-	requestedExpiryCache *cache.Cache
+	oidcProvider *oidc.Provider
+	oauth2Config *oauth2.Config
 
 	registrationCache *cache.Cache
 
@@ -204,25 +201,19 @@ func NewHeadscale(cfg Config) (*Headscale, error) {
 		return nil, errUnsupportedDatabase
 	}
 
-	requestedExpiryCache := cache.New(
-		requestedExpiryCacheExpiration,
-		requestedExpiryCacheCleanupInterval,
-	)
-
 	registrationCache := cache.New(
 		// TODO(kradalby): Add unified cache expiry config options
-		requestedExpiryCacheExpiration,
-		requestedExpiryCacheCleanupInterval,
+		registerCacheExpiration,
+		registerCacheCleanup,
 	)
 
 	app := Headscale{
-		cfg:                  cfg,
-		dbType:               cfg.DBtype,
-		dbString:             dbString,
-		privateKey:           privKey,
-		aclRules:             tailcfg.FilterAllowAll, // default allowall
-		requestedExpiryCache: requestedExpiryCache,
-		registrationCache:    registrationCache,
+		cfg:               cfg,
+		dbType:            cfg.DBtype,
+		dbString:          dbString,
+		privateKey:        privKey,
+		aclRules:          tailcfg.FilterAllowAll, // default allowall
+		registrationCache: registrationCache,
 	}
 
 	err = app.initDB()