config: set max token limit to 1M (pingcap#53361)

close pingcap#53312

pkg/config/BUILD.bazel

@@ -37,7 +37,7 @@ go_test(
     data = glob(["**"]),
     embed = [":config"],
     flaky = True,
-    shard_count = 24,
+    shard_count = 25,
     deps = [
         "//pkg/testkit/testsetup",
         "//pkg/util/logutil",

pkg/config/config.go

@@ -97,6 +97,8 @@ const (
 	DefAuthTokenRefreshInterval = time.Hour
 	// EnvVarKeyspaceName is the system env name for keyspace name.
 	EnvVarKeyspaceName = "KEYSPACE_NAME"
+	// MaxTokenLimit is the max token limit value.
+	MaxTokenLimit = 1024 * 1024
 )
 
 // Valid config maps
@@ -1275,6 +1277,8 @@ func (c *Config) Load(confFile string) error {
 	}
 	if c.TokenLimit == 0 {
 		c.TokenLimit = 1000
+	} else if c.TokenLimit > MaxTokenLimit {
+		c.TokenLimit = MaxTokenLimit
 	}
 	// If any items in confFile file are not mapped into the Config struct, issue
 	// an error and stop the server from starting.

pkg/config/config_test.go

@@ -1173,6 +1173,44 @@ func TestTableColumnCountLimit(t *testing.T) {
 	checkValid(DefMaxOfTableColumnCountLimit+1, false)
 }
 
+func TestTokenLimit(t *testing.T) {
+	storeDir := t.TempDir()
+	configFile := filepath.Join(storeDir, "config.toml")
+	f, err := os.Create(configFile)
+	require.NoError(t, err)
+	defer func(configFile string) {
+		require.NoError(t, os.Remove(configFile))
+	}(configFile)
+
+	tests := []struct {
+		tokenLimit         uint
+		expectedTokenLimit uint
+	}{
+		{
+			0,
+			1000,
+		},
+		{
+			99999999999,
+			MaxTokenLimit,
+		},
+	}
+
+	for _, test := range tests {
+		require.NoError(t, f.Truncate(0))
+		_, err = f.Seek(0, 0)
+		require.NoError(t, err)
+		_, err = f.WriteString(fmt.Sprintf(`
+token-limit = %d
+`, test.tokenLimit))
+		require.NoError(t, err)
+		require.NoError(t, f.Sync())
+		conf := NewConfig()
+		require.NoError(t, conf.Load(configFile))
+		require.Equal(t, test.expectedTokenLimit, conf.TokenLimit)
+	}
+}
+
 func TestEncodeDefTempStorageDir(t *testing.T) {
 	tests := []struct {
 		host       string