feat: add batch size global config value

Signed-off-by: Brian McGee <brian@bmcgee.ie>

cli/format.go

@@ -23,6 +23,10 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
+const (
+	DefaultBatchSize = 1024
+)
+
 var (
 	ErrFailOnChange     = errors.New("unexpected changes detected, --fail-on-change is enabled")
 	ErrInvalidBatchSize = errors.New("batch size must be >= 1")
@@ -32,6 +36,8 @@ func (f *Format) Run() (err error) {
 	// set log level and other options
 	f.configureLogging()
 
+	// validate the cli batch size
+	// todo move this into kong validation
 	if f.BatchSize < 1 {
 		return ErrInvalidBatchSize
 	}
@@ -99,6 +105,12 @@ func (f *Format) Run() (err error) {
 		return fmt.Errorf("failed to read config file %v: %w", f.ConfigFile, err)
 	}
 
+	// update the batch size only if it has not already been set by the cli arg
+	// cli arg takes precedence over config
+	if f.BatchSize == DefaultBatchSize && cfg.Global.BatchSize != 0 {
+		f.BatchSize = cfg.Global.BatchSize
+	}
+
 	// compile global exclude globs
 	if f.globalExcludes, err = format.CompileGlobs(cfg.Global.Excludes); err != nil {
 		return fmt.Errorf("failed to compile global excludes: %w", err)

config/config.go

@@ -9,6 +9,8 @@ import (
 // Config is used to represent the list of configured Formatters.
 type Config struct {
 	Global struct {
+		// BatchSize controls the maximum number of paths to batch before applying them to a sequence of formatters.
+		BatchSize int `toml:"batch_size"`
 		// Excludes is an optional list of glob patterns used to exclude certain files from all formatters.
 		Excludes []string `toml:"excludes"`
 	} `toml:"global"`

config/config_test.go

@@ -14,6 +14,7 @@ func TestReadConfigFile(t *testing.T) {
 
 	as.NotNil(cfg)
 
+	as.Equal(10, cfg.Global.BatchSize)
 	as.Equal([]string{"*.toml"}, cfg.Global.Excludes)
 
 	// python

test/examples/treefmt.toml

@@ -1,6 +1,7 @@
 # One CLI to format the code tree - https://git.numtide.com/numtide/treefmt
 
 [global]
+batch_size = 10
 excludes = ["*.toml"]
 
 [formatter.python]