Add DoneGeneratingRules language hook

cmd/gazelle/fix-update.go

@@ -356,6 +356,12 @@ func runFixUpdate(wd string, cmd command, args []string) (err error) {
  }
  })
 
+ for _, lang := range languages {
+ if finishable, ok := lang.(language.FinishableLanguage); ok {
+ finishable.DoneGeneratingRules()
+ }
+ }
+
  // Finish building the index for dependency resolution.
  ruleIndex.Finish()
 

internal/language/test_filegroup/BUILD.bazel

@@ -6,7 +6,11 @@ go_library(
  importpath = "github.com/bazelbuild/bazel-gazelle/internal/language/test_filegroup",
  visibility = ["//visibility:public"],
  deps = [
+ "//config",
+ "//label",
  "//language",
+ "//repo",
+ "//resolve",
  "//rule",
  ],
 )

internal/language/test_filegroup/lang.go

@@ -26,14 +26,20 @@ package test_filegroup
 import (
  "path"
 
+ "github.com/bazelbuild/bazel-gazelle/config"
+ "github.com/bazelbuild/bazel-gazelle/label"
  "github.com/bazelbuild/bazel-gazelle/language"
+ "github.com/bazelbuild/bazel-gazelle/repo"
+ "github.com/bazelbuild/bazel-gazelle/resolve"
  "github.com/bazelbuild/bazel-gazelle/rule"
 )
 
 const testFilegroupName = "test_filegroup"
 
 type testFilegroupLang struct {
  language.BaseLang
+
+ sawDone bool
 }
 
 func NewLanguage() language.Language {
@@ -53,7 +59,11 @@ var kinds = map[string]rule.KindInfo{
  },
 }
 
-func (*testFilegroupLang) GenerateRules(args language.GenerateArgs) language.GenerateResult {
+func (l *testFilegroupLang) GenerateRules(args language.GenerateArgs) language.GenerateResult {
+ if l.sawDone {
+ panic("GenerateRules must not be called after DoneGeneratingRules")
+ }
+
  r := rule.NewRule("filegroup", "all_files")
  srcs := make([]string, 0, len(args.Subdirs)+len(args.RegularFiles))
  srcs = append(srcs, args.RegularFiles...)
@@ -71,3 +81,13 @@ func (*testFilegroupLang) GenerateRules(args language.GenerateArgs) language.Gen
  Imports: []interface{}{nil},
  }
 }
+
+func (l *testFilegroupLang) DoneGeneratingRules() {
+ l.sawDone = true
+}
+
+func (l *testFilegroupLang) Resolve(c *config.Config, ix *resolve.RuleIndex, rc *repo.RemoteCache, r *rule.Rule, imports interface{}, from label.Label) {
+ if !l.sawDone {
+ panic("Expected a call to DoneGeneratingRules before Resolve")
+ }
+}

language/base.go

@@ -67,4 +67,6 @@ func (b *BaseLang) GenerateRules(args GenerateArgs) GenerateResult {
  return GenerateResult{}
 }
 
+func (b *BaseLang) DoneGeneratingRules() {}
+
 func (b *BaseLang) Fix(c *config.Config, f *rule.File) {}

language/lang.go

@@ -96,6 +96,18 @@ type Language interface {
  Fix(c *config.Config, f *rule.File)
 }
 
+// FinishableLanguage allows a Language to be notified when Generate is finished
+// being called.
+type FinishableLanguage interface {
+ // DoneGeneratingRules is called when all calls to GenerateRules have been
+ // completed.
+ // This allows for hooks to be called, for instance to release resources
+ // such as shutting down a background server.
+ // No further calls will be made to GenerateRules on this Language instance
+ // after this method has been called.
+ DoneGeneratingRules()
+}
+
 // GenerateArgs contains arguments for language.GenerateRules. Arguments are
 // passed in a struct value so that new fields may be added in the future
 // without breaking existing implementations.