Merge "Allow n2 as a replacement for ninja in builds" into main

ui/build/config.go

@@ -121,6 +121,10 @@ type configImpl struct {
 	// There's quite a bit of overlap with module-info.json and soong module graph. We
 	// could consider merging them.
 	moduleDebugFile string
+
+	// Whether to use n2 instead of ninja.  This is controlled with the
+	// environment variable SOONG_USE_N2
+	useN2 bool
 }
 
 type NinjaWeightListSource uint
@@ -283,6 +287,10 @@ func NewConfig(ctx Context, args ...string) Config {
 		ret.moduleDebugFile, _ = filepath.Abs(shared.JoinPath(ret.SoongOutDir(), "soong-debug-info.json"))
 	}
 
+	if os.Getenv("SOONG_USE_N2") == "true" {
+		ret.useN2 = true
+	}
+
 	ret.environ.Unset(
 		// We're already using it
 		"USE_SOONG_UI",
@@ -339,6 +347,9 @@ func NewConfig(ctx Context, args ...string) Config {
 
 		// We read it here already, don't let others share in the fun
 		"GENERATE_SOONG_DEBUG",
+
+		// Use config.useN2 instead.
+		"SOONG_USE_N2",
 	)
 
 	if ret.UseGoma() || ret.ForceUseGoma() {

ui/build/ninja.go

@@ -56,6 +56,17 @@ func runNinjaForBuild(ctx Context, config Config) {
 		"-d", "stats",
 		"--frontend_file", fifo,
 	}
+	if config.useN2 {
+		executable = config.PrebuiltBuildTool("n2")
+		args = []string{
+			"-d", "trace",
+			// TODO: implement these features, or remove them.
+			//"-d", "keepdepfile",
+			//"-d", "keeprsp",
+			//"-d", "stats",
+			"--frontend-file", fifo,
+		}
+	}
 
 	args = append(args, config.NinjaArgs()...)
 
@@ -72,17 +83,21 @@ func runNinjaForBuild(ctx Context, config Config) {
 
 	args = append(args, "-f", config.CombinedNinjaFile())
 
-	args = append(args,
-		"-o", "usesphonyoutputs=yes",
-		"-w", "dupbuild=err",
-		"-w", "missingdepfile=err")
+	if !config.useN2 {
+		args = append(args,
+			"-o", "usesphonyoutputs=yes",
+			"-w", "dupbuild=err",
+			"-w", "missingdepfile=err")
+	}
 
 	if !config.BuildBrokenMissingOutputs() {
 		// Missing outputs will be treated as errors.
 		// BUILD_BROKEN_MISSING_OUTPUTS can be used to bypass this check.
-		args = append(args,
-			"-w", "missingoutfile=err",
-		)
+		if !config.useN2 {
+			args = append(args,
+				"-w", "missingoutfile=err",
+			)
+		}
 	}
 
 	cmd := Command(ctx, config, "ninja", executable, args...)
@@ -97,16 +112,22 @@ func runNinjaForBuild(ctx Context, config Config) {
 
 	switch config.NinjaWeightListSource() {
 	case NINJA_LOG:
-		cmd.Args = append(cmd.Args, "-o", "usesninjalogasweightlist=yes")
+		if !config.useN2 {
+			cmd.Args = append(cmd.Args, "-o", "usesninjalogasweightlist=yes")
+		}
 	case EVENLY_DISTRIBUTED:
 		// pass empty weight list means ninja considers every tasks's weight as 1(default value).
-		cmd.Args = append(cmd.Args, "-o", "usesweightlist=/dev/null")
+		if !config.useN2 {
+			cmd.Args = append(cmd.Args, "-o", "usesweightlist=/dev/null")
+		}
 	case EXTERNAL_FILE:
 		fallthrough
 	case HINT_FROM_SOONG:
 		// The weight list is already copied/generated.
-		ninjaWeightListPath := filepath.Join(config.OutDir(), ninjaWeightListFileName)
-		cmd.Args = append(cmd.Args, "-o", "usesweightlist="+ninjaWeightListPath)
+		if !config.useN2 {
+			ninjaWeightListPath := filepath.Join(config.OutDir(), ninjaWeightListFileName)
+			cmd.Args = append(cmd.Args, "-o", "usesweightlist="+ninjaWeightListPath)
+		}
 	}
 
 	// Allow both NINJA_ARGS and NINJA_EXTRA_ARGS, since both have been
@@ -206,11 +227,16 @@ func runNinjaForBuild(ctx Context, config Config) {
 			// We don't want this build broken flag to cause reanalysis, so allow it through to the
 			// actions.
 			"BUILD_BROKEN_INCORRECT_PARTITION_IMAGES",
+			"SOONG_USE_N2",
+			"RUST_BACKTRACE",
 		}, config.BuildBrokenNinjaUsesEnvVars()...)...)
 	}
 
 	cmd.Environment.Set("DIST_DIR", config.DistDir())
 	cmd.Environment.Set("SHELL", "/bin/bash")
+	if config.useN2 {
+		cmd.Environment.Set("RUST_BACKTRACE", "1")
+	}
 
 	// Print the environment variables that Ninja is operating in.
 	ctx.Verboseln("Ninja environment: ")

ui/build/soong.go

@@ -638,6 +638,22 @@ func runSoong(ctx Context, config Config) {
 			"--frontend_file", fifo,
 			"-f", filepath.Join(config.SoongOutDir(), "bootstrap.ninja"),
 		}
+		if config.useN2 {
+			ninjaArgs = []string{
+				// TODO: implement these features, or remove them.
+				//"-d", "keepdepfile",
+				//"-d", "stats",
+				//"-o", "usesphonyoutputs=yes",
+				//"-o", "preremoveoutputs=yes",
+				//"-w", "dupbuild=err",
+				//"-w", "outputdir=err",
+				//"-w", "missingoutfile=err",
+				"-v",
+				"-j", strconv.Itoa(config.Parallel()),
+				"--frontend-file", fifo,
+				"-f", filepath.Join(config.SoongOutDir(), "bootstrap.ninja"),
+			}
+		}
 
 		if extra, ok := config.Environment().Get("SOONG_UI_NINJA_ARGS"); ok {
 			ctx.Printf(`CAUTION: arguments in $SOONG_UI_NINJA_ARGS=%q, e.g. "-n", can make soong_build FAIL or INCORRECT`, extra)
@@ -645,8 +661,13 @@ func runSoong(ctx Context, config Config) {
 		}
 
 		ninjaArgs = append(ninjaArgs, targets...)
+		ninjaCmd := config.PrebuiltBuildTool("ninja")
+		if config.useN2 {
+			ninjaCmd = config.PrebuiltBuildTool("n2")
+		}
+
 		cmd := Command(ctx, config, "soong bootstrap",
-			config.PrebuiltBuildTool("ninja"), ninjaArgs...)
+			ninjaCmd, ninjaArgs...)
 
 		var ninjaEnv Environment