Enable bazel profiling in soong_build.

Bazel is executed several times during the execution of soong_build.
For each bazel execution, generate a profile and save under the
BAZEL_METRICS_DIR which is defined in soong_ui.

Bug: b/174479924
Test: * USE_BAZEL_ANALYSIS=1 USE_BAZEL=1 m nothing and checked
        if the cquery and graph build bazel profiles were generated.
      * Verified that the generated bazel profiles were uploaded
        to the local dev metrics pipeline.

Change-Id: I3d20204484dc6c5a1525a5d3eec1d62cfb33535b

android/bazel_handler.go

@@ -26,6 +26,8 @@ import (
 	"strings"
 	"sync"
 
+	"android/soong/bazel"
+	"android/soong/shared"
 	"github.com/google/blueprint/bootstrap"
 )
 
@@ -68,6 +70,7 @@ type bazelContext struct {
 	outputBase   string
 	workspaceDir string
 	buildDir     string
+	metricsDir   string
 
 	requests     map[cqueryKey]bool // cquery requests that have not yet been issued to Bazel
 	requestMutex sync.Mutex         // requests can be written in parallel
@@ -153,6 +156,11 @@ func NewBazelContext(c *config) (BazelContext, error) {
 	} else {
 		missingEnvVars = append(missingEnvVars, "BAZEL_WORKSPACE")
 	}
+	if len(c.Getenv("BAZEL_METRICS_DIR")) > 1 {
+		bazelCtx.metricsDir = c.Getenv("BAZEL_METRICS_DIR")
+	} else {
+		missingEnvVars = append(missingEnvVars, "BAZEL_METRICS_DIR")
+	}
 	if len(missingEnvVars) > 0 {
 		return nil, errors.New(fmt.Sprintf("missing required env vars to use bazel: %s", missingEnvVars))
 	} else {
@@ -160,6 +168,10 @@ func NewBazelContext(c *config) (BazelContext, error) {
 	}
 }
 
+func (context *bazelContext) BazelMetricsDir() string {
+	return context.metricsDir
+}
+
 func (context *bazelContext) BazelEnabled() bool {
 	return true
 }
@@ -189,12 +201,13 @@ func pwdPrefix() string {
 	return ""
 }
 
-func (context *bazelContext) issueBazelCommand(command string, labels []string,
+func (context *bazelContext) issueBazelCommand(runName bazel.RunName, command string, labels []string,
 	extraFlags ...string) (string, error) {
 
 	cmdFlags := []string{"--output_base=" + context.outputBase, command}
 	cmdFlags = append(cmdFlags, labels...)
 	cmdFlags = append(cmdFlags, "--package_path=%workspace%/"+context.intermediatesDir())
+	cmdFlags = append(cmdFlags, "--profile="+shared.BazelMetricsFilename(context, runName))
 	cmdFlags = append(cmdFlags, extraFlags...)
 
 	bazelCmd := exec.Command(context.bazelPath, cmdFlags...)
@@ -341,7 +354,7 @@ func (context *bazelContext) InvokeBazel() error {
 		return err
 	}
 	buildroot_label := "//:buildroot"
-	cqueryOutput, err = context.issueBazelCommand("cquery",
+	cqueryOutput, err = context.issueBazelCommand(bazel.CqueryBuildRootRunName, "cquery",
 		[]string{fmt.Sprintf("deps(%s)", buildroot_label)},
 		"--output=starlark",
 		"--starlark:file="+cquery_file_relpath)
@@ -371,7 +384,7 @@ func (context *bazelContext) InvokeBazel() error {
 	// bazel actions should either be added to the Ninja file and executed later,
 	// or bazel should handle execution.
 	// TODO(cparsons): Use --target_pattern_file to avoid command line limits.
-	_, err = context.issueBazelCommand("build", []string{buildroot_label})
+	_, err = context.issueBazelCommand(bazel.BazelBuildPhonyRootRunName, "build", []string{buildroot_label})
 
 	if err != nil {
 		return err

bazel/Android.bp

@@ -2,6 +2,7 @@ bootstrap_go_package {
     name: "soong-bazel",
     pkgPath: "android/soong/bazel",
     srcs: [
+        "constants.go",
         "properties.go",
     ],
     pluginFor: [

bazel/constants.go

@@ -0,0 +1,26 @@
+package bazel
+
+type RunName string
+
+// Below is a list bazel execution run names used through out the
+// Platform Build systems. Each run name represents an unique key
+// to query the bazel metrics.
+const (
+	// Perform a bazel build of the phony root to generate symlink forests
+	// for dependencies of the bazel build.
+	BazelBuildPhonyRootRunName = RunName("bazel-build-phony-root")
+
+	// Perform aquery of the bazel build root to retrieve action information.
+	AqueryBuildRootRunName = RunName("aquery-buildroot")
+
+	// Perform cquery of the Bazel build root and its dependencies.
+	CqueryBuildRootRunName = RunName("cquery-buildroot")
+
+	// Run bazel as a ninja executer
+	BazelNinjaExecRunName = RunName("bazel-ninja-exec")
+)
+
+// String returns the name of the run.
+func (c RunName) String() string {
+	return string(c)
+}

shared/Android.bp

@@ -4,4 +4,7 @@ bootstrap_go_package {
     srcs: [
         "paths.go",
     ],
+    deps: [
+        "soong-bazel",
+    ],
 }

shared/paths.go

@@ -18,6 +18,8 @@ package shared
 
 import (
 	"path/filepath"
+
+	"android/soong/bazel"
 )
 
 // A SharedPaths represents a list of paths that are shared between
@@ -37,6 +39,6 @@ func TempDirForOutDir(outDir string) (tempPath string) {
 // on the action name. This is to help to store a set of bazel
 // profiles since bazel may execute multiple times during a single
 // build.
-func BazelMetricsFilename(s SharedPaths, actionName string) string {
-	return filepath.Join(s.BazelMetricsDir(), actionName+"_bazel_profile.gz")
+func BazelMetricsFilename(s SharedPaths, actionName bazel.RunName) string {
+	return filepath.Join(s.BazelMetricsDir(), actionName.String()+"_bazel_profile.gz")
 }

ui/build/bazel.go

@@ -22,6 +22,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"android/soong/bazel"
 	"android/soong/shared"
 	"android/soong/ui/metrics"
 )
@@ -97,9 +98,9 @@ func runBazel(ctx Context, config Config) {
 	}
 
 	// Start constructing the `build` command.
-	actionName := "build"
+	actionName := bazel.BazelNinjaExecRunName
 	cmd.Args = append(cmd.Args,
-		actionName,
+		"build",
 		// Use output_groups to select the set of outputs to produce from a
 		// ninja_build target.
 		"--output_groups="+outputGroups,

ui/build/soong.go

@@ -156,6 +156,7 @@ func runSoong(ctx Context, config Config) {
 		cmd.Environment.Set("BAZEL_HOME", filepath.Join(config.BazelOutDir(), "bazelhome"))
 		cmd.Environment.Set("BAZEL_OUTPUT_BASE", filepath.Join(config.BazelOutDir(), "output"))
 		cmd.Environment.Set("BAZEL_WORKSPACE", absPath(ctx, "."))
+		cmd.Environment.Set("BAZEL_METRICS_DIR", config.BazelMetricsDir())
 
 		cmd.Environment.Set("SOONG_SANDBOX_SOONG_BUILD", "true")
 		cmd.Sandbox = soongSandbox