Upload build metrics after a build is completed.

Soong now supports the ability to upload metrics to another location
by setting the ANDROID_ENABLE_METRICS_UPLOAD to an uploader that
accepts the upload.proto proto buffer message. When the environment
variable is set, a set of build metrics files (soong_metrics,
rbe_metrics.pb and build_error) is uploaded.

Bug: 140638454
Test: * Wrote unit test cases
      * Setup the uploader, built a succcessful and failed aosp_arm-eng
        target and monitor the uploading of the metrics.
Change-Id: I76a65739c557dc90345e098ca03119a950ece2d2
diff --git a/ui/build/upload.go b/ui/build/upload.go
new file mode 100644
index 0000000..75a5e2f
--- /dev/null
+++ b/ui/build/upload.go
@@ -0,0 +1,80 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package build
+
+// This file contains the functionality to upload data from one location to
+// another.
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+
+	upload_proto "android/soong/ui/metrics/upload_proto"
+)
+
+const (
+	uploadPbFilename = ".uploader.pb"
+)
+
+// UploadMetrics uploads a set of metrics files to a server for analysis. An
+// uploader full path is required to be specified in order to upload the set
+// of metrics files. This is accomplished by defining the ANDROID_ENABLE_METRICS_UPLOAD
+// environment variable.
+func UploadMetrics(ctx Context, config Config, buildStartedMilli int64, files ...string) {
+	uploader := config.MetricsUploaderApp()
+	// No metrics to upload if the path to the uploader was not specified.
+	if uploader == "" {
+		return
+	}
+
+	// Some files may not exist. For example, build errors protobuf file
+	// may not exist since the build was successful.
+	var metricsFiles []string
+	for _, f := range files {
+		if _, err := os.Stat(f); err == nil {
+			metricsFiles = append(metricsFiles, f)
+		}
+	}
+
+	if len(metricsFiles) == 0 {
+		return
+	}
+
+	// For platform builds, the branch and target name is hardcoded to specific
+	// values for later extraction of the metrics in the data metrics pipeline.
+	data, err := proto.Marshal(&upload_proto.Upload{
+		CreationTimestampMs:   proto.Uint64(uint64(buildStartedMilli)),
+		CompletionTimestampMs: proto.Uint64(uint64(time.Now().UnixNano() / int64(time.Millisecond))),
+		BranchName:            proto.String("developer-metrics"),
+		TargetName:            proto.String("platform-build-systems-metrics"),
+		MetricsFiles:          metricsFiles,
+	})
+	if err != nil {
+		ctx.Fatalf("failed to marshal metrics upload proto buffer message: %v\n", err)
+	}
+
+	pbFile := filepath.Join(config.OutDir(), uploadPbFilename)
+	if err := ioutil.WriteFile(pbFile, data, 0644); err != nil {
+		ctx.Fatalf("failed to write the marshaled metrics upload protobuf to %q: %v\n", pbFile, err)
+	}
+	// Remove the upload file as it's not longer needed after it has been processed by the uploader.
+	defer os.Remove(pbFile)
+
+	Command(ctx, config, "upload metrics", uploader, "--upload-metrics", pbFile).RunAndStreamOrFatal()
+}