Refactor upload-only to process bazel metrics outside of upload.go

Bug: 279987768
Test: m nothing
Test: b build libcore:all (with prints to verify similiar data)
Change-Id: I01d960a7215be30728c9e90f52c2455fd21cf1b8
diff --git a/ui/build/bazel_metrics.go b/ui/build/bazel_metrics.go
new file mode 100644
index 0000000..c0690c1
--- /dev/null
+++ b/ui/build/bazel_metrics.go
@@ -0,0 +1,135 @@
+// Copyright 2023 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 functionality to parse bazel profile data into
+// a bazel_metrics proto, defined in build/soong/ui/metrics/bazel_metrics_proto
+// These metrics are later uploaded in upload.go
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+
+	"android/soong/shared"
+	"google.golang.org/protobuf/proto"
+
+	bazel_metrics_proto "android/soong/ui/metrics/bazel_metrics_proto"
+)
+
+func parseTimingToNanos(str string) int64 {
+	millisString := removeDecimalPoint(str)
+	timingMillis, _ := strconv.ParseInt(millisString, 10, 64)
+	return timingMillis * 1000000
+}
+
+func parsePercentageToTenThousandths(str string) int32 {
+	percentageString := removeDecimalPoint(str)
+	//remove the % at the end of the string
+	percentage := strings.ReplaceAll(percentageString, "%", "")
+	percentagePortion, _ := strconv.ParseInt(percentage, 10, 32)
+	return int32(percentagePortion)
+}
+
+func removeDecimalPoint(numString string) string {
+	// The format is always 0.425 or 10.425
+	return strings.ReplaceAll(numString, ".", "")
+}
+
+func parseTotal(line string) int64 {
+	words := strings.Fields(line)
+	timing := words[3]
+	return parseTimingToNanos(timing)
+}
+
+func parsePhaseTiming(line string) bazel_metrics_proto.PhaseTiming {
+	words := strings.Fields(line)
+	getPhaseNameAndTimingAndPercentage := func([]string) (string, int64, int32) {
+		// Sample lines include:
+		// Total launch phase time   0.011 s    2.59%
+		// Total target pattern evaluation phase time  0.011 s    2.59%
+		var beginning int
+		var end int
+		for ind, word := range words {
+			if word == "Total" {
+				beginning = ind + 1
+			} else if beginning > 0 && word == "phase" {
+				end = ind
+				break
+			}
+		}
+		phaseName := strings.Join(words[beginning:end], " ")
+
+		// end is now "phase" - advance by 2 for timing and 4 for percentage
+		percentageString := words[end+4]
+		timingString := words[end+2]
+		timing := parseTimingToNanos(timingString)
+		percentagePortion := parsePercentageToTenThousandths(percentageString)
+		return phaseName, timing, percentagePortion
+	}
+
+	phaseName, timing, portion := getPhaseNameAndTimingAndPercentage(words)
+	phaseTiming := bazel_metrics_proto.PhaseTiming{}
+	phaseTiming.DurationNanos = &timing
+	phaseTiming.PortionOfBuildTime = &portion
+
+	phaseTiming.PhaseName = &phaseName
+	return phaseTiming
+}
+
+// This method takes a file created by bazel's --analyze-profile mode and
+// writes bazel metrics data to the provided filepath.
+func ProcessBazelMetrics(bazelProfileFile string, bazelMetricsFile string, ctx Context, config Config) {
+	if bazelProfileFile == "" {
+		return
+	}
+
+	readBazelProto := func(filepath string) bazel_metrics_proto.BazelMetrics {
+		//serialize the proto, write it
+		bazelMetrics := bazel_metrics_proto.BazelMetrics{}
+
+		file, err := os.ReadFile(filepath)
+		if err != nil {
+			ctx.Fatalln("Error reading metrics file\n", err)
+		}
+
+		scanner := bufio.NewScanner(strings.NewReader(string(file)))
+		scanner.Split(bufio.ScanLines)
+
+		var phaseTimings []*bazel_metrics_proto.PhaseTiming
+		for scanner.Scan() {
+			line := scanner.Text()
+			if strings.HasPrefix(line, "Total run time") {
+				total := parseTotal(line)
+				bazelMetrics.Total = &total
+			} else if strings.HasPrefix(line, "Total") {
+				phaseTiming := parsePhaseTiming(line)
+				phaseTimings = append(phaseTimings, &phaseTiming)
+			}
+		}
+		bazelMetrics.PhaseTimings = phaseTimings
+
+		return bazelMetrics
+	}
+
+	if _, err := os.Stat(bazelProfileFile); err != nil {
+		// We can assume bazel didn't run if the profile doesn't exist
+		return
+	}
+	bazelProto := readBazelProto(bazelProfileFile)
+	bazelProto.ExitCode = proto.Int32(config.bazelExitCode)
+	shared.Save(&bazelProto, bazelMetricsFile)
+}