Add microfactory tracing

Test: m clean; load out/build.trace.gz in chrome://tracing
Test: m -j nothing; load again
Change-Id: I67d4e006a4bdde593b54c20d6d93a48278fe696d

ui/tracer/microfactory.go

@@ -0,0 +1,63 @@
+// Copyright 2017 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 tracer
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func (t *tracerImpl) ImportMicrofactoryLog(filename string) {
+	if _, err := os.Stat(filename); err != nil {
+		return
+	}
+
+	f, err := os.Open(filename)
+	if err != nil {
+		t.log.Println("Error opening microfactory trace:", err)
+		return
+	}
+	defer f.Close()
+
+	entries := []*eventEntry{}
+	begin := map[string][]uint64{}
+	s := bufio.NewScanner(f)
+	for s.Scan() {
+		fields := strings.SplitN(s.Text(), " ", 3)
+		if len(fields) != 3 {
+			t.log.Verboseln("Unknown line in microfactory trace:", s.Text())
+			continue
+		}
+		timestamp, err := strconv.ParseUint(fields[0], 10, 64)
+		if err != nil {
+			t.log.Verboseln("Failed to parse timestamp in microfactory trace:", err)
+		}
+
+		if fields[1] == "B" {
+			begin[fields[2]] = append(begin[fields[2]], timestamp)
+		} else if beginTimestamps, ok := begin[fields[2]]; ok {
+			entries = append(entries, &eventEntry{
+				Name:  fields[2],
+				Begin: beginTimestamps[len(beginTimestamps)-1],
+				End:   timestamp,
+			})
+			begin[fields[2]] = beginTimestamps[:len(beginTimestamps)-1]
+		}
+	}
+
+	t.importEvents(entries)
+}