Add BuildBotClient to abstract http/logdog access

tools/gardening/bin/compare_failures.dart

Index: tools/gardening/bin/compare_failures.dart
diff --git a/tools/gardening/bin/compare_failures.dart b/tools/gardening/bin/compare_failures.dart
index 8ccf5d66ce898ebf4e27ef016d073cd13e011397..4005a7c716502e74a78759bc77dfea5ddcb2feb6 100644
--- a/tools/gardening/bin/compare_failures.dart
+++ b/tools/gardening/bin/compare_failures.dart
@@ -11,13 +11,18 @@ import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:gardening/src/buildbot_structures.dart';
-import 'package:gardening/src/buildbot_loading.dart';
+import 'package:gardening/src/client.dart';
 import 'package:gardening/src/util.dart';
 
 main(List<String> args) async {
   ArgParser argParser = createArgParser();
   ArgResults argResults = argParser.parse(args);
   processArgResults(argResults);
+
+  BuildbotClient client = argResults['logdog']
+      ? new LogdogBuildbotClient()
+      : new HttpBuildbotClient();
+
   if (argResults.rest.length != 1) {
     print('Usage: compare_failures [options] <log-uri>');
     print('where <log-uri> is the uri the stdio output of a failing test step');
@@ -31,7 +36,6 @@ main(List<String> args) async {
     url += '/text';
   }
   Uri uri = Uri.parse(url);
-  HttpClient client = new HttpClient();
   BuildUri buildUri = new BuildUri(uri);
   List<BuildResult> results = await readBuildResults(client, buildUri);
   print(generateBuildResultsSummary(buildUri, results));
@@ -41,14 +45,15 @@ main(List<String> args) async {
 /// Creates a [BuildResult] for [buildUri] and, if it contains failures, the
 /// [BuildResult]s for the previous 5 builds.
 Future<List<BuildResult>> readBuildResults(
-    HttpClient client, BuildUri buildUri) async {
+    BuildbotClient client, BuildUri buildUri) async {
   List<BuildResult> summaries = <BuildResult>[];
-  BuildResult firstSummary = await readBuildResult(client, buildUri);
-  summaries.add(firstSummary);
-  if (firstSummary.hasFailures) {
+  BuildResult summary = await client.readResult(buildUri);
+  summaries.add(summary);
+  if (summary.hasFailures) {
     for (int i = 0; i < 10; i++) {
-      buildUri = buildUri.prev();
-      summaries.add(await readBuildResult(client, buildUri));
+      buildUri = summary.buildUri.prev();
+      summary = await client.readResult(buildUri);
+      summaries.add(summary);
     }
   }
   return summaries;
@@ -64,8 +69,6 @@ String generateBuildResultsSummary(
     timeoutIds.addAll(result.timeouts.map((TestFailure failure) => failure.id));
   }
   if (timeoutIds.isNotEmpty) {
-    int firstBuildNumber = results.first.buildUri.buildNumber;
-    int lastBuildNumber = results.last.buildUri.buildNumber;
     Map<TestConfiguration, Map<int, Map<String, Timing>>> map =
         <TestConfiguration, Map<int, Map<String, Timing>>>{};
     Set<String> stepNames = new Set<String>();
@@ -84,9 +87,8 @@ String generateBuildResultsSummary(
       sb.write('$id\n');
       sb.write(
           '${' ' * 8} ${stepNames.map((t) => padRight(t, 14)).join(' ')}\n');
-      for (int buildNumber = firstBuildNumber;
-          buildNumber >= lastBuildNumber;
-          buildNumber--) {
+      for (BuildResult result in results) {
+        int buildNumber = result.buildUri.buildNumber;
         Map<String, Timing> steps = timings[buildNumber] ?? const {};
         sb.write(padRight(' ${buildNumber}: ', 8));
         for (String stepName in stepNames) {
@@ -107,8 +109,6 @@ String generateBuildResultsSummary(
     errorIds.addAll(result.errors.map((TestFailure failure) => failure.id));
   }
   if (errorIds.isNotEmpty) {
-    int firstBuildNumber = results.first.buildUri.buildNumber;
-    int lastBuildNumber = results.last.buildUri.buildNumber;
     Map<TestConfiguration, Map<int, TestFailure>> map =
         <TestConfiguration, Map<int, TestFailure>>{};
     for (BuildResult result in results) {
@@ -122,9 +122,8 @@ String generateBuildResultsSummary(
     map.forEach((TestConfiguration id, Map<int, TestFailure> failures) {
       if (!errorIds.contains(id)) return;
       sb.write('$id\n');
-      for (int buildNumber = firstBuildNumber;
-          buildNumber >= lastBuildNumber;
-          buildNumber--) {
+      for (BuildResult result in results) {
+        int buildNumber = result.buildUri.buildNumber;
         TestFailure failure = failures[buildNumber];
         sb.write(padRight(' ${buildNumber}: ', 8));
         if (failure != null) {