Add find_timeouts and caching to tools/gardening

tools/gardening/lib/src/logdog.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:io';
 import 'dart:async';
 import 'dart:collection';
 
+final String cit = Platform.isWindows ? 'cit.bat' : 'cit';
+
 class LogdogException implements Exception {
   final int errorCode;
   final String stdout;
   final String stderr;
 
   LogdogException(this.errorCode, this.stdout, this.stderr);
   LogdogException.fromProcessResult(ProcessResult result)
       : this(result.exitCode, result.stdout, result.stderr);
 
   toString() => "Error during logdog execution:\n$stderr";
 }
 
 bool logdogCheckDone = false;
 
 void checkLogdog({bool tryToInstall: true}) {
   if (logdogCheckDone) return;
-  var result = Process.runSync("cit", []);
+  var result = Process.runSync(cit, []);
   if (result.exitCode != 0) {
     print("cit (from depot_tools) must be in the path.");
     throw new StateError("cit not accessible");
   }
   String stdout = result.stdout;
   if (stdout.contains("logdog")) {
     logdogCheckDone = true;
     return;
   }
   if (tryToInstall) {
     print("logdog isn't yet installed. Installation might take some time");
-    result = Process.runSync("cit", ["logdog"]);
+    result = Process.runSync(cit, ["logdog"]);
     checkLogdog(tryToInstall: false);
   } else {
     print("Couldn't install logdog");
     throw new StateError("logdog not accessible");
   }
 }
 
 String logdog(List<String> args) {
   checkLogdog();
   args = args.toList()..insert(0, "logdog");
-  var result = Process.runSync("cit", args);
+  var result = Process.runSync(cit, args);
   if (result.exitCode == 0) return result.stdout;
   throw new LogdogException.fromProcessResult(result);
 }
 
 String cat(String log) {
   return logdog(["cat", "-raw", log]);
 }
 
+/// Returns the content for [path], for instance the available build numbers
+/// for 'dart2js-linux-chromeff-1-4-be' using the path
+/// `chromium/bb/client.dart/dart2js-linux-chromeff-1-4-be`.
+String ls(String path) {
+  return logdog(["ls", path]);
+}
+
 class LogResult<T> {
   final String log;
   final T result;
 
   LogResult(this.log, this.result);
 }
 
 const int maxConcurrentLogdogs = 20;
 
 /// Fetches the given [logs] concurrently using [logdog].
 ///
 /// At most [maxConcurrentLogdogs] connections are opened at the same time.
 ///
 /// The resulting [LogResult] has a [LogResult.result] equal to `null` if
 /// the log didn't exist.
 Stream<LogResult<String>> catN(Iterable<String> logs) async* {
   var queue = new Queue<Future<LogResult<ProcessResult>>>();
   var it = logs.iterator;
 
   // Launches a new logdog to fetch the next log.
   // Returns false when nothing was left to enqueue.
   bool enqueueNext() {
     if (!it.moveNext()) return false;
     var log = it.current;
     queue.add(new Future.sync(() async {
       var logPath = log.substring(0, log.lastIndexOf("/"));
-      var lsResult = await Process.run("cit", ["logdog", "ls", logPath]);
+      var lsResult = await Process.run(cit, ["logdog", "ls", logPath]);
       if (lsResult.exitCode != 0) return new LogResult(log, lsResult);
       if (lsResult.stdout == "") return new LogResult(log, null);
       return new LogResult(
-          log, await Process.run("cit", ["logdog", "cat", "-raw", log]));
+          log, await Process.run(cit, ["logdog", "cat", "-raw", log]));
     }));
     return true;
   }
 
   for (int i = 0; i < maxConcurrentLogdogs; i++) {
     enqueueNext();
   }
 
   while (queue.isNotEmpty) {
     var logResult =
@@ skipping 19 matching lines @@
         "/+/recipes/steps/dart2js_ie11_tests/0/stdout";
   })).listen((logResult) {
     print("--------------------------");
     if (logResult.result == null) {
       print("${logResult.log} - empty");
     } else {
       print(logResult.result.substring(0, 200));
     }
   });
 }
-*/
+*/