Record Error Prone initialization time

RELNOTES=N/A
PiperOrigin-RevId: 498571979

check_api/src/main/java/com/google/errorprone/ErrorProneAnalyzer.java

@@ -72,13 +72,17 @@ private static Supplier<CodeTransformer> scansPlugins(
         () -> {
           // we can't load plugins from the processorpath until the filemanager has been
           // initialized, so do it lazily
-          try {
+          ErrorProneTimings timings = ErrorProneTimings.instance(context);
+          try (AutoCloseable unused = timings.initializationTimeSpan()) {
             return ErrorProneScannerTransformer.create(
                 ErrorPronePlugins.loadPlugins(scannerSupplier, context)
                     .applyOverrides(errorProneOptions)
                     .get());
           } catch (InvalidCommandLineOptionException e) {
             throw new PropagatedException(e);
+          } catch (Exception e) {
+            // for the timing span, should be impossible
+            throw new AssertionError(e);
           }
         });
   }

check_api/src/main/java/com/google/errorprone/ErrorProneTimings.java

@@ -45,16 +45,29 @@ private ErrorProneTimings(Context context) {
 
   private final Map<String, Stopwatch> timers = new HashMap<>();
 
+  private final Stopwatch initializationTime = Stopwatch.createUnstarted();
+
   /** Creates a timing span for the given {@link Suppressible}. */
   public AutoCloseable span(Suppressible suppressible) {
     String key = suppressible.canonicalName();
     Stopwatch sw = timers.computeIfAbsent(key, k -> Stopwatch.createUnstarted()).start();
     return () -> sw.stop();
   }
 
+  /** Creates a timing span for initialization. */
+  public AutoCloseable initializationTimeSpan() {
+    initializationTime.start();
+    return () -> initializationTime.stop();
+  }
+
   /** Returns the elapsed durations of each timer. */
   public ImmutableMap<String, Duration> timings() {
     return timers.entrySet().stream()
         .collect(toImmutableMap(e -> e.getKey(), e -> e.getValue().elapsed()));
   }
+
+  /** Returns the elapsed initialization time. */
+  public Duration initializationTime() {
+    return initializationTime.elapsed();
+  }
 }