From 488e4ea5c6bc47be1d777bf5c26e2ffa2c436e28 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Jeli=C5=84ski?= <djelinski@openjdk.org>
Date: Fri, 23 May 2025 11:55:21 +0000
Subject: [PATCH] 8357539: TimeSource.now() is not monotonic

Reviewed-by: dfuchs, jpai
---
 .../jdk/internal/net/http/common/TimeSource.java  | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/java.net.http/share/classes/jdk/internal/net/http/common/TimeSource.java b/src/java.net.http/share/classes/jdk/internal/net/http/common/TimeSource.java
index 98ed50de77d..489fbe7ffd8 100644
--- a/src/java.net.http/share/classes/jdk/internal/net/http/common/TimeSource.java
+++ b/src/java.net.http/share/classes/jdk/internal/net/http/common/TimeSource.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -69,6 +69,8 @@ public final class TimeSource implements TimeLine {
         }
 
         Deadline instant(long nanos, long delay) {
+            assert firstNanos + delay == nanos :
+                    "%d + %d != %d".formatted(firstNanos, delay, nanos);
             Instant now = first.plusNanos(delay);
             if (!isInWindow(delay)) {
                 // Shifts the time reference (firstNanos) to
@@ -85,18 +87,19 @@ public final class TimeSource implements TimeLine {
         }
 
         boolean isInWindow(long delay) {
-            return delay >= 0 && delay <= TIME_WINDOW;
+            return delay >= -TIME_WINDOW && delay <= TIME_WINDOW;
         }
 
     }
 
     @Override
     public Deadline instant() {
-        long nanos = System.nanoTime();
-        long delay = localSource.delay(nanos);
         // use localSource if possible to avoid a volatile read
-        if (localSource.isInWindow(delay)) {
-            return localSource.instant(nanos, delay);
+        NanoSource source = localSource;
+        long nanos = System.nanoTime();
+        long delay = source.delay(nanos);
+        if (source.isInWindow(delay)) {
+            return source.instant(nanos, delay);
         } else {
             // will cause the time reference to shift forward,
             // at the cost of a volatile write + a volatile read