From cf3c6456239f51d70be3fe3edbd04d57c6b26400 Mon Sep 17 00:00:00 2001
From: "Vassiliy.Kudryashov" <Vassiliy.Kudryashov@jetbrains.com>
Date: Mon, 26 Dec 2016 17:18:33 +0300
Subject: [PATCH] Check for system time jump back (logging only)

---
 .../src/com/intellij/ide/IdeEventQueue.java           | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/platform/platform-impl/src/com/intellij/ide/IdeEventQueue.java b/platform/platform-impl/src/com/intellij/ide/IdeEventQueue.java
index 9610ccbdd8a5..100b7b72e702 100644
--- a/platform/platform-impl/src/com/intellij/ide/IdeEventQueue.java
+++ b/platform/platform-impl/src/com/intellij/ide/IdeEventQueue.java
@@ -114,6 +114,7 @@ public class IdeEventQueue extends EventQueue {
   private boolean myIsInInputEvent;
   private AWTEvent myCurrentEvent;
   private long myLastActiveTime;
+  private long myLastEventTime = System.currentTimeMillis();
   private WindowManagerEx myWindowManager;
   private final List<EventDispatcher> myDispatchers = ContainerUtil.createLockFreeCopyOnWriteList();
   private final List<EventDispatcher> myPostProcessors = ContainerUtil.createLockFreeCopyOnWriteList();
@@ -338,6 +339,7 @@ public class IdeEventQueue extends EventQueue {
 
   @Override
   public void dispatchEvent(@NotNull AWTEvent e) {
+    checkForTimeJump();
     if (!appIsLoaded()) {
       try {
         super.dispatchEvent(e);
@@ -382,6 +384,15 @@ public class IdeEventQueue extends EventQueue {
     }
   }
 
+  //As we rely on system time monotonicity in many places let's log anomalies at least.
+  private void checkForTimeJump() {
+    long now = System.currentTimeMillis();
+    if (myLastEventTime > now + 1000) {
+      LOG.error("System clock's jumped back by ~" + (myLastEventTime - now) / 1000 + " sec");
+    }
+    myLastEventTime = now;
+  }
+
   private static boolean isInputEvent(@NotNull AWTEvent e) {
     return e instanceof InputEvent || e instanceof InputMethodEvent || e instanceof WindowEvent || e instanceof ActionEvent;
   }