From 40163c6bb7980fa1faf8413bd0bbededd8d033d0 Mon Sep 17 00:00:00 2001
From: "Maxim.Mossienko" <Maxim.Mossienko@jetbrains.com>
Date: Thu, 18 Jul 2013 18:52:22 +0200
Subject: [PATCH] coalesce change file events in small frame, usually merge
 e.g. large copy file change notifications

---
 .../openapi/vfs/impl/local/FileWatcher.java   | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/FileWatcher.java b/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/FileWatcher.java
index be846330cae2..f80e320d81c0 100644
--- a/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/FileWatcher.java
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/impl/local/FileWatcher.java
@@ -91,6 +91,8 @@ public class FileWatcher {
 
   private final Object myLock = new Object();
   private DirtyPaths myDirtyPaths = new DirtyPaths();
+  private final String[] myLastChangedPathes = new String[2];
+  private int myLastChangedPathIndex;
 
   /** @deprecated use {@linkplain com.intellij.openapi.vfs.impl.local.LocalFileSystemImpl#getFileWatcher()} (to remove in IDEA 13) */
   public static FileWatcher getInstance() {
@@ -153,6 +155,8 @@ public class FileWatcher {
     synchronized (myLock) {
       DirtyPaths dirtyPaths = myDirtyPaths;
       myDirtyPaths = new DirtyPaths();
+      myLastChangedPathIndex = 0;
+      for(int i = 0; i < myLastChangedPathes.length; ++i) myLastChangedPathes[i] = null;
       return dirtyPaths;
     }
   }
@@ -522,6 +526,8 @@ public class FileWatcher {
       notifyOnEvent();
     }
 
+    private int myChangeRequests, myFilteredRequests;
+
     private void processChange(String path, WatcherOp op) {
       if (SystemInfo.isWindows && op == WatcherOp.RECDIRTY && path.length() == 3 && Character.isLetter(path.charAt(0))) {
         VirtualFile root = LocalFileSystem.getInstance().findFileByPath(path);
@@ -534,6 +540,27 @@ public class FileWatcher {
         return;
       }
 
+      if (op == WatcherOp.CHANGE) {
+        synchronized (myLock) {
+          ++myChangeRequests;
+
+          // TODO: remove logging once finalized
+          if ((myChangeRequests & 0x3ff) == 0) LOG.info("Change requests:" + myChangeRequests + ", filtered:" + myFilteredRequests);
+
+          for(int i = 0; i < myLastChangedPathes.length; ++i) {
+            int last = myLastChangedPathIndex - i - 1;
+            if (last < 0) last += myLastChangedPathes.length;
+            String lastChangedPath = myLastChangedPathes[last];
+            if (lastChangedPath != null && lastChangedPath.equals(path)) {
+              ++myFilteredRequests;
+              return;
+            }
+          }
+          myLastChangedPathes[myLastChangedPathIndex ++] = path;
+          if (myLastChangedPathIndex == myLastChangedPathes.length) myLastChangedPathIndex = 0;
+        }
+      }
+
       boolean exactPath = op != WatcherOp.DIRTY && op != WatcherOp.RECDIRTY;
       Collection<String> paths = checkWatchable(path, exactPath, false);