Improve performance and memory by caching XML Schema / DTD

Fixes #534

Signed-off-by: azerr <[email protected]>

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/extensions/contentmodel/model/FileChangedTracker.java

@@ -0,0 +1,44 @@
+package org.eclipse.lsp4xml.extensions.contentmodel.model;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.FileTime;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class FileChangedTracker {
+
+	private static final Logger LOGGER = Logger.getLogger(FileChangedTracker.class.getName());
+
+	private final Path file;
+	private FileTime lastModified;
+
+	public FileChangedTracker(Path file) {
+		this.file = file;
+		try {
+			lastModified = Files.getLastModifiedTime(file);
+		} catch (IOException e) {
+			LOGGER.log(Level.SEVERE, "Get last modified time failed", e);
+		}
+	}
+
+	public boolean isDirty() {
+		try {
+			if (!Files.exists(file)) {
+				// This case occurs when user delete the XML Schema / DTD file
+				return true;
+			}
+			FileTime currentLastMofied = Files.getLastModifiedTime(file);
+			if (!currentLastMofied.equals(lastModified)) {
+				lastModified = currentLastMofied;
+				return true;
+			}
+		} catch (IOException e) {
+			LOGGER.log(Level.SEVERE, "Get last modified time failed", e);
+			return true;
+		}
+		return false;
+	}
+
+}

org.eclipse.lsp4xml/src/main/java/org/eclipse/lsp4xml/extensions/contentmodel/model/FilesChangedTracker.java

@@ -9,13 +9,9 @@
 *******************************************************************************/
 package org.eclipse.lsp4xml.extensions.contentmodel.model;
 
-import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
-import java.nio.file.Files;
-import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.nio.file.attribute.FileTime;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Level;
@@ -31,40 +27,6 @@ public class FilesChangedTracker {
 
 	private static final Logger LOGGER = Logger.getLogger(FilesChangedTracker.class.getName());
 
-	private static class FileChangedTracker {
-
-		private final Path file;
-		private FileTime lastModified;
-
-		public FileChangedTracker(Path file) {
-			this.file = file;
-			try {
-				lastModified = Files.getLastModifiedTime(file);
-			} catch (IOException e) {
-				LOGGER.log(Level.SEVERE, "Get last modified time failed", e);
-			}
-		}
-
-		public boolean isDirty() {
-			try {
-				if (!Files.exists(file)) {
-					// This case occurs when user delete the XML Schema / DTD file
-					return true;
-				}
-				FileTime currentLastMofied = Files.getLastModifiedTime(file);
-				if (!currentLastMofied.equals(lastModified)) {
-					lastModified = currentLastMofied;
-					return true;
-				}
-			} catch (IOException e) {
-				LOGGER.log(Level.SEVERE, "Get last modified time failed", e);
-				return true;
-			}
-			return false;
-		}
-
-	}
-
 	private final List<FileChangedTracker> files;
 
 	public FilesChangedTracker() {