[performance] Cache platform name in SystemReader

SystemReader.isMacOs() and SystemReader.isWindows() return values are
unlikely to change during the JVM lifetime (except tests). Don't read
system properties each time the methods are called, just use previously
calculated value.

Change-Id: I495521f67a8b544e7b7247d99bbd05a42ea16d20
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>

1 files changed, 18 insertions, 0 deletions

diff --git a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
index 65551d6579..d24dd44fff 100644
--- a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
+++ b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
@@ -47,6 +47,7 @@ package org.eclipse.jgit.junit;
 
 import java.io.File;
 import java.io.IOException;
+import java.lang.reflect.Field;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.HashMap;
@@ -170,6 +171,7 @@ public class MockSystemReader extends SystemReader {
 	 * Assign some properties for the currently executing platform
 	 */
 	public void setCurrentPlatform() {
+		resetOsNames();
 		setProperty("os.name", System.getProperty("os.name"));
 		setProperty("file.separator", System.getProperty("file.separator"));
 		setProperty("path.separator", System.getProperty("path.separator"));
@@ -180,6 +182,7 @@ public class MockSystemReader extends SystemReader {
 	 * Emulate Windows
 	 */
 	public void setWindows() {
+		resetOsNames();
 		setProperty("os.name", "Windows");
 		setProperty("file.separator", "\\");
 		setProperty("path.separator", ";");
@@ -191,10 +194,25 @@ public class MockSystemReader extends SystemReader {
 	 * Emulate Unix
 	 */
 	public void setUnix() {
+		resetOsNames();
 		setProperty("os.name", "*nix"); // Essentially anything but Windows
 		setProperty("file.separator", "/");
 		setProperty("path.separator", ":");
 		setProperty("line.separator", "\n");
 		setPlatformChecker();
 	}
+
+	private void resetOsNames() {
+		Field field;
+		try {
+			field = SystemReader.class.getDeclaredField("isWindows");
+			field.setAccessible(true);
+			field.set(null, null);
+			field = SystemReader.class.getDeclaredField("isMacOS");
+			field.setAccessible(true);
+			field.set(null, null);
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
+	}
 }