Merge branch 'fix/cache-md5' into 'master'

Fix: if a file has been modified them its md5 is not the same anymore

See merge request sheepitrenderfarm/client!229

src/main/java/com/sheepit/client/Md5.java

@@ -19,6 +19,7 @@
 
 package com.sheepit.client;
 
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.file.Files;
@@ -32,17 +33,18 @@ import java.util.Map;
 public class Md5 {
 	private static Map<String, String> cache = new HashMap<>();
 	
-	// TODO: check if the file has changed (cache the time of modification)
 	// TODO: to avoid memory increase, check if files are deleted
 	
 	public String get(String path) {
-		if (cache.containsKey(path) == false) {
+		String key = getUniqueKey(path);
+		if (cache.containsKey(key) == false) {
 			generate(path);
 		}
-		return cache.get(path);
+		return cache.get(key);
 	}
 	
-	public void generate(String path) {
+	private void generate(String path) {
+		String key = getUniqueKey(path);
 		try {
 			MessageDigest md = MessageDigest.getInstance("MD5");
 			InputStream is = Files.newInputStream(Paths.get(path));
@@ -53,10 +55,15 @@ public class Md5 {
 			String data = Utils.convertBinaryToHex(md.digest());
 			dis.close();
 			is.close();
-			cache.put(path, data);
+			cache.put(key, data);
 		}
 		catch (NoSuchAlgorithmException | IOException e) {
-			cache.put(path, "");
+			cache.put(key, "");
 		}
 	}
+	
+	private String getUniqueKey(String path) {
+		File file = new File(path);
+		return Long.toString(file.lastModified()) + '_' + path;
+	}
 }