Merge pull request #109 from fa93hws/faster-bytes-to-string

Author: tinder-maxwellelliott

src/main/java/com/bazel_diff/TargetHashingClient.java

@@ -8,6 +8,7 @@
 import java.util.*;
 import java.util.stream.Collectors;
 import com.google.common.primitives.Bytes;
+import java.nio.charset.StandardCharsets;
 
 interface TargetHashingClient {
     Map<String, String> hashAllBazelTargetsAndSourcefiles(Set<Path> seedFilepaths) throws IOException, NoSuchAlgorithmException;
@@ -17,6 +18,7 @@ interface TargetHashingClient {
 class TargetHashingClientImpl implements TargetHashingClient {
     private BazelClient bazelClient;
     private FilesClient files;
+    private static final byte[] HEX_ARRAY = "0123456789abcdef".getBytes(StandardCharsets.US_ASCII);
 
     TargetHashingClientImpl(BazelClient bazelClient, FilesClient files) {
         this.bazelClient = bazelClient;
@@ -136,11 +138,13 @@ private byte[] getDigestForSourceTargetName(
     }
 
     private String convertByteArrayToString(byte[] bytes) {
-        StringBuilder result = new StringBuilder();
-        for (byte aByte : bytes) {
-            result.append(String.format("%02x", aByte));
+        byte[] hexChars = new byte[bytes.length * 2];
+        for (int j = 0; j < bytes.length; j++) {
+            int v = bytes[j] & 0xFF;
+            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
+            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
         }
-        return result.toString();
+        return new String(hexChars, StandardCharsets.UTF_8);
     }
 
     private String getNameForTarget(BazelTarget target) {