Reduce Base64::encode allocations, close AsyncHttpClient#1344

Motivation:

`Base64::encode` allocates a StringBuilder on every call.

Modifications:

* Extract `StringBuilderPool` from `SringUtils`
* Use such pool for `Base64::encode`

Result:

Less allocations

Author: slandelle

client/src/main/java/org/asynchttpclient/Realm.java

@@ -16,10 +16,10 @@
  */
 package org.asynchttpclient;
 
-import static org.asynchttpclient.util.Assertions.*;
-
 import static java.nio.charset.StandardCharsets.*;
+import static org.asynchttpclient.util.Assertions.assertNotNull;
 import static org.asynchttpclient.util.MiscUtils.isNonEmpty;
+import static org.asynchttpclient.util.StringUtils.*;
 
 import java.nio.charset.Charset;
 import java.security.MessageDigest;
@@ -28,6 +28,7 @@
 
 import org.asynchttpclient.uri.Uri;
 import org.asynchttpclient.util.AuthenticatorUtils;
+import org.asynchttpclient.util.StringBuilderPool;
 import org.asynchttpclient.util.StringUtils;
 
 /**
@@ -459,7 +460,7 @@ private void newResponse(MessageDigest md) {
             // BEWARE: compute first as it used the cached StringBuilder
             String digestUri = AuthenticatorUtils.computeRealmURI(uri, useAbsoluteURI, omitQuery);
 
-            StringBuilder sb = StringUtils.stringBuilder();
+            StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
 
             // WARNING: DON'T MOVE, BUFFER IS RECYCLED!!!!
             byte[] secretDigest = secretDigest(sb, md);
@@ -473,30 +474,6 @@ private void newResponse(MessageDigest md) {
             response = toHexString(responseDigest);
         }
 
-        private static String toHexString(byte[] data) {
-            StringBuilder buffer = StringUtils.stringBuilder();
-            for (byte aData : data) {
-                buffer.append(Integer.toHexString((aData & 0xf0) >>> 4));
-                buffer.append(Integer.toHexString(aData & 0x0f));
-            }
-            return buffer.toString();
-        }
-
-        private static void appendBase16(StringBuilder buf, byte[] bytes) {
-            int base = 16;
-            for (byte b : bytes) {
-                int bi = 0xff & b;
-                int c = '0' + (bi / base) % base;
-                if (c > '9')
-                    c = 'a' + (c - '0' - 10);
-                buf.append((char) c);
-                c = '0' + bi % base;
-                if (c > '9')
-                    c = 'a' + (c - '0' - 10);
-                buf.append((char) c);
-            }
-        }
-
         /**
          * Build a {@link Realm}
          * 

client/src/main/java/org/asynchttpclient/cookie/CookieEncoder.java

@@ -16,7 +16,7 @@
 import java.util.Collection;
 import java.util.Comparator;
 
-import org.asynchttpclient.util.StringUtils;
+import org.asynchttpclient.util.StringBuilderPool;
 
 public final class CookieEncoder {
 
@@ -49,7 +49,7 @@ private CookieEncoder() {
     }
 
     public static String encode(Collection<Cookie> cookies) {
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
 
         if (cookies.isEmpty()) {
             return "";

client/src/main/java/org/asynchttpclient/oauth/OAuthSignatureCalculatorInstance.java

@@ -31,6 +31,7 @@
 import org.asynchttpclient.RequestBuilderBase;
 import org.asynchttpclient.SignatureCalculator;
 import org.asynchttpclient.util.Base64;
+import org.asynchttpclient.util.StringBuilderPool;
 import org.asynchttpclient.util.StringUtils;
 import org.asynchttpclient.util.Utf8UrlEncoder;
 
@@ -103,7 +104,7 @@ StringBuilder signatureBaseString(ConsumerKey consumerAuth, RequestToken userAut
         String baseUrl = request.getUri().toBaseUrl();
         String encodedParams = encodedParams(consumerAuth, userAuth, oauthTimestamp, nonce, request.getFormParams(), request.getQueryParams());
 
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
         sb.append(request.getMethod()); // POST / GET etc (nothing to URL encode)
         sb.append('&');
         Utf8UrlEncoder.encodeAndAppendPercentEncoded(sb, baseUrl);
@@ -154,7 +155,7 @@ private String percentEncodeAlreadyFormUrlEncoded(String s) {
     }
 
     private byte[] digest(ConsumerKey consumerAuth, RequestToken userAuth, ByteBuffer message) throws InvalidKeyException {
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
         Utf8UrlEncoder.encodeAndAppendQueryElement(sb, consumerAuth.getSecret());
         sb.append('&');
         if (userAuth != null && userAuth.getSecret() != null) {
@@ -170,7 +171,7 @@ private byte[] digest(ConsumerKey consumerAuth, RequestToken userAuth, ByteBuffe
     }
 
     String constructAuthHeader(ConsumerKey consumerAuth, RequestToken userAuth, String signature, String nonce, long oauthTimestamp) {
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
         sb.append("OAuth ");
         sb.append(KEY_OAUTH_CONSUMER_KEY).append("=\"").append(consumerAuth.getKey()).append("\", ");
         if (userAuth.getKey() != null) {

client/src/main/java/org/asynchttpclient/oauth/Parameters.java

@@ -17,7 +17,7 @@
 import java.util.Collections;
 import java.util.List;
 
-import org.asynchttpclient.util.StringUtils;
+import org.asynchttpclient.util.StringBuilderPool;
 
 class Parameters {
 
@@ -37,7 +37,7 @@ String sortAndConcat() {
         Collections.sort(parameters);
 
         // and build parameter section using pre-encoded pieces:
-        StringBuilder encodedParams = StringUtils.stringBuilder();
+        StringBuilder encodedParams = StringBuilderPool.DEFAULT.stringBuilder();
         for (int i = 0; i < parameters.size(); i++) {
             Parameter param = parameters.get(i);
             encodedParams.append(param.key).append('=').append(param.value).append('&');

client/src/main/java/org/asynchttpclient/request/body/multipart/MultipartUtils.java

@@ -28,7 +28,7 @@
 import org.asynchttpclient.request.body.multipart.part.MessageEndMultipartPart;
 import org.asynchttpclient.request.body.multipart.part.MultipartPart;
 import org.asynchttpclient.request.body.multipart.part.StringMultipartPart;
-import org.asynchttpclient.util.StringUtils;
+import org.asynchttpclient.util.StringBuilderPool;
 
 public class MultipartUtils {
 
@@ -105,7 +105,7 @@ private static byte[] generateBoundary() {
     }
 
     private static String computeContentType(CharSequence base, byte[] boundary) {
-        StringBuilder buffer = StringUtils.stringBuilder().append(base);
+        StringBuilder buffer = StringBuilderPool.DEFAULT.stringBuilder().append(base);
         if (base.length() != 0 && base.charAt(base.length() - 1) != ';')
             buffer.append(';');
         return buffer.append(" boundary=").append(new String(boundary, US_ASCII)).toString();

client/src/main/java/org/asynchttpclient/uri/Uri.java

@@ -12,14 +12,14 @@
  */
 package org.asynchttpclient.uri;
 
-import static org.asynchttpclient.util.Assertions.*;
+import static org.asynchttpclient.util.Assertions.assertNotNull;
 import static org.asynchttpclient.util.MiscUtils.isNonEmpty;
 
 import java.net.URI;
 import java.net.URISyntaxException;
 
 import org.asynchttpclient.util.MiscUtils;
-import org.asynchttpclient.util.StringUtils;
+import org.asynchttpclient.util.StringBuilderPool;
 
 public class Uri {
 
@@ -117,7 +117,7 @@ public int getSchemeDefaultPort() {
 
     public String toUrl() {
         if (url == null) {
-            StringBuilder sb = StringUtils.stringBuilder();
+            StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
             sb.append(scheme).append("://");
             if (userInfo != null)
                 sb.append(userInfo).append('@');
@@ -138,7 +138,7 @@ public String toUrl() {
      * @return [scheme]://[hostname](:[port]). Port is ommitted if it matches the scheme's default one.
      */
     public String toBaseUrl() {
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
         sb.append(scheme).append("://").append(host);
         if (port != -1 && port != getSchemeDefaultPort()) {
             sb.append(':').append(port);
@@ -150,7 +150,7 @@ public String toBaseUrl() {
     }
 
     public String toRelativeUrl() {
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
         if (MiscUtils.isNonEmpty(path))
             sb.append(path);
         else

client/src/main/java/org/asynchttpclient/util/Base64.java

@@ -13,59 +13,55 @@
 package org.asynchttpclient.util;
 
 /**
- * Implements the "base64" binary encoding scheme as defined by
- * <a href="http://tools.ietf.org/html/rfc2045">RFC 2045</a>.
- * <br>
+ * Implements the "base64" binary encoding scheme as defined by <a href="http://tools.ietf.org/html/rfc2045">RFC 2045</a>. <br>
  * Portions of code here are taken from Apache Pivot
  */
 public final class Base64 {
-    private static final char[] lookup = new char[64];
-    private static final byte[] reverseLookup = new byte[256];
+    private static final StringBuilderPool SB_POOL = new StringBuilderPool();
+    private static final char[] LOOKUP = new char[64];
+    private static final byte[] REVERSE_LOOKUP = new byte[256];
 
     static {
         // Populate the lookup array
 
         for (int i = 0; i < 26; i++) {
-            lookup[i] = (char) ('A' + i);
+            LOOKUP[i] = (char) ('A' + i);
         }
 
         for (int i = 26, j = 0; i < 52; i++, j++) {
-            lookup[i] = (char) ('a' + j);
+            LOOKUP[i] = (char) ('a' + j);
         }
 
         for (int i = 52, j = 0; i < 62; i++, j++) {
-            lookup[i] = (char) ('0' + j);
+            LOOKUP[i] = (char) ('0' + j);
         }
 
-        lookup[62] = '+';
-        lookup[63] = '/';
+        LOOKUP[62] = '+';
+        LOOKUP[63] = '/';
 
         // Populate the reverse lookup array
 
         for (int i = 0; i < 256; i++) {
-            reverseLookup[i] = -1;
+            REVERSE_LOOKUP[i] = -1;
         }
 
         for (int i = 'Z'; i >= 'A'; i--) {
-            reverseLookup[i] = (byte) (i - 'A');
+            REVERSE_LOOKUP[i] = (byte) (i - 'A');
         }
 
         for (int i = 'z'; i >= 'a'; i--) {
-            reverseLookup[i] = (byte) (i - 'a' + 26);
+            REVERSE_LOOKUP[i] = (byte) (i - 'a' + 26);
         }
 
         for (int i = '9'; i >= '0'; i--) {
-            reverseLookup[i] = (byte) (i - '0' + 52);
+            REVERSE_LOOKUP[i] = (byte) (i - '0' + 52);
         }
 
-        reverseLookup['+'] = 62;
-        reverseLookup['/'] = 63;
-        reverseLookup['='] = 0;
+        REVERSE_LOOKUP['+'] = 62;
+        REVERSE_LOOKUP['/'] = 63;
+        REVERSE_LOOKUP['='] = 0;
     }
 
-    /**
-     * This class is not instantiable.
-     */
     private Base64() {
     }
 
@@ -76,30 +72,29 @@ private Base64() {
      * @return the encoded data
      */
     public static String encode(byte[] bytes) {
-        // always sequence of 4 characters for each 3 bytes; padded with '='s as necessary:
-        StringBuilder buf = new StringBuilder(((bytes.length + 2) / 3) * 4);
+        StringBuilder buf = SB_POOL.stringBuilder();
 
         // first, handle complete chunks (fast loop)
         int i = 0;
         for (int end = bytes.length - 2; i < end;) {
             int chunk = ((bytes[i++] & 0xFF) << 16) | ((bytes[i++] & 0xFF) << 8) | (bytes[i++] & 0xFF);
-            buf.append(lookup[chunk >> 18]);
-            buf.append(lookup[(chunk >> 12) & 0x3F]);
-            buf.append(lookup[(chunk >> 6) & 0x3F]);
-            buf.append(lookup[chunk & 0x3F]);
+            buf.append(LOOKUP[chunk >> 18]);
+            buf.append(LOOKUP[(chunk >> 12) & 0x3F]);
+            buf.append(LOOKUP[(chunk >> 6) & 0x3F]);
+            buf.append(LOOKUP[chunk & 0x3F]);
         }
 
         // then leftovers, if any
         int len = bytes.length;
         if (i < len) { // 1 or 2 extra bytes?
             int chunk = ((bytes[i++] & 0xFF) << 16);
-            buf.append(lookup[chunk >> 18]);
+            buf.append(LOOKUP[chunk >> 18]);
             if (i < len) { // 2 bytes
                 chunk |= ((bytes[i] & 0xFF) << 8);
-                buf.append(lookup[(chunk >> 12) & 0x3F]);
-                buf.append(lookup[(chunk >> 6) & 0x3F]);
+                buf.append(LOOKUP[(chunk >> 12) & 0x3F]);
+                buf.append(LOOKUP[(chunk >> 6) & 0x3F]);
             } else { // 1 byte
-                buf.append(lookup[(chunk >> 12) & 0x3F]);
+                buf.append(LOOKUP[(chunk >> 12) & 0x3F]);
                 buf.append('=');
             }
             buf.append('=');
@@ -124,10 +119,10 @@ public static byte[] decode(String encoded) {
         byte[] bytes = new byte[length];
 
         for (int i = 0, index = 0, n = encoded.length(); i < n; i += 4) {
-            int word = reverseLookup[encoded.charAt(i)] << 18;
-            word += reverseLookup[encoded.charAt(i + 1)] << 12;
-            word += reverseLookup[encoded.charAt(i + 2)] << 6;
-            word += reverseLookup[encoded.charAt(i + 3)];
+            int word = REVERSE_LOOKUP[encoded.charAt(i)] << 18;
+            word += REVERSE_LOOKUP[encoded.charAt(i + 1)] << 12;
+            word += REVERSE_LOOKUP[encoded.charAt(i + 2)] << 6;
+            word += REVERSE_LOOKUP[encoded.charAt(i + 3)];
 
             for (int j = 0; j < 3 && index + j < length; j++) {
                 bytes[index + j] = (byte) (word >> (8 * (2 - j)));

client/src/main/java/org/asynchttpclient/util/HttpUtils.java

@@ -83,7 +83,7 @@ public static boolean followRedirect(AsyncHttpClientConfig config, Request reque
     }
 
     private static StringBuilder urlEncodeFormParams0(List<Param> params) {
-        StringBuilder sb = StringUtils.stringBuilder();
+        StringBuilder sb = StringBuilderPool.DEFAULT.stringBuilder();
         for (Param param : params) {
             encodeAndAppendFormParam(sb, param.getName(), param.getValue());
         }

client/src/main/java/org/asynchttpclient/util/StringBuilderPool.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2017 AsyncHttpClient Project. All rights reserved.
+ *
+ * This program is licensed to you under the Apache License Version 2.0,
+ * and you may not use this file except in compliance with the Apache License Version 2.0.
+ * You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the Apache License Version 2.0 is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
+ */
+package org.asynchttpclient.util;
+
+public class StringBuilderPool {
+
+    public static final StringBuilderPool DEFAULT = new StringBuilderPool();
+
+    private final ThreadLocal<StringBuilder> pool = ThreadLocal.withInitial(() -> new StringBuilder(512));
+
+    /**
+     * BEWARE: MUSN'T APPEND TO ITSELF!
+     * 
+     * @return a pooled StringBuilder
+     */
+    public StringBuilder stringBuilder() {
+        StringBuilder sb = pool.get();
+        sb.setLength(0);
+        return sb;
+    }
+}