Improve performance 20%-110%

.gitignore

@@ -4,3 +4,4 @@
 /target
 /.idea
 /*.iml
+*.jfr

pom.xml

@@ -27,6 +27,7 @@
 		<logback-classic.version>1.1.3</logback-classic.version>
 		<hamcrest-all.version>1.3</hamcrest-all.version>
 		<junit.version>4.12</junit.version>
+		<jmh.version>1.21</jmh.version>
 	</properties>
 
 	<developers>
@@ -105,8 +106,11 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>3.2</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.7</source>
+					<target>1.7</target>
+					<compilerArgs>
+						<arg>-Werror</arg>
+					</compilerArgs>
 					<compilerArgument></compilerArgument>
 				</configuration>
 			</plugin>
@@ -214,6 +218,16 @@
 			<artifactId>hamcrest-all</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.openjdk.jmh</groupId>
+			<artifactId>jmh-core</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.openjdk.jmh</groupId>
+			<artifactId>jmh-generator-annprocess</artifactId>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<dependencyManagement>
@@ -243,6 +257,18 @@
 				<artifactId>hamcrest-all</artifactId>
 				<version>${hamcrest-all.version}</version>
 			</dependency>
+			<dependency>
+				<groupId>org.openjdk.jmh</groupId>
+				<artifactId>jmh-core</artifactId>
+				<version>${jmh.version}</version>
+				<scope>test</scope>
+			</dependency>
+			<dependency>
+				<groupId>org.openjdk.jmh</groupId>
+				<artifactId>jmh-generator-annprocess</artifactId>
+				<version>${jmh.version}</version>
+				<scope>test</scope>
+			</dependency>
 		</dependencies>
 	</dependencyManagement>
 

src/main/java/com/arangodb/velocypack/VPackBuilder.java

@@ -23,6 +23,7 @@
 import java.io.UnsupportedEncodingException;
 import java.math.BigDecimal;
 import java.math.BigInteger;
+import java.nio.charset.StandardCharsets;
 import java.sql.Timestamp;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -46,6 +47,7 @@
 import com.arangodb.velocypack.internal.DefaultVPackBuilderOptions;
 import com.arangodb.velocypack.internal.Value;
 import com.arangodb.velocypack.internal.util.NumberUtil;
+import com.fasterxml.jackson.core.io.CharTypes;
 
 /**
  * @author Mark Vollmary
@@ -216,7 +218,7 @@ public void append(final VPackBuilder builder, final VPackSlice value) throws VP
 	private int size;
 	private final List<Integer> stack; // Start positions of open
 										// objects/arrays
-	private final Map<Integer, List<Integer>> index; // Indices for starts
+	private List<List<Integer>> index; // Indices for starts
 														// of
 														// subindex
 	private boolean keyWritten; // indicates that in the current object the key
@@ -233,7 +235,7 @@ public VPackBuilder(final BuilderOptions options) {
 		size = 0;
 		buffer = new byte[10];
 		stack = new ArrayList<Integer>();
-		index = new HashMap<Integer, List<Integer>>();
+		index = new ArrayList<List<Integer>>(4);
 	}
 
 	public BuilderOptions getOptions() {
@@ -546,7 +548,7 @@ private void set(final Value item) throws VPackBuilderException {
 				throw new VPackBuilderUnexpectedValueException(ValueType.UINT, Long.class, Integer.class,
 						BigInteger.class);
 			}
-			if (-1 == vUInt.compareTo(BigInteger.ZERO)) {
+			if (vUInt.compareTo(BigInteger.ZERO) < 0) {
 				throw new VPackBuilderUnexpectedValueException(ValueType.UINT, "non-negative", Long.class,
 						Integer.class, BigInteger.class);
 			}
@@ -620,22 +622,18 @@ private void appendSQLTimestamp(final Timestamp value) {
 		append(value.getTime(), LONG_BYTES);
 	}
 
-	private void appendString(final String value) throws VPackBuilderException {
-		try {
-			final byte[] bytes = value.getBytes("UTF-8");
-			final int length = bytes.length;
-			if (length <= 126) {
-				// short string
-				add((byte) (0x40 + length));
-			} else {
-				// long string
-				add((byte) 0xbf);
-				appendLength(length);
-			}
-			appendString(bytes);
-		} catch (final UnsupportedEncodingException e) {
-			throw new VPackBuilderException(e);
+	private void appendString(final String value) {
+		final byte[] bytes = value.getBytes(StandardCharsets.UTF_8);
+		final int length = bytes.length;
+		if (length <= 126) {
+			// short string
+			add((byte) (0x40 + length));
+		} else {
+			// long string
+			add((byte) 0xbf);
+			appendLength(length);
 		}
+		appendString(bytes);
 	}
 
 	private void appendString(final byte[] bytes) {
@@ -670,7 +668,7 @@ private void addObject(final boolean unindexed) {
 	private void addCompoundValue(final byte head) {
 		// an Array or Object is started:
 		stack.add(size);
-		index.put(stack.size() - 1, new ArrayList<Integer>());
+		index.add(stack.size() - 1, new ArrayList<Integer>());
 		add(head);
 		// Will be filled later with bytelength and nr subs
 		size += 8;
@@ -990,10 +988,10 @@ private VPackBuilder closeArray(final int tos, final List<Integer> in) {
 	}
 
 	private static class SortEntry {
-		private final VPackSlice slice;
+		private final VPackStringSlice slice;
 		private final int offset;
 
-		public SortEntry(final VPackSlice slice, final int offset) {
+		public SortEntry(final VPackStringSlice slice, final int offset) {
 			super();
 			this.slice = slice;
 			this.offset = offset;
@@ -1002,17 +1000,18 @@ public SortEntry(final VPackSlice slice, final int offset) {
 
 	private void sortObjectIndex(final int start, final List<Integer> offsets)
 			throws VPackKeyTypeException, VPackNeedAttributeTranslatorException {
-		final List<VPackBuilder.SortEntry> attributes = new ArrayList<VPackBuilder.SortEntry>();
-		for (final Integer offset : offsets) {
-			attributes.add(new SortEntry(new VPackSlice(buffer, start + offset).makeKey(), offset));
+		VPackBuilder.SortEntry[] attributes = new VPackBuilder.SortEntry[offsets.size()];
+		for (int i = 0; i < offsets.size(); i++) {
+			Integer offset = offsets.get(i);
+			attributes[i] = new SortEntry(new VPackSlice(buffer, start + offset).makeKey().getAsStringSlice(), offset);
 		}
 		final Comparator<SortEntry> comparator = new Comparator<SortEntry>() {
 			@Override
 			public int compare(final SortEntry o1, final SortEntry o2) {
-				return o1.slice.getAsString().compareTo(o2.slice.getAsString());
+				return o1.slice.compareTo(o2.slice);
 			}
 		};
-		Collections.sort(attributes, comparator);
+		Arrays.sort(attributes, comparator);
 		offsets.clear();
 		for (final SortEntry sortEntry : attributes) {
 			offsets.add(sortEntry.offset);

src/main/java/com/arangodb/velocypack/VPackSlice.java

@@ -24,10 +24,12 @@
 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Date;
 import java.util.Iterator;
 import java.util.Map.Entry;
+import java.lang.Comparable;
 
 import com.arangodb.velocypack.exception.VPackException;
 import com.arangodb.velocypack.exception.VPackKeyTypeException;
@@ -294,6 +296,10 @@ public java.sql.Timestamp getAsSQLTimestamp() {
 	}
 
 	public String getAsString() {
+		return getAsStringSlice().toString();
+	}
+
+	public VPackStringSlice getAsStringSlice() {
 		if (!isString()) {
 			throw new VPackValueTypeException(ValueType.STRING);
 		}
@@ -308,12 +314,12 @@ private boolean isLongString() {
 		return head() == (byte) 0xbf;
 	}
 
-	private String getShortString() {
-		return new String(vpack, start + 1, length(), Charset.forName("UTF-8"));
+	private VPackStringSlice getShortString() {
+		return new VPackStringSlice(vpack, start + 1, length());
 	}
 
-	private String getLongString() {
-		return new String(vpack, start + 9, getLongStringLength(), Charset.forName("UTF-8"));
+	private VPackStringSlice getLongString() {
+		return new VPackStringSlice(vpack, start + 9, getLongStringLength());
 	}
 
 	private int getLongStringLength() {
@@ -574,6 +580,7 @@ private VPackSlice searchObjectKeyBinary(
 		long l = 0;
 		long r = n - 1;
 
+		byte[] attributeBytes = attribute.getBytes(StandardCharsets.UTF_8);
 		for (;;) {
 			// midpoint
 			final long index = l + ((r - l) / 2);
@@ -582,14 +589,14 @@ private VPackSlice searchObjectKeyBinary(
 			final VPackSlice key = new VPackSlice(vpack, (int) (start + keyIndex));
 			int res = 0;
 			if (key.isString()) {
-				res = key.compareString(attribute);
+				res = key.getAsStringSlice().compareToBytes(attributeBytes);
 			} else if (key.isInteger()) {
 				// translate key
 				if (!useTranslator) {
 					// no attribute translator
 					throw new VPackNeedAttributeTranslatorException();
 				}
-				res = key.translateUnchecked().compareString(attribute);
+				res = key.translateUnchecked().getAsStringSlice().compareToBytes(attributeBytes);
 			} else {
 				// invalid key
 				result = new VPackSlice();
@@ -816,4 +823,5 @@ public boolean equals(final Object obj) {
 		return true;
 	}
 
+
 }

src/main/java/com/arangodb/velocypack/VPackStringSlice.java

@@ -0,0 +1,46 @@
+package com.arangodb.velocypack;
+
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Wrapper around a {@link ValueType#STRING} supporting fast bytewise comparison.
+ *
+ * @see <a href="https://github.com/arangodb/velocypack/blob/master/VelocyPack.md#objects">VelocyPack Objects</a>
+ */
+public class VPackStringSlice implements Comparable<VPackStringSlice> {
+    private byte[] vpack;
+    /**
+     * Index of the string bytes within {@link vpack},
+     * i.e. tag byte and length are somewhere before this index.
+     */
+    private int start;
+    private int length;
+
+    public VPackStringSlice(byte[] vpack, int start, int length) {
+        this.vpack = vpack;
+        this.start = start;
+        this.length = length;
+    }
+
+    @Override
+    public int compareTo(VPackStringSlice o) {
+        return compareToBytes(o.vpack, o.start, o.length);
+    }
+
+    public int compareToBytes(byte[] other) {
+        return compareToBytes(other, 0, other.length);
+    }
+
+    public int compareToBytes(byte[] other, int off, int oLen) {
+        for (int i = 0; i < length && i < oLen; i++) {
+            int c = (vpack[start + i] & 0xff) - (other[off + i] & 0xff);
+            if (c != 0) return c;
+        }
+        return length - oLen;
+    }
+
+    @Override
+    public String toString() {
+        return new String(vpack, start, length, StandardCharsets.UTF_8);
+    }
+}