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8316426: Optimization for HexFormat.formatHex
Reviewed-by: liach, rriggs
This commit is contained in:
wenshao
Claes Redestad
parent
32ccf018eb
commit
935543146b
3 changed files with 69 additions and 27 deletions
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@ -27,6 +27,7 @@ package java.util;
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import jdk.internal.access.JavaLangAccess;
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import jdk.internal.access.SharedSecrets;
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import jdk.internal.util.HexDigits;
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import java.io.IOException;
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import java.io.UncheckedIOException;
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@ -150,15 +151,7 @@ public final class HexFormat {
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-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
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};
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/**
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* Format each byte of an array as a pair of hexadecimal digits.
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@ -403,21 +396,20 @@ public final class HexFormat {
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int length = toIndex - fromIndex;
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if (length > 0) {
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try {
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out.append(prefix);
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toHexDigits(out, bytes[fromIndex]);
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if (suffix.isEmpty() && delimiter.isEmpty() && prefix.isEmpty()) {
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for (int i = 1; i < length; i++) {
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toHexDigits(out, bytes[fromIndex + i]);
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}
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String s = formatOptDelimiter(bytes, fromIndex, toIndex);
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if (s != null) {
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out.append(s);
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} else {
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out.append(prefix);
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toHexDigits(out, bytes[fromIndex]);
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for (int i = 1; i < length; i++) {
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out.append(suffix);
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out.append(delimiter);
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out.append(prefix);
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toHexDigits(out, bytes[fromIndex + i]);
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}
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out.append(suffix);
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}
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out.append(suffix);
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} catch (IOException ioe) {
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throw new UncheckedIOException(ioe.getMessage(), ioe);
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}
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@ -438,29 +430,36 @@ public final class HexFormat {
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* or non-empty prefix or suffix
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*/
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private String formatOptDelimiter(byte[] bytes, int fromIndex, int toIndex) {
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char sep;
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byte[] rep;
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if (!prefix.isEmpty() || !suffix.isEmpty()) {
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return null;
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}
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boolean ucase = digitCase == Case.UPPERCASE;
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int length = toIndex - fromIndex;
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if (delimiter.isEmpty()) {
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// Allocate the byte array and fill in the hex pairs for each byte
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rep = new byte[checkMaxArraySize(length * 2L)];
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for (int i = 0; i < length; i++) {
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rep[i * 2] = (byte)toHighHexDigit(bytes[fromIndex + i]);
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rep[i * 2 + 1] = (byte)toLowHexDigit(bytes[fromIndex + i]);
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short pair = HexDigits.digitPair(bytes[fromIndex + i], ucase);
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int pos = i * 2;
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rep[pos] = (byte)pair;
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rep[pos + 1] = (byte)(pair >>> 8);
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}
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} else if (delimiter.length() == 1 && delimiter.charAt(0) < 256) {
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} else if (delimiter.length() == 1 && (sep = delimiter.charAt(0)) < 256) {
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// Allocate the byte array and fill in the characters for the first byte
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// Then insert the delimiter and hexadecimal characters for each of the remaining bytes
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char sep = delimiter.charAt(0);
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rep = new byte[checkMaxArraySize(length * 3L - 1L)];
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rep[0] = (byte) toHighHexDigit(bytes[fromIndex]);
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rep[1] = (byte) toLowHexDigit(bytes[fromIndex]);
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short pair = HexDigits.digitPair(bytes[fromIndex], ucase);
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rep[0] = (byte)pair;
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rep[1] = (byte)(pair >>> 8);
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for (int i = 1; i < length; i++) {
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rep[i * 3 - 1] = (byte) sep;
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rep[i * 3 ] = (byte) toHighHexDigit(bytes[fromIndex + i]);
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rep[i * 3 + 1] = (byte) toLowHexDigit(bytes[fromIndex + i]);
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int pos = i * 3;
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pair = HexDigits.digitPair(bytes[fromIndex + i], ucase);
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rep[pos - 1] = (byte) sep;
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rep[pos] = (byte)pair;
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rep[pos + 1] = (byte)(pair >>> 8);
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}
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} else {
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// Delimiter formatting not to a single byte
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@ -887,7 +886,7 @@ public final class HexFormat {
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* otherwise {@code false}
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*/
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public static boolean isHexDigit(int ch) {
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return ((ch >>> 8) == 0 && DIGITS[ch] >= 0);
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return ((ch >>> 7) == 0 && DIGITS[ch] >= 0);
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}
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/**
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@ -905,7 +904,7 @@ public final class HexFormat {
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*/
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public static int fromHexDigit(int ch) {
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int value;
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if ((ch >>> 8) == 0 && (value = DIGITS[ch]) >= 0) {
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if ((ch >>> 7) == 0 && (value = DIGITS[ch]) >= 0) {
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return value;
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}
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throw new NumberFormatException("not a hexadecimal digit: \"" + (char) ch + "\" = " + ch);
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@ -91,6 +91,30 @@ public final class HexDigits implements Digits {
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private HexDigits() {
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}
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/**
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* For values from 0 to 255 return a short encoding a pair of hex ASCII-encoded digit characters in little-endian
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* @param i value to convert
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* @param ucase true uppper case, false lower case
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* @return a short encoding a pair of hex ASCII-encoded digit characters
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*/
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public static short digitPair(int i, boolean ucase) {
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/*
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* 0b0100_0000_0100_0000 is a selector that selects letters (1 << 6),
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* uppercase or not, and shifting it right by 1 bit incidentally
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* becomes a bit offset between cases (1 << 5).
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*
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* ([0-9] & 0b100_0000) >> 1 => 0
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* ([a-f] & 0b100_0000) >> 1 => 32
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*
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* [0-9] - 0 => [0-9]
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* [a-f] - 32 => [A-F]
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*/
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short v = DIGITS[i & 0xff];
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return ucase
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? (short) (v - ((v & 0b0100_0000_0100_0000) >> 1))
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: v;
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}
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/**
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* Return a little-endian packed integer for the 4 ASCII bytes for an input unsigned 2-byte integer.
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* {@code b0} is the most significant byte and {@code b1} is the least significant byte.
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@ -93,6 +93,25 @@ public class HexFormatBench {
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return UPPER_FORMATTER.formatHex(builder, bytes);
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}
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@Benchmark
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public String formatLower() {
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return HexFormat.of().formatHex(bytes);
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}
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@Benchmark
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public String formatUpper() {
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return HexFormat.of().withUpperCase().formatHex(bytes);
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}
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@Benchmark
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public String formatLowerCached() {
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return LOWER_FORMATTER.formatHex(bytes);
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}
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@Benchmark
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public String formatUpperCached() {
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return UPPER_FORMATTER.formatHex(bytes);
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}
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@Benchmark
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public void toHexLower(Blackhole bh) {
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