The current versions of FloatToDecimal and DoubleToDecimal allocate additional
objects. Reducing these allocations can improve the performance of
Float/Double.toString and AbstractStringBuilder's append(float/double).
This patch is just a code refactoring to reduce object allocation, but does not
change the Float/Double to decimal algorithm.
The following code comments the allocated objects to be removed.
class FloatToDecimal {
public static String toString(float v) {
// allocate object FloatToDecimal
return new FloatToDecimal().toDecimalString(v);
}
public static Appendable appendTo(float v, Appendable app)
throws IOException {
// allocate object FloatToDecimal
return new FloatToDecimal().appendDecimalTo(v, app);
}
private Appendable appendDecimalTo(float v, Appendable app)
throws IOException {
switch (toDecimal(v)) {
case NON_SPECIAL:
// allocate object char[]
char[] chars = new char[index + 1];
for (int i = 0; i < chars.length; ++i) {
chars[i] = (char) bytes[i];
}
if (app instanceof StringBuilder builder) {
return builder.append(chars);
}
if (app instanceof StringBuffer buffer) {
return buffer.append(chars);
}
for (char c : chars) {
app.append(c);
}
return app;
// ...
}
}
}
class DoubleToDecimal {
public static String toString(double v) {
// allocate object DoubleToDecimal
return new DoubleToDecimal(false).toDecimalString(v);
}
public static Appendable appendTo(double v, Appendable app)
throws IOException {
// allocate object DoubleToDecimal
return new DoubleToDecimal(false).appendDecimalTo(v, app);
}
private Appendable appendDecimalTo(double v, Appendable app)
throws IOException {
switch (toDecimal(v, null)) {
case NON_SPECIAL:
// allocate object char[]
char[] chars = new char[index + 1];
for (int i = 0; i < chars.length; ++i) {
chars[i] = (char) bytes[i];
}
if (app instanceof StringBuilder builder) {
return builder.append(chars);
}
if (app instanceof StringBuffer buffer) {
return buffer.append(chars);
}
for (char c : chars) {
app.append(c);
}
return app;
// ...
}
}
}
-------------
Commit messages:
- Reduce object allocation for FloatToDecimal and DoubleToDecimal
Changes: https://git.openjdk.org/jdk/pull/19730/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19730&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8334328
Stats: 641 lines in 5 files changed: 293 ins; 211 del; 137 mod
Patch: https://git.openjdk.org/jdk/pull/19730.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/19730/head:pull/19730
PR: https://git.openjdk.org/jdk/pull/19730
