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prefer instanceOf instead of getClass() (#9366)

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Motivation:

`instanceOf` doesn't perform null check like `getClass()` does. So `instanceOf` may be faster. However, it not true for all cases, as C2 could eliminate these null checks for `getClass()`.

Modification:

Replaced `string.getClass() == AsciiString.class` with `string instanceof AsciiString`.

Proof:

```
@BenchmarkMode(Mode.Throughput)
@Fork(value = 1)
@State(Scope.Thread)
@Warmup(iterations = 5, time = 1, batchSize = 1000)
@Measurement(iterations = 10, time = 1, batchSize = 1000)
public class GetClassInstanceOf {

    Object key;

    @Setup
    public void setup() {
        key = "123";
    }

    @Benchmark
    public boolean getClassEquals() {
        return key.getClass() == String.class;
    }

    @Benchmark
    public boolean instanceOf() {
        return key instanceof String;
    }

}
```

```
Benchmark                           Mode  Cnt       Score      Error  Units
GetClassInstanceOf.getClassEquals  thrpt   10  401863.130 ± 3092.568  ops/s
GetClassInstanceOf.instanceOf      thrpt   10  421386.176 ± 4317.328  ops/s
```
This commit is contained in:
Dmitriy Dumanskiy 2019-07-16 22:20:12 +03:00 committed by Norman Maurer
parent d07d7e2b9a
commit a82d62ae67
1 changed files with 10 additions and 10 deletions
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20
common/src/main/java/io/netty/util/AsciiString.java
View File

@ -477,7 +477,7 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
return this; return this;
} }
if (string.getClass() == AsciiString.class) { if (string instanceof AsciiString) {
AsciiString that = (AsciiString) string; AsciiString that = (AsciiString) string;
if (isEmpty()) { if (isEmpty()) {
return that; return that;
@ -530,7 +530,7 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
return false; return false;
} }
if (string.getClass() == AsciiString.class) { if (string instanceof AsciiString) {
AsciiString rhs = (AsciiString) string; AsciiString rhs = (AsciiString) string;
for (int i = arrayOffset(), j = rhs.arrayOffset(); i < length(); ++i, ++j) { for (int i = arrayOffset(), j = rhs.arrayOffset(); i < length(); ++i, ++j) {
if (!equalsIgnoreCase(value[i], rhs.value[j])) { if (!equalsIgnoreCase(value[i], rhs.value[j])) {
@ -989,7 +989,7 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
* @return a new string with characters {@code <= \\u0020} removed from the beginning and the end. * @return a new string with characters {@code <= \\u0020} removed from the beginning and the end.
*/ */
public static CharSequence trim(CharSequence c) { public static CharSequence trim(CharSequence c) {
if (c.getClass() == AsciiString.class) { if (c instanceof AsciiString) {
return ((AsciiString) c).trim(); return ((AsciiString) c).trim();
} }
if (c instanceof String) { if (c instanceof String) {
@ -1044,7 +1044,7 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
if (a == null || a.length() != length()) { if (a == null || a.length() != length()) {
return false; return false;
} }
if (a.getClass() == AsciiString.class) { if (a instanceof AsciiString) {
return equals(a); return equals(a);
} }
@ -1393,7 +1393,7 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
* {@link AsciiString}, just returns the same instance. * {@link AsciiString}, just returns the same instance.
*/ */
public static AsciiString of(CharSequence string) { public static AsciiString of(CharSequence string) {
return string.getClass() == AsciiString.class ? (AsciiString) string : new AsciiString(string); return string instanceof AsciiString ? (AsciiString) string : new AsciiString(string);
} }
/** /**
@ -1417,7 +1417,7 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
if (value == null) { if (value == null) {
return 0; return 0;
} }
if (value.getClass() == AsciiString.class) { if (value instanceof AsciiString) {
return value.hashCode(); return value.hashCode();
} }
@ -1447,10 +1447,10 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
return a == b; return a == b;
} }
if (a.getClass() == AsciiString.class) { if (a instanceof AsciiString) {
return ((AsciiString) a).contentEqualsIgnoreCase(b); return ((AsciiString) a).contentEqualsIgnoreCase(b);
} }
if (b.getClass() == AsciiString.class) { if (b instanceof AsciiString) {
return ((AsciiString) b).contentEqualsIgnoreCase(a); return ((AsciiString) b).contentEqualsIgnoreCase(a);
} }
@ -1509,11 +1509,11 @@ public final class AsciiString implements CharSequence, Comparable<CharSequence>
return a == b; return a == b;
} }
if (a.getClass() == AsciiString.class) { if (a instanceof AsciiString) {
return ((AsciiString) a).contentEquals(b); return ((AsciiString) a).contentEquals(b);
} }
if (b.getClass() == AsciiString.class) { if (b instanceof AsciiString) {
return ((AsciiString) b).contentEquals(a); return ((AsciiString) b).contentEquals(a);
} }