Simplify Tracer.shouldObserve #870
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Uses a simple condition rather than a switch statement
After:
`javap -c -p ./tracing/build/classes/java/main/com/palantir/tracing/Tracer.class`
```
private static boolean shouldObserve(com.palantir.tracing.Observability);
Code:
0: aload_0
1: getstatic #10 // Field com/palantir/tracing/Observability.SAMPLE:Lcom/palantir/tracing/Observability;
4: if_acmpeq 25
7: aload_0
8: getstatic #11 // Field com/palantir/tracing/Observability.UNDECIDED:Lcom/palantir/tracing/Observability;
11: if_acmpne 29
14: getstatic #12 // Field sampler:Lcom/palantir/tracing/TraceSampler;
17: invokeinterface #13, 1 // InterfaceMethod com/palantir/tracing/TraceSampler.sample:()Z
22: ifeq 29
25: iconst_1
26: goto 30
29: iconst_0
30: ireturn
```
Before:
`javap -c -p ./tracing/build/classes/java/main/com/palantir/tracing/Tracer.class`
```
private static boolean shouldObserve(com.palantir.tracing.Observability);
Code:
0: getstatic #10 // Field com/palantir/tracing/Tracer$1.$SwitchMap$com$palantir$tracing$Observability:[I
3: aload_0
4: invokevirtual #11 // Method com/palantir/tracing/Observability.ordinal:()I
7: iaload
8: tableswitch { // 1 to 3
1: 36
2: 38
3: 40
default: 49
}
36: iconst_1
37: ireturn
38: iconst_0
39: ireturn
40: getstatic #12 // Field sampler:Lcom/palantir/tracing/TraceSampler;
43: invokeinterface #13, 1 // InterfaceMethod com/palantir/tracing/TraceSampler.sample:()Z
48: ireturn
49: new #14 // class com/palantir/logsafe/exceptions/SafeIllegalArgumentException
52: dup
53: ldc #15 // String Unknown observability
55: iconst_1
56: anewarray #16 // class com/palantir/logsafe/Arg
59: dup
60: iconst_0
61: ldc #17 // String observability
63: aload_0
64: invokestatic #18 // Method com/palantir/logsafe/SafeArg.of:(Ljava/lang/String;Ljava/lang/Object;)Lcom/palantir/logsafe/SafeArg;
67: aastore
68: invokespecial #19 // Method com/palantir/logsafe/exceptions/SafeIllegalArgumentException."<init>":(Ljava/lang/String;[Lcom/palantir/logsafe/Arg;)V
71: athrow
```
Benchmarks show improvement within variance:
Benchmarks AFTER:
```
Benchmark (observability) Mode Cnt Score Error Units
TracingBenchmark.traceWithSingleSpan SAMPLE avgt 3 533.719 ± 164.796 ns/op
TracingBenchmark.traceWithSingleSpan DO_NOT_SAMPLE avgt 3 100.138 ± 35.819 ns/op
TracingBenchmark.traceWithSingleSpan UNDECIDED avgt 3 122.807 ± 64.274 ns/op
```
Benchmarks BEFORE:
```
Benchmark (observability) Mode Cnt Score Error Units
TracingBenchmark.traceWithSingleSpan SAMPLE avgt 3 522.865 ± 65.310 ns/op
TracingBenchmark.traceWithSingleSpan DO_NOT_SAMPLE avgt 3 112.647 ± 48.826 ns/op
TracingBenchmark.traceWithSingleSpan UNDECIDED avgt 3 118.643 ± 6.733 ns/op
```
Generate changelog in
|
fawind
approved these changes
Mar 9, 2022
|
Released 6.11.0 |
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Uses a simple condition rather than a switch statement so that shouldObserve falls below the
-XX:MaxInlineSizedefault value of 35 bytes.After:
javap -c -p ./tracing/build/classes/java/main/com/palantir/tracing/Tracer.classBefore:
javap -c -p ./tracing/build/classes/java/main/com/palantir/tracing/Tracer.classBenchmarks show improvement within variance:
Benchmarks AFTER:
Benchmarks BEFORE:
==COMMIT_MSG==
Simplify Tracer.shouldObserve to avoid JIT friction
==COMMIT_MSG==