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Minor optimization to avoid using BigInteger if possible #1016

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Merged
merged 2 commits into from
Sep 27, 2019
Merged

Minor optimization to avoid using BigInteger if possible #1016

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05c9510
Minor optimization to avoid using BigInteger if possible
tylerbenson Sep 26, 2019
82d60c2
Fix codeNarc
tylerbenson Sep 27, 2019
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11 changes: 10 additions & 1 deletion dd-trace-ot/src/main/java/datadog/opentracing/DDSpan.java
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Original file line number Diff line number Diff line change
Expand Up @@ -417,6 +417,7 @@ public String toString() {
}

protected static class UInt64IDStringSerializer extends StdSerializer<String> {
private static final int LONG_PARSE_LIMIT = String.valueOf(Long.MAX_VALUE).length();

public UInt64IDStringSerializer() {
this(null);
Expand All @@ -430,7 +431,15 @@ public UInt64IDStringSerializer(final Class<String> stringClass) {
public void serialize(
final String value, final JsonGenerator gen, final SerializerProvider provider)
throws IOException {
gen.writeNumber(new BigInteger(value));
final int length = value.length();
// BigInteger's are expensive, so lets try to avoid using them if possible.
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Can we use JsonGenerator::writeNumber(String)?
The doc says it isn't support for all generators, but if it is available it would save us parsing & allocating.

My other thought was a custom Number class to represent UInt64, but JsonGenerator doesn't support that.

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While I agree, that would be nice to use, but unfortunately this is what that would end up using: https://github.com/msgpack/msgpack-java/blob/0.8.18/msgpack-jackson/src/main/java/org/msgpack/jackson/dataformat/MessagePackGenerator.java#L437-L477

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Ah, fair enough. I was hoping that it would be implemented more efficiently, but apparently, it is less efficient.

// This is a rough approximation for optimization.
// There are some values that would pass this test that could be parsed with Long.parseLong.
if (length > LONG_PARSE_LIMIT || (length == LONG_PARSE_LIMIT && value.startsWith("9"))) {
gen.writeNumber(new BigInteger(value));
} else {
gen.writeNumber(Long.parseLong(value));
}
}
}
}
3 changes: 2 additions & 1 deletion dd-trace-ot/src/test/groovy/datadog/opentracing/DDSpanSerializationTest.groovy
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@@ -1,6 +1,5 @@
package datadog.opentracing


import com.fasterxml.jackson.databind.ObjectMapper
import com.google.common.collect.Maps
import datadog.trace.agent.test.utils.ConfigUtils
Expand Down Expand Up @@ -128,7 +127,9 @@ class DDSpanSerializationTest extends Specification {
value | _
BigInteger.ZERO | _
BigInteger.ONE | _
8223372036854775807G | _
BigInteger.valueOf(Long.MAX_VALUE).subtract(BigInteger.ONE) | _
BigInteger.valueOf(Long.MAX_VALUE).add(BigInteger.ONE) | _
BigInteger.valueOf(2).pow(64).subtract(BigInteger.ONE) | _
}
}