add utility for computing 64-bit hash (#1058)

Currently based on XXH64. Allows for data to be incrementally
fed to the hash accumulator to make it more convenient to use
and avoid allocations creating the structure needed to pass
into the hash. Though in some cases the incremental processing
is slower than just passing in something like a precomputed
string.

build.gradle

@@ -102,6 +102,7 @@ subprojects {
     toolVersion = '9.3'
     ignoreFailures = false 
     configFile = rootProject.file('codequality/checkstyle.xml')
+    configDirectory = rootProject.file("codequality")
     sourceSets = [sourceSets.main]
   }
 

codequality/checkstyle-suppressions.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+
+<!DOCTYPE suppressions PUBLIC
+    "-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
+    "https://checkstyle.org/dtds/suppressions_1_2.dtd">
+
+<suppressions>
+  <suppress checks="IllegalImport" files="UnsafeUtils.java"/>
+</suppressions>

codequality/checkstyle.xml

@@ -170,4 +170,7 @@
         <module name="SuppressWarningsHolder"/>
     </module>
     <module name="SuppressWarningsFilter"/>
+    <module name="SuppressionFilter">
+      <property name="file" value="${config_loc}/checkstyle-suppressions.xml"/>
+    </module>
 </module>

codequality/findbugs-exclude.xml

@@ -6,6 +6,12 @@
       <Bug pattern="EQ_COMPARETO_USE_OBJECT_EQUALS"/>
     </And>
   </Match>
+  <Match>
+    <And>
+      <Class name="com.netflix.spectator.impl.UnsafeUtils"/>
+      <Bug pattern="REC_CATCH_EXCEPTION"/>
+    </And>
+  </Match>
   <Match>
     <Bug pattern="EI_EXPOSE_REP"/>
   </Match>

dependencies.properties

@@ -18,6 +18,7 @@ com.typesafe:config = 1.4.2
 io.dropwizard.metrics5:metrics-core = 5.0.0-rc15 # 5.0.0 is a bad version do not use
 io.micrometer:micrometer-core = 1.10.6
 javax.inject:javax.inject = 1
+net.openhft:zero-allocation-hashing = 0.16
 nl.jqno.equalsverifier:equalsverifier = 3.14.1
 org.apache.logging.log4j:log4j-api = 2.20.0
 org.apache.logging.log4j:log4j-core = 2.20.0

spectator-api/build.gradle

@@ -2,9 +2,11 @@
 dependencies {
   testImplementation files("$projectDir/src/test/lib/compatibility-0.68.0.jar")
   testImplementation "com.google.re2j:re2j"
+  testImplementation "net.openhft:zero-allocation-hashing"
   testImplementation "org.hsqldb:hsqldb"
   jmh "com.google.re2j:re2j"
   jmh "com.github.ben-manes.caffeine:caffeine"
+  jmh "net.openhft:zero-allocation-hashing"
 }
 
 javadoc {

spectator-api/src/jmh/java/com/netflix/spectator/perf/IdHash.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2014-2023 Netflix, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.netflix.spectator.perf;
+
+import com.netflix.spectator.api.Id;
+import com.netflix.spectator.impl.Hash64;
+import net.openhft.hashing.LongHashFunction;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.infra.Blackhole;
+
+/**
+ * Benchmark                             Mode  Cnt        Score        Error   Units
+ * IdHash.hash64                        thrpt    5  2379245.474 ±   7379.034   ops/s
+ * IdHash.hash64_2                      thrpt    5  4817014.307 ±   5704.027   ops/s
+ * IdHash.openhft                       thrpt    5  4910133.221 ± 100296.076   ops/s
+ *
+ * Benchmark                             Mode  Cnt        Score        Error   Units
+ * IdHash.hash64:·gc.alloc.rate.norm    thrpt    5        0.188 ±      0.002    B/op
+ * IdHash.hash64_2:·gc.alloc.rate.norm  thrpt    5     1152.095 ±      0.001    B/op
+ * IdHash.openhft:·gc.alloc.rate.norm   thrpt    5     1128.095 ±      0.002    B/op
+ */
+@State(Scope.Thread)
+public class IdHash {
+
+  private final Id id = Id.create("http.req.complete")
+      .withTag(    "nf.app", "test_app")
+      .withTag("nf.cluster", "test_app-main")
+      .withTag(    "nf.asg", "test_app-main-v042")
+      .withTag(  "nf.stack", "main")
+      .withTag(    "nf.ami", "ami-0987654321")
+      .withTag( "nf.region", "us-east-1")
+      .withTag(   "nf.zone", "us-east-1e")
+      .withTag(   "nf.node", "i-1234567890")
+      .withTag(   "country", "US")
+      .withTag(    "device", "xbox")
+      .withTag(    "status", "200")
+      .withTag(    "client", "ab");
+
+  private final Hash64 h64 = new Hash64();
+  private final LongHashFunction xx = LongHashFunction.xx();
+
+  @Benchmark
+  public void hash64(Blackhole bh) {
+    h64.updateString(id.name());
+    for (int i = 1; i < id.size(); ++i) {
+      h64.updateChar(':');
+      h64.updateString(id.getKey(i));
+      h64.updateChar('=');
+      h64.updateString(id.getValue(i));
+    }
+    bh.consume(h64.computeAndReset());
+  }
+
+  @Benchmark
+  public void hash64_2(Blackhole bh) {
+    bh.consume(h64.updateString(id.toString()).computeAndReset());
+  }
+
+  @Benchmark
+  public void openhft(Blackhole bh) {
+    bh.consume(xx.hashChars(id.toString()));
+  }
+}