SHC - moved to XXH3

NadavKeren · Nov 1, 2024 · 98c154b · 98c154b
1 parent 2f65e91
commit 98c154b
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Showing 4 changed files with 34 additions and 2 deletions.
diff --git a/gradle/dependencies.gradle b/gradle/dependencies.gradle
@@ -63,6 +63,7 @@ ext {
     univocityParsers: '2.9.1',
     ycsb: '0.17.0',
     xz: '1.9',
+    hash4j: '0.18.0',
     zstd: '1.5.2-3',
   ]
   testVersions = [
@@ -167,6 +168,7 @@ ext {
       transitive = false
     },
     xz: "org.tukaani:xz:${versions.xz}",
+    hash4j: "com.dynatrace.hash4j:hash4j:${versions.hash4j}",
     zstd: "com.github.luben:zstd-jni:${versions.zstd}",
   ]
   testLibraries = [

diff --git a/simulator/build.gradle b/simulator/build.gradle
@@ -36,6 +36,7 @@ dependencies {
   implementation libraries.commonsMath3
   implementation libraries.commonsCompress
   implementation libraries.univocityParsers
+  implementation libraries.hash4j
 
   testImplementation testLibraries.testng
 

diff --git a/...b/benmanes/caffeine/cache/simulator/policy/latency_aware/pipeline/SampledHillClimber.java b/...b/benmanes/caffeine/cache/simulator/policy/latency_aware/pipeline/SampledHillClimber.java
@@ -46,7 +46,8 @@ public SampledHillClimber(Config config) {
         stats = new PolicyStats("Sampled " + sampleOrder + " " + mainPipeline.generatePipelineName());
         adaptionTimeframe = settings.adaptionMultiplier() * mainPipeline.cacheCapacity();
 
-        sampler = new FarmHashSampler(sampleOrder);
+//        sampler = new FarmHashSampler(sampleOrder); Testing xxHash3 to see if there is performance improvement, need to check if FarmHash allows for different seeds.
+        sampler = new XXH3Sampler(sampleOrder, settings.randomSeed());
         sampledMainCache = new PipelinePolicy(config, sampleOrder);
         final int numOfCaches = blockCount * (blockCount - 1);
         ghostCaches = new ArrayList<>(numOfCaches);
@@ -64,7 +65,6 @@ private void createGhostCaches() {
         }
 
         ghostCaches.clear();
-
         int idx = 0;
         for (int inc = 0; inc < blockCount; ++inc) {
             for (int dec = 0; dec < blockCount; ++dec) {

diff --git a/...m/github/benmanes/caffeine/cache/simulator/policy/latency_aware/pipeline/XXH3Sampler.java b/...m/github/benmanes/caffeine/cache/simulator/policy/latency_aware/pipeline/XXH3Sampler.java
@@ -0,0 +1,29 @@
+package com.github.benmanes.caffeine.cache.simulator.policy.latency_aware.pipeline;
+import com.dynatrace.hash4j.hashing.Hasher64;
+import com.dynatrace.hash4j.hashing.XXH3_64;
+import com.dynatrace.hash4j.hashing.HashFunnel;
+
+public class XXH3Sampler implements LongSampler{
+    private HashFunnel<Long> funnel = (o, sink) -> sink.putLong(o);
+    private long mask;
+
+    private Hasher64 hash;
+    public XXH3Sampler(int order, long seed) {
+        mask = createMask(order);
+        hash = XXH3_64.create(seed);
+    }
+
+    @Override
+    public boolean shouldSample(long key) {
+        return (hash.hashToLong(key, funnel) & mask) == 0;
+    }
+
+    private static long createMask(int exp) {
+        long mask = 0;
+        for (int i = 0; i < exp; ++i) {
+            mask = mask << 1 | 1;
+        }
+
+        return mask;
+    }
+}