From b76d374699def8d8d117b0765631c2ed06486283 Mon Sep 17 00:00:00 2001
From: Anuraag Agrawal <aanuraag@amazon.co.jp>
Date: Tue, 9 Jun 2020 09:03:27 +0900
Subject: [PATCH] Use singleton SecureRandom (#162)

---
 .../amazonaws/xray/entities/IdsBenchmark.java | 85 +++++++++++++++++++
 .../amazonaws/xray/ThreadLocalStorage.java    | 12 +--
 2 files changed, 88 insertions(+), 9 deletions(-)
 create mode 100644 aws-xray-recorder-sdk-benchmark/tst/main/java/com/amazonaws/xray/entities/IdsBenchmark.java

diff --git a/aws-xray-recorder-sdk-benchmark/tst/main/java/com/amazonaws/xray/entities/IdsBenchmark.java b/aws-xray-recorder-sdk-benchmark/tst/main/java/com/amazonaws/xray/entities/IdsBenchmark.java
new file mode 100644
index 00000000..fe966ef5
--- /dev/null
+++ b/aws-xray-recorder-sdk-benchmark/tst/main/java/com/amazonaws/xray/entities/IdsBenchmark.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file 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.amazonaws.xray.entities;
+
+import com.amazonaws.xray.ThreadLocalStorage;
+import java.math.BigInteger;
+import java.security.SecureRandom;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Threads;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+@Measurement(iterations = 5, time = 1)
+@Warmup(iterations = 10, time = 1)
+@Fork(3)
+@BenchmarkMode(Mode.SampleTime)
+@OutputTimeUnit(TimeUnit.MICROSECONDS)
+@Threads(16)
+public class IdsBenchmark {
+
+    private static final SecureRandom SECURE_RANDOM = new SecureRandom();
+
+    @Benchmark
+    public BigInteger traceId_secureRandom() {
+        return new BigInteger(96, SECURE_RANDOM);
+    }
+
+    @Benchmark
+    public BigInteger traceId_threadLocalSecureRandom() {
+        return new BigInteger(96, ThreadLocalStorage.getRandom());
+    }
+
+    @Benchmark
+    public BigInteger traceId_threadLocalRandom() {
+        return new BigInteger(96, ThreadLocalRandom.current());
+    }
+
+    @Benchmark
+    public String segmentId_secureRandom() {
+        return Long.toString(SECURE_RANDOM.nextLong() >>> 1, 16);
+    }
+
+    @Benchmark
+    public String segmentId_threadLocalSecureRandom() {
+        return Long.toString(ThreadLocalStorage.getRandom().nextLong() >>> 1, 16);
+    }
+
+    @Benchmark
+    public String segmentId_threadLocalRandom() {
+        return Long.toString(ThreadLocalRandom.current().nextLong() >>> 1, 16);
+    }
+
+    // Convenience main entry-point
+    public static void main(String[] args) throws RunnerException {
+        Options opt = new OptionsBuilder()
+            .addProfiler("gc")
+            .include(".*" + IdsBenchmark.class.getSimpleName())
+            .build();
+
+        new Runner(opt).run();
+    }
+}
diff --git a/aws-xray-recorder-sdk-core/src/main/java/com/amazonaws/xray/ThreadLocalStorage.java b/aws-xray-recorder-sdk-core/src/main/java/com/amazonaws/xray/ThreadLocalStorage.java
index 2f3992e0..f1c4b940 100644
--- a/aws-xray-recorder-sdk-core/src/main/java/com/amazonaws/xray/ThreadLocalStorage.java
+++ b/aws-xray-recorder-sdk-core/src/main/java/com/amazonaws/xray/ThreadLocalStorage.java
@@ -25,6 +25,8 @@
 @Deprecated
 public class ThreadLocalStorage {
 
+    private static final SecureRandom SECURE_RANDOM = new SecureRandom();
+
     static class LocalEntity extends ThreadLocal<Entity> {
         @Override
         protected Entity initialValue() {
@@ -32,15 +34,7 @@ protected Entity initialValue() {
         }
     }
 
-    static class LocalSecureRandom extends ThreadLocal<SecureRandom> {
-        @Override
-        protected SecureRandom initialValue() {
-            return new SecureRandom();
-        }
-    }
-
     private static final LocalEntity CURRENT_ENTITY = new LocalEntity();
-    private static final LocalSecureRandom CURRENT_RANDOM = new LocalSecureRandom();
 
     public static Entity get() {
         return CURRENT_ENTITY.get();
@@ -63,6 +57,6 @@ public static void clear() {
     }
 
     public static SecureRandom getRandom() {
-        return CURRENT_RANDOM.get();
+        return SECURE_RANDOM;
     }
 }