Add RNGPerformanceTest to help diagnose performance bottlenecks

Related to https://github.com/pgpainless/pgpainless/issues/309

pgpainless-core/src/test/java/investigations/RNGPerformanceTest.java

@@ -0,0 +1,88 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package investigations;
+
+import org.bouncycastle.crypto.digests.SHA1Digest;
+import org.bouncycastle.crypto.digests.SHA256Digest;
+import org.bouncycastle.crypto.prng.DigestRandomGenerator;
+import org.junit.jupiter.api.Test;
+import org.junit.platform.commons.logging.Logger;
+import org.junit.platform.commons.logging.LoggerFactory;
+
+import java.security.SecureRandom;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Random;
+
+/**
+ * Evaluate performance of random number generators.
+ */
+public class RNGPerformanceTest {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(RNGPerformanceTest.class);
+    private static final int bytesInMebiByte = 1024 * 1024;
+
+    @Test
+    public void evaluateRandomPerformance() {
+        Random random = new Random();
+        byte[] bytes = new byte[bytesInMebiByte];
+
+        Instant start = Instant.now();
+        random.nextBytes(bytes);
+        Instant end = Instant.now();
+
+        Duration duration = Duration.between(start, end);
+        LOGGER.info(() -> String.format(
+                "Random.nextBytes() took %s milliseconds to generate 1 MiB of data",
+                duration.toMillis()));
+    }
+
+    @Test
+    public void evaluateSecureRandomPerformance() {
+        SecureRandom random = new SecureRandom();
+        byte[] bytes = new byte[bytesInMebiByte];
+
+        Instant start = Instant.now();
+        random.nextBytes(bytes);
+        Instant end = Instant.now();
+
+        Duration duration = Duration.between(start, end);
+        LOGGER.info(() -> String.format(
+                "SecureRandom.nextBytes() took %s milliseconds to generate 1 MiB of data",
+                duration.toMillis()));
+    }
+
+    @Test
+    public void evaluateSHA256BasedDigestRandomGeneratorPerformance() {
+        SHA256Digest digest = new SHA256Digest();
+        DigestRandomGenerator random = new DigestRandomGenerator(digest);
+        byte[] bytes = new byte[bytesInMebiByte];
+
+        Instant start = Instant.now();
+        random.nextBytes(bytes);
+        Instant end = Instant.now();
+
+        Duration duration = Duration.between(start, end);
+        LOGGER.info(() -> String.format(
+                "SHA256-based DigestRandomGenerator.nextBytes() took %s milliseconds to generate 1 MiB of data",
+                duration.toMillis()));
+    }
+
+    @Test
+    public void evaluateSHA1BasedDigestRandomGeneratorPerformance() {
+        SHA1Digest digest = new SHA1Digest();
+        DigestRandomGenerator random = new DigestRandomGenerator(digest);
+        byte[] bytes = new byte[bytesInMebiByte];
+
+        Instant start = Instant.now();
+        random.nextBytes(bytes);
+        Instant end = Instant.now();
+
+        Duration duration = Duration.between(start, end);
+        LOGGER.info(() -> String.format(
+                "SHA1-based DigestRandomGenerator.nextBytes() took %s milliseconds to generate 1 MiB of data",
+                duration.toMillis()));
+    }
+}