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+// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2012 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include <cstring>
+#include <vector>
+
+#include "test_util/testharness.h"
+#include "util/random.h"
+
+using ROCKSDB_NAMESPACE::Random;
+
+TEST(RandomTest, Uniform) {
+ const int average = 20;
+ for (uint32_t seed : {0, 1, 2, 37, 4096}) {
+ Random r(seed);
+ for (int range : {1, 2, 8, 12, 100}) {
+ std::vector<int> counts(range, 0);
+
+ for (int i = 0; i < range * average; ++i) {
+ ++counts.at(r.Uniform(range));
+ }
+ int max_variance = static_cast<int>(std::sqrt(range) * 2 + 4);
+ for (int i = 0; i < range; ++i) {
+ EXPECT_GE(counts[i], std::max(1, average - max_variance));
+ EXPECT_LE(counts[i], average + max_variance + 1);
+ }
+ }
+ }
+}
+
+TEST(RandomTest, OneIn) {
+ Random r(42);
+ for (int range : {1, 2, 8, 12, 100, 1234}) {
+ const int average = 100;
+ int count = 0;
+ for (int i = 0; i < average * range; ++i) {
+ if (r.OneIn(range)) {
+ ++count;
+ }
+ }
+ if (range == 1) {
+ EXPECT_EQ(count, average);
+ } else {
+ int max_variance = static_cast<int>(std::sqrt(average) * 1.5);
+ EXPECT_GE(count, average - max_variance);
+ EXPECT_LE(count, average + max_variance);
+ }
+ }
+}
+
+TEST(RandomTest, OneInOpt) {
+ Random r(42);
+ for (int range : {-12, 0, 1, 2, 8, 12, 100, 1234}) {
+ const int average = 100;
+ int count = 0;
+ for (int i = 0; i < average * range; ++i) {
+ if (r.OneInOpt(range)) {
+ ++count;
+ }
+ }
+ if (range < 1) {
+ EXPECT_EQ(count, 0);
+ } else if (range == 1) {
+ EXPECT_EQ(count, average);
+ } else {
+ int max_variance = static_cast<int>(std::sqrt(average) * 1.5);
+ EXPECT_GE(count, average - max_variance);
+ EXPECT_LE(count, average + max_variance);
+ }
+ }
+}
+
+TEST(RandomTest, PercentTrue) {
+ Random r(42);
+ for (int pct : {-12, 0, 1, 2, 10, 50, 90, 98, 99, 100, 1234}) {
+ const int samples = 10000;
+
+ int count = 0;
+ for (int i = 0; i < samples; ++i) {
+ if (r.PercentTrue(pct)) {
+ ++count;
+ }
+ }
+ if (pct <= 0) {
+ EXPECT_EQ(count, 0);
+ } else if (pct >= 100) {
+ EXPECT_EQ(count, samples);
+ } else {
+ int est = (count * 100 + (samples / 2)) / samples;
+ EXPECT_EQ(est, pct);
+ }
+ }
+}
+
+int main(int argc, char** argv) {
+ ::testing::InitGoogleTest(&argc, argv);
+
+ return RUN_ALL_TESTS();
+}