From b832dce8489ef7b6231384909fd9b68d5a5ff2b7 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 25 Feb 2020 22:27:31 +0100 Subject: Creation of LTS branch "lts_2020_02_25" - 0033c9ea91a52ade7c6b725aa2ef3cbe15463421 Fix build on FreeBSD/powerpc (#616) by kgotlinux <60880393+kgotlinux@users.noreply.github.com> - 0d5ce2797eb695aee7e019e25323251ef6ffc277 Export of internal Abseil changes by Abseil Team - b69c7d880caddfc25bf348dbcfe9d45fdd8bc6e6 Export of internal Abseil changes by Abseil Team - 2a5633fc077a58528cdbfe78720f3f6bfdc6044d Merge "Export of internal Abseil changes" by Xiaoyi Zhang - f9b3d6e493c1b6ab3dbdab71c5f8fa849db4abaf Add RISCV support to GetProgramCounter() (#621) by Khem Raj - 0232c87f21c26718aa3eb2d86678070f3b498a4e Add missing ABSL_HAVE_VDSO_SUPPORT conditional (#622) by Sinan Kaya <41809318+franksinankaya@users.noreply.github.com> - 3c814105108680997d0821077694f663693b5382 Export of internal Abseil changes by Abseil Team - c44657f55692eddf5504156645d1f4ec7b3acabd Export of internal Abseil changes by Abseil Team - 98eb410c93ad059f9bba1bf43f5bb916fc92a5ea Export of internal Abseil changes by Abseil Team - bf78e977309c4cb946914b456404141ddac1c302 Export of internal Abseil changes by Abseil Team - d95d1567165d449e4c213ea31a15cbb112a9865f Export of internal Abseil changes by Abseil Team - 24713a7036a81498334807fa5c7ad3cb7c643711 Export of internal Abseil changes by Abseil Team - 72382c21fefed981b4b8a2a1b82e2d231c2c2e39 Export of internal Abseil changes by Abseil Team - 08a7e7bf972c8451855a5022f2faf3d3655db015 Export of internal Abseil changes by Abseil Team - 36bcd9599b3f48c99357ba61cf33584889306d6a Fix pointer format specifier in documentation (#614) by Andre Nguyen - 0f86336b6939ea673cc1cbe29189286cae67d63a Export of internal Abseil changes by Abseil Team - c512f118dde6ffd51cb7d8ac8804bbaf4d266c3a Export of internal Abseil changes by Abseil Team - 37dd2562ec830d547a1524bb306be313ac3f2556 Export of internal Abseil changes by Abseil Team - 44427702614d7b86b064ba06a390f5eb2f85dbf6 fix: Add support for more ARM processors detection (#608) by Andre Nguyen - 159bf2bf6d1cc8087e02468d071e94d1177d1bae Export of internal Abseil changes by Abseil Team - a2e6adecc294dc4cd98cc285a9134ce58e0f2ad0 Use https links. (#586) by nlewycky - 564001ae506a17c51fa1223684a78f05f91d3d91 Export of internal Abseil changes by Abseil Team - b3aaac8a37c467a1125c794196caa90d0957bdc3 Export of internal Abseil changes by Abseil Team - 63ee2f8877915a3565c29707dba8fe4d7822596a Export of internal Abseil changes by Abseil Team - a048203a881f11f4b7b8df5fb563aec85522f8db Export of internal Abseil changes by Abseil Team - 1de0166368e2ae67347f92099d6dca3ab3a4a496 Export of internal Abseil changes by Abseil Team - ad904b6cd3906ddf79878003d92b7bc08d7786ae Export of internal Abseil changes by Abseil Team - 29235139149790f5afc430c11cec8f1eb1677607 Export of internal Abseil changes by Abseil Team - bf86cfe165ef7d70dfe68f0b8fc0c018bc79a577 Export of internal Abseil changes by Abseil Team - 12bc53e0318d80569270a5b26ccbc62b52022b89 Export of internal Abseil changes by Abseil Team - 1e39f8626a4dadec1f56920b999dd4c3cfae333e Export of internal Abseil changes by Abseil Team - 77f87009a34c745255bd84d8f2647040d831a2b3 Export of internal Abseil changes by Abseil Team - d659fe54b35ab9b8e35c72e50a4b8814167d5a84 Export of internal Abseil changes by Abseil Team - a4b757b5d42694306a9de853cee0a5fba9c7bbe9 Export of internal Abseil changes by Abseil Team - 0514227d2547793b23e209809276375e41c76617 Export of internal Abseil changes by Abseil Team - 7f4fe64af80fe3c84db8ea938276c3690573c45e Export of internal Abseil changes by Abseil Team - 16d9fd58a51c6083234e2e9f8f50e49ed5ed02e4 Export of internal Abseil changes by Abseil Team - bcaae6009c0833b73c6fa7bdd972921d8081a724 Export of internal Abseil changes by Abseil Team - 8ba96a8244bbe334d09542e92d566673a65c1f78 Export of internal Abseil changes by Abseil Team - 2103fd9acdf58279f739860bff3f8c9f4b845605 Export of internal Abseil changes by Abseil Team - 3df7b52a6ada51a72a23796b844549a7b282f1b8 Export of internal Abseil changes by Abseil Team - fa8c75182fbfdeddb2485fc0d53baeda3f40b7a3 Export of internal Abseil changes by Abseil Team - 85092b4b648ca729c6263c4a302a41dfff28705e Fix Conan builds (#400) by Adrian Ostrowski - e96ae2203b80d5ae2e0b7abe0c77b722b224b16d Export of internal Abseil changes by Abseil Team - 20de2db748ca0471cfb61cb53e813dd12938c12b Export of internal Abseil changes by Abseil Team - 846e5dbedac123d12455adcfe6f53c8b5dcbfeef Export of internal Abseil changes by Abseil Team - 8207907f4f7fbaeeaa2b7340c76875e06fd345ba Export of internal Abseil changes by Abseil Team - 078b89b3c046d230ef3ad39494e5852184eb528b Export of internal Abseil changes by Abseil Team - 19b021cb3ff23048dfbe236a4e611925d8930831 Export of internal Abseil changes by Abseil Team - ecc0033b54847f6c9ee37dbb0be8aa17e5b6d37b Always enable proper symbolize implementation on Windows ... by Loo Rong Jie - 2796d500aea5a31d26b8b24a33fab7a1c8fa2f32 Export of internal Abseil changes by Abseil Team - e4c8d0eb8ef4acb5d7a4252b3b87feb391ef7e41 Export of internal Abseil changes by Abseil Team - a15364ce4d88534ae2295127e5d8e32aefb6b446 Export of internal Abseil changes by Abseil Team - ab3552a18964e7063c8324f45b3896a6a20b08a8 Export of internal Abseil changes by Abseil Team - e9f9000c7c80993cb589d011616b7a8016e42f4a Fix ABSL_WAITER_MODE detection for mingw (#342) by Joe Sylve - abea769b551f7a100f540967cb95debdb0080df8 Fix ABSL_HAVE_ALARM check on mingw (#341) by Joe Sylve - 25597bdfc148e91e27678ec30efa52f4fc8c164f Export of internal Abseil changes by Abseil Team - aad33fefaa8f744d71ce747a53717b835bdf8e84 Export of internal Abseil changes by Abseil Team - 8fe7214fe2d7a45ecc4d85f6a524c6b1532426de Export of internal Abseil changes by Abseil Team - debac94cfb5a0fa75d1d97c399682bd1c72e3191 Export of internal Abseil changes by Abseil Team - 882b3501a31eb0e4ae4213afb91a0e43feda7d5f Fix spelling errors (#384) by Sungmann Cho <55860394+chosungmann@users.noreply.github.com> - 502efe6d7841bff82b1aeef5500491fe9a48c635 Export of internal Abseil changes by Abseil Team - ccdd1d57b6386ebc26fb0c7d99b604672437c124 Export of internal Abseil changes by Abseil Team - ddf8e52a2918dd0ccec75d3e2426125fa3926724 Export of internal Abseil changes by Abseil Team - 6ec136281086b71da32b5fb068bd6e46b78a5c79 Export of internal Abseil changes by Abseil Team - ac78ffc3bc0a8b295cab9a03817760fd460df2a1 Export of internal Abseil changes by Abseil Team - 5374c56e5196320681993869e3126b51edac2a43 Export of internal Abseil changes by Abseil Team - 97c1664b4bbab5f78fac2b151ab02656268fb34b Export of internal Abseil changes by Abseil Team - 325fd7b042ff4ec34f7dd32e602cd81ad0e24b22 Export of internal Abseil changes by Abseil Team - 83c1d65c90a92aa49632b9ac5a793214bb0768bc Export of internal Abseil changes by Abseil Team - eb6b7bd23bc0815bfd784e1a74021ce166765280 Export of internal Abseil changes by Abseil Team - 9ddac555b7861dc178d0dbe758a1cfbed718784b Export of internal Abseil changes by Abseil Team - 1948f6f967e34db9793cfa8b4bcbaf370d039fd8 Export of internal Abseil changes by Abseil Team - a0d1e098c2f99694fa399b175a7ccf920762030e Export of internal Abseil changes by Abseil Team - 2d2d7fbc283315b676159716376e739d3d23ed94 Export of internal Abseil changes by Abseil Team - 0302d1e5fa4fcdd1763b7d1bb3212943b1ae911d supppress unused variable warning for gcc (#372) by Martin - 262d74ba81b1fc4d71f459555cde8ecb39786d68 Export of internal Abseil changes by Abseil Team - f0afae0d49af3e15a7169e019634d7719143d94d Export of internal Abseil changes by Abseil Team - 0e7afdcbd24c7e5b7cab4e0217d8886f1525b520 Export of internal Abseil changes by Abseil Team - 9a41ffdd3a0ccbcdd29c4e3886b28e06f2cd9c66 Export of internal Abseil changes by Abseil Team - 36910d3d7e9fccadd6603f232d0c4f54dcd47c7e [bazel] Add fixes for --incompatible_load_cc_rules_from_b... by Yannic - aae8143cf9aa611f70d7ea9b95b8b8b383b2271a Export of internal Abseil changes by Abseil Team - d9aa92d7fb324314f9df487ac23d32a25650b742 Export of internal Abseil changes by Abseil Team - 321ab5303023c86cd15d9ddc5740fb4b4fde32e1 Export of internal Abseil changes by Abseil Team - 4ef574064e75b86f115549e9eb4c7e806781b3ab Export of internal Abseil changes by Abseil Team GitOrigin-RevId: 0033c9ea91a52ade7c6b725aa2ef3cbe15463421 Change-Id: I8a2b70063cb3ab40c6943a6db0fe40cae71ed8d7 --- absl/base/internal/exponential_biased_test.cc | 199 ++++++++++++++++++++++++++ 1 file changed, 199 insertions(+) create mode 100644 absl/base/internal/exponential_biased_test.cc (limited to 'absl/base/internal/exponential_biased_test.cc') diff --git a/absl/base/internal/exponential_biased_test.cc b/absl/base/internal/exponential_biased_test.cc new file mode 100644 index 00000000..90a482d2 --- /dev/null +++ b/absl/base/internal/exponential_biased_test.cc @@ -0,0 +1,199 @@ +// Copyright 2019 The Abseil Authors. +// +// 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 +// +// https://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. + +#include "absl/base/internal/exponential_biased.h" + +#include + +#include +#include +#include + +#include "gmock/gmock.h" +#include "gtest/gtest.h" +#include "absl/strings/str_cat.h" + +using ::testing::Ge; + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace base_internal { + +MATCHER_P2(IsBetween, a, b, + absl::StrCat(std::string(negation ? "isn't" : "is"), " between ", a, + " and ", b)) { + return a <= arg && arg <= b; +} + +// Tests of the quality of the random numbers generated +// This uses the Anderson Darling test for uniformity. +// See "Evaluating the Anderson-Darling Distribution" by Marsaglia +// for details. + +// Short cut version of ADinf(z), z>0 (from Marsaglia) +// This returns the p-value for Anderson Darling statistic in +// the limit as n-> infinity. For finite n, apply the error fix below. +double AndersonDarlingInf(double z) { + if (z < 2) { + return exp(-1.2337141 / z) / sqrt(z) * + (2.00012 + + (0.247105 - + (0.0649821 - (0.0347962 - (0.011672 - 0.00168691 * z) * z) * z) * + z) * + z); + } + return exp( + -exp(1.0776 - + (2.30695 - + (0.43424 - (0.082433 - (0.008056 - 0.0003146 * z) * z) * z) * z) * + z)); +} + +// Corrects the approximation error in AndersonDarlingInf for small values of n +// Add this to AndersonDarlingInf to get a better approximation +// (from Marsaglia) +double AndersonDarlingErrFix(int n, double x) { + if (x > 0.8) { + return (-130.2137 + + (745.2337 - + (1705.091 - (1950.646 - (1116.360 - 255.7844 * x) * x) * x) * x) * + x) / + n; + } + double cutoff = 0.01265 + 0.1757 / n; + if (x < cutoff) { + double t = x / cutoff; + t = sqrt(t) * (1 - t) * (49 * t - 102); + return t * (0.0037 / (n * n) + 0.00078 / n + 0.00006) / n; + } else { + double t = (x - cutoff) / (0.8 - cutoff); + t = -0.00022633 + + (6.54034 - (14.6538 - (14.458 - (8.259 - 1.91864 * t) * t) * t) * t) * + t; + return t * (0.04213 + 0.01365 / n) / n; + } +} + +// Returns the AndersonDarling p-value given n and the value of the statistic +double AndersonDarlingPValue(int n, double z) { + double ad = AndersonDarlingInf(z); + double errfix = AndersonDarlingErrFix(n, ad); + return ad + errfix; +} + +double AndersonDarlingStatistic(const std::vector& random_sample) { + int n = random_sample.size(); + double ad_sum = 0; + for (int i = 0; i < n; i++) { + ad_sum += (2 * i + 1) * + std::log(random_sample[i] * (1 - random_sample[n - 1 - i])); + } + double ad_statistic = -n - 1 / static_cast(n) * ad_sum; + return ad_statistic; +} + +// Tests if the array of doubles is uniformly distributed. +// Returns the p-value of the Anderson Darling Statistic +// for the given set of sorted random doubles +// See "Evaluating the Anderson-Darling Distribution" by +// Marsaglia and Marsaglia for details. +double AndersonDarlingTest(const std::vector& random_sample) { + double ad_statistic = AndersonDarlingStatistic(random_sample); + double p = AndersonDarlingPValue(random_sample.size(), ad_statistic); + return p; +} + +TEST(ExponentialBiasedTest, CoinTossDemoWithGetSkipCount) { + ExponentialBiased eb; + for (int runs = 0; runs < 10; ++runs) { + for (int flips = eb.GetSkipCount(1); flips > 0; --flips) { + printf("head..."); + } + printf("tail\n"); + } + int heads = 0; + for (int i = 0; i < 10000000; i += 1 + eb.GetSkipCount(1)) { + ++heads; + } + printf("Heads = %d (%f%%)\n", heads, 100.0 * heads / 10000000); +} + +TEST(ExponentialBiasedTest, SampleDemoWithStride) { + ExponentialBiased eb; + int stride = eb.GetStride(10); + int samples = 0; + for (int i = 0; i < 10000000; ++i) { + if (--stride == 0) { + ++samples; + stride = eb.GetStride(10); + } + } + printf("Samples = %d (%f%%)\n", samples, 100.0 * samples / 10000000); +} + + +// Testing that NextRandom generates uniform random numbers. Applies the +// Anderson-Darling test for uniformity +TEST(ExponentialBiasedTest, TestNextRandom) { + for (auto n : std::vector({ + 10, // Check short-range correlation + 100, 1000, + 10000 // Make sure there's no systemic error + })) { + uint64_t x = 1; + // This assumes that the prng returns 48 bit numbers + uint64_t max_prng_value = static_cast(1) << 48; + // Initialize. + for (int i = 1; i <= 20; i++) { + x = ExponentialBiased::NextRandom(x); + } + std::vector int_random_sample(n); + // Collect samples + for (int i = 0; i < n; i++) { + int_random_sample[i] = x; + x = ExponentialBiased::NextRandom(x); + } + // First sort them... + std::sort(int_random_sample.begin(), int_random_sample.end()); + std::vector random_sample(n); + // Convert them to uniform randoms (in the range [0,1]) + for (int i = 0; i < n; i++) { + random_sample[i] = + static_cast(int_random_sample[i]) / max_prng_value; + } + // Now compute the Anderson-Darling statistic + double ad_pvalue = AndersonDarlingTest(random_sample); + EXPECT_GT(std::min(ad_pvalue, 1 - ad_pvalue), 0.0001) + << "prng is not uniform: n = " << n << " p = " << ad_pvalue; + } +} + +// The generator needs to be available as a thread_local and as a static +// variable. +TEST(ExponentialBiasedTest, InitializationModes) { + ABSL_CONST_INIT static ExponentialBiased eb_static; + EXPECT_THAT(eb_static.GetSkipCount(2), Ge(0)); + +#if ABSL_HAVE_THREAD_LOCAL + thread_local ExponentialBiased eb_thread; + EXPECT_THAT(eb_thread.GetSkipCount(2), Ge(0)); +#endif + + ExponentialBiased eb_stack; + EXPECT_THAT(eb_stack.GetSkipCount(2), Ge(0)); +} + +} // namespace base_internal +ABSL_NAMESPACE_END +} // namespace absl -- cgit v1.2.3