143 lines
4.0 KiB
C++
143 lines
4.0 KiB
C++
/*
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* DeterministicRandom.cpp
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "flow/DeterministicRandom.h"
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#include <cstring>
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uint64_t DeterministicRandom::gen64() {
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uint64_t curr = next;
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next = (uint64_t(random()) << 32) ^ random();
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if (TRACE_SAMPLE())
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TraceEvent(SevSample, "Random").log();
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return curr;
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}
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DeterministicRandom::DeterministicRandom(uint32_t seed, bool useRandLog)
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: random((unsigned long)seed), next((uint64_t(random()) << 32) ^ random()), useRandLog(useRandLog) {
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UNSTOPPABLE_ASSERT(seed != 0); // docs for mersenne twister say x0>0
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};
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double DeterministicRandom::random01() {
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double d = gen64() / double(uint64_t(-1));
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if (randLog && useRandLog)
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fprintf(randLog, "R01 %f\n", d);
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return d;
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}
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int DeterministicRandom::randomInt(int min, int maxPlusOne) {
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ASSERT(min < maxPlusOne);
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unsigned int range;
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if (maxPlusOne < 0)
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range = std::abs(maxPlusOne - min);
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else {
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range = maxPlusOne;
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range -= min;
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}
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uint64_t v = (gen64() % range);
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int i;
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if (min < 0 && (-static_cast<unsigned int>(min + 1)) >= v)
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i = -static_cast<int>(-static_cast<unsigned int>(min + 1) - v) - 1;
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else
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i = v + min;
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if (randLog && useRandLog)
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fprintf(randLog, "Rint %d\n", i);
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return i;
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}
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int64_t DeterministicRandom::randomInt64(int64_t min, int64_t maxPlusOne) {
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ASSERT(min < maxPlusOne);
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uint64_t range;
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if (maxPlusOne < 0)
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range = std::abs(maxPlusOne - min);
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else {
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range = maxPlusOne;
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range -= min;
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}
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uint64_t v = (gen64() % range);
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int64_t i;
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if (min < 0 && (-static_cast<uint64_t>(min + 1)) >= v)
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i = -static_cast<int64_t>(-static_cast<uint64_t>(min + 1) - v) - 1;
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else
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i = v + min;
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if (randLog && useRandLog)
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fprintf(randLog, "Rint64 %" PRId64 "\n", i);
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return i;
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}
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uint32_t DeterministicRandom::randomUInt32() {
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return gen64();
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}
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uint64_t DeterministicRandom::randomUInt64() {
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return gen64();
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}
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uint32_t DeterministicRandom::randomSkewedUInt32(uint32_t min, uint32_t maxPlusOne) {
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std::uniform_real_distribution<double> distribution(std::log(min), std::log(maxPlusOne - 1));
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double logpower = distribution(random);
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uint32_t loguniform = static_cast<uint32_t>(std::pow(10, logpower));
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// doubles can be imprecise, so let's make sure we don't violate an edge case.
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return std::max(std::min(loguniform, maxPlusOne - 1), min);
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}
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UID DeterministicRandom::randomUniqueID() {
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uint64_t x, y;
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x = gen64();
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y = gen64();
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if (randLog && useRandLog)
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fprintf(randLog, "Ruid %" PRIx64 " %" PRIx64 "\n", x, y);
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return UID(x, y);
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}
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char DeterministicRandom::randomAlphaNumeric() {
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static const char alphanum[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
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char c = alphanum[gen64() % 62];
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if (randLog && useRandLog)
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fprintf(randLog, "Rchar %c\n", c);
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return c;
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}
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std::string DeterministicRandom::randomAlphaNumeric(int length) {
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std::string s;
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s.reserve(length);
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for (int i = 0; i < length; i++)
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s += randomAlphaNumeric();
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return s;
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}
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uint64_t DeterministicRandom::peek() const {
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return next;
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}
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void DeterministicRandom::addref() {
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ReferenceCounted<DeterministicRandom>::addref();
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}
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void DeterministicRandom::delref() {
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ReferenceCounted<DeterministicRandom>::delref();
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}
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void generateRandomData(uint8_t* buffer, int length) {
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for (int i = 0; i < length; i += sizeof(uint32_t)) {
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uint32_t val = deterministicRandom()->randomUInt32();
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memcpy(&buffer[i], &val, std::min(length - i, (int)sizeof(uint32_t)));
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}
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}
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