/*
 * BackgroundSelectors.actor.cpp
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2013-2022 Apple Inc. and the FoundationDB project 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
 *
 *     http://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 "fdbrpc/ContinuousSample.h"
#include "fdbclient/NativeAPI.actor.h"
#include "fdbserver/TesterInterface.actor.h"
#include "fdbserver/workloads/workloads.actor.h"
#include "flow/actorcompiler.h" // This must be the last #include.

KeySelector randomizedSelector(const KeyRef& key, bool orEqual, int offset) {
	if (orEqual && deterministicRandom()->random01() > 0.5)
		return KeySelectorRef(keyAfter(key), false, offset);
	return KeySelectorRef(key, orEqual, offset);
}

struct BackgroundSelectorWorkload : TestWorkload {
	int actorsPerClient, maxDiff, minDrift, maxDrift, resultLimit;
	double testDuration, transactionsPerSecond;

	std::vector<Future<Void>> clients;
	PerfIntCounter operations, checks, retries;

	BackgroundSelectorWorkload(WorkloadContext const& wcx)
	  : TestWorkload(wcx), operations("Operations"), checks("Checks"), retries("Retries") {
		testDuration = getOption(options, LiteralStringRef("testDuration"), 10.0);
		actorsPerClient = std::max(getOption(options, LiteralStringRef("actorsPerClient"), 1), 1);
		maxDiff = std::max(getOption(options, LiteralStringRef("maxDiff"), 100), 2);
		minDrift = getOption(options, LiteralStringRef("minDiff"), -10);
		maxDrift = getOption(options, LiteralStringRef("minDiff"), 100);
		transactionsPerSecond =
		    getOption(options, LiteralStringRef("transactionsPerSecond"), 10.0) / (clientCount * actorsPerClient);
		resultLimit = 10 * maxDiff;
	}

	std::string description() const override { return "BackgroundSelector"; }

	Future<Void> setup(Database const& cx) override { return Void(); }

	Future<Void> start(Database const& cx) override { return _start(cx, this); }

	ACTOR Future<Void> _start(Database cx, BackgroundSelectorWorkload* self) {
		for (int c = 0; c < self->actorsPerClient; c++)
			self->clients.push_back(timeout(self->backgroundSelectorWorker(cx, self), self->testDuration, Void()));
		wait(waitForAll(self->clients));
		return Void();
	}

	Future<bool> check(Database const& cx) override {
		bool ok = true;
		for (int i = 0; i < clients.size(); i++)
			if (clients[i].isError())
				ok = false;
		clients.clear();
		return ok;
	}

	void getMetrics(std::vector<PerfMetric>& m) override {
		double duration = testDuration;
		m.emplace_back("Operations/sec", operations.getValue() / duration, Averaged::False);
		m.push_back(operations.getMetric());
		m.push_back(checks.getMetric());
		m.push_back(retries.getMetric());
	}

	ACTOR Future<Void> backgroundSelectorWorker(Database cx, BackgroundSelectorWorkload* self) {
		state double lastTime = now();
		state bool forward;
		state int direction;
		state Key startKey;
		state Key endKey;
		state int diff;
		state Transaction tr(cx);
		state RangeResult rangeResult;
		state Standalone<StringRef> startResult;
		state Standalone<StringRef> endResult;
		state int startDrift;
		state int endDrift;
		state bool restartProcess;

		loop {
			forward = deterministicRandom()->randomInt(0, 2) != 0;
			direction = forward ? 1 : -1;
			diff = deterministicRandom()->randomInt(0, self->maxDiff);

			// Setup start and end key
			loop {
				try {
					if (forward) {
						{
							Standalone<StringRef> res = wait(tr.getKey(KeySelectorRef(allKeys.begin, false, 1)));
							startKey = res;
						}

						{
							Standalone<StringRef> res = wait(tr.getKey(randomizedSelector(startKey, true, diff)));
							endKey = res;
						}
					} else {
						{
							Standalone<StringRef> res = wait(tr.getKey(KeySelectorRef(allKeys.end, false, 0)));
							endKey = res;
						}

						{
							Standalone<StringRef> res = wait(tr.getKey(randomizedSelector(endKey, true, -1 * diff)));
							startKey = res;
						}
					}
					break;
				} catch (Error& e) {
					wait(tr.onError(e));
				}
			}

			loop {
				wait(poisson(&lastTime, 1.0 / self->transactionsPerSecond));
				tr.reset();
				startDrift = direction * deterministicRandom()->randomInt(self->minDrift, self->maxDrift);
				endDrift = direction * deterministicRandom()->randomInt(self->minDrift, self->maxDrift);

				// max sure the end drift does not violate maxDiff
				endDrift = std::max(endDrift, startDrift - self->maxDiff - diff);
				endDrift = std::min(endDrift, startDrift + self->maxDiff - diff);

				diff = diff + endDrift - startDrift;
				if (diff == 0) {
					endDrift++;
					diff++;
				}

				loop {
					try {
						if (diff < 0) {
							RangeResult rangeResult_ =
							    wait(tr.getRange(randomizedSelector(endKey, true, endDrift),
							                     randomizedSelector(startKey, true, startDrift + 1),
							                     self->resultLimit));
							rangeResult = rangeResult_;
							Standalone<StringRef> endResult_ =
							    wait(tr.getKey(randomizedSelector(startKey, true, startDrift)));
							endResult = endResult_;
							Standalone<StringRef> startResult_ =
							    wait(tr.getKey(randomizedSelector(endKey, true, endDrift)));
							startResult = startResult_;
						} else {
							RangeResult rangeResult_ = wait(tr.getRange(randomizedSelector(startKey, true, startDrift),
							                                            randomizedSelector(endKey, true, endDrift + 1),
							                                            self->resultLimit));
							rangeResult = rangeResult_;
							Standalone<StringRef> startResult_ =
							    wait(tr.getKey(randomizedSelector(startKey, true, startDrift)));
							startResult = startResult_;
							Standalone<StringRef> endResult_ =
							    wait(tr.getKey(randomizedSelector(endKey, true, endDrift)));
							endResult = endResult_;
						}

						restartProcess = false;
						if (rangeResult.size() == 0) {
							restartProcess = true;
							break;
						}

						if (rangeResult.size() < self->resultLimit && startResult != allKeys.begin &&
						    startResult != allKeys.end) {
							if (startResult != rangeResult[0].key)
								TraceEvent(SevError, "BackgroundSelectorError")
								    .detail("Diff", diff)
								    .detail("ResultSize", rangeResult.size())
								    .detail("StartResult", printable(startResult))
								    .detail("RangeResult", printable(rangeResult[0].key));
						} else
							restartProcess = true;

						if (rangeResult.size() < self->resultLimit && endResult != allKeys.begin &&
						    endResult != allKeys.end) {
							if (endResult != rangeResult[rangeResult.size() - 1].key)
								TraceEvent(SevError, "BackgroundSelectorError")
								    .detail("Diff", diff)
								    .detail("ResultSize", rangeResult.size())
								    .detail("EndResult  ", printable(endResult))
								    .detail("RangeResult", printable(rangeResult[rangeResult.size() - 1].key));
						} else
							restartProcess = true;

						diff = std::min(rangeResult.size() - 1, self->maxDiff);
						startKey = rangeResult[0].key;
						endKey = rangeResult[diff].key;

						break;
					} catch (Error& e) {
						wait(tr.onError(e));
						++self->retries;
					}
				}
				++self->operations;
				if (restartProcess)
					break;
				++self->checks;
			}
		}
	}
};

WorkloadFactory<BackgroundSelectorWorkload> BackgroundSelectorWorkloadFactory("BackgroundSelector");