/*
 * IndexScan.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 "fdbserver/workloads/BulkSetup.actor.h"
#include "fdbclient/ReadYourWrites.h"
#include "flow/actorcompiler.h" // This must be the last #include.

struct IndexScanWorkload : KVWorkload {
	uint64_t rowsRead, chunks;
	int bytesPerRead, failedTransactions, scans;
	double totalTimeFetching, testDuration, transactionDuration;
	bool singleProcess, readYourWrites;

	IndexScanWorkload(WorkloadContext const& wcx)
	  : KVWorkload(wcx), rowsRead(0), chunks(0), failedTransactions(0), scans(0) {
		testDuration = getOption(options, LiteralStringRef("testDuration"), 10.0);
		bytesPerRead = getOption(options, LiteralStringRef("bytesPerRead"), 80000);
		transactionDuration = getOption(options, LiteralStringRef("transactionDuration"), 1.0);
		singleProcess = getOption(options, LiteralStringRef("singleProcess"), true);
		readYourWrites = getOption(options, LiteralStringRef("readYourWrites"), true);
	}

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

	Future<Void> setup(Database const& cx) override {
		// this will be set up by and external force!
		return Void();
	}

	Future<Void> start(Database const& cx) override {
		if (singleProcess && clientId != 0) {
			return Void();
		}
		return _start(cx, this);
	}

	Future<bool> check(const Database&) override { return true; }

	void getMetrics(std::vector<PerfMetric>& m) override {
		if (singleProcess && clientId != 0)
			return;

		m.emplace_back("FailedTransactions", failedTransactions, Averaged::False);
		m.emplace_back("RowsRead", rowsRead, Averaged::False);
		m.emplace_back("Scans", scans, Averaged::False);
		m.emplace_back("Chunks", chunks, Averaged::False);
		m.emplace_back("TimeFetching", totalTimeFetching, Averaged::True);
		m.emplace_back("Rows/sec", totalTimeFetching == 0 ? 0 : rowsRead / totalTimeFetching, Averaged::True);
		m.emplace_back("Rows/chunk", chunks == 0 ? 0 : rowsRead / (double)chunks, Averaged::True);
	}

	ACTOR Future<Void> _start(Database cx, IndexScanWorkload* self) {
		// Boilerplate: "warm" the location cache so that the location of all keys is known before test starts
		state double startTime = now();
		loop {
			state Transaction tr(cx);
			try {
				wait(tr.warmRange(allKeys));
				break;
			} catch (Error& e) {
				wait(tr.onError(e));
			}
		}

		// Wait some small amount of time for things to "settle". Maybe this is historical?
		wait(delay(std::max(0.1, 1.0 - (now() - startTime))));

		wait(timeout(serialScans(cx, self), self->testDuration, Void()));
		return Void();
	}

	ACTOR static Future<Void> serialScans(Database cx, IndexScanWorkload* self) {
		state double start = now();
		try {
			loop { wait(scanDatabase(cx, self)); }
		} catch (...) {
			self->totalTimeFetching = now() - start;
			throw;
		}
	}

	ACTOR static Future<Void> scanDatabase(Database cx, IndexScanWorkload* self) {
		state int startNode =
		    deterministicRandom()->randomInt(0, self->nodeCount / 2); // start in the first half of the database
		state KeySelector begin = firstGreaterOrEqual(self->keyForIndex(startNode));
		state KeySelector end = firstGreaterThan(self->keyForIndex(self->nodeCount));
		state GetRangeLimits limits(GetRangeLimits::ROW_LIMIT_UNLIMITED, self->bytesPerRead);

		state int rowsRead;
		state int chunks;
		state double startTime;
		loop {
			state ReadYourWritesTransaction tr(cx);
			if (!self->readYourWrites)
				tr.setOption(FDBTransactionOptions::READ_YOUR_WRITES_DISABLE);
			startTime = now();
			rowsRead = 0;
			chunks = 0;

			try {
				loop {
					RangeResult r = wait(tr.getRange(begin, end, limits));
					chunks++;
					rowsRead += r.size();
					if (!r.size() || !r.more || (now() - startTime) > self->transactionDuration) {
						break;
					}
					begin = firstGreaterThan(r[r.size() - 1].key);
				}

				break;
			} catch (Error& e) {
				if (e.code() != error_code_actor_cancelled)
					++self->failedTransactions;
				wait(tr.onError(e));
			}
		}

		self->rowsRead += rowsRead;
		self->chunks += chunks;
		self->scans++;
		return Void();
	}
};

WorkloadFactory<IndexScanWorkload> IndexScanWorkloadFactory("IndexScan");