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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/snapshot_window_util.h"
#include "mongo/db/client.h"
#include "mongo/db/service_context.h"
#include "mongo/db/service_context_devnull_test_fixture.h"
#include "mongo/db/snapshot_window_options.h"
#include "mongo/db/storage/storage_options.h"
#include "mongo/unittest/unittest.h"
namespace mongo {
namespace {
using namespace SnapshotWindowUtil;
/**
* Tests the functions in snapshot_window_util.h using a devnull storage engine.
*/
class SnapshotWindowTest : public ServiceContextDevnullTestFixture {
public:
void setUp() override {
ServiceContextDevnullTestFixture::setUp();
_opCtx = cc().makeOperationContext();
}
void tearDown() override {
_opCtx.reset();
ServiceContextDevnullTestFixture::tearDown();
}
ServiceContext::UniqueOperationContext _opCtx;
};
TEST_F(SnapshotWindowTest, DecreaseAndIncreaseSnapshotWindow) {
auto engine = getServiceContext()->getStorageEngine();
invariant(engine);
snapshotWindowParams.maxTargetSnapshotHistoryWindowInSeconds.store(100);
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.store(100);
// Lower the time enforced between function calls to speed up testing.
snapshotWindowParams.minMillisBetweenSnapshotWindowInc.store(100);
// Stabilize for the test so we know that we are testing things as expected.
snapshotWindowParams.snapshotWindowAdditiveIncreaseSeconds.store(2);
snapshotWindowParams.snapshotWindowMultiplicativeDecrease.store(0.75);
auto maxTargetSnapshotWindowSeconds =
snapshotWindowParams.maxTargetSnapshotHistoryWindowInSeconds.load();
auto snapshotWindowSeconds = snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(maxTargetSnapshotWindowSeconds, snapshotWindowSeconds);
auto windowMultiplicativeDecrease =
snapshotWindowParams.snapshotWindowMultiplicativeDecrease.load();
auto windowAdditiveIncrease = snapshotWindowParams.snapshotWindowAdditiveIncreaseSeconds.load();
auto minTimeBetweenInc = snapshotWindowParams.minMillisBetweenSnapshotWindowInc.load();
/**
* Test that trying to decrease the window size FAILS when there have been no writes to the
* cache overflow table.
*/
decreaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsOne =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(snapshotWindowSeconds, snapshotWindowSecondsOne);
/**
* Test that trying to decrease the window size SUCCEEDS when there have been writes to the
* cache overflow table.
*/
engine->setCacheOverflowTableInsertCountForTest(1);
decreaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsTwo =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_GT(snapshotWindowSecondsOne, snapshotWindowSecondsTwo);
ASSERT_EQ(snapshotWindowSecondsTwo,
static_cast<int>(snapshotWindowSeconds * windowMultiplicativeDecrease));
/**
* Test that trying to decrease the window size FAILS when there have been writes to the
* cache overflow table AND SnapshotTooOld errors have occurred.
*/
engine->setCacheOverflowTableInsertCountForTest(2);
incrementSnapshotTooOldErrorCount();
decreaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsThree =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(snapshotWindowSecondsTwo, snapshotWindowSecondsThree);
/**
* Now test again that decreasing the size SUCCEEDS when there have been writes to the cache
* overflow table again (without any further SnapshotTooOld errors).
*/
engine->setCacheOverflowTableInsertCountForTest(3);
decreaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsFour =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_GT(snapshotWindowSecondsThree, snapshotWindowSecondsFour);
ASSERT_EQ(snapshotWindowSecondsFour,
static_cast<int>(snapshotWindowSecondsThree * windowMultiplicativeDecrease));
/**
* Test that increasing the size SUCCEEDS.
*/
increaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsFive =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(snapshotWindowSecondsFive, snapshotWindowSecondsFour + windowAdditiveIncrease);
/**
* Test that increasing the size SUCCEEDS even when there have been writes to the cache overflow
* table.
*/
// Sleep for a time because increaseTargetSnapshotWindowSize() enforces a wait time between
// updates.
sleepmillis(2 * minTimeBetweenInc);
engine->setCacheOverflowTableInsertCountForTest(4);
increaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsSix =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(snapshotWindowSecondsSix, snapshotWindowSecondsFive + windowAdditiveIncrease);
/**
* Test that the size cannot be increased above the maximum size.
*/
// Bump up the additive increase to make this run faster.
snapshotWindowParams.snapshotWindowAdditiveIncreaseSeconds.store(9);
windowAdditiveIncrease = snapshotWindowParams.snapshotWindowAdditiveIncreaseSeconds.load();
// Integers round down, so add 1 to make sure it reaches the max.
int numIncreasesToReachMax =
(maxTargetSnapshotWindowSeconds - snapshotWindowSecondsSix) / windowAdditiveIncrease + 1;
for (int i = 0; i < numIncreasesToReachMax; ++i) {
sleepmillis(2 * minTimeBetweenInc);
increaseTargetSnapshotWindowSize(_opCtx.get());
}
// Should be at max.
auto snapshotWindowSecondsSeven =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(snapshotWindowSecondsSeven, maxTargetSnapshotWindowSeconds);
// An attempt to increase beyond max should have no effect.
sleepmillis(2 * minTimeBetweenInc);
increaseTargetSnapshotWindowSize(_opCtx.get());
auto snapshotWindowSecondsEight =
snapshotWindowParams.targetSnapshotHistoryWindowInSeconds.load();
ASSERT_EQ(snapshotWindowSecondsEight, maxTargetSnapshotWindowSeconds);
}
} // namespace
} // namespace mongo
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