SERVER-73824 Unit test throughput probing algorithm

1 files changed, 266 insertions, 0 deletions

diff --git a/src/mongo/db/storage/execution_control/throughput_probing_test.cpp b/src/mongo/db/storage/execution_control/throughput_probing_test.cpp
new file mode 100644
index 00000000000..340cb616b5a
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+++ b/src/mongo/db/storage/execution_control/throughput_probing_test.cpp
@@ -0,0 +1,266 @@
+/**
+ *    Copyright (C) 2023-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/db/storage/execution_control/throughput_probing.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo::execution_control {
+namespace {
+
+class MockPeriodicJob : public PeriodicRunner::ControllableJob {
+public:
+    explicit MockPeriodicJob(PeriodicRunner::PeriodicJob job) : _job(std::move(job)) {}
+
+    void start() override {}
+    void pause() override {}
+    void resume() override {}
+    void stop() override {}
+
+    Milliseconds getPeriod() override {
+        return _job.interval;
+    }
+
+    void setPeriod(Milliseconds period) override {
+        _job.interval = period;
+    }
+
+    void run(Client* client) {
+        _job.job(client);
+    }
+
+private:
+    PeriodicRunner::PeriodicJob _job;
+};
+
+class MockPeriodicRunner : public PeriodicRunner {
+public:
+    JobAnchor makeJob(PeriodicJob job) override {
+        invariant(!_job);
+        auto mockJob = std::make_shared<MockPeriodicJob>(std::move(job));
+        _job = mockJob;
+        return JobAnchor{std::move(mockJob)};
+    }
+
+    void run(Client* client) {
+        invariant(_job);
+        _job->run(client);
+    }
+
+private:
+    std::shared_ptr<MockPeriodicJob> _job;
+};
+
+class ThroughputProbingTest : public unittest::Test {
+protected:
+    explicit ThroughputProbingTest(int32_t size = 64)
+        : _runner([svcCtx = _svcCtx.get()] {
+              auto runner = std::make_unique<MockPeriodicRunner>();
+              auto runnerPtr = runner.get();
+              svcCtx->setPeriodicRunner(std::move(runner));
+              return runnerPtr;
+          }()),
+          _readTicketHolder(size),
+          _writeTicketHolder(size) {}
+
+    void _run() {
+        _runner->run(_client.get());
+    }
+
+    ServiceContext::UniqueServiceContext _svcCtx = ServiceContext::make();
+    ServiceContext::UniqueClient _client = _svcCtx->makeClient("ThroughputProbingTest");
+
+    MockPeriodicRunner* _runner;
+    MockTicketHolder _readTicketHolder;
+    MockTicketHolder _writeTicketHolder;
+
+    ThroughputProbing _througputProbing{
+        _svcCtx.get(), &_readTicketHolder, &_writeTicketHolder, Milliseconds{1}};
+};
+
+class ThroughputProbingMaxConcurrencyTest : public ThroughputProbingTest {
+protected:
+    ThroughputProbingMaxConcurrencyTest() : ThroughputProbingTest(128) {}
+};
+
+class ThroughputProbingMinConcurrencyTest : public ThroughputProbingTest {
+protected:
+    ThroughputProbingMinConcurrencyTest() : ThroughputProbingTest(5) {}
+};
+
+TEST_F(ThroughputProbingTest, ProbeUpSucceeds) {
+    // Tickets are exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size);
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Probe up next since tickets are exhausted.
+    _run();
+    ASSERT_GT(_readTicketHolder.outof(), size);
+    ASSERT_GT(_writeTicketHolder.outof(), size);
+
+    // Throughput inreases.
+    size = _readTicketHolder.outof();
+    _readTicketHolder.setNumFinishedProcessing(3);
+
+    // Probing up succeeds; the new value is promoted to stable.
+    _run();
+    ASSERT_EQ(_readTicketHolder.outof(), size);
+    ASSERT_EQ(_writeTicketHolder.outof(), size);
+}
+
+TEST_F(ThroughputProbingTest, ProbeUpFailsDownSucceeds) {
+    // Tickets are exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size);
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Probe up next since tickets are exhausted.
+    _run();
+    ASSERT_GT(_readTicketHolder.outof(), size);
+    ASSERT_GT(_writeTicketHolder.outof(), size);
+
+    // Throughput does not increase.
+    _readTicketHolder.setNumFinishedProcessing(2);
+
+    // Probing up fails since throughput did not increase. Probe down next.
+    _run();
+    ASSERT_LT(_readTicketHolder.outof(), size);
+    ASSERT_LT(_writeTicketHolder.outof(), size);
+
+    // Throughput inreases.
+    size = _readTicketHolder.outof();
+    _readTicketHolder.setNumFinishedProcessing(4);
+
+    // Probing down succeeds; the new value is promoted to stable.
+    _run();
+    ASSERT_EQ(_readTicketHolder.outof(), size);
+    ASSERT_EQ(_writeTicketHolder.outof(), size);
+}
+
+TEST_F(ThroughputProbingTest, ProbeUpFailsDownFails) {
+    // Tickets are exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size);
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Probe up next since tickets are exhausted.
+    _run();
+    ASSERT_GT(_readTicketHolder.outof(), size);
+    ASSERT_GT(_writeTicketHolder.outof(), size);
+
+    // Throughput does not increase.
+    _readTicketHolder.setNumFinishedProcessing(2);
+
+    // Probing up fails since throughput did not increase. Probe down next.
+    _run();
+    ASSERT_LT(_readTicketHolder.outof(), size);
+    ASSERT_LT(_writeTicketHolder.outof(), size);
+
+    // Throughput does not increase.
+    _readTicketHolder.setNumFinishedProcessing(3);
+
+    // Probing down fails since throughput did not increase. Return back to stable.
+    _run();
+    ASSERT_EQ(_readTicketHolder.outof(), size);
+    ASSERT_EQ(_writeTicketHolder.outof(), size);
+}
+
+TEST_F(ThroughputProbingTest, ProbeDownSucceeds) {
+    // Tickets are not exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Probe down next since tickets are not exhausted.
+    _run();
+    ASSERT_LT(_readTicketHolder.outof(), size);
+    ASSERT_LT(_writeTicketHolder.outof(), size);
+
+    // Throughput increases.
+    size = _readTicketHolder.outof();
+    _readTicketHolder.setNumFinishedProcessing(3);
+
+    // Probing down succeeds; the new value is promoted to stable.
+    _run();
+    ASSERT_EQ(_readTicketHolder.outof(), size);
+    ASSERT_EQ(_writeTicketHolder.outof(), size);
+}
+
+TEST_F(ThroughputProbingTest, ProbeDownFails) {
+    // Tickets are not exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Probe down next since tickets are not exhausted.
+    _run();
+    ASSERT_LT(_readTicketHolder.outof(), size);
+    ASSERT_LT(_writeTicketHolder.outof(), size);
+
+    // Throughput does not increase.
+    _readTicketHolder.setNumFinishedProcessing(2);
+
+    // Probing down fails since throughput did not increase. Return back to stable.
+    _run();
+    ASSERT_EQ(_readTicketHolder.outof(), size);
+    ASSERT_EQ(_writeTicketHolder.outof(), size);
+}
+
+TEST_F(ThroughputProbingMaxConcurrencyTest, NoProbeUp) {
+    // Tickets are exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size);
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Probe down since concurrency is already at its maximum allowed value, even though
+    // ticktes are exhausted.
+    _run();
+    ASSERT_LT(_readTicketHolder.outof(), size);
+    ASSERT_LT(_writeTicketHolder.outof(), size);
+}
+
+TEST_F(ThroughputProbingMinConcurrencyTest, NoProbeDown) {
+    // Tickets are not exhausted.
+    auto size = _readTicketHolder.outof();
+    _readTicketHolder.setUsed(size - 1);
+    _readTicketHolder.setNumFinishedProcessing(1);
+
+    // Stable. Do not probe in either direction since tickets are not exhausted but concurrency is
+    // already at its minimum allowed value.
+    _run();
+    ASSERT_EQ(_readTicketHolder.outof(), size);
+    ASSERT_EQ(_writeTicketHolder.outof(), size);
+}
+
+}  // namespace
+}  // namespace mongo::execution_control