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/**
* Copyright (C) 2021-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/executor/cancelable_executor.h"
#include "mongo/executor/thread_pool_task_executor_test_fixture.h"
#include "mongo/unittest/barrier.h"
#include "mongo/unittest/thread_assertion_monitor.h"
#include "mongo/unittest/unittest.h"
#include "mongo/util/cancellation.h"
#include "mongo/util/executor_test_util.h"
#include "mongo/util/future.h"
namespace mongo {
namespace executor {
namespace {
class CancelableExecutorTest : public unittest::Test {
public:
void setUp() override {
auto network = std::make_unique<executor::NetworkInterfaceMock>();
_network = network.get();
_executor = makeSharedThreadPoolTestExecutor(std::move(network));
_executor->startup();
}
void tearDown() override {
_executor->shutdown();
_executor->join();
_executor.reset();
}
std::shared_ptr<executor::ThreadPoolTaskExecutor> executor() {
return _executor;
}
executor::NetworkInterfaceMock* network() {
return _network;
}
private:
std::shared_ptr<executor::ThreadPoolTaskExecutor> _executor;
executor::NetworkInterfaceMock* _network;
};
// Just check that a CancelableExecutor correctly schedules & runs work
// in the uncanceled case.
TEST(CancelableExecutor, SchedulesWorkCorrectly) {
auto exec = InlineQueuedCountingExecutor::make();
auto [promise, future] = makePromiseFuture<void>();
CancellationSource source;
auto fut2 =
std::move(future).thenRunOn(CancelableExecutor::make(exec, source.token())).then([] {
return 42;
});
promise.emplaceValue();
ASSERT_EQ(fut2.get(), 42);
ASSERT_EQ(exec->tasksRun.load(), 1);
}
// Check that if the token passed to a CancelableExecutor is canceled before
// any work on the executor is ready to run, no work runs.
TEST(CancelableExecutor, WorkCanceledBeforeScheduleDoesNotRun) {
auto exec = InlineQueuedCountingExecutor::make();
auto [promise, future] = makePromiseFuture<void>();
CancellationSource source;
auto fut2 =
std::move(future).thenRunOn(CancelableExecutor::make(exec, source.token())).then([] {
return 42;
});
source.cancel();
promise.emplaceValue();
ASSERT_EQ(fut2.getNoThrow(), ErrorCodes::CallbackCanceled);
ASSERT_EQ(exec->tasksRun.load(), 1);
}
// Check that if the token passed CancelableExecutor is cancelled in between
// continuations scheduled on the executor, those ready before the token is cancelled
// are run and those ready after the token is canceled are not.
TEST_F(CancelableExecutorTest, WorkCanceledAfterPreviousWorkOnExecutorHasRunDoesNotRun) {
mongo::unittest::threadAssertionMonitoredTest([this](auto& assertionMonitor) {
auto [promise, future] = makePromiseFuture<void>();
auto [innerPromise, innerFuture] = makePromiseFuture<void>();
CancellationSource source;
unittest::Barrier barrier(2);
auto fut2 = std::move(future)
.thenRunOn(CancelableExecutor::make(executor(), source.token()))
.then([&barrier, innerFuture = std::move(innerFuture)] {
barrier.countDownAndWait();
innerFuture.wait();
})
.then([&assertionMonitor] {
assertionMonitor.exec([] { FAIL("This shouldn't run."); });
});
promise.emplaceValue();
// Ensure we've executed the first continuation and are waiting on innerFuture.
barrier.countDownAndWait();
// Now that we're waiting on innerFuture, we'll cancel the executor...
source.cancel();
// And ensure that the final continuation doesn't run.
innerPromise.emplaceValue();
ASSERT_EQ(fut2.getNoThrow(), ErrorCodes::CallbackCanceled);
});
}
// Ensure that if a callback should be invoked with an error status due both to
// the CancelableExecutor being canceled before the callback is ready, and
// because the backing executor refuses work for some other reason, the backing
// executor's error status takes precedence.
TEST(CancelableExecutor, ExecutorRejectionsTakePrecedenceOverCancellation) {
auto exec = RejectingExecutor::make();
auto [promise, future] = makePromiseFuture<void>();
CancellationSource source;
auto fut2 =
std::move(future).thenRunOn(CancelableExecutor::make(exec, source.token())).then([] {
return 42;
});
source.cancel();
promise.emplaceValue();
ASSERT_EQ(fut2.getNoThrow(), ErrorCodes::ShutdownInProgress);
}
// Check that no continuations (even error-handling ones) scheduled on a CancelableExecutor
// run after it is canceled, and that the cancellation error status is passed to the next
// error-handling callback on the future chain that runs in a non-canceled execution context/
// on an executor that accepts the work.
TEST(CancelableExecutor, ErrorsArePropagatedToAcceptingExecutor) {
auto exec = InlineQueuedCountingExecutor::make();
auto [promise, future] = makePromiseFuture<void>();
CancellationSource source;
auto cancelExec = CancelableExecutor::make(exec, source.token());
source.cancel();
// It's safe to FAIL in the continuations here, because this executor runs
// scheduled work inline on the main thread.
auto fut2 = std::move(future)
.thenRunOn(exec)
.then([] { return 42; })
.thenRunOn(cancelExec)
.then([](int) { FAIL("This shouldn't run"); })
.onError([](Status) { FAIL("This shouldn't run"); })
.thenRunOn(exec)
.then([]() { FAIL("This shouldn't run."); })
.onError([](Status s) { return s; });
promise.emplaceValue();
ASSERT_EQ(fut2.getNoThrow(), ErrorCodes::CallbackCanceled);
}
// Just ensure that an uncanceled CancelableExecutor correctly propagates callback
// results forward in the future chain.
TEST(CancelableExecutor, UncanceledExecutorCanBeChainedCorrectly) {
auto exec = InlineQueuedCountingExecutor::make();
auto [promise, future] = makePromiseFuture<void>();
CancellationSource source;
auto cancelExec = CancelableExecutor::make(exec, source.token());
auto fut2 = std::move(future)
.thenRunOn(exec)
.then([] { return 42; })
.thenRunOn(cancelExec)
.then([](int i) { return i + 2; });
promise.emplaceValue();
ASSERT_EQ(fut2.get(), 44);
}
} // namespace
} // namespace executor
} // namespace mongo
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