SERVER-55102 Create CancelableOperationContext class.

4 files changed, 371 insertions, 0 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index c9a65ce3bd5..00520a3b284 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -452,6 +452,7 @@ env.Library(
     target='service_context',
     source=[
         'baton.cpp',
+        'cancelable_operation_context.cpp',
         'client.cpp',
         'client_strand.cpp',
         'default_baton.cpp',
@@ -2304,6 +2305,7 @@ if wiredtiger:
     envWithAsio.CppUnitTest(
         target='db_unittest_test',
         source=[
+            'cancelable_operation_context_test.cpp',
             'catalog_raii_test.cpp',
             'client_strand_test.cpp',
             'client_context_test.cpp',
diff --git a/src/mongo/db/cancelable_operation_context.cpp b/src/mongo/db/cancelable_operation_context.cpp
new file mode 100644
index 00000000000..c929f33f9e6
--- /dev/null
+++ b/src/mongo/db/cancelable_operation_context.cpp
@@ -0,0 +1,65 @@
+/**
+ *    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/db/cancelable_operation_context.h"
+
+#include "mongo/db/client.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/stdx/mutex.h"
+#include "mongo/util/cancelation.h"
+
+namespace mongo {
+
+CancelableOperationContext::CancelableOperationContext(ServiceContext::UniqueOperationContext opCtx,
+                                                       const CancelationToken& cancelToken,
+                                                       ExecutorPtr executor)
+    : _sharedBlock{std::make_shared<SharedBlock>()},
+      _opCtx{std::move(opCtx)},
+      _markKilledFinished{cancelToken.onCancel()
+                              .thenRunOn(std::move(executor))
+                              .then([sharedBlock = _sharedBlock, opCtx = _opCtx.get()] {
+                                  if (!sharedBlock->done.swap(true)) {
+                                      stdx::lock_guard<Client> lk(*opCtx->getClient());
+                                      opCtx->markKilled(ErrorCodes::CallbackCanceled);
+                                  }
+                              })
+                              .semi()} {}
+
+CancelableOperationContext::~CancelableOperationContext() {
+    if (_sharedBlock->done.swap(true)) {
+        // _sharedBlock->done was already true so our onCancel() continuation must have started to
+        // run. We must wait for it to finish running to avoid markKilled() being called while the
+        // OperationContext is being destructed.
+        _markKilledFinished.wait();
+    }
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/cancelable_operation_context.h b/src/mongo/db/cancelable_operation_context.h
new file mode 100644
index 00000000000..ca9493a58c2
--- /dev/null
+++ b/src/mongo/db/cancelable_operation_context.h
@@ -0,0 +1,95 @@
+/**
+ *    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.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include "mongo/db/service_context.h"
+#include "mongo/platform/atomic_word.h"
+#include "mongo/util/future.h"
+#include "mongo/util/out_of_line_executor.h"
+
+namespace mongo {
+
+class CancelationToken;
+class OperationContext;
+
+/**
+ * Wrapper class around an OperationContext that calls markKilled(ErrorCodes::CallbackCanceled) when
+ * the supplied CancelationToken is canceled.
+ *
+ * This class is useful for having an OperationContext be interrupted when a CancelationToken is
+ * canceled. Note that OperationContext::getCancelationToken() is instead useful for having a
+ * CancelationToken be canceled when an OperationContext is interrupted. The combination of the two
+ * enables bridging between OperationContext interruption and CancelationToken cancellation
+ * arbitrarily.
+ *
+ * IMPORTANT: Executors are allowed to refuse work. markKilled(ErrorCodes::CallbackCanceled) won't
+ * be called when the supplied CancelationToken is canceled if the task executor has already been
+ * shut down, for example. Use a task executor bound to the process lifetime if you must guarantee
+ * that the OperationContext is interrupted when the CancelationToken is canceled.
+ */
+class CancelableOperationContext {
+public:
+    CancelableOperationContext(ServiceContext::UniqueOperationContext opCtx,
+                               const CancelationToken& cancelToken,
+                               ExecutorPtr executor);
+
+    CancelableOperationContext(const CancelableOperationContext&) = delete;
+    CancelableOperationContext& operator=(const CancelableOperationContext&) = delete;
+
+    CancelableOperationContext(CancelableOperationContext&&) = delete;
+    CancelableOperationContext& operator=(CancelableOperationContext&&) = delete;
+
+    ~CancelableOperationContext();
+
+    OperationContext* get() const noexcept {
+        return _opCtx.get();
+    }
+
+    OperationContext* operator->() const noexcept {
+        return get();
+    }
+
+    OperationContext& operator*() const noexcept {
+        return *get();
+    }
+
+private:
+    struct SharedBlock {
+        AtomicWord<bool> done{false};
+    };
+
+    const std::shared_ptr<SharedBlock> _sharedBlock;
+    const ServiceContext::UniqueOperationContext _opCtx;
+    const SemiFuture<void> _markKilledFinished;
+};
+
+}  // namespace mongo
diff --git a/src/mongo/db/cancelable_operation_context_test.cpp b/src/mongo/db/cancelable_operation_context_test.cpp
new file mode 100644
index 00000000000..bcdf7f5e22d
--- /dev/null
+++ b/src/mongo/db/cancelable_operation_context_test.cpp
@@ -0,0 +1,209 @@
+/**
+ *    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/db/cancelable_operation_context.h"
+#include "mongo/db/client.h"
+#include "mongo/db/operation_context.h"
+#include "mongo/stdx/mutex.h"
+#include "mongo/unittest/unittest.h"
+#include "mongo/util/concurrency/thread_pool.h"
+
+namespace mongo {
+namespace {
+
+class CancelableOperationContextTest : public unittest::Test {
+public:
+    void setUp() override {
+        ThreadPool::Options options;
+        options.poolName = "CancelableOperationContextTest";
+        options.minThreads = 1;
+        options.maxThreads = 1;
+
+        _threadPool = std::make_shared<ThreadPool>(std::move(options));
+        _threadPool->startup();
+    }
+
+    void tearDown() override {
+        _threadPool->shutdown();
+        _threadPool->join();
+        _threadPool.reset();
+    }
+
+    ExecutorPtr executor() {
+        return _threadPool;
+    }
+
+    void waitForAllEarlierTasksToComplete() {
+        _threadPool->waitForIdle();
+    }
+
+    void shutDownExecutor() {
+        _threadPool->shutdown();
+    }
+
+private:
+    std::shared_ptr<ThreadPool> _threadPool;
+};
+
+TEST_F(CancelableOperationContextTest, ActsAsNormalOperationContext) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+    auto opCtx = CancelableOperationContext{
+        client->makeOperationContext(), CancelationToken::uncancelable(), executor()};
+
+    ASSERT_EQ(opCtx->getClient(), client.get());
+    ASSERT_EQ(opCtx.get()->getClient(), client.get());
+
+    // The CancelationSource underlying the OperationContext* is unassociated with the one supplied
+    // to the CancelableOperationContext constructor.
+    ASSERT_TRUE(opCtx->getCancelationToken().isCancelable());
+}
+
+TEST_F(CancelableOperationContextTest, KilledWhenCancelationSourceIsCanceled) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    CancelationSource cancelSource;
+    auto opCtx = CancelableOperationContext{
+        client->makeOperationContext(), cancelSource.token(), executor()};
+
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+
+    cancelSource.cancel();
+    waitForAllEarlierTasksToComplete();
+    ASSERT_EQ(opCtx->checkForInterruptNoAssert(), ErrorCodes::CallbackCanceled);
+}
+
+TEST_F(CancelableOperationContextTest, SafeWhenCancelationSourceIsCanceledUnderClientMutex) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    CancelationSource cancelSource;
+    auto opCtx = CancelableOperationContext{
+        client->makeOperationContext(), cancelSource.token(), executor()};
+
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+
+    {
+        // Holding the Client mutex while canceling the CancelationSource won't lead to
+        // self-deadlock.
+        stdx::lock_guard<Client> lk(*opCtx->getClient());
+        cancelSource.cancel();
+    }
+    waitForAllEarlierTasksToComplete();
+    ASSERT_EQ(opCtx->checkForInterruptNoAssert(), ErrorCodes::CallbackCanceled);
+}
+
+TEST_F(CancelableOperationContextTest, SafeWhenDestructedBeforeCancelationSourceIsCanceled) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    CancelationSource cancelSource;
+    boost::optional<CancelableOperationContext> opCtx;
+    opCtx.emplace(client->makeOperationContext(), cancelSource.token(), executor());
+
+    opCtx.reset();
+    cancelSource.cancel();
+}
+
+TEST_F(CancelableOperationContextTest, NotKilledWhenCancelationSourceIsDestructed) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    boost::optional<CancelationSource> cancelSource;
+    cancelSource.emplace();
+    auto opCtx = CancelableOperationContext{
+        client->makeOperationContext(), cancelSource->token(), executor()};
+
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+
+    cancelSource.reset();
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+}
+
+TEST_F(CancelableOperationContextTest,
+       NotKilledWhenCancelationSourceIsCanceledAndTaskExecutorAlreadyShutDown) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    CancelationSource cancelSource;
+    auto opCtx = CancelableOperationContext{
+        client->makeOperationContext(), cancelSource.token(), executor()};
+
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+
+    shutDownExecutor();
+    cancelSource.cancel();
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+}
+
+TEST_F(CancelableOperationContextTest, SafeWhenOperationContextOwnCancelationTokenIsUsed) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    auto opCtx = client->makeOperationContext();
+    auto cancelToken = opCtx->getCancelationToken();
+    auto cancelableOpCtx = CancelableOperationContext{std::move(opCtx), cancelToken, executor()};
+
+    ASSERT_OK(cancelableOpCtx->checkForInterruptNoAssert());
+
+    auto expectedErrorCode = ErrorCodes::Error(5510299);
+    {
+        // Acquiring the Client mutex is technically unnecessary here but we do it specifically to
+        // demonstrate that holding it won't lead to self-deadlock.
+        stdx::lock_guard<Client> lk(*cancelableOpCtx->getClient());
+        cancelableOpCtx->markKilled(expectedErrorCode);
+    }
+    ASSERT_EQ(cancelableOpCtx->checkForInterruptNoAssert(), expectedErrorCode);
+}
+
+TEST_F(CancelableOperationContextTest, SafeWhenOperationContextKilledManually) {
+    auto serviceCtx = ServiceContext::make();
+    auto client = serviceCtx->makeClient("CancelableOperationContextTest");
+
+    CancelationSource cancelSource;
+    auto opCtx = CancelableOperationContext{
+        client->makeOperationContext(), cancelSource.token(), executor()};
+
+    ASSERT_OK(opCtx->checkForInterruptNoAssert());
+
+    auto expectedErrorCode = ErrorCodes::Error(5510298);
+    {
+        // Acquiring the Client mutex is technically unnecessary here but we do it specifically to
+        // demonstrate that holding it won't lead to self-deadlock.
+        stdx::lock_guard<Client> lk(*opCtx->getClient());
+        opCtx->markKilled(expectedErrorCode);
+    }
+    ASSERT_EQ(opCtx->checkForInterruptNoAssert(), expectedErrorCode);
+}
+
+}  // namespace
+}  // namespace mongo