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author | Jason Carey <jcarey@argv.me> | 2019-01-23 13:18:49 -0500 |
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committer | Jason Carey <jcarey@argv.me> | 2019-02-05 22:41:49 -0500 |
commit | a23cdb1bd0f8fbe9cd79db08a24b8a89dc54ff81 (patch) | |
tree | 1adc2fdb36e6c8babaab134d53f84de3020c2404 /src/mongo/db/baton.h | |
parent | 5fd66f15797c45c9bab7b59f9e55e0a2f7ad5cd0 (diff) | |
download | mongo-a23cdb1bd0f8fbe9cd79db08a24b8a89dc54ff81.tar.gz |
SERVER-39146 Refactor Baton
Refactor the baton into regular and networking batons while also
cleaning up the basic baton implementation.
Diffstat (limited to 'src/mongo/db/baton.h')
-rw-r--r-- | src/mongo/db/baton.h | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/src/mongo/db/baton.h b/src/mongo/db/baton.h new file mode 100644 index 00000000000..6e1d1319d2b --- /dev/null +++ b/src/mongo/db/baton.h @@ -0,0 +1,107 @@ +/** + * Copyright (C) 2019-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/util/functional.h" +#include "mongo/util/future.h" +#include "mongo/util/time_support.h" +#include "mongo/util/waitable.h" + +namespace mongo { + +class OperationContext; + +namespace transport { + +class NetworkingBaton; + +} // namespace transport + +/** + * A Baton is lightweight executor, with parallel forward progress guarantees. Rather than + * asynchronously running tasks through one, the baton records the intent of those tasks and defers + * waiting and execution to a later call to run(). + * + * Note: This occurs automatically when opCtx waiting on a condition variable. + */ +class Baton : public Waitable, public std::enable_shared_from_this<Baton> { +public: + virtual ~Baton() = default; + + /** + * Detaches a baton from an associated opCtx. + * + * This invokes all callbacks currently inside the baton (from the detaching thread) with a void + * opCtx. Also, any calls to schedule after this point will immediately invoke their callback + * with a null opCtx. + */ + void detach() noexcept { + // We make this anchor so that deleting the shared_ptr inside opCtx doesn't remove the last + // reference to this type until we return from detach. + const auto anchor = shared_from_this(); + + detachImpl(); + } + + /** + * Schedules a callback to run on the baton. + * + * The function will be invoked in one of 3 ways: + * 1. With an opCtx inside run() (I.e. opCtx->waitForConditionOrInterrupt) + * 2. Without an opCtx inside detach() + * 3. Without an opCtx inside schedule() after detach() + * + * Note that the latter two cases are indistinguishable, so the callback should be safe to run + * inline if passed a nullptr. Examples of such work are logging, simple cleanup and + * rescheduling the task on another executor. + */ + virtual void schedule(unique_function<void(OperationContext*)> func) noexcept = 0; + + /** + * Returns a networking view of the baton, if this baton supports networking functionality + */ + virtual transport::NetworkingBaton* networking() noexcept { + return nullptr; + } + + /** + * Marks the baton to wake up on client socket disconnect + */ + virtual void markKillOnClientDisconnect() noexcept = 0; + +private: + virtual void detachImpl() noexcept = 0; +}; + +using BatonHandle = std::shared_ptr<Baton>; + +} // namespace mongo |