SERVER-59360 Health observer registration and basic mock class

1 files changed, 74 insertions, 0 deletions

diff --git a/src/mongo/db/process_health/health_observer_registration.h b/src/mongo/db/process_health/health_observer_registration.h
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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.
+ */
+#pragma once
+
+#include <functional>
+#include <vector>
+
+#include "mongo/db/process_health/health_observer.h"
+
+#include "mongo/db/service_context.h"
+#include "mongo/platform/mutex.h"
+
+namespace mongo {
+namespace process_health {
+
+/**
+ * Registration mechanism for all health observers.
+ */
+class HealthObserverRegistration {
+public:
+    static HealthObserverRegistration* get(ServiceContext* svcCtx);
+
+    explicit HealthObserverRegistration(ServiceContext* svcCtx);
+
+    /**
+     * Registers a factory method, which will be invoked later to instantiate the observer.
+     *
+     * @param factoryCallback creates observer instance when invoked.
+     */
+    void registerObserverFactory(
+        std::function<std::unique_ptr<HealthObserver>(ServiceContext* svcCtx)> factoryCallback);
+
+    /**
+     * Invokes all registered factories and returns new instances.
+     * The ownership of all observers is transferred to the invoker.
+     */
+    std::vector<std::unique_ptr<HealthObserver>> instantiateAllObservers() const;
+
+private:
+    ServiceContext* const _svcCtx;
+
+    mutable Mutex _mutex =
+        MONGO_MAKE_LATCH(HierarchicalAcquisitionLevel(0), "HealthObserverRegistration::_mutex");
+    std::vector<std::function<std::unique_ptr<HealthObserver>(ServiceContext* svcCtx)>> _factories;
+};
+
+}  // namespace process_health
+}  // namespace mongo