SERVER-28300 Implement mock libraries to test logical session cache

1 files changed, 138 insertions, 0 deletions

diff --git a/src/mongo/db/sessions_collection_mock.h b/src/mongo/db/sessions_collection_mock.h
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+++ b/src/mongo/db/sessions_collection_mock.h
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+/**
+ *    Copyright (C) 2017 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    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
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    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 GNU Affero General 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 "mongo/db/logical_session_id.h"
+#include "mongo/db/logical_session_record.h"
+#include "mongo/db/sessions_collection.h"
+#include "mongo/stdx/functional.h"
+#include "mongo/stdx/mutex.h"
+#include "mongo/stdx/unordered_map.h"
+
+namespace mongo {
+
+/**
+ * To allow us to move a MockSessionCollection into the session cache while
+ * maintaining a hold on it from within our unit tests, the MockSessionCollection
+ * will have an internal pointer to a MockSessionsCollectionImpl object that the
+ * test creates and controls.
+ *
+ * This class can operate in two modes:
+ *
+ * - if no custom hooks are set, then the test caller may add() and remove() items
+ *   from the _sessions map, and this class will simply perform the required
+ *   operations against that set.
+ *
+ * - if custom hooks are set, then the hooks will be run instead of the provided
+ *   defaults, and the internal _sessions map will NOT be updated.
+ */
+class MockSessionsCollectionImpl {
+public:
+    using SessionList = std::list<LogicalSessionId>;
+    using SessionMap =
+        stdx::unordered_map<LogicalSessionId, LogicalSessionRecord, LogicalSessionId::Hash>;
+
+    MockSessionsCollectionImpl();
+
+    using FetchHook = stdx::function<StatusWith<LogicalSessionRecord>(LogicalSessionId)>;
+    using InsertHook = stdx::function<Status(LogicalSessionRecord)>;
+    using RefreshHook = stdx::function<SessionList(SessionList)>;
+    using RemoveHook = stdx::function<void(SessionList)>;
+
+    // Set custom hooks to override default behavior
+    void setFetchHook(FetchHook hook);
+    void setInsertHook(InsertHook hook);
+    void setRefreshHook(RefreshHook hook);
+    void setRemoveHook(RemoveHook hook);
+
+    // Reset all hooks to their defaults
+    void clearHooks();
+
+    // Forwarding methods from the MockSessionsCollection
+    StatusWith<LogicalSessionRecord> fetchRecord(LogicalSessionId lsid);
+    Status insertRecord(LogicalSessionRecord record);
+    SessionList refreshSessions(SessionList sessions);
+    void removeRecords(SessionList sessions);
+
+    // Test-side methods that operate on the _sessions map
+    void add(LogicalSessionRecord record);
+    void remove(LogicalSessionId lsid);
+    bool has(LogicalSessionId lsid);
+    void clearSessions();
+    const SessionMap& sessions() const;
+
+private:
+    // Default implementations, may be overridden with custom hooks.
+    StatusWith<LogicalSessionRecord> _fetchRecord(LogicalSessionId lsid);
+    Status _insertRecord(LogicalSessionRecord record);
+    SessionList _refreshSessions(SessionList sessions);
+    void _removeRecords(SessionList sessions);
+
+    stdx::mutex _mutex;
+    SessionMap _sessions;
+
+    FetchHook _fetch;
+    InsertHook _insert;
+    RefreshHook _refresh;
+    RemoveHook _remove;
+};
+
+/**
+ * To allow us to move this into the session cache while maintaining a hold
+ * on it from the test side, the MockSessionCollection will have an internal pointer
+ * to an impl that we maintain access to.
+ */
+class MockSessionsCollection : public SessionsCollection {
+public:
+    using SessionList = std::list<LogicalSessionId>;
+
+    explicit MockSessionsCollection(std::shared_ptr<MockSessionsCollectionImpl> impl)
+        : _impl(std::move(impl)) {}
+
+    StatusWith<LogicalSessionRecord> fetchRecord(LogicalSessionId lsid) override {
+        return _impl->fetchRecord(std::move(lsid));
+    }
+
+    Status insertRecord(LogicalSessionRecord record) override {
+        return _impl->insertRecord(std::move(record));
+    }
+
+    SessionList refreshSessions(SessionList sessions) override {
+        return _impl->refreshSessions(std::move(sessions));
+    }
+
+    void removeRecords(SessionList sessions) override {
+        return _impl->removeRecords(std::move(sessions));
+    }
+
+private:
+    std::shared_ptr<MockSessionsCollectionImpl> _impl;
+};
+
+}  // namespace mongo