SERVER-27257 Deduplicate symbol `newHarnessHelper`

The `newHarnessHelper` function was defined by multiple test driver
modules, each one specializing it to return a specific kind of
storage test driver's `HarnessHelper`.  The two different kinds
of `HarnessHelper` class were given a common base class, and the
`newHarnessHelper` function was changed to a single implementation.
This new implementation returns the results of a `HarnessHelper`
factory function which can be registered by a MONGO_INITIALIZER
statement.

1 files changed, 101 insertions, 0 deletions

diff --git a/src/mongo/db/storage/test_harness_helper.h b/src/mongo/db/storage/test_harness_helper.h
new file mode 100644
index 00000000000..935d54cbb86
--- /dev/null
+++ b/src/mongo/db/storage/test_harness_helper.h
@@ -0,0 +1,101 @@
+/**
+ *    Copyright (C) 2016 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 <cstdint>
+#include <initializer_list>
+#include <memory>
+
+#include "mongo/db/jsobj.h"
+#include "mongo/db/operation_context_noop.h"
+#include "mongo/db/record_id.h"
+#include "mongo/db/service_context.h"
+#include "mongo/db/service_context_noop.h"
+#include "mongo/db/storage/sorted_data_interface.h"
+#include "mongo/stdx/functional.h"
+#include "mongo/stdx/memory.h"
+#include "mongo/util/unowned_ptr.h"
+
+namespace mongo {
+class HarnessHelper {
+public:
+    virtual ~HarnessHelper() = 0;
+
+    explicit HarnessHelper() = default;
+
+    virtual ServiceContext::UniqueOperationContext newOperationContext(Client* const client) {
+        auto opCtx = client->makeOperationContext();
+        opCtx->setRecoveryUnit(newRecoveryUnit().release(), OperationContext::kNotInUnitOfWork);
+        return opCtx;
+    }
+
+    virtual ServiceContext::UniqueOperationContext newOperationContext() {
+        return newOperationContext(_client.get());
+    }
+
+    Client* client() const {
+        return _client.get();
+    }
+
+    ServiceContext* serviceContext() {
+        return &_serviceContext;
+    }
+
+    const ServiceContext* serviceContext() const {
+        return &_serviceContext;
+    }
+
+private:
+    virtual std::unique_ptr<RecoveryUnit> newRecoveryUnit() = 0;
+
+    ServiceContextNoop _serviceContext;
+    ServiceContext::UniqueClient _client = _serviceContext.makeClient("hh");
+};
+
+namespace harness_helper_detail {
+template <typename Target, typename Current>
+std::unique_ptr<Target> noexcept_ptr_conversion(std::unique_ptr<Current>&& p, Target& t) noexcept {
+    p.release();
+    return std::unique_ptr<Target>(std::addressof(t));
+}
+}  // namespace harness_helper_detail
+
+extern void registerHarnessHelperFactory(stdx::function<std::unique_ptr<HarnessHelper>()> factory);
+
+template <typename Target, typename Current>
+std::unique_ptr<Target> dynamic_ptr_cast(std::unique_ptr<Current>&& p) {
+    if (!p) {
+        throw std::runtime_error("Must not be null.");
+    }
+    Target& target = dynamic_cast<Target&>(*p);
+    return harness_helper_detail::noexcept_ptr_conversion(std::move(p), target);
+}
+
+std::unique_ptr<HarnessHelper> newHarnessHelper();
+}  // namespace mongo