feat: add partition guardian to keep one primary and two secondaries

src/meta/partition_guardian.cpp

@@ -0,0 +1,79 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "partition_guardian.h"
+namespace dsn {
+namespace replication {
+partition_guardian::partition_guardian(meta_service *svc) : _svc(svc) {}
+
+pc_status partition_guardian::cure(meta_view view,
+                                   const dsn::gpid &gpid,
+                                   configuration_proposal_action &action)
+{
+    if (from_proposals(view, gpid, action))
+        return pc_status::ill;
+
+    std::shared_ptr<app_state> &app = (*view.apps)[gpid.get_app_id()];
+    const partition_configuration &pc = *get_config(*(view.apps), gpid);
+    const proposal_actions &acts = get_config_context(*view.apps, gpid)->lb_actions;
+
+    dassert(app->is_stateful, "");
+    dassert(acts.empty(), "");
+
+    pc_status status;
+    if (pc.primary.is_invalid())
+        status = on_missing_primary(view, gpid);
+    else if (static_cast<int>(pc.secondaries.size()) + 1 < pc.max_replica_count)
+        status = on_missing_secondary(view, gpid);
+    else if (static_cast<int>(pc.secondaries.size()) >= pc.max_replica_count)
+        status = on_redundant_secondary(view, gpid);
+    else
+        status = pc_status::healthy;
+
+    if (!acts.empty()) {
+        action = *acts.front();
+    }
+    return status;
+}
+
+bool partition_guardian::from_proposals(meta_view &view,
+                                        const dsn::gpid &gpid,
+                                        configuration_proposal_action &action)
+{
+    // TBD(zlw)
+    return false;
+}
+
+pc_status partition_guardian::on_missing_primary(meta_view &view, const dsn::gpid &gpid)
+{
+    // TBD(zlw)
+    return pc_status::invalid;
+}
+
+pc_status partition_guardian::on_missing_secondary(meta_view &view, const dsn::gpid &gpid)
+{
+    // TBD(zlw)
+    return pc_status::invalid;
+}
+
+pc_status partition_guardian::on_redundant_secondary(meta_view &view, const dsn::gpid &gpid)
+{
+    // TBD(zlw)
+    return pc_status::invalid;
+}
+} // namespace replication
+} // namespace dsn

src/meta/partition_guardian.h

@@ -0,0 +1,45 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#pragma once
+
+#include "meta_data.h"
+
+namespace dsn {
+namespace replication {
+class meta_service;
+
+class partition_guardian
+{
+public:
+    explicit partition_guardian(meta_service *svc);
+    ~partition_guardian() = default;
+
+    pc_status cure(meta_view view, const dsn::gpid &gpid, configuration_proposal_action &action);
+
+private:
+    bool
+    from_proposals(meta_view &view, const dsn::gpid &gpid, configuration_proposal_action &action);
+    pc_status on_missing_primary(meta_view &view, const dsn::gpid &gpid);
+    pc_status on_missing_secondary(meta_view &view, const dsn::gpid &gpid);
+    pc_status on_redundant_secondary(meta_view &view, const dsn::gpid &gpid);
+
+    meta_service *_svc;
+};
+
+} // namespace replication
+} // namespace dsn