WL#11338: Backport changes to uniquely identify different node incarnations

In GCS/XCOM, a node can receive messages such as ping(s) and paxos
proposals and act upon them immediately after rebooting. However,
a node that has recently rebooted suffers from amnesia and does not
know anything about its prior states unless it has written them into
a stable storage. Unfortunately, GCS/XCOM does not use any stable
storage in order to improve performance but pings and paxos are still
indiscriminately processed after reboot. This scenario can lead to a
variety of strange problems, and in the extreme case, it can generate
data inconsistency.

We have identified the problem and started augmenting GCS/XCOM with
the notion of incarnation. Basically, every node has a unique
identifier assigned to it every time it joins the cluster and this
information can be used to distinguish among different node
incarnations.

This fix contains the following set of patches backported from 8.0:
  . BUG#25311008
  . BUG#22204121

Author: alfranio

rapid/plugin/group_replication/libmysqlgcs/include/mysql/gcs/gcs_member_identifier.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -17,6 +17,73 @@
 #define GCS_MEMBER_IDENTIFIER_INCLUDED
 
 #include <string>
+#include "gcs_types.h"
+
+
+/*
+  Internal GCS unique identifier.
+*/
+class Gcs_uuid
+{
+public:
+  /*
+    Create a GCS unique identifier.
+  */
+
+  static Gcs_uuid create_uuid();
+
+
+  /*
+    Default constructor
+  */
+  Gcs_uuid();
+
+
+  /*
+    Copies the internal buffer which is used to store a uuid to an
+    external buffer. If the parameters buffer or size point to NULL,
+    nothing is returned.
+
+    @param [out] buffer storage buffer
+    @param [out] size data size
+    @return Whether the data was returned or not.
+  */
+
+  bool encode(uchar **buffer, unsigned int *size) const;
+
+
+  /*
+    Copies the external buffer to an internal buffer. If the
+    parameter buffer points to NULL, nothing is returned.
+
+    @param [in] buffer storage buffer
+    @param [in] size data size
+    @return Whether the data was copied or not.
+  */
+
+  bool decode(const uchar *buffer, const unsigned int size);
+
+  /*
+    Return the size of the UUID in use.
+  */
+  size_t size() const;
+
+  /*
+    Unique identifier which currently only accommodates 64 bits but
+    can easily be extended to 128 bits and become a truly UUID in
+    the future.
+  */
+
+  std::string actual_value;
+
+private:
+  /*
+    Create a GCS unique identifier.
+  */
+
+  static const std::string do_create_uuid();
+};
+
 
 /**
   @class Gcs_member_identifier
@@ -41,6 +108,17 @@ class Gcs_member_identifier
   explicit Gcs_member_identifier(const std::string &member_id);
 
 
+  /**
+    Gcs_member_identifier constructor.
+
+    @param[in] member_id the member identifier
+    @param[in] uuid the member uuid
+  */
+
+  explicit Gcs_member_identifier(const std::string &member_id,
+                                 const Gcs_uuid &uuid);
+
+
   virtual ~Gcs_member_identifier() {}
 
 
@@ -50,6 +128,18 @@ class Gcs_member_identifier
 
   const std::string& get_member_id() const;
 
+  /**
+    @return the member uuid
+  */
+
+  const Gcs_uuid& get_member_uuid() const;
+
+
+  /**
+    Regenerate the member uuid
+  */
+
+  void regenerate_member_uuid();
 
   /**
     Redefinition of the operator less, to allow usage as key in maps.
@@ -76,7 +166,8 @@ class Gcs_member_identifier
 
 
 private:
-  std::string member_id;
+  std::string m_member_id;
+  Gcs_uuid m_uuid;
 };
 
 #endif // GCS_MEMBER_IDENTIFIER_INCLUDED

rapid/plugin/group_replication/libmysqlgcs/include/mysql/gcs/gcs_view.h

@@ -1,4 +1,4 @@
-/* Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,6 +21,7 @@
 #include "gcs_member_identifier.h"
 
 #include <vector>
+#include <string>
 
 /**
   @class Gcs_view
@@ -146,6 +147,23 @@ class Gcs_view
   Gcs_view::Gcs_view_error_code get_error_code() const;
 
 
+  /*
+    @param[in] address Member's identifier which is usually its address
+    @return the member whose identifier matches the one provided as
+            parameter
+  */
+
+  const Gcs_member_identifier *get_member(const std::string &member_id) const;
+
+
+  /*
+    @param[in] member_id Member's identifier which is usually its address
+    @return whether there is a member whose identifier matches the one
+            provided as parameter
+  */
+
+  bool has_member(const std::string &member_id) const;
+
 private:
   std::vector<Gcs_member_identifier> *m_members;
   Gcs_view_identifier                *m_view_id;