include/machi_projection.hrl

@@ -82,6 +82,8 @@
           mode           :: pv1_consistency_mode(),
           full           :: [p_srvr()],
           witnesses      :: [p_srvr()],
+          old_all        :: [pv1_server()],
+          old_witnesses  :: [pv1_server()],
           props = []     :: list()  % proplist for other related info
          }).
 

src/machi_chain_manager1.erl

@@ -1255,7 +1255,7 @@ react_to_env_A20(Retries, #ch_mgr{name=MyName, proj=P_current}=S) ->
             P_none0 = make_none_projection(Epoch,
                                            MyName, All_list, Witness_list, MembersDict),
             P_none = P_none0#projection_v1{chain_name=ChainName},
-            {{x,y,z,42,77}, set_proj(S2, P_none)};
+            {{now_using,[],Epoch}, set_proj(S2, P_none)};
         _ ->
             react_to_env_A21(Retries, UnanimousTag, P_latest, ReadExtra, S2)
     end.

src/machi_lifecycle_mgr.erl

@@ -126,6 +126,9 @@
 %% </li>
 %% </ul>
 %%
+%% A FLU may be created or removed (via implicit or explicit policy).
+%% An existing FLU may not be reconfigured.
+%%
 %% == The Chain Lifecycle ==
 %%
 %% If a FLU on the local machine is expected to participate in a
@@ -176,6 +179,17 @@
 %% </li>
 %% </ul>
 %%
+%% A chain may be created, removed, or modified.
+%%
+%% A modification request writes a `#chain_def_v1{}' record with the
+%% same name but different `full' and/or `witnesses' list to each
+%% machine that hosts a FLU in the chain (in both the old and new
+%% versions of the chain).
+%%
+%% A deletion request writes a `#chain_def_v1{}' record with the same
+%% name but empty lists for `full' and `witnesses' to each machine
+%% that hosts a FLU in the chain (in the old version of the chain).
+%%
 %% == Conflicts with TCP ports, FLU &amp; chain names, etc ==
 %%
 %% This manager is not responsible for managing conflicts in resource
@@ -273,7 +287,9 @@ get_initial_chains() ->
                         ok = filelib:ensure_dir(Dir ++ "/unused"),
                         Dir
                 end,
-    sanitize_chain_def_records(machi_flu_sup:load_rc_d_files_from_dir(ConfigDir)).
+    CDefs = [CDef || {_File, CDef} <- machi_flu_sup:load_rc_d_files_from_dir(
+                                        ConfigDir)],
+    sanitize_chain_def_records(CDefs).
 
 sanitize_chain_def_records(Ps) ->
     {Sane, _} = lists:foldl(fun sanitize_chain_def_rec/2, {[], dict:new()}, Ps),
@@ -285,23 +301,22 @@ sanitize_chain_def_rec(Whole, {Acc, D}) ->
                       mode=Mode,
                       full=Full,
                       witnesses=Witnesses} = Whole,
-        true = is_atom(Name),
+        {true, 10} = {is_atom(Name), 10},
         NameK = {name, Name},
-        error = dict:find(NameK, D),
-        true = (Mode == ap_mode orelse Mode == cp_mode),
+        {error, 20} = {dict:find(NameK, D), 20},
+        {true, 30} = {(Mode == ap_mode orelse Mode == cp_mode), 30},
         IsPSrvr = fun(X) when is_record(X, p_srvr) -> true;
                      (_)                           -> false
                   end,
-        true = lists:all(IsPSrvr, Full),
-        true = lists:all(IsPSrvr, Witnesses),
+        {true, 40} = {lists:all(IsPSrvr, Full), 40},
+        {true, 50} = {lists:all(IsPSrvr, Witnesses), 50},
 
         %% All is sane enough.
         D2 = dict:store(NameK, Name, D),
         {[Whole|Acc], D2}
-    catch _X:_Y ->
-            _ = lager:log(error, self(),
-                          "~s: Bad chain_def record (~w ~w), skipping: ~P\n",
-                          [?MODULE, _X, _Y, Whole, 15]),
+    catch X:Y ->
+            lager:error("~s: Bad chain_def record (~w ~w), skipping: ~P\n",
+                        [?MODULE, X, Y, Whole, 15]),
             {Acc, D}
     end.
 
@@ -323,25 +338,62 @@ perhaps_bootstrap_chains([CD|ChainDefs], LocalFLUs_at_zero, LocalFLUs) ->
             perhaps_bootstrap_chains(ChainDefs, LocalFLUs_at_zero, LocalFLUs);
         [FLU1|_]=FLUs ->
             %% One FLU is enough: Humming Consensus will config the remaining
-            bootstrap_chain(CD, FLU1),
+            _ = bootstrap_chain(CD, FLU1),
             perhaps_bootstrap_chains(ChainDefs, LocalFLUs_at_zero -- FLUs,
                                     LocalFLUs -- FLUs)
     end.
 
-bootstrap_chain(#chain_def_v1{name=ChainName, mode=CMode, full=Full,
-                              witnesses=Witnesses, props=Props}=CD, FLU) ->
-    All_p_srvrs = Full ++ Witnesses,
+bootstrap_chain(CD, FLU) ->
+    bootstrap_chain2(CD, FLU, 20).
+
+bootstrap_chain2(CD, FLU, 0) ->
+    lager:warning("Failed all attempts to bootstrap chain ~w via FLU ~w ",
+                  [CD,FLU]),
+    failed;
+bootstrap_chain2(#chain_def_v1{name=NewChainName, mode=CMode, full=Full,
+                               witnesses=Witnesses, props=Props}=CD,
+                 FLU, N) ->
+    All_p_srvrs = Witnesses ++ Full,
     L = [{Name, P_srvr} || #p_srvr{name=Name}=P_srvr <- All_p_srvrs],
     MembersDict = orddict:from_list(L),
     Mgr = machi_chain_manager1:make_chmgr_regname(FLU),
-    case machi_chain_manager1:set_chain_members(Mgr, ChainName, 0, CMode,
-                                                MembersDict, Props) of
+    PStore = machi_flu1:make_projection_server_regname(FLU),
+    {ok, #projection_v1{epoch_number=OldEpoch, chain_name=OldChainName,
+                        all_members=OldAll_list, witnesses=OldWitnesses}} =
+        machi_projection_store:read_latest_projection(PStore, private),
+    NewAll_list = [Name || #p_srvr{name=Name} <- All_p_srvrs],
+    case set_chain_members(OldChainName, NewChainName,
+                           OldAll_list, OldWitnesses,
+                           NewAll_list, NewWitnesses,
+                           Mgr, NewChainName, OldEpoch,
+                           CMode, MembersDict, NewWitnesses) of
         ok ->
-            ok;
+            lager:info("Bootstrapped chain ~w via FLU ~w to "
+                       "mode=~w all=~w witnesses=~w\n",
+                       [NewChainName, FLU, CMode, All_list, NewWitnesses]),
+            AddedFLUs = NewAll_list -- OldAll_list,
+            RemovedFLUs = OldAll_list -- NewAll_list,
+            {ok, AddedFLUs, RemovedFLUs};
         Else ->
-            error_logger:warning("Attempt to bootstrap chain ~w via FLU ~w "
-                                 "failed: ~w (defn ~w)\n", [Else, CD]),
-            ok
+            lager:error("Attempt to bootstrap chain ~w via FLU ~w "
+                        "failed: ~w (defn ~w)\n",
+                        [NewChainName, FLU, Else, CD]),
+            timer:sleep(555),
+            bootstrap_chain2(CD, FLU, N-1)
+    end.
+
+set_chain_members(OldChainName, NewChainName,
+                  OldAll_list, OldWitnesses, NewAll_list, NewWitnesses,
+                  Mgr, ChainName, OldEpoch, CMode, MembersDict, Props) ->
+    if OldChainName == NewChainName,
+       OldAll_list == NewAll_list, OldWitnesses == NewWitnesses ->
+            ok;
+       OldEpoch == 0 orelse (OldChainName == NewChainName) ->
+            machi_chain_manager1:set_chain_members(Mgr, ChainName, OldEpoch,
+                                                   CMode,
+                                                   MembersDict, NewWitnesses);
+       true ->
+            chain_bad_arg
     end.
 
 do_process_pending(S) ->
@@ -398,7 +450,47 @@ process_pending_flu({File, P}, S) ->
 process_pending_chains(P_Chains, S) ->
     lists:foldl(fun process_pending_chain/2, S, P_Chains).
 
-process_pending_chain({_File, #chain_def_v1{}}, S) ->
+process_pending_chain({File, CD}, S) ->
+    #chain_def_v1{name=Name, mode=CMode, full=Full, witnesses=Witnesses} = CD,
+    case sanitize_chain_def_records([CD]) of
+        [CD] ->
+            RunningFLUs = get_local_running_flus(),
+            AllNames = [Name || #p_srvr{name=Name} <- Full ++ Witnesses],
+            case ordsets:intersection(ordsets:from_list(AllNames),
+                                      ordsets:from_list(RunningFLUs)) of
+                [] ->
+                    lager:error("Pending chain config file ~s "
+                                "has no local FLUs on this machine, rejected\n",
+                                [File]),
+                    _ = move_to_rejected(File, S),
+                    S;
+                [FLU|_]=LocalFLUs ->
+                    %% TODO: Between the successful chain change inside of
+                    %% bootstrap_chain() (and before it returns to us!) and
+                    %% the return of process_pending_chain2(), we have a race
+                    %% window if this process crashes.
+                    case bootstrap_chain(CD, FLU) of
+                        {ok, AddedFLUs, RemovedFLUs} ->
+                            process_pending_chain2(File, CD, LocalFLUs,
+                                                   AddedFLUs, RemovedFLUs, S);
+                        Else ->
+                            lager:error("Pending chain config file ~s "
+                                        "has failed (~w), rejected\n",
+                                        [Else, File]),
+                            _ = move_to_rejected(File, S),
+                            S
+                    end
+            end;
+        [] ->
+            lager:error("Pending chain config file ~s has been rejected\n",
+                        [File]),
+            _ = move_to_rejected(File, S),
+            S
+    end.
+
+process_pending_chain2(File, CD, LocalFLUs, AddedFLUs, RemovedFLUs, S) ->
+    %% AddedFLUs: no any extra work.
+    %% RemovedFLUs: Stop the FLU, config -> j-i-c, data -> j-i-c
     io:format(user, "TODO: ~s LINE ~p\n", [?MODULE, ?LINE]),
     S.
 
@@ -418,25 +510,3 @@ move_to_flu_config(FLU, File, S) ->
     Dst = get_flu_config_dir(S),
     ok = file:rename(File, Dst ++ "/" ++ atom_to_list(FLU)),
     S.
-
-%% 1. Don't worry about partial writes to config dir: that's a Policy
-%%    implementation worry: create a temp file, fsync(2), then rename(2)
-%%    and possibly fsync(2) on the dir.
-%%
-%% 2. Add periodic re-scan check FLUs & chains (in that order).
-%%
-%% 3. Add force re-rescan of FLUs *or* chains.  (separate is better?)
-%%
-%% 4. For chain modification: add "change" directory?  Scan looks in
-%%    "change"?
-%%
-%% 5. Easy comparison for current vs. new chain config.
-%%    - identify new FLUs: no action required, HC will deal with it?
-%%    - identify removed FLUs: set_chain_members() to change HC
-%%                           : stop FLU package (after short pause)
-%%                           : move config file -> just-in-case
-%%                           : move data files -> just-in-case
-%%                             - identify j-i-c dir in case resuming from interruption??? to avoid problem of putting config & data files in different places?
-%%                             - move data files itself may be interrupted?
-%%    - move chain def'n from change -> chain_config_dir
-