Merge branch 'richcarl/dcd-dumps'

* richcarl/dcd-dumps:
  Make Mnesia DCD dump behaviour available via API
  Make Mnesia DCD dump behaviour available via configuration

OTP-12481

5 files changed, 80 insertions, 26 deletions

diff --git a/lib/mnesia/doc/src/mnesia.xml b/lib/mnesia/doc/src/mnesia.xml
index c23c2cb226..3eeb6f0247 100644
--- a/lib/mnesia/doc/src/mnesia.xml
+++ b/lib/mnesia/doc/src/mnesia.xml
@@ -3017,6 +3017,12 @@ raise(Name, Amount) ->
           totally unpredictable.</p>
       </item>
       <item>
+        <p><c>-mnesia dump_disc_copies_at_startup true | false</c>.
+          If set to false, this disables the dumping of <c>disc_copies</c>
+          tables during startup while tables are being loaded. The default
+          is true.</p>
+      </item>
+      <item>
         <p><c>-mnesia dump_log_load_regulation true | false</c>.
           Controls if the log dumps should be performed as fast as
           possible or if the dumper should do its own load
diff --git a/lib/mnesia/src/mnesia_controller.erl b/lib/mnesia/src/mnesia_controller.erl
index 5a9bae54da..aa72de7594 100644
--- a/lib/mnesia/src/mnesia_controller.erl
+++ b/lib/mnesia/src/mnesia_controller.erl
@@ -51,6 +51,7 @@
 	 force_load_table/1,
 	 async_dump_log/1,
 	 sync_dump_log/1,
+	 snapshot_dcd/1,
 	 connect_nodes/1,
          connect_nodes/2,
 	 wait_for_schema_commit_lock/0,
@@ -139,7 +140,8 @@ max_loaders() ->
 -record(block_controller, {owner}).
 
 -record(dump_log, {initiated_by,
-		   opt_reply_to
+		   opt_reply_to,
+		   operation = dump_log
 		  }).
 
 -record(net_load, {table,
@@ -201,6 +203,15 @@ async_dump_log(InitBy) ->
     ?SERVER_NAME ! {async_dump_log, InitBy},
     ok.
 
+snapshot_dcd(Tables) when is_list(Tables) ->
+    case [T || T <- Tables,
+	       mnesia_lib:storage_type_at_node(node(), T) =/= disc_copies] of
+	[] ->
+	    call({snapshot_dcd, Tables});
+	BadTabs ->
+	    {error, {not_disc_copies, BadTabs}}
+    end.
+
 %% Wait for tables to be active
 %% If needed, we will wait for Mnesia to start
 %% If Mnesia stops, we will wait for Mnesia to restart
@@ -646,6 +657,15 @@ handle_call({sync_dump_log, InitBy}, From, State) ->
     State2 = add_worker(Worker, State),
     noreply(State2);
 
+handle_call({snapshot_dcd, Tables}, From, State) ->
+    Worker = #dump_log{initiated_by = user,
+		       opt_reply_to = From,
+		       operation = fun() ->
+					   mnesia_dumper:snapshot_dcd(Tables)
+				   end},
+    State2 = add_worker(Worker, State),
+    noreply(State2);
+
 handle_call(wait_for_schema_commit_lock, From, State) ->
     Worker = #schema_commit_lock{owner = From},
     State2 = add_worker(Worker, State),
@@ -2089,7 +2109,12 @@ start_remote_sender(Node, Tab, Receiver, Storage) ->
 
 dump_and_reply(ReplyTo, Worker) ->
     %% No trap_exit, die intentionally instead
-    Res = mnesia_dumper:opt_dump_log(Worker#dump_log.initiated_by),
+    Res = case Worker#dump_log.operation of
+	      dump_log ->
+		  mnesia_dumper:opt_dump_log(Worker#dump_log.initiated_by);
+	      F when is_function(F, 0) ->
+		  F()
+	  end,
     ReplyTo ! #dumper_done{worker_pid = self(),
 			   worker_res = Res},
     unlink(ReplyTo),
diff --git a/lib/mnesia/src/mnesia_dumper.erl b/lib/mnesia/src/mnesia_dumper.erl
index 14665797a0..509b765dee 100644
--- a/lib/mnesia/src/mnesia_dumper.erl
+++ b/lib/mnesia/src/mnesia_dumper.erl
@@ -34,11 +34,13 @@
 -export([
 	 get_log_writes/0,
 	 incr_log_writes/0,
+         needs_dump_ets/1,
 	 raw_dump_table/2,
 	 raw_named_dump_table/2,
 	 start_regulator/0,
 	 opt_dump_log/1,
-	 update/3
+	 update/3,
+	 snapshot_dcd/1
 	]).
 
  %% Internal stuff
@@ -99,6 +101,19 @@ opt_dump_log(InitBy) ->
 	  end,
     perform_dump(InitBy, Reg).
 
+snapshot_dcd(Tables) ->
+    lists:foreach(
+      fun(Tab) ->
+	      case mnesia_lib:storage_type_at_node(node(), Tab) of
+		  disc_copies ->
+		      mnesia_log:ets2dcd(Tab);
+		  _ ->
+		      %% Storage type was checked before queueing the op, though
+		      skip
+	      end
+      end, Tables),
+    dumped.
+
 %% Scan for decisions
 perform_dump(InitBy, Regulator) when InitBy == scan_decisions ->
     ?eval_debug_fun({?MODULE, perform_dump}, [InitBy]),
@@ -981,28 +996,10 @@ open_files(_Tab, _Storage, _UpdateInPlace, _InitBy) ->
     false.
 
 open_disc_copies(Tab, InitBy) ->
-    DclF = mnesia_lib:tab2dcl(Tab),
-    DumpEts =
-	case file:read_file_info(DclF) of
-	    {error, enoent} ->
-		false;
-	    {ok, DclInfo} ->
-		DcdF =  mnesia_lib:tab2dcd(Tab),
-		case file:read_file_info(DcdF) of
-		    {error, Reason} ->
-			mnesia_lib:dbg_out("File ~p info_error ~p ~n",
-					   [DcdF, Reason]),
-			true;
-		    {ok, DcdInfo} ->
-			Mul = case ?catch_val(dc_dump_limit) of
-				  {'EXIT', _} -> ?DumpToEtsMultiplier;
-				  Val -> Val
-			      end,
-			DcdInfo#file_info.size =< (DclInfo#file_info.size * Mul)
-		end
-	end,
+    DumpEts = needs_dump_ets(Tab),
     if
 	DumpEts == false; InitBy == startup ->
+            DclF = mnesia_lib:tab2dcl(Tab),
 	    mnesia_log:open_log({?MODULE,Tab},
 				mnesia_log:dcl_log_header(),
 				DclF,
@@ -1017,6 +1014,27 @@ open_disc_copies(Tab, InitBy) ->
 	    false
     end.
 
+needs_dump_ets(Tab) ->
+    DclF = mnesia_lib:tab2dcl(Tab),
+    case file:read_file_info(DclF) of
+        {error, enoent} ->
+            false;
+        {ok, DclInfo} ->
+            DcdF =  mnesia_lib:tab2dcd(Tab),
+            case file:read_file_info(DcdF) of
+                {error, Reason} ->
+                    mnesia_lib:dbg_out("File ~p info_error ~p ~n",
+                                       [DcdF, Reason]),
+                    true;
+                {ok, DcdInfo} ->
+                    Mul = case ?catch_val(dc_dump_limit) of
+                              {'EXIT', _} -> ?DumpToEtsMultiplier;
+                              Val -> Val
+                          end,
+                    DcdInfo#file_info.size =< (DclInfo#file_info.size * Mul)
+            end
+    end.
+
 %% Always opens the dcl file for writing overriding already_dumped
 %% mechanismen, used for schema transactions.
 open_dcl(Tab) ->
diff --git a/lib/mnesia/src/mnesia_loader.erl b/lib/mnesia/src/mnesia_loader.erl
index 530317bcdd..cbb3d7e430 100644
--- a/lib/mnesia/src/mnesia_loader.erl
+++ b/lib/mnesia/src/mnesia_loader.erl
@@ -69,9 +69,10 @@ do_get_disc_copy2(Tab, Reason, Storage, Type) when Storage == disc_copies ->
 	    ignore;
 	_ ->
 	    mnesia_monitor:mktab(Tab, Args),
-	    Count = mnesia_log:dcd2ets(Tab, Repair),
-	    case ets:info(Tab, size) of
-		X when X < Count * 4 ->
+	    _Count = mnesia_log:dcd2ets(Tab, Repair),
+	    case mnesia_monitor:get_env(dump_disc_copies_at_startup)
+		andalso mnesia_dumper:needs_dump_ets(Tab) of
+		true ->
 		    ok = mnesia_log:ets2dcd(Tab);
 		_ ->
 		    ignore
diff --git a/lib/mnesia/src/mnesia_monitor.erl b/lib/mnesia/src/mnesia_monitor.erl
index 6fc1a394a6..a0e0e630ec 100644
--- a/lib/mnesia/src/mnesia_monitor.erl
+++ b/lib/mnesia/src/mnesia_monitor.erl
@@ -664,6 +664,7 @@ env() ->
      backup_module,
      debug,
      dir,
+     dump_disc_copies_at_startup,
      dump_log_load_regulation,
      dump_log_time_threshold,
      dump_log_update_in_place,
@@ -692,6 +693,8 @@ default_env(debug) ->
 default_env(dir) ->
     Name = lists:concat(["Mnesia.", node()]),
     filename:absname(Name);
+default_env(dump_disc_copies_at_startup) ->
+    true;
 default_env(dump_log_load_regulation) ->
     false;
 default_env(dump_log_time_threshold) ->
@@ -741,6 +744,7 @@ do_check_type(debug, trace) -> trace;
 do_check_type(debug, true) -> debug;
 do_check_type(debug, verbose) -> verbose;
 do_check_type(dir, V) -> filename:absname(V);
+do_check_type(dump_disc_copies_at_startup, B) -> bool(B);
 do_check_type(dump_log_load_regulation, B) -> bool(B);
 do_check_type(dump_log_time_threshold, I) when is_integer(I), I > 0 -> I;
 do_check_type(dump_log_update_in_place, B) -> bool(B);