Fix a bug concerning truncated Dets files

When several clients accessed a Dets table simultaneously, inserted or
updated objects were sometimes lost due to the Dets file being
truncated.

2 files changed, 42 insertions, 21 deletions

diff --git a/lib/stdlib/src/dets.erl b/lib/stdlib/src/dets.erl
index 4584b8184f..79bebada4d 100644
--- a/lib/stdlib/src/dets.erl
+++ b/lib/stdlib/src/dets.erl
@@ -1363,37 +1363,35 @@ start_auto_save_timer(Head) ->
 %% lookup requests in parallel. Evalute delete_object, delete and
 %% insert as well.
 stream_op(Op, Pid, Pids, Head, N) ->
-    stream_op(Head, Pids, [], N, Pid, Op, Head#head.fixed).
+    #head{fixed = Fxd, update_mode = M} = Head, 
+    stream_op(Head, Pids, [], N, Pid, Op, Fxd, M).
 
-stream_loop(Head, Pids, C, N, false = Fxd) ->
+stream_loop(Head, Pids, C, N, false = Fxd, M) ->
     receive
 	?DETS_CALL(From, Message) ->
-	    stream_op(Head, Pids, C, N, From, Message, Fxd)
+	    stream_op(Head, Pids, C, N, From, Message, Fxd, M)
     after 0 ->
 	    stream_end(Head, Pids, C, N, no_more)
     end;
-stream_loop(Head, Pids, C, N, _Fxd) ->
+stream_loop(Head, Pids, C, N, _Fxd, _M) ->
     stream_end(Head, Pids, C, N, no_more).
 
-stream_op(Head, Pids, C, N, Pid, {lookup_keys,Keys}, Fxd) ->
+stream_op(Head, Pids, C, N, Pid, {lookup_keys,Keys}, Fxd, M) ->
     NC = [{{lookup,Pid},Keys} | C],
-    stream_loop(Head, Pids, NC, N, Fxd);
-stream_op(Head, Pids, C, N, Pid, {insert, _Objects} = Op, Fxd) ->
+    stream_loop(Head, Pids, NC, N, Fxd, M);
+stream_op(Head, Pids, C, N, Pid, {insert, _Objects} = Op, Fxd, dirty = M) ->
     NC = [Op | C],
-    stream_loop(Head, [Pid | Pids], NC, N, Fxd);
-stream_op(Head, Pids, C, N, Pid, {insert_new, _Objects} = Op, Fxd) ->
+    stream_loop(Head, [Pid | Pids], NC, N, Fxd, M);
+stream_op(Head, Pids, C, N, Pid, {delete_key, _Keys} = Op, Fxd, dirty = M) ->
     NC = [Op | C],
-    stream_loop(Head, [Pid | Pids], NC, N, Fxd);
-stream_op(Head, Pids, C, N, Pid, {delete_key, _Keys} = Op, Fxd) ->
+    stream_loop(Head, [Pid | Pids], NC, N, Fxd, M);
+stream_op(Head, Pids, C, N, Pid, {delete_object, _Os} = Op, Fxd, dirty = M) ->
     NC = [Op | C],
-    stream_loop(Head, [Pid | Pids], NC, N, Fxd);
-stream_op(Head, Pids, C, N, Pid, {delete_object, _Objects} = Op, Fxd) ->
-    NC = [Op | C],
-    stream_loop(Head, [Pid | Pids], NC, N, Fxd);
-stream_op(Head, Pids, C, N, Pid, {member, Key}, Fxd) ->
+    stream_loop(Head, [Pid | Pids], NC, N, Fxd, M);
+stream_op(Head, Pids, C, N, Pid, {member, Key}, Fxd, M) ->
     NC = [{{lookup,[Pid]},[Key]} | C],
-    stream_loop(Head, Pids, NC, N, Fxd);
-stream_op(Head, Pids, C, N, Pid, Op, _Fxd) ->
+    stream_loop(Head, Pids, NC, N, Fxd, M);
+stream_op(Head, Pids, C, N, Pid, Op, _Fxd, _M) ->
     stream_end(Head, Pids, C, N, {Pid,Op}).
 
 stream_end(Head, Pids0, C, N, Next) ->
diff --git a/lib/stdlib/test/dets_SUITE.erl b/lib/stdlib/test/dets_SUITE.erl
index 760e610e00..82684000bb 100644
--- a/lib/stdlib/test/dets_SUITE.erl
+++ b/lib/stdlib/test/dets_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1996-2009. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2010. All Rights Reserved.
 %% 
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -50,7 +50,7 @@
 	 otp_4208/1, otp_4989/1, many_clients/1, otp_4906/1, otp_5402/1,
          simultaneous_open/1, insert_new/1, repair_continuation/1,
          otp_5487/1, otp_6206/1, otp_6359/1, otp_4738/1, otp_7146/1,
-         otp_8070/1]).
+         otp_8070/1, otp_8898/1]).
 
 -export([dets_dirty_loop/0]).
 
@@ -108,7 +108,7 @@ all(suite) ->
 	      cache_duplicate_bags_v9, otp_4208, otp_4989, many_clients,
               otp_4906, otp_5402, simultaneous_open, insert_new, 
               repair_continuation, otp_5487, otp_6206, otp_6359, otp_4738,
-              otp_7146, otp_8070]} 
+              otp_7146, otp_8070, otp_8898]} 
     end.
 
 not_run(suite) -> [];
@@ -2935,6 +2935,29 @@ ets_init(Tab, N) ->
     ets:insert(Tab, {N,N}),
     ets_init(Tab, N - 1).
 
+otp_8898(doc) ->
+    ["OTP-8898. Truncated Dets file."];
+otp_8898(suite) ->
+    [];
+otp_8898(Config) when is_list(Config) ->
+    Tab = otp_8898,
+    ?line FName = filename(Tab, Config),
+
+    Server = self(),
+
+    ?line file:delete(FName),
+    ?line {ok, _} = dets:open_file(Tab,[{file, FName}]),
+    ?line [P1,P2,P3] = new_clients(3, Tab),
+
+    Seq = [{P1,[sync]},{P2,[{lookup,1,[]}]},{P3,[{insert,{1,b}}]}],
+    ?line atomic_requests(Server, Tab, [[]], Seq),
+    ?line true = get_replies([{P1,ok},{P2,ok},{P3,ok}]),
+    ?line ok = dets:close(Tab),
+    ?line {ok, _} = dets:open_file(Tab,[{file, FName}]),
+    ?line file:delete(FName),
+
+    ok.
+
 many_clients(doc) ->
     ["Several clients accessing a table simultaneously."];
 many_clients(suite) ->