From ac96033fc95304a43813cd5a4a75aeefe6299a2d Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Tue, 19 Oct 2010 13:12:06 +0200
Subject: Fix a bug that could cause 'bad_object' errors

When several clients accessed a Dets table simultaneously,
modifications of the Dets server's internal state were sometimes
thrown away. The symptoms are diverse: error with reason 'bad_object';
inserted objects not returned by lookup(); et cetera.
---
 lib/stdlib/src/dets.erl        |  6 ++++--
 lib/stdlib/test/dets_SUITE.erl | 39 ++++++++++++++++++++++++++++++++++++---
 2 files changed, 40 insertions(+), 5 deletions(-)

(limited to 'lib')

diff --git a/lib/stdlib/src/dets.erl b/lib/stdlib/src/dets.erl
index 4584b8184f..1d4d664841 100644
--- a/lib/stdlib/src/dets.erl
+++ b/lib/stdlib/src/dets.erl
@@ -1094,7 +1094,9 @@ do_apply_op(Op, From, Head, N) ->
         {N2, H2} when is_record(H2, head), is_integer(N2) ->
             open_file_loop(H2, N2);
         H2 when is_record(H2, head) ->
-            open_file_loop(H2, N)
+            open_file_loop(H2, N);
+        {{more,From1,Op1,N1}, NewHead} ->
+            do_apply_op(Op1, From1, NewHead, N1)
     catch 
         exit:normal -> 
             exit(normal);
@@ -1438,7 +1440,7 @@ stream_end2([], Ps, no_more, N, C, Head, _Reply) ->
     penalty(Head, Ps, C),
     {N, Head};
 stream_end2([], _Ps, {From, Op}, N, _C, Head, _Reply) ->
-    apply_op(Op, From, Head, N).
+    {{more,From,Op,N},Head}.
 
 penalty(H, _Ps, _C) when H#head.fixed =:= false ->
     ok;
diff --git a/lib/stdlib/test/dets_SUITE.erl b/lib/stdlib/test/dets_SUITE.erl
index 760e610e00..29f5a295a1 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_8899/1]).
 
 -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_8899]}
     end.
 
 not_run(suite) -> [];
@@ -2935,6 +2935,34 @@ ets_init(Tab, N) ->
     ets:insert(Tab, {N,N}),
     ets_init(Tab, N - 1).
 
+otp_8899(doc) ->
+    ["OTP-8899. Several clients. Updated Head was ignored."];
+otp_8899(suite) ->
+    [];
+otp_8899(Config) when is_list(Config) ->
+    Tab = many_clients,
+    ?line FName = filename(Tab, Config),
+
+    Server = self(),
+
+    ?line file:delete(FName),
+    ?line {ok, _} = dets:open_file(Tab,[{file, FName},{version,9}]),
+    ?line [P1,P2,P3,P4] = new_clients(4, Tab),
+
+    MC = [Tab],
+    Seq6a = [{P1,[{insert,[{used_to_be_skipped_by,match}]},
+                  {lookup,1,[{1,a}]}]},
+             {P2,[{verbose,true,MC}]},
+             {P3,[{lookup,1,[{1,a}]}]}, {P4,[{verbose,true,MC}]}],
+    ?line atomic_requests(Server, Tab, [[{1,a},{2,b},{3,c}]], Seq6a),
+    ?line true = get_replies([{P1,ok}, {P2,ok}, {P3,ok}, {P4,ok}]),
+    ?line [{1,a},{2,b},{3,c},{used_to_be_skipped_by,match}] =
+        lists:sort(dets:match_object(Tab, '_')),
+    ?line _ = dets:close(Tab),
+    ?line file:delete(FName),
+
+    ok.
+
 many_clients(doc) ->
     ["Several clients accessing a table simultaneously."];
 many_clients(suite) ->
@@ -3071,6 +3099,11 @@ client(S, Tab) ->
 
 eval([], _Tab) ->
     ok;
+eval([{verbose,Bool,Expected} | L], Tab) ->
+    ?line case dets:verbose(Bool) of
+	      Expected -> eval(L, Tab);
+	      Error -> {error, {verbose,Error}}
+	  end;
 eval([sync | L], Tab) ->
     ?line case dets:sync(Tab) of
 	      ok -> eval(L, Tab);
-- 
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