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Handle exceptions inside sync_fold_range

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Someone tried (tsk, tsk) to terminate a fold operation
by throwing an exception.  Now we also should handle
such situations gracefully.
This commit is contained in:
Kresten Krab Thorup 2012-04-17 00:29:28 +02:00
parent a911734134
commit 454a111ad7
1 changed files with 40 additions and 4 deletions
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44
src/lsm_btree.erl
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@ -74,18 +74,54 @@ sync_range(Ref, #btree_range{}=Range) ->
sync_fold_range(Ref,Fun,Acc0,Range) ->
{ok, PID} = sync_range(Ref, Range),
sync_receive_fold_range(PID,Fun,Acc0).
MRef = erlang:monitor(process, PID),
sync_receive_fold_range(MRef, PID,Fun,Acc0).
sync_receive_fold_range(PID,Fun,Acc0) ->
sync_receive_fold_range(MRef, PID,Fun,Acc0) ->
receive
{fold_result, PID, K,V} ->
sync_receive_fold_range(PID, Fun, Fun(K,V,Acc0));
case
try
{ok, Fun(K,V,Acc0)}
catch
Class:Exception ->
lager:warning("Exception in lsm_btree fold: ~p", [Exception]),
{'EXIT', Class, Exception, erlang:get_stacktrace()}
end
of
{ok, Acc1} ->
sync_receive_fold_range(MRef, PID, Fun, Acc1);
Exit ->
%% kill the fold worker ...
erlang:exit(PID, kill),
drain_worker_and_throw(MRef,PID,Exit)
end;
{fold_limit, PID, _} ->
erlang:demonitor(MRef, [flush]),
Acc0;
{fold_done, PID} ->
Acc0
erlang:demonitor(MRef, [flush]),
Acc0;
{'DOWN', MRef, _, _, Reason} ->
error({fold_worker_died, Reason})
end.
raise({'EXIT', Class, Exception, Trace}) ->
erlang:raise(Class, Exception, Trace).
drain_worker_and_throw(MRef, PID, ExitTuple) ->
receive
{fold_result, PID, _, _} ->
drain_worker_and_throw(MRef, PID, ExitTuple);
{'DOWN', MRef, _, _, _} ->
raise(ExitTuple);
{fold_limit, PID, _} ->
erlang:demonitor(MRef, [flush]),
raise(ExitTuple);
{fold_done, PID} ->
erlang:demonitor(MRef, [flush]),
raise(ExitTuple)
end.
async_range(Ref, #btree_range{}=Range) ->