From 67f8f2afbc6a6a6c6391a78214b2602c973a7cff Mon Sep 17 00:00:00 2001
From: Gregory Burd <greg@basho.com>
Date: Tue, 24 Jul 2012 10:41:37 -0400
Subject: [PATCH] Consoladate two 99.9% identical functions into one.

---
 src/hanoidb.erl | 33 ++++++---------------------------
 1 file changed, 6 insertions(+), 27 deletions(-)

diff --git a/src/hanoidb.erl b/src/hanoidb.erl
index 11ce2fb..3798834 100644
--- a/src/hanoidb.erl
+++ b/src/hanoidb.erl
@@ -151,16 +151,16 @@ fold_range(Ref,Fun,Acc0,#key_range{limit=Limit}=Range) ->
            true ->       snapshot_range
         end,
     {ok, FoldWorkerPID} = hanoidb_fold_worker:start(self()),
-    ?log("fold_range begin: self=~p, worker=~p~n", [self(), FoldWorkerPID]),
-    ok = gen_server:call(Ref, {RangeType, FoldWorkerPID, Range}, infinity),
     MRef = erlang:monitor(process, FoldWorkerPID),
+    ?log("fold_range begin: self=~p, worker=~p monitor=~p~n", [self(), FoldWorkerPID, MRef]),
+    ok = gen_server:call(Ref, {RangeType, FoldWorkerPID, Range}, infinity),
     Result = receive_fold_range(MRef, FoldWorkerPID, Fun, Acc0, Limit),
     ?log("fold_range done: self:~p, result=~p~n", [self(), Result]),
     Result.
 
 receive_fold_range(MRef,PID,_,Acc0, 0) ->
     erlang:exit(PID, shutdown),
-    drain_worker_and_return(MRef,PID,Acc0);
+    drain_worker(MRef,PID,Acc0);
 
 receive_fold_range(MRef,PID,Fun,Acc0, Limit) ->
     ?log("receive_fold_range:~p,~P~n", [PID,Acc0,10]),
@@ -183,7 +183,7 @@ receive_fold_range(MRef,PID,Fun,Acc0, Limit) ->
                 Exit ->
                     %% kill the fold worker ...
                     erlang:exit(PID, shutdown),
-                    drain_worker_and_throw(MRef,PID,Exit)
+                    raise(drain_worker(MRef,PID,Exit))
             end;
 
         ?CAST(_,{fold_limit, PID, _}) ->
@@ -213,31 +213,11 @@ decr(N) ->
 raise({'EXIT', Class, Exception, Trace}) ->
     erlang:raise(Class, Exception, Trace).
 
-%%
-%% When an exception has happened in the fold function, we use
-%% this to drain messages coming from the fold_worker before
-%% re-throwing the exception.
-%%
-drain_worker_and_throw(MRef, PID, ExitTuple) ->
-    receive
-        ?CALL(_From,{fold_result, PID, _, _}) ->
-            drain_worker_and_throw(MRef, PID, ExitTuple);
-        {'DOWN', MRef, _, _, _} ->
-            raise(ExitTuple);
-        ?CAST(_,{fold_limit, PID, _}) ->
-            erlang:demonitor(MRef, [flush]),
-            raise(ExitTuple);
-        ?CAST(_,{fold_done, PID}) ->
-            erlang:demonitor(MRef, [flush]),
-            raise(ExitTuple)
-    after 0 ->
-            raise(ExitTuple)
-    end.
 
-drain_worker_and_return(MRef, PID, Value) ->
+drain_worker(MRef, PID, Value) ->
     receive
         ?CALL(_From,{fold_result, PID, _, _}) ->
-            drain_worker_and_return(MRef, PID, Value);
+            drain_worker(MRef, PID, Value);
         {'DOWN', MRef, _, _, _} ->
             Value;
         ?CAST(_,{fold_limit, PID, _}) ->
@@ -315,7 +295,6 @@ open_levels(Dir, Options) ->
 
 do_merge(TopLevel, _Inc, N) when N =< 0 ->
     ok = hanoidb_level:await_incremental_merge(TopLevel);
-
 do_merge(TopLevel, Inc, N) ->
     ok = hanoidb_level:begin_incremental_merge(TopLevel, ?BTREE_SIZE(?TOP_LEVEL)),
     do_merge(TopLevel, Inc, N-Inc).