Added transaction retry logic.

src/bdberl.erl

@@ -12,7 +12,7 @@
          txn_commit/0, txn_commit/1, txn_abort/0,
          get_cache_size/0, set_cache_size/3,
          get_txn_timeout/0, set_txn_timeout/1,
-         transaction/1,
+         transaction/1, transaction/2,
          put/3, put/4,
          put_r/3, put_r/4,
          put_commit/3, put_commit/4, 
@@ -24,6 +24,8 @@
 
 -include("bdberl.hrl").
 
+-define(is_lock_error(Error), (Error =:= deadlock orelse Error =:= lock_not_granted)).
+
 
 open(Name, Type) ->
     open(Name, Type, [create]).
@@ -97,18 +99,34 @@ txn_abort() ->
         Error ->
             {error, {txn_abort, Error}}
     end.
-            
+
 transaction(Fun) ->
+    transaction(Fun, infinity).
+
+transaction(_Fun, 0) ->
+    txn_abort(),
+    {error, {transaction_failed, retry_limit_reached}};
+transaction(Fun, Retries) ->
     txn_begin(),
     try Fun() of
         abort ->
             txn_abort(),
             {error, transaction_aborted};
+
         Value ->
             txn_commit(),
             {ok, Value}
     catch
-        _ : Reason -> 
+        throw : {error, {_Op, Error}} when ?is_lock_error(Error) ->
+            txn_abort(),
+            erlang:yield(),
+            R = case Retries of
+                    infinity -> infinity;
+                    Retries -> Retries - 1
+                end,
+            transaction(Fun, R);
+
+        _ : Reason ->
             txn_abort(),
             {error, {transaction_failed, Reason}}
     end.
@@ -142,7 +160,6 @@ put_commit_r(Db, Key, Value, Opts) ->
         ok -> ok;
         Error -> throw(Error)
     end.
-            
 
 get(Db, Key) ->
     get(Db, Key, []).
@@ -178,7 +195,7 @@ update(Db, Key, Fun) ->
 
 update(Db, Key, Fun, Args) ->
     F = fun() ->
-            Value = case get(Db, Key, [rmw]) of
+            Value = case get_r(Db, Key, [rmw]) of
                         not_found -> not_found;
                         {ok, Val} -> Val
                     end,
@@ -186,7 +203,7 @@ update(Db, Key, Fun, Args) ->
                            undefined -> Fun(Key, Value);
                            Args      -> Fun(Key, Value, Args)
                        end,
-            ok = put_commit(Db, Key, NewValue),
+            put_commit_r(Db, Key, NewValue),
             NewValue
         end,
     transaction(F).

test/thrash_SUITE.erl

@@ -29,7 +29,7 @@ wait_for_finish(0) ->
 wait_for_finish(Count) ->
     receive
         {finished, Pid} ->
-            io:format("~p is done; ~p remaining.\n", [Pid, Count-1]),
+            ct:print("~p is done; ~p remaining.\n", [Pid, Count-1]),
             wait_for_finish(Count-1)
     end.
 
@@ -47,34 +47,16 @@ thrash_run(Owner) ->
 thrash_incr_loop(Owner, 0) ->
     Owner ! {finished, self()};
 thrash_incr_loop(Owner, Count) ->
-    ct:print("~p\n", [Count]),
+    ct:print("~p", [Count]),
     %% Choose random key
     Key = random:uniform(1200),
     
     %% Start a txn that will read the current value of the key and increment by 1
-    F = fun() ->
-                case bdberl:get(0, Key, [rmw]) of
-                    not_found ->
-                        Value = 0;
-
-                    {ok, Value} ->
-                        Value
-                end,
-                ok = bdberl:put(0, Key, Value)
+    F = fun(_Key, Value) ->
+            case Value of
+                not_found -> 0;
+                Value     -> Value + 1
+            end
         end,
-    ok = do_txn(F, 0),
+    {ok, _} = bdberl:update(0, Key, F),
     thrash_incr_loop(Owner, Count-1).
-
-do_txn(F, Count) ->
-    case bdberl:txn_begin() of
-        ok ->
-            case catch(F()) of
-                {'EXIT', _Reason} ->
-                    io:format("Txn attempt ~p failed; retrying", [Count]),
-                    do_txn(F, Count+1);
-                _Other ->
-                    ok = bdberl:txn_commit()
-            end;
-        {error, _Reason} ->
-            do_txn(F, Count+1)
-    end.