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-rw-r--r--lib/mnesia/src/mnesia_frag_hash.erl18
-rw-r--r--lib/mnesia/test/mnesia_frag_hash_test.erl94
2 files changed, 102 insertions, 10 deletions
diff --git a/lib/mnesia/src/mnesia_frag_hash.erl b/lib/mnesia/src/mnesia_frag_hash.erl
index 610ba2535c..d70579c3b3 100644
--- a/lib/mnesia/src/mnesia_frag_hash.erl
+++ b/lib/mnesia/src/mnesia_frag_hash.erl
@@ -101,21 +101,19 @@ del_frag(OldState) ->
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-key_to_frag_number(#hash_state{function = phash, next_n_to_split = SplitN, n_doubles = L}, Key) ->
- P = SplitN,
- A = erlang:phash(Key, power2(L)),
+key_to_frag_number(#hash_state{function = phash, n_fragments = N, n_doubles = L}, Key) ->
+ A = erlang:phash(Key, power2(L + 1)),
if
- A < P ->
- erlang:phash(Key, power2(L + 1));
+ A > N ->
+ A - power2(L);
true ->
A
end;
-key_to_frag_number(#hash_state{function = phash2, next_n_to_split = SplitN, n_doubles = L}, Key) ->
- P = SplitN,
- A = erlang:phash2(Key, power2(L)) + 1,
+key_to_frag_number(#hash_state{function = phash2, n_fragments = N, n_doubles = L}, Key) ->
+ A = erlang:phash2(Key, power2(L + 1)) + 1,
if
- A < P ->
- erlang:phash2(Key, power2(L + 1)) + 1;
+ A > N ->
+ A - power2(L);
true ->
A
end;
diff --git a/lib/mnesia/test/mnesia_frag_hash_test.erl b/lib/mnesia/test/mnesia_frag_hash_test.erl
new file mode 100644
index 0000000000..095d25e74f
--- /dev/null
+++ b/lib/mnesia/test/mnesia_frag_hash_test.erl
@@ -0,0 +1,94 @@
+-module(mnesia_frag_hash_test).
+
+-export([test/0]).
+
+-define(NUM_FRAGS, 20).
+-define(NUM_KEYS, 10000).
+
+-record(hash_state,
+ {n_fragments,
+ next_n_to_split,
+ n_doubles,
+ function}).
+
+% OLD mnesia_frag_hash:key_to_frag_number/2.
+old_key_to_frag_number(#hash_state{function = phash, next_n_to_split = SplitN, n_doubles = L}, Key) ->
+ P = SplitN,
+ A = erlang:phash(Key, power2(L)),
+ if
+ A < P ->
+ erlang:phash(Key, power2(L + 1));
+ true ->
+ A
+ end;
+old_key_to_frag_number(#hash_state{function = phash2, next_n_to_split = SplitN, n_doubles = L}, Key) ->
+ P = SplitN,
+ A = erlang:phash2(Key, power2(L)) + 1,
+ if
+ A < P ->
+ erlang:phash2(Key, power2(L + 1)) + 1;
+ true ->
+ A
+ end;
+old_key_to_frag_number(OldState, Key) ->
+ State = convert_old_state(OldState),
+ old_key_to_frag_number(State, Key).
+
+
+% NEW mnesia_frag_hash:key_to_frag_number/2.
+new_key_to_frag_number(#hash_state{function = phash, n_fragments = N, n_doubles = L}, Key) ->
+ A = erlang:phash(Key, power2(L + 1)),
+ if
+ A > N ->
+ A - power2(L);
+ true ->
+ A
+ end;
+new_key_to_frag_number(#hash_state{function = phash2, n_fragments = N, n_doubles = L}, Key) ->
+ A = erlang:phash2(Key, power2(L + 1)) + 1,
+ if
+ A > N ->
+ A - power2(L);
+ true ->
+ A
+ end;
+new_key_to_frag_number(OldState, Key) ->
+ State = convert_old_state(OldState),
+ new_key_to_frag_number(State, Key).
+
+
+% Helpers for key_to_frag_number functions.
+
+power2(Y) ->
+ 1 bsl Y. % trunc(math:pow(2, Y)).
+
+convert_old_state({hash_state, N, P, L}) ->
+ #hash_state{n_fragments = N,
+ next_n_to_split = P,
+ n_doubles = L,
+ function = phash}.
+
+
+test() ->
+ test2(mnesia_frag_hash:init_state(undefined, undefined)), % phash2
+ test2({hash_state, 1, 1, 0}). % phash
+
+test2(I) ->
+ test_keys(I),
+ lists:foldl(
+ fun(_, S) -> test_frag(S) end,
+ I, lists:seq(1, ?NUM_FRAGS)),
+ ok.
+
+test_frag(State) ->
+ {State2,_,_} = mnesia_frag_hash:add_frag(State),
+ test_keys(State2),
+ State2.
+
+test_keys(State) ->
+ [test_key(State, Key) || Key <- lists:seq(1, ?NUM_KEYS)].
+
+test_key(State, Key) ->
+ Old = old_key_to_frag_number(State, Key),
+ New = new_key_to_frag_number(State, Key),
+ Old = New.