The R13B03 release.OTP_R13B03

1 files changed, 151 insertions, 0 deletions

diff --git a/lib/mnesia/src/mnesia_frag_hash.erl b/lib/mnesia/src/mnesia_frag_hash.erl
new file mode 100644
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+++ b/lib/mnesia/src/mnesia_frag_hash.erl
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+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2002-2009. 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
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+%%
+%%%----------------------------------------------------------------------
+%%% Purpose : Implements hashing functionality for fragmented tables
+%%%----------------------------------------------------------------------
+
+%header_doc_include
+-module(mnesia_frag_hash).
+
+%% Fragmented Table Hashing callback functions
+-export([
+	 init_state/2,
+	 add_frag/1,
+	 del_frag/1,
+	 key_to_frag_number/2,
+	 match_spec_to_frag_numbers/2
+	]).
+
+%header_doc_include
+%%-behaviour(mnesia_frag_hash).
+
+%impl_doc_include
+-record(hash_state,
+	{n_fragments,
+	 next_n_to_split,
+	 n_doubles,
+	 function}).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+init_state(_Tab, State) when State == undefined ->
+    #hash_state{n_fragments     = 1,
+		next_n_to_split = 1,
+		n_doubles       = 0,
+		function        = phash2}.
+
+convert_old_state({hash_state, N, P, L}) ->
+    #hash_state{n_fragments     = N,
+		next_n_to_split = P,
+		n_doubles       = L,
+		function        = phash}.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+add_frag(#hash_state{next_n_to_split = SplitN, n_doubles = L, n_fragments = N} = State) ->
+    P = SplitN + 1,
+    NewN = N + 1,
+    State2 = case power2(L) + 1 of
+		 P2 when P2 == P ->
+		     State#hash_state{n_fragments      = NewN,
+				      n_doubles        = L + 1,
+				      next_n_to_split = 1};
+		 _ ->
+		     State#hash_state{n_fragments     = NewN,
+				      next_n_to_split = P}
+	     end,
+    {State2, [SplitN], [NewN]};
+add_frag(OldState) ->
+    State = convert_old_state(OldState),
+    add_frag(State).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+del_frag(#hash_state{next_n_to_split = SplitN, n_doubles = L, n_fragments = N} = State) ->
+    P = SplitN - 1,
+    if
+	P < 1 ->
+	    L2 = L - 1,
+	    MergeN = power2(L2),
+	    State2 = State#hash_state{n_fragments     = N - 1,
+				      next_n_to_split = MergeN,
+				      n_doubles       = L2},
+	    {State2, [N], [MergeN]};
+	true ->
+	    MergeN = P,
+	    State2 = State#hash_state{n_fragments     = N - 1,
+				      next_n_to_split = MergeN},
+	    {State2, [N], [MergeN]}
+	end;
+del_frag(OldState) ->
+    State = convert_old_state(OldState),
+    del_frag(State).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+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;
+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;
+key_to_frag_number(OldState, Key) ->
+    State = convert_old_state(OldState),
+    key_to_frag_number(State, Key).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+match_spec_to_frag_numbers(#hash_state{n_fragments = N} = State, MatchSpec) ->
+    case MatchSpec of
+	[{HeadPat, _, _}] when is_tuple(HeadPat), tuple_size(HeadPat) > 2 ->
+	    KeyPat = element(2, HeadPat),
+	    case has_var(KeyPat) of
+		false ->
+		    [key_to_frag_number(State, KeyPat)];
+		true ->
+		    lists:seq(1, N)
+	    end;
+	_ -> 
+	    lists:seq(1, N)
+    end;
+match_spec_to_frag_numbers(OldState, MatchSpec) ->
+    State = convert_old_state(OldState),
+    match_spec_to_frag_numbers(State, MatchSpec).
+
+power2(Y) ->
+    1 bsl Y. % trunc(math:pow(2, Y)).
+
+%impl_doc_include
+
+has_var(Pat) ->
+    mnesia:has_var(Pat).