diff options
| -rw-r--r-- | src/rabbit_guid.erl | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/src/rabbit_guid.erl b/src/rabbit_guid.erl index 262487a5f4..4fe6eaee45 100644 --- a/src/rabbit_guid.erl +++ b/src/rabbit_guid.erl @@ -80,20 +80,30 @@ fresh() -> Serial = gen_server:call(?SERVER, serial, infinity), {Serial, node(), make_ref()}. +advance_blocks({B1, B2, B3, B4}, I) -> + B5 = erlang:phash2({B1, I}), + {{(B2 bxor B5), (B3 bxor B5), (B4 bxor B5), B5}, I+1}. + +blocks_to_binary({B1, B2, B3, B4}) -> + <<B1:32/integer,B2:32/integer, B3:32/integer,B4:32/integer>>. + %% generate a GUID. This function should be used when performance is a %% priority and predictability is not an issue. Otherwise, use gen_secure/0. gen() -> %% We hash a fresh GUID and then XOR it with a process-local counter %% to get a new GUID each time. - {S, I} = + {BS, I} = case get(guid) of - undefined -> G = fresh(), - <<S0:128/integer>> = erlang:md5(term_to_binary(G)), - {S0, 0}; - {S0, I0} -> {S0, I0+1} + undefined -> + G = fresh(), + <<B1:32/integer,B2:32/integer, B3:32/integer,B4:32/integer>> = + erlang:md5(term_to_binary(G)), + {{B1,B2,B3,B4}, 0}; + {BS0, I0} -> + advance_blocks(BS0, I0) end, - put(guid, {S, I}), - <<(S bxor I):128>>. + put(guid, {BS, I}), + blocks_to_binary(BS). %% generate a non-predictable GUID. %% |