11. Appendix C: Fragmented Table Hashing Callback Interface

11 Appendix C: Fragmented Table Hashing Callback Interface

11.1 mnesia_frag_hash Callback Behavior

-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
	]).

-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_do
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