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-module(mongoose_node_num_mnesia). |
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-export([init/0]). |
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-record(node_num, {name :: atom(), |
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num :: mongoose_node_num:node_num() }). |
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init() -> |
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mongoose_mnesia:create_table(node_num, |
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[{ram_copies, [node()]}, {type, set}, |
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{attributes, record_info(fields, node_num)}]), |
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mnesia:add_table_index(node_num, num), |
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register_node(node()), |
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[#node_num{num = Num}] = mnesia:dirty_read(node_num, node()), |
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mongoose_node_num:set_node_num(Num), |
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ok. |
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-spec register_node(atom()) -> ok. |
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register_node(NodeName) -> |
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{atomic, _} = mnesia:transaction(fun() -> |
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case mnesia:read(node_num, NodeName) of |
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[] -> |
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mnesia:write(#node_num{name = NodeName, num = next_node_num()}); |
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:-( |
[_] -> ok |
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end |
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end), |
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ok. |
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-spec next_node_num() -> mongoose_node_num:node_num(). |
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next_node_num() -> |
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max_node_num() + 1. |
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-spec max_node_num() -> mongoose_node_num:node_num(). |
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max_node_num() -> |
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mnesia:foldl(fun(#node_num{num = Num}, Max) -> max(Num, Max) end, 0, node_num). |