Ulf Wiger
75 lines
2.1 KiB
Erlang
75 lines
2.1 KiB
Erlang
%% -*- mode: erlang; erlang-indent-level: 4; indent-tabs-mode: nil -*-
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%% @doc Statistics API for the mnesia_rocksdb plugin
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%%
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%% Some counters are maintained for each active alias. Currently, the following
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%% counters are supported:
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%% * inner_retries
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%% * outer_retries
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%%
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-module(mrdb_stats).
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-export([new/0]).
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-export([incr/3,
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get/1,
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get/2]).
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-type alias() :: mnesia_rocksdb:alias().
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-type db_ref() :: mrdb:db_ref().
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-type counter() :: atom().
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-type increment() :: integer().
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-type counters() :: #{ counter() := integer() }.
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new() ->
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#{ ref => counters:new(map_size(ctr_meta()), [write_concurrency])
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, meta => ctr_meta()}.
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ctr_meta() ->
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#{ inner_retries => 1
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, outer_retries => 2 }.
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-spec incr(alias() | db_ref(), counter(), increment()) -> ok.
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%% @doc Increment `Ctr' counter for `Alias` with increment `N'.
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%%
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%% Note that the first argument may also be a `db_ref()' map,
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%% corresponding to `mrdb:get_ref({admin, Alias})'.
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%% @end
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incr(Alias, Ctr, N) when is_atom(Alias) ->
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#{stats := #{ref := Ref, meta := Meta}} = mrdb:get_ref({admin, Alias}),
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incr_(Ref, Meta, Ctr, N);
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incr(#{stats := #{ref := Ref, meta := Meta}}, Ctr, N) ->
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incr_(Ref, Meta, Ctr, N).
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-spec get(alias() | db_ref(), counter()) -> integer().
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%% @doc Fetches the integer value of the known counter `Ctr' for `Alias'.
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%% @end
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get(Alias, Ctr) when is_atom(Alias) ->
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#{stats := #{ref := Ref, meta := Meta}} = mrdb:get_ref({admin, Alias}),
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get_(Ref, Meta, Ctr);
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get(#{stats := #{ref := Ref, meta := Meta}}, Ctr) ->
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get_(Ref, Meta, Ctr).
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-spec get(alias() | db_ref()) -> counters().
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%% @doc Fetches all known counters for `Alias', in the form of a map,
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%% `#{Counter => Value}'.
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%% @end
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get(Alias) when is_atom(Alias) ->
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get_(mrdb:get_ref({admin, Alias}));
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get(Ref) when is_map(Ref) ->
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get_(Ref).
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get_(#{stats := #{ref := Ref, meta := Meta}}) ->
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lists:foldl(
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fun({K, P}, M) ->
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M#{K := counters:get(Ref, P)}
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end, Meta, maps:to_list(Meta)).
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get_(Ref, Meta, Attr) ->
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Ix = maps:get(Attr, Meta),
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counters:get(Ref, Ix).
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incr_(Ref, Meta, Attr, N) ->
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Ix = maps:get(Attr, Meta),
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counters:add(Ref, Ix, N).
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