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Implement backoff algorithm for configuration worker (#324)
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| %%%------------------------------------------------------------------- | ||
| %% @doc Backoff Handling | ||
| %% | ||
| %% Based on `db_connection': | ||
| %% [https://github.com/elixir-ecto/db_connection/blob/8ef1f2ea54922873590b8939f2dad6b031c5b49c/lib/db_connection/backoff.ex#L24] | ||
| %% @end | ||
| %% @since 3.2.0 | ||
| %%%------------------------------------------------------------------- | ||
| -module(oidcc_backoff). | ||
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| -export_type([type/0]). | ||
| -export_type([min/0]). | ||
| -export_type([max/0]). | ||
| -export_type([state/0]). | ||
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| -export([handle_retry/4]). | ||
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| -type type() :: stop | exponential | random | random_exponential. | ||
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| -type min() :: pos_integer(). | ||
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| -type max() :: pos_integer(). | ||
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| -opaque state() :: pos_integer() | {pos_integer(), pos_integer()}. | ||
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| %% @private | ||
| -spec handle_retry(Type, Min, Max, State) -> stop | {Wait, State} when | ||
| Type :: type(), Min :: min(), Max :: max(), State :: undefined | state(), Wait :: pos_integer(). | ||
| handle_retry(stop, _Min, _Max, undefined) -> | ||
| stop; | ||
| handle_retry(random, Min, Max, State) -> | ||
| {rand(Min, Max), State}; | ||
| handle_retry(exponential, Min, _Max, undefined) -> | ||
| {Min, Min}; | ||
| handle_retry(exponential, _Min, Max, State) -> | ||
| Wait = min(State * 2, Max), | ||
| {Wait, Wait}; | ||
| handle_retry(random_exponential, Min, Max, undefined) -> | ||
| Lower = max(Min, Max div 3), | ||
| handle_retry(random_exponential, Min, Max, {Lower, Lower}); | ||
| handle_retry(random_exponential, _Min, Max, {Prev, Lower}) -> | ||
| NextMin = min(Prev, Lower), | ||
| NextMax = min(Prev * 3, Max), | ||
| Next = rand(NextMin, NextMax), | ||
| handle_retry(random, NextMin, NextMax, {Next, Lower}). | ||
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| rand(Min, Max) -> rand:uniform(Max - Min + 1) + Min - 1. |
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| @@ -0,0 +1,114 @@ | ||
| %% Based on https://github.com/elixir-ecto/db_connection/blob/8ef1f2ea54922873590b8939f2dad6b031c5b49c/test/db_connection/backoff_test.exs | ||
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| -module(oidcc_backoff_test). | ||
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| -include_lib("eunit/include/eunit.hrl"). | ||
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| exp_backoff_in_min_max_test() -> | ||
| Min = 1000, | ||
| Max = 30000, | ||
| lists:map( | ||
| fun(Retry) -> | ||
| ?assertMatch({wait, _}, Retry), | ||
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| {wait, Wait} = Retry, | ||
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| ?assert(Wait >= Min), | ||
| ?assert(Wait =< Max) | ||
| end, | ||
| calculate_backoffs(20, exponential, Min, Max) | ||
| ). | ||
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| exp_backoff_double_until_max_test() -> | ||
| Min = 1000, | ||
| Max = 30000, | ||
| lists:foldl( | ||
| fun | ||
| ({wait, Wait}, undefined) -> | ||
| Wait; | ||
| (Retry, Prev) -> | ||
| ?assertMatch({wait, _}, Retry), | ||
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| {wait, Wait} = Retry, | ||
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| ?assert(((Wait div 2) =:= Prev) or (Wait =:= Max)), | ||
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| Wait | ||
| end, | ||
| undefined, | ||
| calculate_backoffs(20, exponential, Min, Max) | ||
| ). | ||
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| rand_backoff_in_min_max_test() -> | ||
| Min = 1000, | ||
| Max = 30000, | ||
| lists:map( | ||
| fun(Retry) -> | ||
| ?assertMatch({wait, _}, Retry), | ||
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| {wait, Wait} = Retry, | ||
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| ?assert(Wait >= Min), | ||
| ?assert(Wait =< Max) | ||
| end, | ||
| calculate_backoffs(20, random, Min, Max) | ||
| ). | ||
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| rand_backoff_different_every_time_test() -> | ||
| Min = 1000, | ||
| Max = 30000, | ||
| Comparison = calculate_backoffs(20, random, Min, Max), | ||
| lists:map( | ||
| fun(_) -> | ||
| ?assertNotEqual(Comparison, calculate_backoffs(20, random, Min, Max)) | ||
| end, | ||
| lists:seq(1, 100) | ||
| ). | ||
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| rand_exp_backoff_in_min_max_test() -> | ||
| Min = 1000, | ||
| Max = 30000, | ||
| lists:map( | ||
| fun(Retry) -> | ||
| ?assertMatch({wait, _}, Retry), | ||
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| {wait, Wait} = Retry, | ||
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| ?assert(Wait >= Min), | ||
| ?assert(Wait =< Max) | ||
| end, | ||
| calculate_backoffs(20, random_exponential, Min, Max) | ||
| ). | ||
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| rand_exp_backoff_increase_until_third_max_test() -> | ||
| Min = 1000, | ||
| Max = 30000, | ||
| lists:foldl( | ||
| fun | ||
| ({wait, Wait}, undefined) -> | ||
| Wait; | ||
| (Retry, Prev) -> | ||
| ?assertMatch({wait, _}, Retry), | ||
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| {wait, Wait} = Retry, | ||
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| ?assert((Wait >= Prev) or (Wait >= (Max div 3))), | ||
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| Wait | ||
| end, | ||
| undefined, | ||
| calculate_backoffs(20, random_exponential, Min, Max) | ||
| ). | ||
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| calculate_backoffs(N, Type, Min, Max) -> | ||
| lists:reverse(calculate_backoffs(N, Type, Min, Max, undefined, [])). | ||
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| calculate_backoffs(0, _Type, _Min, _Max, _State, Acc) -> | ||
| Acc; | ||
| calculate_backoffs(N, Type, Min, Max, State, Acc) -> | ||
| case oidcc_backoff:handle_retry(Type, Min, Max, State) of | ||
| stop -> | ||
| [stop | Acc]; | ||
| {Wait, NewState} -> | ||
| calculate_backoffs(N - 1, Type, Min, Max, NewState, [{wait, Wait} | Acc]) | ||
| end. |
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