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jesperesjesperes
authoredApr 12, 2023
Erlang solution (PlummersSoftwareLLC#909)
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‎PrimeErlang/solution_1/.gitignore

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.rebar3
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_*
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.eunit
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*.o
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*.beam
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*.plt
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*.swp
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*.swo
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.erlang.cookie
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ebin
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log
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erl_crash.dump
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.rebar
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logs
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_build
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.idea
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*.iml
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rebar3.crashdump
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*~

‎PrimeErlang/solution_1/Dockerfile

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FROM erlang:26
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WORKDIR /home/primes
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COPY rebar.config run.sh ./
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COPY src/*.erl src/*.src ./src/
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ENTRYPOINT ["./run.sh"]

‎PrimeErlang/solution_1/README.md

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# Erlang solution by jesperes
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Straight-forward single-threaded Erlang solution using `atomics` to
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track the prime numbers.
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![Algorithm](https://img.shields.io/badge/Algorithm-base-green)
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![Faithfulness](https://img.shields.io/badge/Faithful-yes-green)
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![Parallelism](https://img.shields.io/badge/Parallel-no-green)
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![Bit count](https://img.shields.io/badge/Bits-64-yellowgreen)
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## Run instructions
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```shell
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$ rebar3 escriptize && _build/default/bin/PrimeErlang
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```
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## Output
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```shell
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> rebar3 escriptize && _build/default/bin/PrimeErlang
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===> Verifying dependencies...
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===> Analyzing applications...
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===> Compiling PrimeErlang
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===> Building escript for PrimeErlang...
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jesperes;46;5.02126;1;algorithm=base,bits=64,faithful=yes
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```

‎PrimeErlang/solution_1/rebar.config

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{deps, []}.
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{escript_incl_apps, ['PrimeErlang']}.
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{escript_main_app, 'PrimeErlang'}.
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{escript_name, 'PrimeErlang'}.
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%% Profiles
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{profiles, [{test, [{erl_opts, [debug_info]}]}]}.

‎PrimeErlang/solution_1/rebar.lock

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[].

‎PrimeErlang/solution_1/run.sh

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#!/bin/bash
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QUIET=t rebar3 escriptize >/dev/null
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exec _build/default/bin/PrimeErlang

‎PrimeErlang/solution_1/src/PrimeErlang.app.src

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{application,
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'PrimeErlang',
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[{description, "Sieve of Erasthotenes"},
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{vsn, "0.1.0"},
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{registered, []},
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{applications, [kernel, stdlib]},
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{env, []},
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{modules, []},
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{licenses, ["Apache-2.0"]},
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{links, []}]}.

‎PrimeErlang/solution_1/src/PrimeErlang.erl

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%% -*- erlang -*-
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%%
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%% Sieve of Erastothenes in Erlang, implemented as a benchmark for
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%% https://github.com/PlummersSoftwareLLC/Primes.
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%%
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%% @author Jesper Eskilson <jesper@eskilson.se>
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%%
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-module('PrimeErlang').
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-export([main/1, run_benchmark/1]).
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-include_lib("eunit/include/eunit.hrl").
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%% ============================================================
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%% Types
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%% ============================================================
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-record(sieve, {q :: float(), size :: integer(), bits :: atomics:atomics_ref()}).
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-type sieve() :: #sieve{}.
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-type prime_idx() :: pos_integer().
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%% ============================================================
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%% Exported API
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%% ============================================================
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%% @doc The escript entry point
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main([]) ->
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main(["1000000"]);
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main([Arg]) ->
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N = list_to_integer(Arg),
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run_benchmark(N).
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%% @doc Run the benchmark for a sieve of the given size.
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run_benchmark(N) ->
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ExpectedNumPrimes = num_primes(N),
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LimitSecs = 5,
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BenchFun =
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fun() ->
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NumPrimes = run_sieve(N),
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?assertEqual(NumPrimes, ExpectedNumPrimes)
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end,
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{TimeUsecs, Iterations} = timer:tc(fun() -> repeat_until(BenchFun, LimitSecs) end),
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TotalTime = TimeUsecs / 1_000_000.0,
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NumThreads = 1,
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Label = "jesperes",
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Tags =
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#{algorithm => base,
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faithful => yes,
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bits => 64},
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print_result(Label, Iterations, TotalTime, NumThreads, Tags).
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%% ============================================================
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%% Implementation
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%% ============================================================
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%% @doc Run the sieve for the given size once, and return the number
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%% of primes found.
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-spec run_sieve(Size :: integer()) -> NumPrimes :: integer().
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run_sieve(Size) ->
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Sieve = sieve_new(Size),
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Sieve0 = run_sieve_loop(2, Sieve),
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sieve_count_primes(Sieve0).
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-spec run_sieve_loop(I :: prime_idx(), Sieve :: sieve()) -> sieve().
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run_sieve_loop(I, #sieve{q = Q} = Sieve) when I > Q ->
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Sieve;
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run_sieve_loop(I, Sieve) ->
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Sieve0 =
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case sieve_is_prime(I, Sieve) of
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true ->
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run_sieve_inner_loop(I * I, I, Sieve);
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false ->
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Sieve
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end,
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run_sieve_loop(I + 1, Sieve0).
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-spec run_sieve_inner_loop(J :: prime_idx(), Incr :: integer(), Sieve :: sieve()) ->
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sieve().
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run_sieve_inner_loop(J, _, #sieve{size = Size} = Sieve) when J > Size ->
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Sieve;
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run_sieve_inner_loop(J, Incr, Sieve) ->
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Sieve0 = sieve_mark_not_prime(J, Sieve),
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run_sieve_inner_loop(J + Incr, Incr, Sieve0).
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%% ============================================================
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%% Sieve
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%% ============================================================
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-spec sieve_new(Size :: integer()) -> sieve().
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sieve_new(Size) ->
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#sieve{q = math:sqrt(Size),
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size = Size,
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bits = atomics:new(Size, [])}.
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-spec sieve_is_prime(N :: prime_idx(), Sieve :: sieve()) -> boolean().
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sieve_is_prime(N, Sieve) ->
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atomics:get(Sieve#sieve.bits, N) == 0.
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-spec sieve_mark_not_prime(N :: prime_idx(), Sieve :: sieve()) -> sieve().
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sieve_mark_not_prime(N, Sieve) ->
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ok = atomics:put(Sieve#sieve.bits, N, 1),
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Sieve.
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-spec sieve_count_primes(Sieve :: sieve()) -> integer().
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sieve_count_primes(Sieve) ->
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sieve_count_primes(2, 0, Sieve).
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sieve_count_primes(I, Acc, #sieve{size = Size}) when I > Size ->
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Acc;
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sieve_count_primes(I, Acc, Sieve) ->
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case atomics:get(Sieve#sieve.bits, I) of
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0 ->
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sieve_count_primes(I + 1, 1 + Acc, Sieve);
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1 ->
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sieve_count_primes(I + 1, Acc, Sieve)
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end.
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%% ============================================================
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%% Helpers
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%% ============================================================
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%% @doc Used to verify the result
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num_primes(10) ->
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4;
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num_primes(100) ->
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25;
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num_primes(1_000) ->
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168;
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num_primes(10_000) ->
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1229;
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num_primes(100_000) ->
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9592;
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num_primes(1_000_000) ->
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78498;
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num_primes(10_000_000) ->
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664579;
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num_primes(100_000_000) ->
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5761455;
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num_primes(1_000_000_000) ->
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50847534;
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num_primes(10_000_000_000) ->
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455052511.
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%% @doc Print the result
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print_result(Label, Iterations, TotalTime, NumThreads, Tags) ->
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io:format("~s;~w;~g;~w;~s~n",
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[Label, Iterations, TotalTime, NumThreads, tags_to_str(Tags)]).
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%% @doc Convert tags on map-format to a comma-separated k=v string
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tags_to_str(Tags) ->
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lists:join(",",
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lists:map(fun({K, V}) -> io_lib:format("~w=~w", [K, V]) end, maps:to_list(Tags))).
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%% @doc Run a function repeatedly for a given number of
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%% seconds. Return the number of times the function was run.
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-spec repeat_until(Fun :: fun(), LimitSecs :: pos_integer()) ->
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Iterations :: pos_integer().
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repeat_until(Fun, LimitSecs) ->
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Start = os:system_time(),
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Limit = erlang:convert_time_unit(LimitSecs, second, native),
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repeat_until(Fun, Start, Limit, 0).
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repeat_until(Fun, Start, Limit, NIters) ->
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Elapsed = os:system_time() - Start,
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if Elapsed >= Limit ->
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NIters;
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true ->
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Fun(),
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repeat_until(Fun, Start, Limit, NIters + 1)
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end.

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