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package org.graalvm.wasm.benchmark;

import org.graalvm.polyglot.Context;
import org.graalvm.wasm.utils.WasmResource;
import org.graalvm.wasm.utils.cases.WasmCase;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import static org.graalvm.wasm.utils.cases.WasmCase.collectFileCase;

For each benchmark case in args, measures the difference in heap size after forced GC before and after the parsing phase. This corresponds to the memory allocated by the parser that is needed to run the program. 

Example usage:

$ java org.graalvm.wasm.benchmark.MemoryProfiler --warmup-iterations 10 --result-iterations 6 go-hello


Example result:

go-hello: warmup iteration[0]: 50.863 MB
go-hello: warmup iteration[1]: 12.708 MB
...
go-hello: iteration[0]: 16.902 MB
go-hello: iteration[1]: 17.161 MB
...
go-hello: median: 17.057 MB
go-hello: min: 17.161 MB
go-hello: max: 16.902 MB
go-hello: average: 17.044 MB


This class is used by the memory mx benchmark suite, runnable with
mx --dy /compiler benchmark memory -- --jvm=server --jvm-config=graal-core. The
suite is defined in MemoryBenchmarkSuite in mx_benchmark.py.

/**
 * For each benchmark case in {@code args}, measures the difference in heap size after forced GC
 * before and after the parsing phase. This corresponds to the memory allocated by the parser that
 * is needed to run the program.
 *
 * <p>
 * Example usage:
 * </p>
 *
 * <pre>
 * $ java org.graalvm.wasm.benchmark.MemoryProfiler --warmup-iterations 10 --result-iterations 6 go-hello
 * </pre>
 *
 * <p>
 * Example result:
 * </p>
 *
 * <pre>
 * go-hello: warmup iteration[0]: 50.863 MB
 * go-hello: warmup iteration[1]: 12.708 MB
 * ...
 * go-hello: iteration[0]: 16.902 MB
 * go-hello: iteration[1]: 17.161 MB
 * ...
 * go-hello: median: 17.057 MB
 * go-hello: min: 17.161 MB
 * go-hello: max: 16.902 MB
 * go-hello: average: 17.044 MB
 * </pre>
 *
 * <p>
 * This class is used by the <code>memory</code> mx benchmark suite, runnable with
 * <code>mx --dy /compiler benchmark memory -- --jvm=server --jvm-config=graal-core</code>. The
 * suite is defined in <code>MemoryBenchmarkSuite</code> in <code>mx_benchmark.py</code>.
 * </p>
 */
public class MemoryFootprintBenchmarkRunner {
    // We currently hardcode the path to memory-footprint-related tests. We might in the future
    // generalize this to include more paths, if that turns out necessary.
    private static String BENCHCASES_TYPE = "bench";
    private static String BENCHCASES_RESOURCE = "wasm/memory";

    public static void main(String[] args) throws IOException, InterruptedException {
        if (args[0].equals("--list")) {
            System.out.println(WasmResource.getResourceIndex(String.format("/%s/%s", BENCHCASES_TYPE, BENCHCASES_RESOURCE)));
            return;
        }

        if (args.length < 5 || !args[0].equals("--warmup-iterations") || !args[2].equals("--result-iterations")) {
            System.err.println("Usage: --warmup-iterations <n> --result-iterations <n> <case_spec>...");
        }

        final int warmup_iterations = Integer.parseInt(args[1]);
        final int result_iterations = Integer.parseInt(args[3]);

        for (final String caseSpec : Arrays.copyOfRange(args, 4, args.length)) {
            final WasmCase benchmarkCase = collectFileCase(BENCHCASES_TYPE, BENCHCASES_RESOURCE, caseSpec);
            assert benchmarkCase != null : String.format("Test case %s/%s not found.", BENCHCASES_RESOURCE, caseSpec);

            final Context.Builder contextBuilder = Context.newBuilder("wasm");

            final List<Double> results = new ArrayList<>();

            for (int i = 0; i < warmup_iterations + result_iterations; ++i) {
                final Context context = contextBuilder.build();

                final double heapSizeBefore = getHeapSize();

                // The code we want to profile:
                benchmarkCase.getSources().forEach(context::eval);

                final double heapSizeAfter = getHeapSize();
                final double result = heapSizeAfter - heapSizeBefore;
                if (i < warmup_iterations) {
                    System.out.format("%s: warmup iteration[%d]: %.3f MB%n", caseSpec, i, result);
                } else {
                    results.add(result);
                    System.out.format("%s: iteration[%d]: %.3f MB%n", caseSpec, i, result);
                }

                context.close();
            }

            Collections.sort(results);

            System.out.format("%s: median: %.3f MB%n", caseSpec, median(results));
            System.out.format("%s: min: %.3f MB%n", caseSpec, results.get(0));
            System.out.format("%s: max: %.3f MB%n", caseSpec, results.get(results.size() - 1));
            System.out.format("%s: average: %.3f MB%n", caseSpec, average(results));
        }
    }

    static double getHeapSize() {
        sleep();
        System.gc();
        sleep();
        final Runtime runtime = Runtime.getRuntime();
        return (runtime.totalMemory() - runtime.freeMemory()) / 1000000.0;
    }

    static void sleep() {
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }

    private static double median(List<Double> xs) {
        final int size = xs.size();
        if (size % 2 == 0) {
            return (xs.get(size / 2) + xs.get(size / 2 - 1)) / 2.0;
        } else {
            return xs.get(size / 2);
        }
    }

    private static double average(List<Double> xs) {
        double result = 0.0;
        for (double x : xs) {
            result += x;
        }
        return result / xs.size();
    }
}