tiny.profiling.order.contrast

1const std = @import("std");2const capture = @import("capture");34pub const minimum_repetitions: usize = 2;5pub const effect_method = "deterministic_percentile_bootstrap_unpaired_mean_percent_change";67pub const Classification = enum {8    insufficient_repetitions,9    no_order_effect_observed,10    order_sensitive_candidate,11};1213pub const Result = struct {14    fixed_count: usize,15    random_count: usize,16    fixed_mean_ns: ?f64,17    random_mean_ns: ?f64,18    mean_percent_change: ?f64,19    effect_interval: ?capture.compare.effect.Interval,20    classification: Classification,21};2223pub fn summarize(24    allocator: std.mem.Allocator,25    workload: []const u8,26    fixed_samples: []const f64,27    random_samples: []const f64,28) !Result {29    const fixed_mean = mean(fixed_samples);30    const random_mean = mean(random_samples);31    const mean_percent_change = if (fixed_mean != null and32        random_mean != null and33        fixed_mean.? != 0)34        ((random_mean.? / fixed_mean.?) - 1) * 10035    else36        null;37    const effect_interval = if (fixed_samples.len >= minimum_repetitions and38        random_samples.len >= minimum_repetitions)39    interval: {40        var effect_storage = try capture.compare.EffectStorage.init(allocator, .{41            .max_samples_per_distribution = @max(42                fixed_samples.len,43                random_samples.len,44            ),45        });46        defer effect_storage.deinit(allocator);47        effect_storage.activate();48        break :interval try capture.compare.effect.bootstrapMeanPercentChangeInterval(49            &effect_storage,50            fixed_samples,51            random_samples,52            seed(workload),53        );54    } else null;55    return .{56        .fixed_count = fixed_samples.len,57        .random_count = random_samples.len,58        .fixed_mean_ns = fixed_mean,59        .random_mean_ns = random_mean,60        .mean_percent_change = mean_percent_change,61        .effect_interval = effect_interval,62        .classification = classify(effect_interval),63    };64}6566fn mean(samples: []const f64) ?f64 {67    if (samples.len == 0) return null;68    var total: f64 = 0;69    for (samples) |sample| total += sample;70    return total / @as(f64, @floatFromInt(samples.len));71}7273fn classify(74    effect_interval: ?capture.compare.effect.Interval,75) Classification {76    const interval = effect_interval orelse return .insufficient_repetitions;77    if (interval.low > 0 or interval.high < 0) {78        return .order_sensitive_candidate;79    }80    return .no_order_effect_observed;81}8283fn seed(workload: []const u8) u64 {84    var hasher = std.hash.Wyhash.init(85        capture.compare.effect.bootstrap_seed ^ 0x4f52_4445_525f_4658,86    );87    hasher.update(workload);88    return hasher.final();89}9091test "order contrast classifies separated repeated process samples" {92    const result = try summarize(93        std.testing.allocator,94        "compiler",95        &.{ 10, 11, 9, 10 },96        &.{ 20, 22, 18, 20 },97    );98    try std.testing.expectEqual(@as(usize, 4), result.fixed_count);99    try std.testing.expectEqual(@as(f64, 10), result.fixed_mean_ns.?);100    try std.testing.expectEqual(@as(f64, 20), result.random_mean_ns.?);101    try std.testing.expectApproxEqAbs(102        @as(f64, 100),103        result.mean_percent_change.?,104        0.0001,105    );106    try std.testing.expectEqual(107        Classification.order_sensitive_candidate,108        result.classification,109    );110    try std.testing.expect(result.effect_interval.?.low > 0);111}112113test "order contrast keeps low repetition and zero reference inconclusive" {114    const single = try summarize(115        std.testing.allocator,116        "single",117        &.{10},118        &.{20},119    );120    try std.testing.expectEqual(121        Classification.insufficient_repetitions,122        single.classification,123    );124    try std.testing.expect(single.effect_interval == null);125126    const zero = try summarize(127        std.testing.allocator,128        "zero",129        &.{ 0, 0 },130        &.{ 1, 2 },131    );132    try std.testing.expect(zero.mean_percent_change == null);133    try std.testing.expect(zero.effect_interval == null);134    try std.testing.expectEqual(135        Classification.insufficient_repetitions,136        zero.classification,137    );138}

1pub const contrast = @import("contrast.zig");