From 4c93ccab5ad48ce61e4136c646b3123a06150083 Mon Sep 17 00:00:00 2001
From: Marc Tiehuis <marc@tiehu.is>
Date: Mon, 1 Jul 2019 23:23:40 +1200
Subject: [PATCH] Add throughput test program for hash functions

---
 std/hash/throughput_test.zig | 148 +++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 std/hash/throughput_test.zig

diff --git a/std/hash/throughput_test.zig b/std/hash/throughput_test.zig
new file mode 100644
index 0000000000..4b7e8ef344
--- /dev/null
+++ b/std/hash/throughput_test.zig
@@ -0,0 +1,148 @@
+const builtin = @import("builtin");
+const std = @import("std");
+const time = std.time;
+const Timer = time.Timer;
+const hash = std.hash;
+
+const KiB = 1024;
+const MiB = 1024 * KiB;
+const GiB = 1024 * MiB;
+
+var prng = std.rand.DefaultPrng.init(0);
+
+const Hash = struct {
+    ty: type,
+    name: []const u8,
+    init_u8s: ?[]const u8 = null,
+    init_u64: ?u64 = null,
+};
+
+const siphash_key = "0123456789abcdef";
+
+const hashes = [_]Hash{
+    Hash{ .ty = hash.Wyhash, .name = "wyhash", .init_u64 = 0 },
+    Hash{ .ty = hash.SipHash64(1, 3), .name = "siphash(1,3)", .init_u8s = siphash_key },
+    Hash{ .ty = hash.SipHash64(2, 4), .name = "siphash(2,4)", .init_u8s = siphash_key },
+    Hash{ .ty = hash.Fnv1a_64, .name = "fnv1a" },
+    Hash{ .ty = hash.Crc32, .name = "crc32" },
+};
+
+const Result = struct {
+    hash: u64,
+    throughput: u64,
+};
+
+pub fn benchmarkHash(comptime H: var, bytes: usize) !Result {
+    var h = blk: {
+        if (H.init_u8s) |init| {
+            break :blk H.ty.init(init);
+        }
+        if (H.init_u64) |init| {
+            break :blk H.ty.init(init);
+        }
+        break :blk H.ty.init();
+    };
+
+    var block: [8192]u8 = undefined;
+    prng.random.bytes(block[0..]);
+
+    var offset: usize = 0;
+    var timer = try Timer.start();
+    const start = timer.lap();
+    while (offset < bytes) : (offset += block.len) {
+        h.update(block[0..]);
+    }
+    const end = timer.read();
+
+    const elapsed_s = @intToFloat(f64, end - start) / time.ns_per_s;
+    const throughput = @floatToInt(u64, @intToFloat(f64, bytes) / elapsed_s);
+
+    return Result{
+        .hash = h.final(),
+        .throughput = throughput,
+    };
+}
+
+fn usage() void {
+    std.debug.warn(
+        \\throughput_test [options]
+        \\
+        \\Options:
+        \\  --filter [test-name]
+        \\  --seed   [int]
+        \\  --count  [int]
+        \\  --help
+        \\
+    );
+}
+
+fn mode(comptime x: comptime_int) comptime_int {
+    return if (builtin.mode == builtin.Mode.Debug) x / 64 else x;
+}
+
+// TODO(#1358): Replace with builtin formatted padding when available.
+fn printPad(stdout: var, s: []const u8) !void {
+    var i: usize = 0;
+    while (i < 12 - s.len) : (i += 1) {
+        try stdout.print(" ");
+    }
+    try stdout.print("{}", s);
+}
+
+pub fn main() !void {
+    var stdout_file = try std.io.getStdOut();
+    var stdout_out_stream = stdout_file.outStream();
+    const stdout = &stdout_out_stream.stream;
+
+    var buffer: [1024]u8 = undefined;
+    var fixed = std.heap.FixedBufferAllocator.init(buffer[0..]);
+    const args = try std.process.argsAlloc(&fixed.allocator);
+
+    var filter: ?[]u8 = "";
+    var count: usize = mode(128 * MiB);
+
+    var i: usize = 1;
+    while (i < args.len) : (i += 1) {
+        if (std.mem.eql(u8, args[i], "--seed")) {
+            i += 1;
+            if (i == args.len) {
+                usage();
+                std.os.exit(1);
+            }
+
+            const seed = try std.fmt.parseUnsigned(u32, args[i], 10);
+            prng.seed(seed);
+        } else if (std.mem.eql(u8, args[i], "--filter")) {
+            i += 1;
+            if (i == args.len) {
+                usage();
+                std.os.exit(1);
+            }
+
+            filter = args[i];
+        } else if (std.mem.eql(u8, args[i], "--count")) {
+            i += 1;
+            if (i == args.len) {
+                usage();
+                std.os.exit(1);
+            }
+
+            const c = try std.fmt.parseUnsigned(u32, args[i], 10);
+            count = c * MiB;
+        } else if (std.mem.eql(u8, args[i], "--help")) {
+            usage();
+            return;
+        } else {
+            usage();
+            std.os.exit(1);
+        }
+    }
+
+    inline for (hashes) |H| {
+        if (filter == null or std.mem.indexOf(u8, H.name, filter.?) != null) {
+            const result = try benchmarkHash(H, count);
+            try printPad(stdout, H.name);
+            try stdout.print(": {:4} MiB/s [{:16}]\n", result.throughput / (1 * MiB), result.hash);
+        }
+    }
+}