yes command in Zig

yes command in Zig

Hi, I came across a [interesting post](https://endler.dev/2017/yes/) about how to optimize unix command `yes`, I rewrite the code in Zig. Is there any way to improve this code?

## First buffered version
```zig
const std = @import("std");

pub fn main() !void {
    const argv = std.os.argv;

    const output: []const u8 = if (argv.len > 1)
        argv.ptr[1][0..std.mem.len(argv.ptr[1])]
    else
        "y";

    const out = std.io.getStdOut();
    var f = std.io.bufferedWriter(out.writer());
    while ((try f.write(output)) > 0) {
        _ = try f.write("\n");
    }
}
```
Compile and run
```
zig build-exe yes.zig -Drelease-safe
./yes | pv -r > /dev/null
```
116Mib/s

## Second reuse buffer version
```zig
const std = @import("std");

const BUFFER_CAP = 64 * 1024;

fn fill_up_buffer(buf: *[BUFFER_CAP]u8, output: []const u8) []const u8 {
    if (output.len > buf.len / 2) {
        return output;
    }

    std.mem.copy(u8, buf, output);
    std.mem.copy(u8, buf[output.len..], "\n");
    var buffer_size = output.len + 1;
    while (buffer_size < buf.len / 2) {
        std.mem.copy(u8, buf[buffer_size..], buf[0..buffer_size]);
        buffer_size *= 2;
    }

    return buf;
}

pub fn main() !void {
    const argv = std.os.argv;

    const output: []const u8 = if (argv.len > 1)
        argv.ptr[1][0..std.mem.len(argv.ptr[1])]
    else
        "y";

    var buffer: [BUFFER_CAP]u8 = undefined;
    const body = fill_up_buffer(&buffer, output);
    const stdout = std.io.getStdOut();
    var writer = stdout.writer();
    while ((try writer.write(body)) > 0) {}
}
```

const std = @import("std");

pub fn main() !void {
    const argv = std.os.argv;

    const output: []const u8 = if (argv.len > 1)
        argv.ptr[1][0..std.mem.len(argv.ptr[1])]
    else
        "y";

    const out = std.io.getStdOut();
    var f = std.io.bufferedWriter(out.writer());
    while ((try f.write(output)) > 0) {
        _ = try f.write("\n");
    }
}
```
Compile and run
```
zig build-exe yes.zig -Drelease-safe
./yes | pv -r > /dev/null
```
116Mib/s

## Second reuse buffer version
```zig
const std = @import("std");

const BUFFER_CAP = 64 * 1024;

fn fill_up_buffer(buf: *[BUFFER_CAP]u8, output: []const u8) []const u8 {
    if (output.len > buf.len / 2) {
        return output;
    }

    std.mem.copy(u8, buf, output);
    std.mem.copy(u8, buf[output.len..], "\n");
    var buffer_size = output.len + 1;
    while (buffer_size < buf.len / 2) {
        std.mem.copy(u8, buf[buffer_size..], buf[0..buffer_size]);
        buffer_size *= 2;
    }

    return buf;
}

pub fn main() !void {
    const argv = std.os.argv;

    const output: []const u8 = if (argv.len > 1)
        argv.ptr[1][0..std.mem.len(argv.ptr[1])]
    else
        "y";

    var buffer: [BUFFER_CAP]u8 = undefined;
    const body = fill_up_buffer(&buffer, output);
    const stdout = std.io.getStdOut();
    var writer = stdout.writer();
    while ((try writer.write(body)) > 0) {}
}

5.4Gib/s

https://www.reddit.com/r/Zig/comments/w65vsu/yes_command_in_zig/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

yes command in Zig

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