Demonstrate proof of keep alive bug

std.http.server-keepalive-bug.zig

pub fn main() !void {
    var server = Server.init(std.heap.page_allocator, .{ .reuse_address = true });
    defer server.deinit();

    try server.listen(try net.Address.parseIp("127.0.0.1", 8080));

    while (true) {
        var buf: [8192]u8 = undefined;
        std.log.info("Waiting for a new connection ...", .{});
        const res = try server.accept(.{ .static = &buf }); // use a buffer for headers
        const thread = try std.Thread.spawn(.{}, handler, .{res});
        thread.detach();
    }
}

fn handler(res: *Server.Response) !void {
    std.log.info("New thread started ...", .{});   // <- this log shows that we are getting a new thread per req 
    try res.headers.append("server", "zwerve");
    while (true) { 
        defer res.reset();
        try res.wait();

        // Add this manual hackery to coerce the closing to FALSE if req is keepalive
        // If you do this, then the before-patch code will correctly keepalive
        // If you remove this, then the after-patch code will correctly keepalive
        
        const req_connection = res.request.headers.getFirstValue("connection");
        const req_keepalive = req_connection != null and !std.ascii.eqlIgnoreCase("close", req_connection.?);
        if (req_keepalive) {
            res.connection.conn.closing = false;
        }

        res.transfer_encoding = .{ .content_length = 3 };
        try res.do();
        try res.writer().writeAll("ZIG");
        try res.finish();

        if (res.connection.conn.closing) break;
    }
}