Are we sure in_use will be initialised to false?

[malcolmstill]

No description provided.

[malcolmstill]

I wonder if this might be a interesting use of arbitrary size integers and @popCount:

const std = @import("std");

const MAX_CLIENTS = @bitSizeOf(u512);
var CLIENTS: [MAX_CLIENTS]Client = undefined;
var CLIENTS_POP: u512 = 0;

pub const Client = struct {
    index: usize,
    data: u32,

    pub fn deinit(self: *Client) void {
        var mask: u512 = 1;
        std.debug.warn("deinit index: {}\n", .{self.index});
        mask <<= @intCast(u9, self.index);
        CLIENTS_POP ^= mask;
    }
};

fn newClient() !*Client {
    var mask: u512 = 1;
    var i: usize = 0;
    while (i < MAX_CLIENTS) {
        // std.debug.warn("i: {}\n", .{i});
        if (mask & CLIENTS_POP == 0) {
            // std.debug.warn("mask {b}, pop {b}\n", .{mask, CLIENTS_POP});
            CLIENTS_POP = CLIENTS_POP | mask;
            CLIENTS[i].index = i;
            return &CLIENTS[i];
        } else {
            mask = mask << 1;
            i = i + 1;
            continue;
        }
    }
    return error.ClientsExhausted;
}

pub fn main() anyerror!void {
    CLIENTS_POP -%= 1;
    CLIENTS_POP ^= 0b00001000000000000000000000000000000000000000000000000000000;
    std.debug.warn("initial population: {}\n", .{@popCount(u512, CLIENTS_POP)});
    var c1: *Client = try newClient();
    std.debug.warn("after c({}) new population: {}\n", .{c1.index, @popCount(u512, CLIENTS_POP)});
    // std.debug.warn("pop {b}\n", .{CLIENTS_POP});

    var save: *Client = undefined;
    var i: usize = 0;
    while (i < 7) {
        std.debug.warn("derp i: {}\n", .{i});
        var c = try newClient();
        if (i == 5) {
            save = c;
        }
        i = i + 1;
    }

    c1.deinit();
    std.debug.warn("after c1 deinit: {}\n", .{@popCount(u512, CLIENTS_POP)});
    // std.debug.warn("pop {b}\n", .{CLIENTS_POP});

    save.deinit();
    std.debug.warn("after save deinit: {}\n", .{@popCount(u512, CLIENTS_POP)});
    // std.debug.warn("pop {b}\n", .{CLIENTS_POP});    
}