-- residency-bench — databasev2 2 task 7.
--
-- Two tables identical except the `resident` annotation (see types.wo), the
-- same fill, the same Weyl key order, the same read count. Run under a cgroup
-- memory cap by scripts/db-bench.py's `residency` leg:
--
--   control : a cap that binds neither mode  -> what the mode COSTS
--   over-cap: a cap between the two resident sets -> what the mode BUYS
--
-- Prints the same shape db-bench's own legs do, so the harness parses it with
-- the same helpers: `<op> <n> <ops/sec> <p50> <p99>` plus an rss/hits line.
use fs
use time

fn hist_add(mut h: map<Int, Int>, us: Int) {
  let b = us;
  if b < 0 {
    b = 0;
  }
  if b > 20000 {
    b = 20000;
  }
  if has(h, b) {
    set(h, b, get(h, b) + 1);
  } else {
    set(h, b, 1);
  }
}

fn hist_pct(h: map<Int, Int>, total: Int, pct: Int) -> Int {
  let target = total * pct / 100;
  if target < 1 {
    target = 1;
  }
  let seen = 0;
  let b = 0;
  while b <= 20000 {
    if has(h, b) {
      seen = seen + get(h, b);
      if seen >= target {
        return b;
      }
    }
    b = b + 1;
  }
  return 20000;
}

fn report(op: Text, n: Int, total_us: Int, h: map<Int, Int>) {
  let us = total_us;
  if us < 1 {
    us = 1;
  }
  let rate = n * 1000000 / us;
  print("${op} ${n} ${rate} ${hist_pct(h, n, 50)} ${hist_pct(h, n, 99)}");
}

fn self_rss_kb() -> Int {
  let st = try fs.read_all("/proc/self/status", 16384) catch (e) "";
  let i = index_of(st, "VmRSS:");
  if i < 0 {
    return 0;
  }
  let rest = substr(st, i + 6, 24);
  let n = 0;
  let j = 0;
  while j < len(rest) {
    let c = byte_at(rest, j);
    if c >= 48 and c <= 57 {
      n = n * 10 + (c - 48);
    } else {
      if n > 0 {
        return n;
      }
    }
    j = j + 1;
  }
  return n;
}

fn wide_pad() -> Text {
  return "0123456789abcdef0123456789abcdef";
}

fn wread_all(n: Int, r: Int) -> Int {
  let pad = wide_pad();
  let i = 1;
  while i <= n {
    insert WideA { k: i, a: "a${i}${pad}", b: "b${i}${pad}", note: "n${i}${pad}${pad}" };
    i = i + 1;
  }
  print("wreadfilled ${n} ${self_rss_kb()}");
  let h: map<Int, Int> = {};
  let hits = 0;
  let t0 = time.ticks();
  let j = 0;
  while j < r {
    let key = 1 + (j * 2654435761) % n;
    let o0 = time.ticks();
    for row in from x in WideA where x.k == key take 1 select x {
      if len(row.a) > 0 { hits = hits + 1; }
    }
    hist_add(h, time.ticks() - o0);
    j = j + 1;
  }
  report("wreadall", r, time.ticks() - t0, h);
  print("wreadallrss ${self_rss_kb()} ${hits}");
  return 0;
}

fn wread_keys(n: Int, r: Int) -> Int {
  let pad = wide_pad();
  let i = 1;
  while i <= n {
    insert WideK { k: i, a: "a${i}${pad}", b: "b${i}${pad}", note: "n${i}${pad}${pad}" };
    i = i + 1;
  }
  print("wreadfilled ${n} ${self_rss_kb()}");
  let h: map<Int, Int> = {};
  let hits = 0;
  let t0 = time.ticks();
  let j = 0;
  while j < r {
    let key = 1 + (j * 2654435761) % n;
    let o0 = time.ticks();
    for row in from x in WideK where x.k == key take 1 select x {
      if len(row.a) > 0 { hits = hits + 1; }
    }
    hist_add(h, time.ticks() - o0);
    j = j + 1;
  }
  report("wreadkeys", r, time.ticks() - t0, h);
  print("wreadkeysrss ${self_rss_kb()} ${hits}");
  return 0;
}

fn main(args: multi Text) -> Int {
  if len(args) < 3 {
    print_err("usage: residency-bench wreadall|wreadkeys N R");
    return 2;
  }
  let n = parse_int(args[1]);
  let r = parse_int(args[2]);
  if n == nil or r == nil {
    print_err("residency-bench: N and R must be positive numbers");
    return 2;
  }
  if args[0] == "wreadall" { return wread_all(n, r); }
  if args[0] == "wreadkeys" { return wread_keys(n, r); }
  print_err("residency-bench: unknown mode ${args[0]}");
  return 2;
}