Operational Remediation Reports

Lock Guard Remediation Report

Turn the number of waiters behind a held guard into an enter, backoff, or page remediation action.

guard contention The waiter count behind a held guard is kept as a scalar, so the remediation action stays deterministic and never depends on lock identity or scheduler timing.

Lock Guard Remediation Report

waiters
lock_guard_remediation_report.swift
Replay: real traced execution (multi-file project)
let waiters = 0
let guardLimit = 2
let acquired = 1

var action = "enter"
if waiters >= 1 {
    action = "backoff"
}
if waiters > guardLimit {
    action = "page"
}

let line = "waiters=\(waiters) acquired=\(acquired) \(action)"
print(line)

let waiters = 1
let guardLimit = 2
let acquired = 1

var action = "enter"
if waiters >= 1 {
    action = "backoff"
}
if waiters > guardLimit {
    action = "page"
}

let line = "waiters=\(waiters) acquired=\(acquired) \(action)"
print(line)

let waiters = 3
let guardLimit = 2
let acquired = 1

var action = "enter"
if waiters >= 1 {
    action = "backoff"
}
if waiters > guardLimit {
    action = "page"
}

let line = "waiters=\(waiters) acquired=\(acquired) \(action)"
print(line)

  1. waiters ← 0, guardLimit ← 2, acquired ← 1, action ← enter, line ← waiters=0 acquired=1 enter

    1let waiters→ 0 = 0  //@waiters=1, 32let guardLimit→ 2 = 23let acquired→ 1 = 145var action→ enter = "enter"6if waiters >= 1 {7    action = "backoff"8}9if waiters > guardLimit {10    action = "page"11}1213let line→ waiters=0 acquired=1 enter = "waiters=\(waiters0) acquired=\(acquired1) \(actionenter)"14print(linewaiters=0 acquired=1 enter)
    outputwaiters=0 acquired=1 enter

  1. waiters ← 1, guardLimit ← 2, acquired ← 1, action ← enter

    1let waiters→ 1 = 12let guardLimit→ 2 = 23let acquired→ 1 = 145var action→ enter = "enter"6if waiters >= 1 {

  2. if waiters >= 1

    5var action = "enter"6if waiters1 >= 1 {7    action = "backoff"8}

  3. line ← waiters=1 acquired=1 backoff

    13let line→ waiters=1 acquired=1 backoff = "waiters=\(waiters1) acquired=\(acquired1) \(actionbackoff)"14print(linewaiters=1 acquired=1 backoff)
    outputwaiters=1 acquired=1 backoff

  1. waiters ← 3, guardLimit ← 2, acquired ← 1, action ← enter

    1let waiters→ 3 = 32let guardLimit→ 2 = 23let acquired→ 1 = 145var action→ enter = "enter"6if waiters >= 1 {

  2. if waiters >= 1

    5var action = "enter"6if waiters3 >= 1 {7    action = "backoff"8}

  3. if waiters > guardLimit

    8}9if waiters3 > guardLimit2 {10    action = "page"11}

  4. line ← waiters=3 acquired=1 page

    13let line→ waiters=3 acquired=1 page = "waiters=\(waiters3) acquired=\(acquired1) \(actionpage)"14print(linewaiters=3 acquired=1 page)
    outputwaiters=3 acquired=1 page