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// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
class TestNSLock: XCTestCase {
func test_lockWait() {
let condition = NSCondition()
let lock = NSLock()
func test(waitTime: TimeInterval, shouldLock: Bool) -> Bool {
let locked = lock.lock(before: Date.init(timeIntervalSinceNow: waitTime))
if locked {
lock.unlock()
}
return locked == shouldLock
}
let thread = Thread() {
lock.lock()
// Now wake up the main thread so it can try to obtain the lock that
// this thread just obtained.
condition.lock()
condition.signal()
condition.unlock()
Thread.sleep(forTimeInterval: 8)
lock.unlock()
}
condition.lock()
thread.start()
condition.wait()
condition.unlock()
XCTAssertTrue(test(waitTime: 0, shouldLock: false))
XCTAssertTrue(test(waitTime: -1, shouldLock: false))
XCTAssertTrue(test(waitTime: 1, shouldLock: false))
XCTAssertTrue(test(waitTime: 4, shouldLock: false))
XCTAssertTrue(test(waitTime: 8, shouldLock: true))
XCTAssertTrue(test(waitTime: -1, shouldLock: true))
}
func test_threadsAndLocks() {
let condition = NSCondition()
let lock = NSLock()
let threadCount = 10
let endSeconds: Double = 2
let endTime = Date.init(timeIntervalSinceNow: endSeconds)
// Protected by arrayLock
nonisolated(unsafe) var threadsStarted = Array<Bool>(repeating: false, count: threadCount)
let arrayLock = NSLock()
for t in 0..<threadCount {
let thread = Thread() {
condition.lock()
arrayLock.lock()
threadsStarted[t] = true
arrayLock.unlock()
condition.wait()
condition.unlock()
for _ in 1...50 {
let r = Double.random(in: 0...0.02)
Thread.sleep(forTimeInterval: r)
if lock.lock(before: endTime) {
lock.unlock()
}
}
arrayLock.lock()
threadsStarted[t] = false
arrayLock.unlock()
}
thread.start()
}
var totalThreads = 0
repeat {
arrayLock.lock()
totalThreads = threadsStarted.filter {$0 == true }.count
arrayLock.unlock()
} while totalThreads < threadCount
XCTAssertEqual(totalThreads, threadCount)
condition.lock()
condition.broadcast()
condition.unlock()
Thread.sleep(until: endTime)
repeat {
arrayLock.lock()
totalThreads = threadsStarted.filter {$0 == false }.count
arrayLock.unlock()
} while totalThreads < threadCount
XCTAssertEqual(totalThreads, threadCount)
let gotLock = lock.try()
XCTAssertTrue(gotLock)
if gotLock {
lock.unlock()
}
}
func test_recursiveLock() {
// We will start 10 threads, and their collective task will be to reduce
// the countdown value to zero in less than 30 seconds.
let threadCount = 10
let countdownPerThread = 1000
let endTime = Date(timeIntervalSinceNow: 30)
// Protected by threadCompletedCondition
nonisolated(unsafe) var completedThreadCount = 0
// Protected by recursive countdownValueLock
nonisolated(unsafe) var countdownValue = threadCount * countdownPerThread
let threadCompletedCondition = NSCondition()
let countdownValueLock = NSRecursiveLock()
for _ in 0..<threadCount {
let thread = Thread {
// Some dummy work on countdown.
// Add/substract operations are balanced to decrease countdown
// exactly by countdownPerThread
for _ in 0..<countdownPerThread {
countdownValueLock.lock()
countdownValue -= 3
countdownValueLock.lock()
countdownValue += 4
countdownValueLock.unlock()
countdownValueLock.unlock()
countdownValueLock.lock()
countdownValue += 2
countdownValueLock.lock()
countdownValue -= 1
countdownValueLock.unlock()
countdownValue -= 3
countdownValueLock.unlock()
countdownValueLock.lock()
countdownValue += 1
countdownValueLock.unlock()
countdownValueLock.lock()
countdownValue -= 1
countdownValueLock.unlock()
}
threadCompletedCondition.lock()
completedThreadCount += 1
threadCompletedCondition.broadcast()
threadCompletedCondition.unlock()
}
thread.start()
}
threadCompletedCondition.lock()
var isTimedOut = false
while !isTimedOut && completedThreadCount < threadCount {
isTimedOut = !threadCompletedCondition.wait(until: endTime)
}
countdownValueLock.lock()
let resultCountdownValue = countdownValue
countdownValueLock.unlock()
XCTAssertEqual(completedThreadCount, threadCount, "Some threads are still not finished, could be hung")
XCTAssertEqual(resultCountdownValue, 0, "Wrong coundtdown means unresolved race conditions, locks broken")
threadCompletedCondition.unlock()
}
func test_withLock() {
let lock = NSLock()
// Protected by lock
nonisolated(unsafe) var counter = 0
let counterIncrementPerThread = 10_000
let threadCount = 10
let threadCompletedExpectation = expectation(description: "Expected threads to complete.")
threadCompletedExpectation.expectedFulfillmentCount = threadCount
for _ in 0..<threadCount {
let thread = Thread {
for _ in 0..<counterIncrementPerThread {
lock.withLock {
counter += 1
}
}
threadCompletedExpectation.fulfill()
}
thread.start()
}
wait(for: [threadCompletedExpectation], timeout: 10)
XCTAssertEqual(counter, counterIncrementPerThread * threadCount)
}
}
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