Deadlock example using dispatch semaphore

Author: codecat15

Deadlock_DispatchSemaphore_Demo/DeadlockDemo.playground/Contents.swift

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+import UIKit
+import PlaygroundSupport
+
+PlaygroundPage.current.needsIndefiniteExecution = true
+
+/*
+ Thank you for watching the video, I hope it was helpful. If you have doubts then please feel free to reach out via comments or social media I will be happy to answer your question.
+
+ If you have not subscribed to the channel then please do subscribe and don't forget to turn on the bell notification, and do share the channel with your friends.
+
+ Regards,
+ Ravi (CodeCat15)
+
+ */
+
+
+let highPriorityQueue = DispatchQueue.global(qos: .userInitiated)
+let lowPriorityQueue = DispatchQueue.global(qos: .utility)
+
+let codecat15Semaphore = DispatchSemaphore(value: 1)
+let codecat15BrotherSemaphore = DispatchSemaphore(value: 1)
+
+
+func requestForResource(resource: String, prioritySymbol: String, semaphore: DispatchSemaphore)
+{
+    debugPrint("\(prioritySymbol) is waiting for resource = \(resource)")
+    semaphore.wait(timeout: DispatchTime.now() + 5)
+}
+
+func prepareBreakfast(queue: DispatchQueue, prioritySymbol: String, firstResource: String, firstSemaphore: DispatchSemaphore, secondResource: String, secondSemaphore: DispatchSemaphore)
+{
+    queue.async {
+
+        requestForResource(resource: firstResource, prioritySymbol: prioritySymbol, semaphore: firstSemaphore)
+
+        for i in 0...10 {
+            if(i == 4)
+            {
+                requestForResource(resource: secondResource, prioritySymbol: prioritySymbol, semaphore: secondSemaphore)
+            }
+            debugPrint("\(prioritySymbol) \(i)")
+        }
+
+        debugPrint("signal called")
+        firstSemaphore.signal()
+        secondSemaphore.signal()
+    }
+}
+
+prepareBreakfast(queue: highPriorityQueue, prioritySymbol: "🐈", firstResource: "Pan", firstSemaphore: codecat15Semaphore, secondResource: "Oil", secondSemaphore: codecat15BrotherSemaphore)
+
+prepareBreakfast(queue: lowPriorityQueue, prioritySymbol: "🦖", firstResource: "Oil", firstSemaphore: codecat15BrotherSemaphore, secondResource: "Pan", secondSemaphore: codecat15Semaphore)
+

Deadlock_DispatchSemaphore_Demo/DeadlockDemo.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>