diff --git a/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java b/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java index 91ba6a8..82c8ce3 100644 --- a/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java +++ b/src/main/java/workshop/exercises/DeadlockPreventionWorkshop.java @@ -20,18 +20,19 @@ public class DeadlockPreventionWorkshop { } public static void useResources(Resource r1, Resource r2) { - // TODO: Prevent deadlock by enforcing a consistent lock acquisition order - // Hint: Compare resource IDs and always synchronize on the resource with the smaller ID first. + + Resource first = r1.getId() < r2.getId() ? r1 : r2; + Resource second = r1.getId() < r2.getId() ? r2 : r1; - System.out.println(Thread.currentThread().getName() + " is attempting to lock " + r1.getName()); - synchronized (r1) { - System.out.println("+ " + Thread.currentThread().getName() + " locked " + r1.getName()); + System.out.println(Thread.currentThread().getName() + " is attempting to lock " + first.getName()); + synchronized (first) { + System.out.println("+ " + Thread.currentThread().getName() + " locked " + first.getName()); try { Thread.sleep(100); } catch (InterruptedException ignored) {} - System.out.println(Thread.currentThread().getName() + " is attempting to lock " + r2.getName()); - synchronized (r2) { - System.out.println("+ " + Thread.currentThread().getName() + " locked " + r2.getName()); - System.out.println(Thread.currentThread().getName() + " using " + r1.getName() + " and " + r2.getName()); + System.out.println(Thread.currentThread().getName() + " is attempting to lock " + second.getName()); + synchronized (second) { + System.out.println("+ " + Thread.currentThread().getName() + " locked " + second.getName()); + System.out.println(Thread.currentThread().getName() + " using " + first.getName() + " and " + second.getName()); } } } diff --git a/src/main/java/workshop/exercises/LockWorkshop.java b/src/main/java/workshop/exercises/LockWorkshop.java index ec24ecf..746c7a1 100644 --- a/src/main/java/workshop/exercises/LockWorkshop.java +++ b/src/main/java/workshop/exercises/LockWorkshop.java @@ -5,16 +5,21 @@ import java.util.concurrent.locks.ReentrantLock; public class LockWorkshop { public static int counter = 0; - - // TODO: Create a ReentrantLock instance to protect the critical section + + private static Lock myLock = new ReentrantLock(); public static class MyRunnable implements Runnable { @Override public void run() { int i; for (i = 0; i < 1_000_000; i++) { - // TODO: Acquire the lock, increment the counter, and release the lock safely in a finally block - counter += 1; + myLock.lock(); + try{ + counter += 1; + }finally { + myLock.unlock(); + } + } System.out.println("Increments completed by " + Thread.currentThread().getName() + ": " + i); } diff --git a/src/main/java/workshop/exercises/SynchronizedWorkshop.java b/src/main/java/workshop/exercises/SynchronizedWorkshop.java index 9259d8e..946d6f9 100644 --- a/src/main/java/workshop/exercises/SynchronizedWorkshop.java +++ b/src/main/java/workshop/exercises/SynchronizedWorkshop.java @@ -1,18 +1,23 @@ package workshop.exercises; +import static java.lang.Thread.sleep; + public class SynchronizedWorkshop { public static int counter = 0; - - // TODO: Define a lock object to prevent race condition + + private static Object lock = new Object(); public static class MyRunnable implements Runnable { @Override public void run() { int i; for (i = 0; i < 1_000_000; i++) { - // TODO: Use a synchronized block to protect the counter increment - counter += 1; + synchronized (lock){ + counter++; + + } } + System.out.println("Increments completed by " + Thread.currentThread().getName() + ": " + i); } } diff --git a/src/main/java/workshop/exercises/TaylorSeries.java b/src/main/java/workshop/exercises/TaylorSeries.java index d63a18e..d3f1dfd 100644 --- a/src/main/java/workshop/exercises/TaylorSeries.java +++ b/src/main/java/workshop/exercises/TaylorSeries.java @@ -19,28 +19,44 @@ public class TaylorSeries { this.n = n; } + @Override public void run() { - // TODO: Calculate the n-th term of the Taylor series for sin(x): - // term = (-1)^n * (x^(2n+1)) / (2n+1)! - // Add the term to the global sum ensuring thread-safety. + + BigDecimal numarator = x.pow((2*n)+1 , mc); + BigDecimal demenator = factorial(2*n+1); + BigDecimal totalvalue = numarator.divide(demenator , mc); + + if(n%2 == 1){ + totalvalue = totalvalue.negate(); + } + + synchronized (sumlock){ + sum = sum.add(totalvalue); + } } - // TODO: Implement factorial(k) using BigDecimal private BigDecimal factorial(int k) { - return BigDecimal.ZERO; + BigDecimal result = BigDecimal.ONE; + for(int i = 1 ; i <= k ; i++){ + result = result.multiply(BigDecimal.valueOf(i) , mc); + } + return result; } } public static BigDecimal sum = BigDecimal.ZERO; + private static Object sumlock = new Object(); public static void main(String[] args) { ExecutorService threadPool = Executors.newFixedThreadPool(4); sum = BigDecimal.ZERO; BigDecimal x = new BigDecimal("0.01"); + // Submit tasks to calculate terms for (int i = 0; i < 100; i++) { + threadPool.execute(new CalculateSin(x , i)); // TODO: Submit task to the thread pool }