Create cond_sig_thread.c

C program to implement cond(), signal() and wait() functions.

Author: holman57

cond_sig_thread.c

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+#include <pthread.h>
+#include <stdio.h>
+#include <unistd.h>
+
+//       Compile and link with -pthread
+
+// Declaration of thread condition variable
+pthread_cond_t cond1 = PTHREAD_COND_INITIALIZER;
+
+// Declaring mutex
+pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
+
+int done = 1;
+
+void* create();
+
+int main()
+{
+    pthread_t tid1, tid2;
+
+    // Create thread 1
+    pthread_create(&tid1, NULL, create, NULL);
+
+    // Sleep for 1 sec so that thread 1
+    // would get a chance to run first
+    sleep(1);
+
+    // Create thread 2
+    pthread_create(&tid2, NULL, create, NULL);
+
+    // Wait for the completion of thread 2
+    pthread_join(tid2, NULL);
+
+    return 0;
+}
+
+void *create()
+{
+    // Acquire a lock
+    pthread_mutex_lock(&lock);
+
+    if (done == 1)
+    {
+        done = 2;
+        printf("Waiting on condition variable cond1\n");
+        pthread_cond_wait(&cond1, &lock);
+    }
+    else
+    {
+        printf("Signaling condition variable cond1\n");
+        pthread_cond_signal(&cond1);
+    }
+
+    // Release lock
+    pthread_mutex_unlock(&lock);
+    printf("Returning thread\n");
+
+    return NULL;
+}