add few pthread examples

3 files changed, 284 insertions, 0 deletions

diff --git a/pthread1.c b/pthread1.c
new file mode 100644
index 0000000..a6e9e7e
--- /dev/null
+++ b/pthread1.c
@@ -0,0 +1,103 @@
+/* extreme case */
+
+#include <stdlib.h> 
+#include <stdio.h> 
+#include <pthread.h> 
+#include <unistd.h> 
+
+int left = 500, right = 500;
+pthread_mutex_t lock, cond_lock;
+pthread_cond_t cond;
+pthread_barrier_t barrier;
+
+void *leftf(void *args)
+{
+    sleep(3);
+    
+    pthread_barrier_wait(&barrier);
+    printf("Left passed barrier\n");
+    sleep(3);
+
+    while (1)
+    {
+        struct timeval tv;
+        struct timespec ts;
+        gettimeofday(&tv,  NULL);
+        ts.tv_sec = tv.tv_sec + 1;
+        ts.tv_nsec = 0;        
+
+        pthread_mutex_lock(&cond_lock);
+        pthread_cond_timedwait(&cond, &cond_lock, &ts);
+        pthread_mutex_unlock(&cond_lock); 
+
+        pthread_mutex_lock(&lock);
+        printf("Now running left\n");
+
+        int i;
+        for (i = 0; i < 250; i++)
+        {
+            if (right > 0)
+            {
+                left++;
+                right--;
+            }
+            usleep(10000);
+        }
+
+        pthread_mutex_unlock(&lock);
+        pthread_cond_signal(&cond);
+    }
+}
+
+void *rightf(void *args)
+{
+    pthread_barrier_wait(&barrier);
+    printf("Right passed barrier\n");
+
+    while (1)
+    {
+        pthread_mutex_lock(&lock);
+        printf("Now running right\n");
+
+        int i;
+        for (i = 0; i < 250; i++)
+        {
+            if (left > 0)
+            {
+                right++;
+                left--;
+            }
+            usleep(10000);
+        }
+
+        pthread_mutex_unlock(&lock);
+        pthread_cond_signal(&cond);
+
+        pthread_mutex_lock(&cond_lock);
+        pthread_cond_wait(&cond, &cond_lock);
+        pthread_mutex_unlock(&cond_lock);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    pthread_t thread1, thread2;
+
+    pthread_mutex_init(&lock, 0);
+    pthread_mutex_init(&cond_lock, 0);
+    pthread_cond_init(&cond, 0);
+    pthread_barrier_init(&barrier, 0, 2);
+
+    pthread_create(&thread2, 0, rightf, 0);
+    pthread_create(&thread1, 0, leftf, 0);
+
+    int i;
+    for (i = 0; i < 1000; i++)
+    {
+        printf("%d+%d = %d\n", left, right, left+right);
+        usleep(100000);
+    }
+
+    return 0;
+}
+
diff --git a/pthread2.c b/pthread2.c
new file mode 100644
index 0000000..701721b
--- /dev/null
+++ b/pthread2.c
@@ -0,0 +1,89 @@
+/* simple */
+
+#include <stdlib.h> 
+#include <stdio.h> 
+#include <pthread.h> 
+#include <unistd.h> 
+
+int left = 500, right = 500;
+pthread_mutex_t cond_lock;
+pthread_cond_t cond;
+pthread_barrier_t barrier;
+
+void *leftf(void *args)
+{
+    pthread_barrier_wait(&barrier);
+    printf("Left passed barrier\n");
+
+    while (1)
+    {
+        pthread_mutex_lock(&cond_lock);
+        pthread_cond_wait(&cond, &cond_lock);
+        pthread_mutex_unlock(&cond_lock);  
+
+        printf("Now running left\n");
+
+        int i;
+        for (i = 0; i < 250; i++)
+        {
+            if (right > 0)
+            {
+                left++;
+                right--;
+            }
+            usleep(10000);
+        }
+
+        pthread_cond_signal(&cond);
+    }
+}
+
+void *rightf(void *args)
+{
+    pthread_barrier_wait(&barrier);
+    printf("Right passed barrier\n");
+
+    while (1)
+    {
+        printf("Now running right\n");
+
+        int i;
+        for (i = 0; i < 250; i++)
+        {
+            if (left > 0)
+            {
+                right++;
+                left--;
+            }
+            usleep(10000);
+        }
+
+        pthread_cond_signal(&cond);
+
+        pthread_mutex_lock(&cond_lock);
+        pthread_cond_wait(&cond, &cond_lock);
+        pthread_mutex_unlock(&cond_lock);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    pthread_t thread1, thread2;
+
+    pthread_mutex_init(&cond_lock, 0);
+    pthread_cond_init(&cond, 0);
+    pthread_barrier_init(&barrier, 0, 2);
+
+    pthread_create(&thread2, 0, rightf, 0);
+    pthread_create(&thread1, 0, leftf, 0);
+
+    int i;
+    for (i = 0; i < 1000; i++)
+    {
+        printf("%d+%d = %d\n", left, right, left+right);
+        usleep(100000);
+    }
+
+    return 0;
+}
+
diff --git a/pthread3.c b/pthread3.c
new file mode 100644
index 0000000..51fadac
--- /dev/null
+++ b/pthread3.c
@@ -0,0 +1,92 @@
+/* with array */
+
+#include <stdlib.h> 
+#include <stdio.h> 
+#include <pthread.h> 
+#include <unistd.h> 
+
+int left = 500, right = 500;
+pthread_mutex_t cond_lock;
+pthread_cond_t cond;
+pthread_barrier_t barrier;
+
+void *leftf(void *args)
+{
+    pthread_barrier_wait(&barrier);
+    printf("Left passed barrier\n");
+
+    while (1)
+    {
+        pthread_mutex_lock(&cond_lock);
+        pthread_cond_wait(&cond, &cond_lock);
+        pthread_mutex_unlock(&cond_lock);
+
+        printf("Now running left\n");
+
+        int i;
+        for (i = 0; i < 250; i++)
+        {
+            if (right > 0)
+            {
+                left++;
+                right--;
+            }
+            usleep(10000);
+        }
+
+        pthread_cond_signal(&cond);
+    }
+}
+
+void *rightf(void *args)
+{
+    pthread_barrier_wait(&barrier);
+    printf("Right passed barrier\n");
+
+    while (1)
+    {
+        printf("Now running right\n");
+
+        int i;
+        for (i = 0; i < 250; i++)
+        {
+            if (left > 0)
+            {
+                right++;
+                left--;
+            }
+            usleep(10000);
+        }
+        sleep(3);
+
+        pthread_cond_signal(&cond);
+
+        pthread_mutex_lock(&cond_lock);
+        pthread_cond_wait(&cond, &cond_lock);
+        pthread_mutex_unlock(&cond_lock);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    pthread_t threads[64], thread2;
+
+    pthread_mutex_init(&cond_lock, 0);
+    pthread_cond_init(&cond, 0);
+    pthread_barrier_init(&barrier, 0, 2);
+
+    pthread_create(&thread2, 0, rightf, 0);
+
+    int i;
+    for (i = 0; i < 64; i++)
+        pthread_create(&threads[i], 0, leftf, 0);
+
+    for (i = 0; i < 1000; i++)
+    {
+        printf("%d+%d = %d\n", left, right, left+right);
+        usleep(100000);
+    }
+
+    return 0;
+}
+