From 87470490676ee6dc087e3ebe2a3ce3cfbd4afbd9 Mon Sep 17 00:00:00 2001
From: Sanjit Bhat <sanjit.bhat@gmail.com>
Date: Wed, 13 Sep 2023 02:01:38 -0400
Subject: release lab thread

---
 notxv6/barrier.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 notxv6/barrier.c

(limited to 'notxv6/barrier.c')

diff --git a/notxv6/barrier.c b/notxv6/barrier.c
new file mode 100644
index 0000000..12793e8
--- /dev/null
+++ b/notxv6/barrier.c
@@ -0,0 +1,78 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <assert.h>
+#include <pthread.h>
+
+static int nthread = 1;
+static int round = 0;
+
+struct barrier {
+  pthread_mutex_t barrier_mutex;
+  pthread_cond_t barrier_cond;
+  int nthread;      // Number of threads that have reached this round of the barrier
+  int round;     // Barrier round
+} bstate;
+
+static void
+barrier_init(void)
+{
+  assert(pthread_mutex_init(&bstate.barrier_mutex, NULL) == 0);
+  assert(pthread_cond_init(&bstate.barrier_cond, NULL) == 0);
+  bstate.nthread = 0;
+}
+
+static void 
+barrier()
+{
+  // YOUR CODE HERE
+  //
+  // Block until all threads have called barrier() and
+  // then increment bstate.round.
+  //
+  
+}
+
+static void *
+thread(void *xa)
+{
+  long n = (long) xa;
+  long delay;
+  int i;
+
+  for (i = 0; i < 20000; i++) {
+    int t = bstate.round;
+    assert (i == t);
+    barrier();
+    usleep(random() % 100);
+  }
+
+  return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+  pthread_t *tha;
+  void *value;
+  long i;
+  double t1, t0;
+
+  if (argc < 2) {
+    fprintf(stderr, "%s: %s nthread\n", argv[0], argv[0]);
+    exit(-1);
+  }
+  nthread = atoi(argv[1]);
+  tha = malloc(sizeof(pthread_t) * nthread);
+  srandom(0);
+
+  barrier_init();
+
+  for(i = 0; i < nthread; i++) {
+    assert(pthread_create(&tha[i], NULL, thread, (void *) i) == 0);
+  }
+  for(i = 0; i < nthread; i++) {
+    assert(pthread_join(tha[i], &value) == 0);
+  }
+  printf("OK; passed\n");
+}
-- 
cgit v1.2.3


From edd523ffcb39c1c57944796fabfc71c70a10ce2e Mon Sep 17 00:00:00 2001
From: Mole Shang <135e2@135e2.dev>
Date: Fri, 16 Feb 2024 11:29:36 +0800
Subject: lab thread: finish

---
 notxv6/barrier.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

(limited to 'notxv6/barrier.c')

diff --git a/notxv6/barrier.c b/notxv6/barrier.c
index 12793e8..b7737a6 100644
--- a/notxv6/barrier.c
+++ b/notxv6/barrier.c
@@ -25,12 +25,20 @@ barrier_init(void)
 static void 
 barrier()
 {
-  // YOUR CODE HERE
-  //
   // Block until all threads have called barrier() and
   // then increment bstate.round.
-  //
-  
+  pthread_mutex_lock(&bstate.barrier_mutex);
+  bstate.nthread++;
+  if(bstate.nthread != nthread) {
+    pthread_cond_wait(&bstate.barrier_cond, &bstate.barrier_mutex);
+  } else {
+    pthread_cond_broadcast(&bstate.barrier_cond);
+    // All threads have reached barrier.
+    // reset and increase round
+    bstate.nthread = 0;
+    bstate.round++;
+  }
+  pthread_mutex_unlock(&bstate.barrier_mutex);
 }
 
 static void *
-- 
cgit v1.2.3