1 files changed, 6 insertions, 3 deletions
diff --git a/notxv6/ph.c b/notxv6/ph.c
index 82afe76..db8a630 100644
--- a/notxv6/ph.c
+++ b/notxv6/ph.c
@@ -16,7 +16,7 @@ struct entry {
 struct entry *table[NBUCKET];
 int keys[NKEYS];
 int nthread = 1;
-
+pthread_mutex_t lock[NBUCKET];
 
 double
 now()
@@ -47,6 +47,7 @@ void put(int key, int value)
     if (e->key == key)
       break;
   }
+  pthread_mutex_lock(&lock[i]);
   if(e){
     // update the existing key.
     e->value = value;
@@ -54,7 +55,7 @@ void put(int key, int value)
     // the new is new.
     insert(key, value, &table[i], table[i]);
   }
-
+  pthread_mutex_unlock(&lock[i]);
 }
 
 static struct entry*
@@ -67,7 +68,6 @@ get(int key)
   for (e = table[i]; e != 0; e = e->next) {
     if (e->key == key) break;
   }
-
   return e;
 }
 
@@ -113,6 +113,9 @@ main(int argc, char *argv[])
   nthread = atoi(argv[1]);
   tha = malloc(sizeof(pthread_t) * nthread);
   srandom(0);
+  for (int i = 0; i < NBUCKET; i++) {
+    pthread_mutex_init(&lock[i], NULL);
+  }
   assert(NKEYS % nthread == 0);
   for (int i = 0; i < NKEYS; i++) {
     keys[i] = random();