Fix data race in `assoc_start_expand`

1 files changed, 5 insertions, 9 deletions

diff --git a/assoc.c b/assoc.c
index b67fc01..68235d5 100644
--- a/assoc.c
+++ b/assoc.c
@@ -48,7 +48,6 @@ static item** old_hashtable = 0;
 
 /* Flag: Are we in the middle of expanding now? */
 static bool expanding = false;
-static bool started_expanding = false;
 
 /*
  * During expansion we migrate values with bucket granularity; this is how
@@ -141,13 +140,11 @@ static void assoc_expand(void) {
 }
 
 void assoc_start_expand(uint64_t curr_items) {
-    if (started_expanding)
-        return;
-
-    if (curr_items > (hashsize(hashpower) * 3) / 2 &&
-          hashpower < HASHPOWER_MAX) {
-        started_expanding = true;
-        pthread_cond_signal(&maintenance_cond);
+    if (pthread_mutex_trylock(&maintenance_lock) == 0) {
+        if (curr_items > (hashsize(hashpower) * 3) / 2 && hashpower < HASHPOWER_MAX) {
+            pthread_cond_signal(&maintenance_cond);
+        }
+        pthread_mutex_unlock(&maintenance_lock);
     }
 }
 
@@ -246,7 +243,6 @@ static void *assoc_maintenance_thread(void *arg) {
 
         if (!expanding) {
             /* We are done expanding.. just wait for next invocation */
-            started_expanding = false;
             pthread_cond_wait(&maintenance_cond, &maintenance_lock);
             /* assoc_expand() swaps out the hash table entirely, so we need
              * all threads to not hold any references related to the hash