void
agent_store_cache_hit (const char *key)
{
- xfree (last_stored_cache_key);
- last_stored_cache_key = key? xtrystrdup (key) : NULL;
+ char *new;
+ char *old;
+
+ /* To make sure the update is atomic under the non-preemptive thread
+ * model, we must make sure not to surrender control to a different
+ * thread. Therefore, we avoid calling the allocator during the
+ * update. */
+ new = key ? xtrystrdup (key) : NULL;
+
+ /* Atomic update. */
+ old = last_stored_cache_key;
+ last_stored_cache_key = new;
+ /* Done. */
+
+ xfree (old);
}