Teach the OOM handler about the DNS cache

1 files changed, 30 insertions, 0 deletions

diff --git a/src/feature/relay/dns.c b/src/feature/relay/dns.c
index 8a49829d55..48319b47c8 100644
--- a/src/feature/relay/dns.c
+++ b/src/feature/relay/dns.c
@@ -2100,6 +2100,36 @@ dump_dns_mem_usage(int severity)
       (unsigned)hash_mem);
 }
 
+/* Do a round of OOM cleanup on all DNS entries. Return the amount of removed
+ * bytes. It is possible that the returned value is lower than min_remove_bytes
+ * if the caches get emptied out so the caller should be aware of this. */
+size_t
+dns_cache_handle_oom(time_t now, size_t min_remove_bytes)
+{
+  time_t time_inc = 0;
+  size_t total_bytes_removed = 0;
+  size_t current_size = dns_cache_total_allocation();
+
+  do {
+    /* If no DNS entries left, break loop. */
+    if (!dns_cache_entry_count())
+      break;
+
+    /* Get cutoff interval and remove entries. */
+    time_t cutoff = now + time_inc;
+    purge_expired_resolves(cutoff);
+
+    /* Update amount of bytes removed and array size. */
+    size_t bytes_removed = current_size - dns_cache_total_allocation();
+    current_size -= bytes_removed;
+    total_bytes_removed += bytes_removed;
+
+    time_inc += 3600; /* Increase time_inc by 1 hour. */
+  } while (total_bytes_removed < min_remove_bytes);
+
+  return total_bytes_removed;
+}
+
 #ifdef DEBUG_DNS_CACHE
 /** Exit with an assertion if the DNS cache is corrupt. */
 static void