1 files changed, 44 insertions, 0 deletions
diff --git a/dnsdist-backoff.hh b/dnsdist-backoff.hh
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+++ b/dnsdist-backoff.hh
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+/*
+ * This file is part of PowerDNS or dnsdist.
+ * Copyright -- PowerDNS.COM B.V. and its contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * In addition, for the avoidance of any doubt, permission is granted to
+ * link this program with OpenSSL and to (re)distribute the binaries
+ * produced as the result of such linking.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#pragma once
+
+class ExponentialBackOffTimer
+{
+public:
+  ExponentialBackOffTimer(unsigned int maxBackOff) :
+    d_maxBackOff(maxBackOff)
+  {
+  }
+
+  unsigned int get(size_t consecutiveFailures) const
+  {
+    unsigned int backOff = d_maxBackOff;
+    if (consecutiveFailures <= 31) {
+      backOff = 1U << consecutiveFailures;
+      backOff = std::min(d_maxBackOff, backOff);
+    }
+    return backOff;
+  }
+
+private:
+  const unsigned int d_maxBackOff;
+};