1 files changed, 229 insertions, 0 deletions
diff --git a/dnsdist-rings.hh b/dnsdist-rings.hh
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+++ b/dnsdist-rings.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
+
+#include <time.h>
+#include <unordered_map>
+
+#include <boost/variant.hpp>
+
+#include "circular_buffer.hh"
+#include "dnsname.hh"
+#include "iputils.hh"
+#include "lock.hh"
+#include "stat_t.hh"
+#include "dnsdist-protocols.hh"
+
+struct Rings {
+  struct Query
+  {
+    ComboAddress requestor;
+    DNSName name;
+    struct timespec when;
+    struct dnsheader dh;
+    uint16_t size;
+    uint16_t qtype;
+    // incoming protocol
+    dnsdist::Protocol protocol;
+  };
+  struct Response
+  {
+    ComboAddress requestor;
+    ComboAddress ds; // who handled it
+    DNSName name;
+    struct timespec when;
+    struct dnsheader dh;
+    unsigned int usec;
+    unsigned int size;
+    uint16_t qtype;
+    // outgoing protocol
+    dnsdist::Protocol protocol;
+  };
+
+  struct Shard
+  {
+    LockGuarded<boost::circular_buffer<Query>> queryRing{boost::circular_buffer<Query>()};
+    LockGuarded<boost::circular_buffer<Response>> respRing{boost::circular_buffer<Response>()};
+  };
+
+  Rings(size_t capacity=10000, size_t numberOfShards=10, size_t nbLockTries=5, bool keepLockingStats=false): d_blockingQueryInserts(0), d_blockingResponseInserts(0), d_deferredQueryInserts(0), d_deferredResponseInserts(0), d_nbQueryEntries(0), d_nbResponseEntries(0), d_currentShardId(0), d_numberOfShards(numberOfShards), d_nbLockTries(nbLockTries), d_keepLockingStats(keepLockingStats)
+  {
+    setCapacity(capacity, numberOfShards);
+  }
+
+  std::unordered_map<int, vector<boost::variant<string,double> > > getTopBandwidth(unsigned int numentries);
+  size_t numDistinctRequestors();
+  /* This function should only be called at configuration time before any query or response has been inserted */
+  void setCapacity(size_t newCapacity, size_t numberOfShards)
+  {
+    if (numberOfShards <= 1) {
+      d_nbLockTries = 0;
+    }
+
+    d_shards.resize(numberOfShards);
+    d_numberOfShards = numberOfShards;
+
+    /* resize all the rings */
+    for (auto& shard : d_shards) {
+      shard = std::make_unique<Shard>();
+      shard->queryRing.lock()->set_capacity(newCapacity / numberOfShards);
+      shard->respRing.lock()->set_capacity(newCapacity / numberOfShards);
+    }
+
+    /* we just recreated the shards so they are now empty */
+    d_nbQueryEntries = 0;
+    d_nbResponseEntries = 0;
+  }
+
+  void setNumberOfLockRetries(size_t retries)
+  {
+    if (d_numberOfShards <= 1) {
+      d_nbLockTries = 0;
+    } else {
+      d_nbLockTries = retries;
+    }
+  }
+
+  size_t getNumberOfShards() const
+  {
+    return d_numberOfShards;
+  }
+
+  size_t getNumberOfQueryEntries() const
+  {
+    return d_nbQueryEntries;
+  }
+
+  size_t getNumberOfResponseEntries() const
+  {
+    return d_nbResponseEntries;
+  }
+
+  void insertQuery(const struct timespec& when, const ComboAddress& requestor, const DNSName& name, uint16_t qtype, uint16_t size, const struct dnsheader& dh, dnsdist::Protocol protocol)
+  {
+    for (size_t idx = 0; idx < d_nbLockTries; idx++) {
+      auto& shard = getOneShard();
+      auto lock = shard->queryRing.try_lock();
+      if (lock.owns_lock()) {
+        insertQueryLocked(*lock, when, requestor, name, qtype, size, dh, protocol);
+        return;
+      }
+      if (d_keepLockingStats) {
+        ++d_deferredQueryInserts;
+      }
+    }
+
+    /* out of luck, let's just wait */
+    if (d_keepLockingStats) {
+      ++d_blockingResponseInserts;
+    }
+    auto& shard = getOneShard();
+    auto lock = shard->queryRing.lock();
+    insertQueryLocked(*lock, when, requestor, name, qtype, size, dh, protocol);
+  }
+
+  void insertResponse(const struct timespec& when, const ComboAddress& requestor, const DNSName& name, uint16_t qtype, unsigned int usec, unsigned int size, const struct dnsheader& dh, const ComboAddress& backend, dnsdist::Protocol protocol)
+  {
+    for (size_t idx = 0; idx < d_nbLockTries; idx++) {
+      auto& shard = getOneShard();
+      auto lock = shard->respRing.try_lock();
+      if (lock.owns_lock()) {
+        insertResponseLocked(*lock, when, requestor, name, qtype, usec, size, dh, backend, protocol);
+        return;
+      }
+      if (d_keepLockingStats) {
+        ++d_deferredResponseInserts;
+      }
+    }
+
+    /* out of luck, let's just wait */
+    if (d_keepLockingStats) {
+      ++d_blockingResponseInserts;
+    }
+    auto& shard = getOneShard();
+    auto lock = shard->respRing.lock();
+    insertResponseLocked(*lock, when, requestor, name, qtype, usec, size, dh, backend, protocol);
+  }
+
+  void clear()
+  {
+    for (auto& shard : d_shards) {
+      shard->queryRing.lock()->clear();
+      shard->respRing.lock()->clear();
+    }
+
+    d_nbQueryEntries.store(0);
+    d_nbResponseEntries.store(0);
+    d_currentShardId.store(0);
+    d_blockingQueryInserts.store(0);
+    d_blockingResponseInserts.store(0);
+    d_deferredQueryInserts.store(0);
+    d_deferredResponseInserts.store(0);
+  }
+
+  /* load the content of the ring buffer from a file in the format emitted by grepq(),
+     only useful for debugging purposes */
+  size_t loadFromFile(const std::string& filepath, const struct timespec& now);
+
+  std::vector<std::unique_ptr<Shard> > d_shards;
+  pdns::stat_t d_blockingQueryInserts;
+  pdns::stat_t d_blockingResponseInserts;
+  pdns::stat_t d_deferredQueryInserts;
+  pdns::stat_t d_deferredResponseInserts;
+
+private:
+  size_t getShardId()
+  {
+    return (d_currentShardId++ % d_numberOfShards);
+  }
+
+  std::unique_ptr<Shard>& getOneShard()
+  {
+    return d_shards[getShardId()];
+  }
+
+  void insertQueryLocked(boost::circular_buffer<Query>& ring, const struct timespec& when, const ComboAddress& requestor, const DNSName& name, uint16_t qtype, uint16_t size, const struct dnsheader& dh, dnsdist::Protocol protocol)
+  {
+    if (!ring.full()) {
+      d_nbQueryEntries++;
+    }
+    ring.push_back({requestor, name, when, dh, size, qtype, protocol});
+  }
+
+  void insertResponseLocked(boost::circular_buffer<Response>& ring, const struct timespec& when, const ComboAddress& requestor, const DNSName& name, uint16_t qtype, unsigned int usec, unsigned int size, const struct dnsheader& dh, const ComboAddress& backend, dnsdist::Protocol protocol)
+  {
+    if (!ring.full()) {
+      d_nbResponseEntries++;
+    }
+    ring.push_back({requestor, backend, name, when, dh, usec, size, qtype, protocol});
+  }
+
+  std::atomic<size_t> d_nbQueryEntries;
+  std::atomic<size_t> d_nbResponseEntries;
+  std::atomic<size_t> d_currentShardId;
+
+  size_t d_numberOfShards;
+  size_t d_nbLockTries = 5;
+  bool d_keepLockingStats{false};
+};
+
+extern Rings g_rings;