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diff --git a/src/shrpx_memcached_connection.h b/src/shrpx_memcached_connection.h
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+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2015 Tatsuhiro Tsujikawa
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#ifndef SHRPX_MEMCACHED_CONNECTION_H
+#define SHRPX_MEMCACHED_CONNECTION_H
+
+#include "shrpx.h"
+
+#include <memory>
+#include <deque>
+
+#include <ev.h>
+
+#include "shrpx_connection.h"
+#include "shrpx_tls.h"
+#include "shrpx_connect_blocker.h"
+#include "buffer.h"
+#include "network.h"
+
+using namespace nghttp2;
+
+namespace shrpx {
+
+struct MemcachedRequest;
+enum class MemcachedOp : uint8_t;
+enum class MemcachedStatusCode : uint16_t;
+
+enum class MemcachedParseState {
+  HEADER24,
+  EXTRA,
+  VALUE,
+};
+
+// Stores state when parsing response from memcached server
+struct MemcachedParseContext {
+  // Buffer for value, dynamically allocated.
+  std::vector<uint8_t> value;
+  // cas in response
+  uint64_t cas;
+  // keylen in response
+  size_t keylen;
+  // extralen in response
+  size_t extralen;
+  // totalbody in response.  The length of value is totalbody -
+  // extralen - keylen.
+  size_t totalbody;
+  // Number of bytes left to read variable length field.
+  size_t read_left;
+  // Parser state; see enum above
+  MemcachedParseState state;
+  // status_code in response
+  MemcachedStatusCode status_code;
+  // op in response
+  MemcachedOp op;
+};
+
+struct MemcachedSendbuf {
+  // Buffer for header + extra + key
+  Buffer<512> headbuf;
+  // MemcachedRequest associated to this object
+  MemcachedRequest *req;
+  // Number of bytes left when sending value
+  size_t send_value_left;
+  // Returns the number of bytes this object transmits.
+  size_t left() const { return headbuf.rleft() + send_value_left; }
+};
+
+constexpr uint8_t MEMCACHED_REQ_MAGIC = 0x80;
+constexpr uint8_t MEMCACHED_RES_MAGIC = 0x81;
+
+// MemcachedConnection implements part of memcached binary protocol.
+// This is not full brown implementation.  Just the part we need is
+// implemented.  We only use GET and ADD.
+//
+// https://github.com/memcached/memcached/blob/master/doc/protocol-binary.xml
+// https://code.google.com/p/memcached/wiki/MemcacheBinaryProtocol
+class MemcachedConnection {
+public:
+  MemcachedConnection(const Address *addr, struct ev_loop *loop,
+                      SSL_CTX *ssl_ctx, const StringRef &sni_name,
+                      MemchunkPool *mcpool, std::mt19937 &gen);
+  ~MemcachedConnection();
+
+  void disconnect();
+
+  int add_request(std::unique_ptr<MemcachedRequest> req);
+  int initiate_connection();
+
+  int connected();
+  int on_write();
+  int on_read();
+
+  int write_clear();
+  int read_clear();
+
+  int tls_handshake();
+  int write_tls();
+  int read_tls();
+
+  size_t fill_request_buffer(struct iovec *iov, size_t iovlen);
+  void drain_send_queue(size_t nwrite);
+
+  void make_request(MemcachedSendbuf *sendbuf, MemcachedRequest *req);
+  int parse_packet();
+  size_t serialized_size(MemcachedRequest *req);
+
+  void signal_write();
+
+  int noop();
+
+  void reconnect_or_fail();
+
+private:
+  Connection conn_;
+  std::deque<std::unique_ptr<MemcachedRequest>> recvq_;
+  std::deque<std::unique_ptr<MemcachedRequest>> sendq_;
+  std::deque<MemcachedSendbuf> sendbufv_;
+  std::function<int(MemcachedConnection &)> do_read_, do_write_;
+  StringRef sni_name_;
+  tls::TLSSessionCache tls_session_cache_;
+  ConnectBlocker connect_blocker_;
+  MemcachedParseContext parse_state_;
+  const Address *addr_;
+  SSL_CTX *ssl_ctx_;
+  // Sum of the bytes to be transmitted in sendbufv_.
+  size_t sendsum_;
+  size_t try_count_;
+  bool connected_;
+  Buffer<8_k> recvbuf_;
+};
+
+} // namespace shrpx
+
+#endif // SHRPX_MEMCACHED_CONNECTION_H