Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1548 insertions, 0 deletions

diff --git a/src/include/encoding.h b/src/include/encoding.h
new file mode 100644
index 000000000..40ba9d39c
--- /dev/null
+++ b/src/include/encoding.h
@@ -0,0 +1,1548 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- 
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software 
+ * Foundation.  See file COPYING.
+ * 
+ */
+#ifndef CEPH_ENCODING_H
+#define CEPH_ENCODING_H
+
+#include <set>
+#include <map>
+#include <deque>
+#include <vector>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <optional>
+#include <boost/container/small_vector.hpp>
+#include <boost/optional/optional_io.hpp>
+#include <boost/tuple/tuple.hpp>
+
+#include "include/unordered_map.h"
+#include "include/unordered_set.h"
+#include "common/ceph_time.h"
+
+#include "include/int_types.h"
+
+#include "common/convenience.h"
+
+#include "byteorder.h"
+#include "buffer.h"
+
+// pull in the new-style encoding so that we get the denc_traits<> definition.
+#include "denc.h"
+
+#include "assert.h"
+
+using namespace ceph;
+
+namespace ceph {
+
+/*
+ * Notes on feature encoding:
+ *
+ * - The default encode() methods have a features argument with a default parameter
+ *   (which goes to zero).
+ * - Normal classes will use WRITE_CLASS_ENCODER, with that features=0 default.
+ * - Classes that _require_ features will use WRITE_CLASS_ENCODER_FEATURES, which
+ *   does not define the default.  Any caller must explicitly pass it in.
+ * - STL container macros have two encode variants: one with a features arg, and one
+ *   without.
+ *
+ * The result:
+ * - A feature encode() method will fail to compile if a value is not
+ *   passed in.
+ * - The feature varianet of the STL templates will be used when the feature arg is
+ *   provided.  It will be passed through to any template arg types, but it will be
+ *   ignored when not needed.
+ */
+
+// --------------------------------------
+// base types
+
+template<class T>
+inline void encode_raw(const T& t, bufferlist& bl)
+{
+  bl.append((char*)&t, sizeof(t));
+}
+template<class T>
+inline void decode_raw(T& t, bufferlist::const_iterator &p)
+{
+  p.copy(sizeof(t), (char*)&t);
+}
+
+#define WRITE_RAW_ENCODER(type)						\
+  inline void encode(const type &v, ::ceph::bufferlist& bl, uint64_t features=0) { ::ceph::encode_raw(v, bl); } \
+  inline void decode(type &v, ::ceph::bufferlist::const_iterator& p) { ::ceph::decode_raw(v, p); }
+
+WRITE_RAW_ENCODER(__u8)
+#ifndef _CHAR_IS_SIGNED
+WRITE_RAW_ENCODER(__s8)
+#endif
+WRITE_RAW_ENCODER(char)
+WRITE_RAW_ENCODER(ceph_le64)
+WRITE_RAW_ENCODER(ceph_le32)
+WRITE_RAW_ENCODER(ceph_le16)
+
+inline void encode(const bool &v, bufferlist& bl) {
+  __u8 vv = v;
+  encode_raw(vv, bl);
+}
+inline void decode(bool &v, bufferlist::const_iterator& p) {
+  __u8 vv;
+  decode_raw(vv, p);
+  v = vv;
+}
+
+
+// -----------------------------------
+// int types
+
+#define WRITE_INTTYPE_ENCODER(type, etype)				\
+  inline void encode(type v, ::ceph::bufferlist& bl, uint64_t features=0) { \
+    ceph_##etype e;					                \
+    e = v;                                                              \
+    ::ceph::encode_raw(e, bl);						\
+  }									\
+  inline void decode(type &v, ::ceph::bufferlist::const_iterator& p) {	\
+    ceph_##etype e;							\
+    ::ceph::decode_raw(e, p);						\
+    v = e;								\
+  }
+
+WRITE_INTTYPE_ENCODER(uint64_t, le64)
+WRITE_INTTYPE_ENCODER(int64_t, le64)
+WRITE_INTTYPE_ENCODER(uint32_t, le32)
+WRITE_INTTYPE_ENCODER(int32_t, le32)
+WRITE_INTTYPE_ENCODER(uint16_t, le16)
+WRITE_INTTYPE_ENCODER(int16_t, le16)
+
+// -----------------------------------
+// float types
+//
+// NOTE: The following code assumes all supported platforms use IEEE binary32
+// as float and IEEE binary64 as double floating-point format.  The assumption
+// is verified by the assertions below.
+//
+// Under this assumption, we can use raw encoding of floating-point types
+// on little-endian machines, but we still need to perform a byte swap
+// on big-endian machines to ensure cross-architecture compatibility.
+// To achive that, we reinterpret the values as integers first, which are
+// byte-swapped via the ceph_le types as above.  The extra conversions
+// are optimized away on little-endian machines by the compiler.
+#define WRITE_FLTTYPE_ENCODER(type, itype, etype)			\
+  static_assert(sizeof(type) == sizeof(itype));				\
+  static_assert(std::numeric_limits<type>::is_iec559,			\
+	      "floating-point type not using IEEE754 format");		\
+  inline void encode(type v, ::ceph::bufferlist& bl, uint64_t features=0) { \
+    ceph_##etype e;							\
+    e = *reinterpret_cast<itype *>(&v);					\
+    ::ceph::encode_raw(e, bl);						\
+  }									\
+  inline void decode(type &v, ::ceph::bufferlist::const_iterator& p) {	\
+    ceph_##etype e;							\
+    ::ceph::decode_raw(e, p);						\
+    *reinterpret_cast<itype *>(&v) = e;					\
+  }
+
+WRITE_FLTTYPE_ENCODER(float, uint32_t, le32)
+WRITE_FLTTYPE_ENCODER(double, uint64_t, le64)
+
+// see denc.h for ENCODE_DUMP_PATH discussion and definition.
+#ifdef ENCODE_DUMP_PATH
+# define ENCODE_DUMP_PRE()			\
+  unsigned pre_off = bl.length()
+# define ENCODE_DUMP_POST(cl)						\
+  do {									\
+    static int i = 0;							\
+    i++;								\
+    int bits = 0;							\
+    for (unsigned t = i; t; bits++)					\
+      t &= t - 1;							\
+    if (bits > 2)							\
+      break;								\
+    char fn[PATH_MAX];							\
+    snprintf(fn, sizeof(fn), ENCODE_STRINGIFY(ENCODE_DUMP_PATH) "/%s__%d.%x", #cl, getpid(), i++); \
+    int fd = ::open(fn, O_WRONLY|O_TRUNC|O_CREAT|O_CLOEXEC|O_BINARY, 0644);		\
+    if (fd >= 0) {							\
+      ::ceph::bufferlist sub;						\
+      sub.substr_of(bl, pre_off, bl.length() - pre_off);		\
+      sub.write_fd(fd);							\
+      ::close(fd);							\
+    }									\
+  } while (0)
+#else
+# define ENCODE_DUMP_PRE()
+# define ENCODE_DUMP_POST(cl)
+#endif
+
+
+#define WRITE_CLASS_ENCODER(cl)						\
+  inline void encode(const cl& c, ::ceph::buffer::list &bl, uint64_t features=0) { \
+    ENCODE_DUMP_PRE(); c.encode(bl); ENCODE_DUMP_POST(cl); }		\
+  inline void decode(cl &c, ::ceph::bufferlist::const_iterator &p) { c.decode(p); }
+
+#define WRITE_CLASS_MEMBER_ENCODER(cl)					\
+  inline void encode(const cl &c, ::ceph::bufferlist &bl) const {	\
+    ENCODE_DUMP_PRE(); c.encode(bl); ENCODE_DUMP_POST(cl); }		\
+  inline void decode(cl &c, ::ceph::bufferlist::const_iterator &p) { c.decode(p); }
+
+#define WRITE_CLASS_ENCODER_FEATURES(cl)				\
+  inline void encode(const cl &c, ::ceph::bufferlist &bl, uint64_t features) { \
+    ENCODE_DUMP_PRE(); c.encode(bl, features); ENCODE_DUMP_POST(cl); }	\
+  inline void decode(cl &c, ::ceph::bufferlist::const_iterator &p) { c.decode(p); }
+
+#define WRITE_CLASS_ENCODER_OPTIONAL_FEATURES(cl)				\
+  inline void encode(const cl &c, ::ceph::bufferlist &bl, uint64_t features = 0) { \
+    ENCODE_DUMP_PRE(); c.encode(bl, features); ENCODE_DUMP_POST(cl); }	\
+  inline void decode(cl &c, ::ceph::bufferlist::const_iterator &p) { c.decode(p); }
+
+
+// string
+inline void encode(std::string_view s, bufferlist& bl, uint64_t features=0)
+{
+  __u32 len = s.length();
+  encode(len, bl);
+  if (len)
+    bl.append(s.data(), len);
+}
+inline void encode(const std::string& s, bufferlist& bl, uint64_t features=0)
+{
+  return encode(std::string_view(s), bl, features);
+}
+inline void decode(std::string& s, bufferlist::const_iterator& p)
+{
+  __u32 len;
+  decode(len, p);
+  s.clear();
+  p.copy(len, s);
+}
+
+inline void encode_nohead(std::string_view s, bufferlist& bl)
+{
+  bl.append(s.data(), s.length());
+}
+inline void encode_nohead(const std::string& s, bufferlist& bl)
+{
+  encode_nohead(std::string_view(s), bl);
+}
+inline void decode_nohead(int len, std::string& s, bufferlist::const_iterator& p)
+{
+  s.clear();
+  p.copy(len, s);
+}
+
+// const char* (encode only, string compatible)
+inline void encode(const char *s, bufferlist& bl) 
+{
+  encode(std::string_view(s, strlen(s)), bl);
+}
+
+// opaque byte vectors
+inline void encode(std::vector<uint8_t>& v, bufferlist& bl)
+{
+  uint32_t len = v.size();
+  encode(len, bl);
+  if (len)
+    bl.append((char *)v.data(), len);
+}
+
+inline void decode(std::vector<uint8_t>& v, bufferlist::const_iterator& p)
+{
+  uint32_t len;
+
+  decode(len, p);
+  v.resize(len);
+  p.copy(len, (char *)v.data());
+}
+
+// -----------------------------
+// buffers
+
+// bufferptr (encapsulated)
+inline void encode(const buffer::ptr& bp, bufferlist& bl) 
+{
+  __u32 len = bp.length();
+  encode(len, bl);
+  if (len)
+    bl.append(bp);
+}
+inline void decode(buffer::ptr& bp, bufferlist::const_iterator& p)
+{
+  __u32 len;
+  decode(len, p);
+
+  bufferlist s;
+  p.copy(len, s);
+
+  if (len) {
+    if (s.get_num_buffers() == 1)
+      bp = s.front();
+    else
+      bp = buffer::copy(s.c_str(), s.length());
+  }
+}
+
+// bufferlist (encapsulated)
+inline void encode(const bufferlist& s, bufferlist& bl) 
+{
+  __u32 len = s.length();
+  encode(len, bl);
+  bl.append(s);
+}
+inline void encode_destructively(bufferlist& s, bufferlist& bl) 
+{
+  __u32 len = s.length();
+  encode(len, bl);
+  bl.claim_append(s);
+}
+inline void decode(bufferlist& s, bufferlist::const_iterator& p)
+{
+  __u32 len;
+  decode(len, p);
+  s.clear();
+  p.copy(len, s);
+}
+
+inline void encode_nohead(const bufferlist& s, bufferlist& bl) 
+{
+  bl.append(s);
+}
+inline void decode_nohead(int len, bufferlist& s, bufferlist::const_iterator& p)
+{
+  s.clear();
+  p.copy(len, s);
+}
+
+// Time, since the templates are defined in std::chrono
+
+template<typename Clock, typename Duration,
+         typename std::enable_if_t<converts_to_timespec_v<Clock>>* = nullptr>
+void encode(const std::chrono::time_point<Clock, Duration>& t,
+	    ceph::bufferlist &bl) {
+  auto ts = Clock::to_timespec(t);
+  // A 32 bit count of seconds causes me vast unhappiness.
+  uint32_t s = ts.tv_sec;
+  uint32_t ns = ts.tv_nsec;
+  encode(s, bl);
+  encode(ns, bl);
+}
+
+template<typename Clock, typename Duration,
+         typename std::enable_if_t<converts_to_timespec_v<Clock>>* = nullptr>
+void decode(std::chrono::time_point<Clock, Duration>& t,
+	    bufferlist::const_iterator& p) {
+  uint32_t s;
+  uint32_t ns;
+  decode(s, p);
+  decode(ns, p);
+  struct timespec ts = {
+    static_cast<time_t>(s),
+    static_cast<long int>(ns)};
+
+  t = Clock::from_timespec(ts);
+}
+
+template<typename Rep, typename Period,
+         typename std::enable_if_t<std::is_integral_v<Rep>>* = nullptr>
+void encode(const std::chrono::duration<Rep, Period>& d,
+	    ceph::bufferlist &bl) {
+  using namespace std::chrono;
+  int32_t s = duration_cast<seconds>(d).count();
+  int32_t ns = (duration_cast<nanoseconds>(d) % seconds(1)).count();
+  encode(s, bl);
+  encode(ns, bl);
+}
+
+template<typename Rep, typename Period,
+         typename std::enable_if_t<std::is_integral_v<Rep>>* = nullptr>
+void decode(std::chrono::duration<Rep, Period>& d,
+	    bufferlist::const_iterator& p) {
+  int32_t s;
+  int32_t ns;
+  decode(s, p);
+  decode(ns, p);
+  d = std::chrono::seconds(s) + std::chrono::nanoseconds(ns);
+}
+
+// -----------------------------
+// STL container types
+
+template<typename T>
+inline void encode(const boost::optional<T> &p, bufferlist &bl);
+template<typename T>
+inline void decode(boost::optional<T> &p, bufferlist::const_iterator &bp);
+template<typename T>
+inline void encode(const std::optional<T> &p, bufferlist &bl);
+template<typename T>
+inline void decode(std::optional<T> &p, bufferlist::const_iterator &bp);
+template<class A, class B, class C>
+inline void encode(const boost::tuple<A, B, C> &t, bufferlist& bl);
+template<class A, class B, class C>
+inline void decode(boost::tuple<A, B, C> &t, bufferlist::const_iterator &bp);
+template<class A, class B,
+	 typename a_traits=denc_traits<A>, typename b_traits=denc_traits<B>>
+inline std::enable_if_t<!a_traits::supported || !b_traits::supported>
+encode(const std::pair<A,B> &p, bufferlist &bl, uint64_t features);
+template<class A, class B,
+	 typename a_traits=denc_traits<A>, typename b_traits=denc_traits<B>>
+inline std::enable_if_t<!a_traits::supported ||
+			!b_traits::supported>
+encode(const std::pair<A,B> &p, bufferlist &bl);
+template<class A, class B,
+	 typename a_traits=denc_traits<A>, typename b_traits=denc_traits<B>>
+inline std::enable_if_t<!a_traits::supported ||
+			!b_traits::supported>
+decode(std::pair<A,B> &pa, bufferlist::const_iterator &p);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::list<T, Alloc>& ls, bufferlist& bl);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::list<T,Alloc>& ls, bufferlist& bl, uint64_t features);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode(std::list<T,Alloc>& ls, bufferlist::const_iterator& p);
+template<class T, class Alloc>
+inline void encode(const std::list<std::shared_ptr<T>, Alloc>& ls,
+		   bufferlist& bl);
+template<class T, class Alloc>
+inline void encode(const std::list<std::shared_ptr<T>, Alloc>& ls,
+		   bufferlist& bl, uint64_t features);
+template<class T, class Alloc>
+inline void decode(std::list<std::shared_ptr<T>, Alloc>& ls,
+		   bufferlist::const_iterator& p);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::set<T,Comp,Alloc>& s, bufferlist& bl);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode(std::set<T,Comp,Alloc>& s, bufferlist::const_iterator& p);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode_nohead(const std::set<T,Comp,Alloc>& s, bufferlist& bl);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode_nohead(int len, std::set<T,Comp,Alloc>& s, bufferlist::iterator& p);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const boost::container::flat_set<T, Comp, Alloc>& s, bufferlist& bl);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode(boost::container::flat_set<T, Comp, Alloc>& s, bufferlist::const_iterator& p);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode_nohead(const boost::container::flat_set<T, Comp, Alloc>& s,
+	      bufferlist& bl);
+template<class T, class Comp, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode_nohead(int len, boost::container::flat_set<T, Comp, Alloc>& s,
+	      bufferlist::iterator& p);
+template<class T, class Comp, class Alloc>
+inline void encode(const std::multiset<T,Comp,Alloc>& s, bufferlist& bl);
+template<class T, class Comp, class Alloc>
+inline void decode(std::multiset<T,Comp,Alloc>& s, bufferlist::const_iterator& p);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::vector<T,Alloc>& v, bufferlist& bl, uint64_t features);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::vector<T,Alloc>& v, bufferlist& bl);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode(std::vector<T,Alloc>& v, bufferlist::const_iterator& p);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode_nohead(const std::vector<T,Alloc>& v, bufferlist& bl);
+template<class T, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode_nohead(int len, std::vector<T,Alloc>& v, bufferlist::const_iterator& p);
+template<class T,class Alloc>
+inline void encode(const std::vector<std::shared_ptr<T>,Alloc>& v,
+		   bufferlist& bl,
+		   uint64_t features);
+template<class T, class Alloc>
+inline void encode(const std::vector<std::shared_ptr<T>,Alloc>& v,
+		   bufferlist& bl);
+template<class T, class Alloc>
+inline void decode(std::vector<std::shared_ptr<T>,Alloc>& v,
+		   bufferlist::const_iterator& p);
+// small_vector
+template<class T, std::size_t N, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const boost::container::small_vector<T,N,Alloc>& v, bufferlist& bl, uint64_t features);
+template<class T, std::size_t N, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const boost::container::small_vector<T,N,Alloc>& v, bufferlist& bl);
+template<class T, std::size_t N, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode(boost::container::small_vector<T,N,Alloc>& v, bufferlist::const_iterator& p);
+template<class T, std::size_t N, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode_nohead(const boost::container::small_vector<T,N,Alloc>& v, bufferlist& bl);
+template<class T, std::size_t N, class Alloc, typename traits=denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode_nohead(int len, boost::container::small_vector<T,N,Alloc>& v, bufferlist::const_iterator& p);
+// std::map
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported ||
+			!u_traits::supported>
+encode(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl, uint64_t features);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+decode(std::map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class U, class Comp, class Alloc>
+inline void decode_noclear(std::map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode_nohead(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode_nohead(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl, uint64_t features);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+decode_nohead(int n, std::map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+  inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode(const boost::container::flat_map<T,U,Comp,Alloc>& m, bufferlist& bl);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode(const boost::container::flat_map<T,U,Comp,Alloc>& m, bufferlist& bl,
+       uint64_t features);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+decode(boost::container::flat_map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class U, class Comp, class Alloc>
+inline void decode_noclear(boost::container::flat_map<T,U,Comp,Alloc>& m,
+			   bufferlist::const_iterator& p);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode_nohead(const boost::container::flat_map<T,U,Comp,Alloc>& m,
+	      bufferlist& bl);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+encode_nohead(const boost::container::flat_map<T,U,Comp,Alloc>& m,
+	      bufferlist& bl, uint64_t features);
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits=denc_traits<T>, typename u_traits=denc_traits<U>>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+decode_nohead(int n, boost::container::flat_map<T,U,Comp,Alloc>& m,
+	      bufferlist::const_iterator& p);
+template<class T, class U, class Comp, class Alloc>
+inline void encode(const std::multimap<T,U,Comp,Alloc>& m, bufferlist& bl);
+template<class T, class U, class Comp, class Alloc>
+inline void decode(std::multimap<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class U, class Hash, class Pred, class Alloc>
+inline void encode(const unordered_map<T,U,Hash,Pred,Alloc>& m, bufferlist& bl,
+		   uint64_t features);
+template<class T, class U, class Hash, class Pred, class Alloc>
+inline void encode(const unordered_map<T,U,Hash,Pred,Alloc>& m, bufferlist& bl);
+template<class T, class U, class Hash, class Pred, class Alloc>
+inline void decode(unordered_map<T,U,Hash,Pred,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class Hash, class Pred, class Alloc>
+inline void encode(const ceph::unordered_set<T,Hash,Pred,Alloc>& m, bufferlist& bl);
+template<class T, class Hash, class Pred, class Alloc>
+inline void decode(ceph::unordered_set<T,Hash,Pred,Alloc>& m, bufferlist::const_iterator& p);
+template<class T, class Alloc>
+inline void encode(const std::deque<T,Alloc>& ls, bufferlist& bl, uint64_t features);
+template<class T, class Alloc>
+inline void encode(const std::deque<T,Alloc>& ls, bufferlist& bl);
+template<class T, class Alloc>
+inline void decode(std::deque<T,Alloc>& ls, bufferlist::const_iterator& p);
+template<class T, size_t N, typename traits = denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::array<T, N>& v, bufferlist& bl, uint64_t features);
+template<class T, size_t N, typename traits = denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+encode(const std::array<T, N>& v, bufferlist& bl);
+template<class T, size_t N, typename traits = denc_traits<T>>
+inline std::enable_if_t<!traits::supported>
+decode(std::array<T, N>& v, bufferlist::const_iterator& p);
+
+// full bl decoder
+template<class T>
+inline void decode(T &o, const bufferlist& bl)
+{
+  auto p = bl.begin();
+  decode(o, p);
+  ceph_assert(p.end());
+}
+
+// boost optional
+template<typename T>
+inline void encode(const boost::optional<T> &p, bufferlist &bl)
+{
+  __u8 present = static_cast<bool>(p);
+  encode(present, bl);
+  if (p)
+    encode(p.get(), bl);
+}
+
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuninitialized"
+template<typename T>
+inline void decode(boost::optional<T> &p, bufferlist::const_iterator &bp)
+{
+  __u8 present;
+  decode(present, bp);
+  if (present) {
+    p = T{};
+    decode(p.get(), bp);
+  } else {
+    p = boost::none;
+  }
+}
+#pragma GCC diagnostic pop
+#pragma GCC diagnostic warning "-Wpragmas"
+
+// std optional
+template<typename T>
+inline void encode(const std::optional<T> &p, bufferlist &bl)
+{
+  __u8 present = static_cast<bool>(p);
+  encode(present, bl);
+  if (p)
+    encode(*p, bl);
+}
+
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuninitialized"
+template<typename T>
+inline void decode(std::optional<T> &p, bufferlist::const_iterator &bp)
+{
+  __u8 present;
+  decode(present, bp);
+  if (present) {
+    p = T{};
+    decode(*p, bp);
+  } else {
+    p = std::nullopt;
+  }
+}
+
+// std::tuple
+template<typename... Ts>
+inline void encode(const std::tuple<Ts...> &t, bufferlist& bl)
+{
+  ceph::for_each(t, [&bl](const auto& e) {
+      encode(e, bl);
+    });
+}
+template<typename... Ts>
+inline void decode(std::tuple<Ts...> &t, bufferlist::const_iterator &bp)
+{
+  ceph::for_each(t, [&bp](auto& e) {
+      decode(e, bp);
+    });
+}
+
+//triple boost::tuple
+template<class A, class B, class C>
+inline void encode(const boost::tuple<A, B, C> &t, bufferlist& bl)
+{
+  encode(boost::get<0>(t), bl);
+  encode(boost::get<1>(t), bl);
+  encode(boost::get<2>(t), bl);
+}
+template<class A, class B, class C>
+inline void decode(boost::tuple<A, B, C> &t, bufferlist::const_iterator &bp)
+{
+  decode(boost::get<0>(t), bp);
+  decode(boost::get<1>(t), bp);
+  decode(boost::get<2>(t), bp);
+}
+
+// std::pair<A,B>
+template<class A, class B,
+	 typename a_traits, typename b_traits>
+inline std::enable_if_t<!a_traits::supported || !b_traits::supported>
+  encode(const std::pair<A,B> &p, bufferlist &bl, uint64_t features)
+{
+  encode(p.first, bl, features);
+  encode(p.second, bl, features);
+}
+template<class A, class B,
+	 typename a_traits, typename b_traits>
+inline std::enable_if_t<!a_traits::supported ||
+			!b_traits::supported>
+  encode(const std::pair<A,B> &p, bufferlist &bl)
+{
+  encode(p.first, bl);
+  encode(p.second, bl);
+}
+template<class A, class B, typename a_traits, typename b_traits>
+inline std::enable_if_t<!a_traits::supported ||
+			!b_traits::supported>
+  decode(std::pair<A,B> &pa, bufferlist::const_iterator &p)
+{
+  decode(pa.first, p);
+  decode(pa.second, p);
+}
+
+// std::list<T>
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const std::list<T, Alloc>& ls, bufferlist& bl)
+{
+  __u32 n = (__u32)(ls.size());  // c++11 std::list::size() is O(1)
+  encode(n, bl);
+  for (auto p = ls.begin(); p != ls.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const std::list<T,Alloc>& ls, bufferlist& bl, uint64_t features)
+{
+  using counter_encode_t = ceph_le32;
+  unsigned n = 0;
+  auto filler = bl.append_hole(sizeof(counter_encode_t));
+  for (const auto& item : ls) {
+    // we count on our own because of buggy std::list::size() implementation
+    // which doesn't follow the O(1) complexity constraint C++11 has brought.
+    ++n;
+    encode(item, bl, features);
+  }
+  counter_encode_t en;
+  en = n;
+  filler.copy_in(sizeof(en), reinterpret_cast<char*>(&en));
+}
+
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode(std::list<T,Alloc>& ls, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  ls.clear();
+  while (n--) {
+    ls.emplace_back();
+    decode(ls.back(), p);
+  }
+}
+
+// std::list<std::shared_ptr<T>>
+template<class T, class Alloc>
+inline void encode(const std::list<std::shared_ptr<T>, Alloc>& ls,
+		   bufferlist& bl)
+{
+  __u32 n = (__u32)(ls.size());  // c++11 std::list::size() is O(1)
+  encode(n, bl);
+  for (const auto& ref : ls) {
+    encode(*ref, bl);
+  }
+}
+template<class T, class Alloc>
+inline void encode(const std::list<std::shared_ptr<T>, Alloc>& ls,
+		   bufferlist& bl, uint64_t features)
+{
+  __u32 n = (__u32)(ls.size());  // c++11 std::list::size() is O(1)
+  encode(n, bl);
+  for (const auto& ref : ls) {
+    encode(*ref, bl, features);
+  }
+}
+template<class T, class Alloc>
+inline void decode(std::list<std::shared_ptr<T>, Alloc>& ls,
+		   bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  ls.clear();
+  while (n--) {
+    auto ref = std::make_shared<T>();
+    decode(*ref, p);
+    ls.emplace_back(std::move(ref));
+  }
+}
+
+// std::set<T>
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const std::set<T,Comp,Alloc>& s, bufferlist& bl)
+{
+  __u32 n = (__u32)(s.size());
+  encode(n, bl);
+  for (auto p = s.begin(); p != s.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode(std::set<T,Comp,Alloc>& s, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  s.clear();
+  while (n--) {
+    T v;
+    decode(v, p);
+    s.insert(v);
+  }
+}
+
+template<class T, class Comp, class Alloc, typename traits>
+inline typename std::enable_if<!traits::supported>::type
+  encode_nohead(const std::set<T,Comp,Alloc>& s, bufferlist& bl)
+{
+  for (auto p = s.begin(); p != s.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode_nohead(int len, std::set<T,Comp,Alloc>& s, bufferlist::const_iterator& p)
+{
+  for (int i=0; i<len; i++) {
+    T v;
+    decode(v, p);
+    s.insert(v);
+  }
+}
+
+// boost::container::flat_set<T>
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+encode(const boost::container::flat_set<T, Comp, Alloc>& s, bufferlist& bl)
+{
+  __u32 n = (__u32)(s.size());
+  encode(n, bl);
+  for (const auto& e : s)
+    encode(e, bl);
+}
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+decode(boost::container::flat_set<T, Comp, Alloc>& s, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  s.clear();
+  s.reserve(n);
+  while (n--) {
+    T v;
+    decode(v, p);
+    s.insert(v);
+  }
+}
+
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+encode_nohead(const boost::container::flat_set<T, Comp, Alloc>& s,
+	      bufferlist& bl)
+{
+  for (const auto& e : s)
+    encode(e, bl);
+}
+template<class T, class Comp, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+decode_nohead(int len, boost::container::flat_set<T, Comp, Alloc>& s,
+	      bufferlist::iterator& p)
+{
+  s.reserve(len);
+  for (int i=0; i<len; i++) {
+    T v;
+    decode(v, p);
+    s.insert(v);
+  }
+}
+
+// multiset
+template<class T, class Comp, class Alloc>
+inline void encode(const std::multiset<T,Comp,Alloc>& s, bufferlist& bl)
+{
+  __u32 n = (__u32)(s.size());
+  encode(n, bl);
+  for (auto p = s.begin(); p != s.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Comp, class Alloc>
+inline void decode(std::multiset<T,Comp,Alloc>& s, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  s.clear();
+  while (n--) {
+    T v;
+    decode(v, p);
+    s.insert(v);
+  }
+}
+
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const std::vector<T,Alloc>& v, bufferlist& bl, uint64_t features)
+{
+  __u32 n = (__u32)(v.size());
+  encode(n, bl);
+  for (auto p = v.begin(); p != v.end(); ++p)
+    encode(*p, bl, features);
+}
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const std::vector<T,Alloc>& v, bufferlist& bl)
+{
+  __u32 n = (__u32)(v.size());
+  encode(n, bl);
+  for (auto p = v.begin(); p != v.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode(std::vector<T,Alloc>& v, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  v.resize(n);
+  for (__u32 i=0; i<n; i++) 
+    decode(v[i], p);
+}
+
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode_nohead(const std::vector<T,Alloc>& v, bufferlist& bl)
+{
+  for (auto p = v.begin(); p != v.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode_nohead(int len, std::vector<T,Alloc>& v, bufferlist::const_iterator& p)
+{
+  v.resize(len);
+  for (__u32 i=0; i<v.size(); i++) 
+    decode(v[i], p);
+}
+
+// small vector
+template<class T, std::size_t N, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const boost::container::small_vector<T,N,Alloc>& v, bufferlist& bl, uint64_t features)
+{
+  __u32 n = (__u32)(v.size());
+  encode(n, bl);
+  for (const auto& i : v)
+    encode(i, bl, features);
+}
+template<class T, std::size_t N, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode(const boost::container::small_vector<T,N,Alloc>& v, bufferlist& bl)
+{
+  __u32 n = (__u32)(v.size());
+  encode(n, bl);
+  for (const auto& i : v)
+    encode(i, bl);
+}
+template<class T, std::size_t N, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode(boost::container::small_vector<T,N,Alloc>& v, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  v.resize(n);
+  for (auto& i : v)
+    decode(i, p);
+}
+
+template<class T, std::size_t N, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  encode_nohead(const boost::container::small_vector<T,N,Alloc>& v, bufferlist& bl)
+{
+  for (const auto& i : v)
+    encode(i, bl);
+}
+template<class T, std::size_t N, class Alloc, typename traits>
+inline std::enable_if_t<!traits::supported>
+  decode_nohead(int len, boost::container::small_vector<T,N,Alloc>& v, bufferlist::const_iterator& p)
+{
+  v.resize(len);
+  for (auto& i : v)
+    decode(i, p);
+}
+
+
+// vector (shared_ptr)
+template<class T,class Alloc>
+inline void encode(const std::vector<std::shared_ptr<T>,Alloc>& v,
+		   bufferlist& bl,
+		   uint64_t features)
+{
+  __u32 n = (__u32)(v.size());
+  encode(n, bl);
+  for (const auto& ref : v) {
+    if (ref)
+      encode(*ref, bl, features);
+    else
+      encode(T(), bl, features);
+  }
+}
+template<class T, class Alloc>
+inline void encode(const std::vector<std::shared_ptr<T>,Alloc>& v,
+		   bufferlist& bl)
+{
+  __u32 n = (__u32)(v.size());
+  encode(n, bl);
+  for (const auto& ref : v) {
+    if (ref)
+      encode(*ref, bl);
+    else
+      encode(T(), bl);
+  }
+}
+template<class T, class Alloc>
+inline void decode(std::vector<std::shared_ptr<T>,Alloc>& v,
+		   bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  v.clear();
+  v.reserve(n);
+  while (n--) {
+    auto ref = std::make_shared<T>();
+    decode(*ref, p);
+    v.emplace_back(std::move(ref));
+  }
+}
+
+// map
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported ||
+			!u_traits::supported>
+  encode(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl);
+    encode(p->second, bl);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl, uint64_t features)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl, features);
+    encode(p->second, bl, features);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  decode(std::map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  m.clear();
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+template<class T, class U, class Comp, class Alloc>
+inline void decode_noclear(std::map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode_nohead(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl)
+{
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl);
+    encode(p->second, bl);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode_nohead(const std::map<T,U,Comp,Alloc>& m, bufferlist& bl, uint64_t features)
+{
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl, features);
+    encode(p->second, bl, features);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  decode_nohead(int n, std::map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p)
+{
+  m.clear();
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+
+// boost::container::flat-map
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+  inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode(const boost::container::flat_map<T,U,Comp,Alloc>& m, bufferlist& bl)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (typename boost::container::flat_map<T,U,Comp>::const_iterator p
+	 = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl);
+    encode(p->second, bl);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+  inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode(const boost::container::flat_map<T,U,Comp,Alloc>& m, bufferlist& bl,
+	 uint64_t features)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl, features);
+    encode(p->second, bl, features);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+  inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  decode(boost::container::flat_map<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  m.clear();
+  m.reserve(n);
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+template<class T, class U, class Comp, class Alloc>
+inline void decode_noclear(boost::container::flat_map<T,U,Comp,Alloc>& m,
+			   bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  m.reserve(m.size() + n);
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+  inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode_nohead(const boost::container::flat_map<T,U,Comp,Alloc>& m,
+		bufferlist& bl)
+{
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl);
+    encode(p->second, bl);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+  inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  encode_nohead(const boost::container::flat_map<T,U,Comp,Alloc>& m,
+		bufferlist& bl, uint64_t features)
+{
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl, features);
+    encode(p->second, bl, features);
+  }
+}
+template<class T, class U, class Comp, class Alloc,
+	 typename t_traits, typename u_traits>
+inline std::enable_if_t<!t_traits::supported || !u_traits::supported>
+  decode_nohead(int n, boost::container::flat_map<T,U,Comp,Alloc>& m,
+		bufferlist::const_iterator& p)
+{
+  m.clear();
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+
+// multimap
+template<class T, class U, class Comp, class Alloc>
+inline void encode(const std::multimap<T,U,Comp,Alloc>& m, bufferlist& bl)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl);
+    encode(p->second, bl);
+  }
+}
+template<class T, class U, class Comp, class Alloc>
+inline void decode(std::multimap<T,U,Comp,Alloc>& m, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  m.clear();
+  while (n--) {
+    typename std::pair<T,U> tu = std::pair<T,U>();
+    decode(tu.first, p);
+    typename std::multimap<T,U,Comp,Alloc>::iterator it = m.insert(tu);
+    decode(it->second, p);
+  }
+}
+
+// ceph::unordered_map
+template<class T, class U, class Hash, class Pred, class Alloc>
+inline void encode(const unordered_map<T,U,Hash,Pred,Alloc>& m, bufferlist& bl,
+		   uint64_t features)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl, features);
+    encode(p->second, bl, features);
+  }
+}
+template<class T, class U, class Hash, class Pred, class Alloc>
+inline void encode(const unordered_map<T,U,Hash,Pred,Alloc>& m, bufferlist& bl)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p) {
+    encode(p->first, bl);
+    encode(p->second, bl);
+  }
+}
+template<class T, class U, class Hash, class Pred, class Alloc>
+inline void decode(unordered_map<T,U,Hash,Pred,Alloc>& m, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  m.clear();
+  while (n--) {
+    T k;
+    decode(k, p);
+    decode(m[k], p);
+  }
+}
+
+// ceph::unordered_set
+template<class T, class Hash, class Pred, class Alloc>
+inline void encode(const ceph::unordered_set<T,Hash,Pred,Alloc>& m, bufferlist& bl)
+{
+  __u32 n = (__u32)(m.size());
+  encode(n, bl);
+  for (auto p = m.begin(); p != m.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Hash, class Pred, class Alloc>
+inline void decode(ceph::unordered_set<T,Hash,Pred,Alloc>& m, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  m.clear();
+  while (n--) {
+    T k;
+    decode(k, p);
+    m.insert(k);
+  }
+}
+
+// deque
+template<class T, class Alloc>
+inline void encode(const std::deque<T,Alloc>& ls, bufferlist& bl, uint64_t features)
+{
+  __u32 n = ls.size();
+  encode(n, bl);
+  for (auto p = ls.begin(); p != ls.end(); ++p)
+    encode(*p, bl, features);
+}
+template<class T, class Alloc>
+inline void encode(const std::deque<T,Alloc>& ls, bufferlist& bl)
+{
+  __u32 n = ls.size();
+  encode(n, bl);
+  for (auto p = ls.begin(); p != ls.end(); ++p)
+    encode(*p, bl);
+}
+template<class T, class Alloc>
+inline void decode(std::deque<T,Alloc>& ls, bufferlist::const_iterator& p)
+{
+  __u32 n;
+  decode(n, p);
+  ls.clear();
+  while (n--) {
+    ls.emplace_back();
+    decode(ls.back(), p);
+  }
+}
+
+// std::array<T, N>
+template<class T, size_t N, typename traits>
+inline std::enable_if_t<!traits::supported>
+encode(const std::array<T, N>& v, bufferlist& bl, uint64_t features)
+{
+  for (const auto& e : v)
+    encode(e, bl, features);
+}
+template<class T, size_t N, typename traits>
+inline std::enable_if_t<!traits::supported>
+encode(const std::array<T, N>& v, bufferlist& bl)
+{
+  for (const auto& e : v)
+    encode(e, bl);
+}
+template<class T, size_t N, typename traits>
+inline std::enable_if_t<!traits::supported>
+decode(std::array<T, N>& v, bufferlist::const_iterator& p)
+{
+  for (auto& e : v)
+    decode(e, p);
+}
+}
+
+/*
+ * guards
+ */
+
+/**
+ * start encoding block
+ *
+ * @param v current (code) version of the encoding
+ * @param compat oldest code version that can decode it
+ * @param bl bufferlist to encode to
+ *
+ */
+#define ENCODE_START(v, compat, bl)			     \
+  __u8 struct_v = v;                                         \
+  __u8 struct_compat = compat;		                     \
+  ceph_le32 struct_len;				             \
+  auto filler = (bl).append_hole(sizeof(struct_v) +	     \
+    sizeof(struct_compat) + sizeof(struct_len));	     \
+  const auto starting_bl_len = (bl).length();		     \
+  using ::ceph::encode;					     \
+  do {
+
+/**
+ * finish encoding block
+ *
+ * @param bl bufferlist we were encoding to
+ * @param new_struct_compat struct-compat value to use
+ */
+#define ENCODE_FINISH_NEW_COMPAT(bl, new_struct_compat)      \
+  } while (false);                                           \
+  if (new_struct_compat) {                                   \
+    struct_compat = new_struct_compat;                       \
+  }                                                          \
+  struct_len = (bl).length() - starting_bl_len;              \
+  filler.copy_in(sizeof(struct_v), (char *)&struct_v);       \
+  filler.copy_in(sizeof(struct_compat),			     \
+    (char *)&struct_compat);				     \
+  filler.copy_in(sizeof(struct_len), (char *)&struct_len);
+
+#define ENCODE_FINISH(bl) ENCODE_FINISH_NEW_COMPAT(bl, 0)
+
+#define DECODE_ERR_OLDVERSION(func, v, compatv)					\
+  (std::string(func) + " no longer understand old encoding version " #v " < " + std::to_string(compatv))
+
+#define DECODE_ERR_PAST(func) \
+  (std::string(func) + " decode past end of struct encoding")
+
+/**
+ * check for very old encoding
+ *
+ * If the encoded data is older than oldestv, raise an exception.
+ *
+ * @param oldestv oldest version of the code we can successfully decode.
+ */
+#define DECODE_OLDEST(oldestv)						\
+  if (struct_v < oldestv)						\
+    throw ::ceph::buffer::malformed_input(DECODE_ERR_OLDVERSION(__PRETTY_FUNCTION__, v, oldestv)); 
+
+/**
+ * start a decoding block
+ *
+ * @param v current version of the encoding that the code supports/encodes
+ * @param bl bufferlist::iterator for the encoded data
+ */
+#define DECODE_START(v, bl)						\
+  __u8 struct_v, struct_compat;						\
+  using ::ceph::decode;							\
+  decode(struct_v, bl);						\
+  decode(struct_compat, bl);						\
+  if (v < struct_compat)						\
+    throw ::ceph::buffer::malformed_input(DECODE_ERR_OLDVERSION(__PRETTY_FUNCTION__, v, struct_compat)); \
+  __u32 struct_len;							\
+  decode(struct_len, bl);						\
+  if (struct_len > bl.get_remaining())					\
+    throw ::ceph::buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
+  unsigned struct_end = bl.get_off() + struct_len;			\
+  do {
+
+/* BEWARE: any change to this macro MUST be also reflected in the duplicative
+ * DECODE_START_LEGACY_COMPAT_LEN! */
+#define __DECODE_START_LEGACY_COMPAT_LEN(v, compatv, lenv, skip_v, bl)	\
+  using ::ceph::decode;							\
+  __u8 struct_v;							\
+  decode(struct_v, bl);						\
+  if (struct_v >= compatv) {						\
+    __u8 struct_compat;							\
+    decode(struct_compat, bl);					\
+    if (v < struct_compat)						\
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_OLDVERSION(__PRETTY_FUNCTION__, v, struct_compat)); \
+  } else if (skip_v) {							\
+    if (bl.get_remaining() < skip_v)					\
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
+    bl +=  skip_v;							\
+  }									\
+  unsigned struct_end = 0;						\
+  if (struct_v >= lenv) {						\
+    __u32 struct_len;							\
+    decode(struct_len, bl);						\
+    if (struct_len > bl.get_remaining())				\
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
+    struct_end = bl.get_off() + struct_len;				\
+  }									\
+  do {
+
+/**
+ * start a decoding block with legacy support for older encoding schemes
+ *
+ * The old encoding schemes has a __u8 struct_v only, or lacked either
+ * the compat version or length.  Skip those fields conditionally.
+ *
+ * Most of the time, v, compatv, and lenv will all match the version
+ * where the structure was switched over to the new macros.
+ *
+ * @param v current version of the encoding that the code supports/encodes
+ * @param compatv oldest version that includes a __u8 compat version field
+ * @param lenv oldest version that includes a __u32 length wrapper
+ * @param bl bufferlist::iterator containing the encoded data
+ */
+
+/* BEWARE: this is duplication of __DECODE_START_LEGACY_COMPAT_LEN which
+ * MUST be changed altogether. For the rationale behind code duplication,
+ * please `git blame` and refer to the commit message. */
+#define DECODE_START_LEGACY_COMPAT_LEN(v, compatv, lenv, bl)		\
+  using ::ceph::decode;							\
+  __u8 struct_v;							\
+  decode(struct_v, bl);							\
+  if (struct_v >= compatv) {						\
+    __u8 struct_compat;							\
+    decode(struct_compat, bl);						\
+    if (v < struct_compat)						\
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_OLDVERSION(	\
+	__PRETTY_FUNCTION__, v, struct_compat));			\
+  }									\
+  unsigned struct_end = 0;						\
+  if (struct_v >= lenv) {						\
+    __u32 struct_len;							\
+    decode(struct_len, bl);						\
+    if (struct_len > bl.get_remaining())				\
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
+    struct_end = bl.get_off() + struct_len;				\
+  }									\
+  do {
+
+/**
+ * start a decoding block with legacy support for older encoding schemes
+ *
+ * This version of the macro assumes the legacy encoding had a 32 bit
+ * version
+ *
+ * The old encoding schemes has a __u8 struct_v only, or lacked either
+ * the compat version or length.  Skip those fields conditionally.
+ *
+ * Most of the time, v, compatv, and lenv will all match the version
+ * where the structure was switched over to the new macros.
+ *
+ * @param v current version of the encoding that the code supports/encodes
+ * @param compatv oldest version that includes a __u8 compat version field
+ * @param lenv oldest version that includes a __u32 length wrapper
+ * @param bl bufferlist::iterator containing the encoded data
+ */
+#define DECODE_START_LEGACY_COMPAT_LEN_32(v, compatv, lenv, bl)		\
+  __DECODE_START_LEGACY_COMPAT_LEN(v, compatv, lenv, 3u, bl)
+
+#define DECODE_START_LEGACY_COMPAT_LEN_16(v, compatv, lenv, bl)		\
+  __DECODE_START_LEGACY_COMPAT_LEN(v, compatv, lenv, 1u, bl)
+
+/**
+ * finish decode block
+ *
+ * @param bl bufferlist::iterator we were decoding from
+ */
+#define DECODE_FINISH(bl)						\
+  } while (false);							\
+  if (struct_end) {							\
+    if (bl.get_off() > struct_end)					\
+      throw ::ceph::buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
+    if (bl.get_off() < struct_end)					\
+      bl += struct_end - bl.get_off();					\
+  }
+
+namespace ceph {
+
+/*
+ * Encoders/decoders to read from current offset in a file handle and
+ * encode/decode the data according to argument types.
+ */
+inline ssize_t decode_file(int fd, std::string &str)
+{
+  bufferlist bl;
+  __u32 len = 0;
+  bl.read_fd(fd, sizeof(len));
+  decode(len, bl);
+  bl.read_fd(fd, len);
+  decode(str, bl);
+  return bl.length();
+}
+
+inline ssize_t decode_file(int fd, bufferptr &bp)
+{
+  bufferlist bl;
+  __u32 len = 0;
+  bl.read_fd(fd, sizeof(len));
+  decode(len, bl);
+  bl.read_fd(fd, len);
+  auto bli = std::cbegin(bl);
+
+  decode(bp, bli);
+  return bl.length();
+}
+}
+
+#endif