Split out marshall code into a new file

[invirt/third/libt4.git] / rpc / marshall.h

diff --git a/rpc/marshall.h b/rpc/marshall.h
index 27cebbb..98856e4 100644 (file)
--- a/rpc/marshall.h
+++ b/rpc/marshall.h
@@ -1,288 +1,438 @@
 #ifndef marshall_h
 #define marshall_h
 
 #ifndef marshall_h
 #define marshall_h
 

-#include <iostream>
-#include <sstream>
-#include <string>
-#include <vector>
-#include <map>
-#include <stdlib.h>
-#include <string.h>
+#include "types.h"
+#include <cstring>

 #include <cstddef>
 #include <cstddef>

-#include <inttypes.h>
-#include "lang/verify.h"
-
-struct req_header {
-       req_header(int x=0, int p=0, int c = 0, int s = 0, int xi = 0):
-               xid(x), proc(p), clt_nonce(c), srv_nonce(s), xid_rep(xi) {}
-       int xid;
-       int proc;
-       unsigned int clt_nonce;
-       unsigned int srv_nonce;
-       int xid_rep;
+#include <cinttypes>
+
+using proc_t = uint32_t;
+using status_t = int32_t;
+
+struct request_header {
+    request_header(int x=0, proc_t p=0, unsigned c=0, unsigned s=0, int xi=0) :
+        xid(x), proc(p), clt_nonce(c), srv_nonce(s), xid_rep(xi) {}
+    int xid;
+    proc_t proc;
+    unsigned int clt_nonce;
+    unsigned int srv_nonce;
+    int xid_rep;

 };
 
 struct reply_header {
 };
 
 struct reply_header {

-       reply_header(int x=0, int r=0): xid(x), ret(r) {}
-       int xid;
-       int ret;
+    reply_header(int x=0, int r=0): xid(x), ret(r) {}
+    int xid;
+    int ret;

 };
 
 };
 

+template<class T> inline T hton(T t);
+
+constexpr union { uint32_t i; uint8_t is_little_endian; } endianness{1};
+
+template<> inline uint8_t hton(uint8_t t) { return t; }
+template<> inline int8_t hton(int8_t t) { return t; }
+template<> inline uint16_t hton(uint16_t t) { return htons(t); }
+template<> inline int16_t hton(int16_t t) { return (int16_t)htons((uint16_t)t); }
+template<> inline uint32_t hton(uint32_t t) { return htonl(t); }
+template<> inline int32_t hton(int32_t t) { return (int32_t)htonl((uint32_t)t); }
+template<> inline uint64_t hton(uint64_t t) {
+    if (!endianness.is_little_endian)
+        return t;
+    return (uint64_t)htonl((uint32_t)(t >> 32)) | ((uint64_t)htonl((uint32_t)t) << 32);
+}
+template<> inline int64_t hton(int64_t t) { return (int64_t)hton((uint64_t)t); }
+template<> inline request_header hton(request_header h) { return {hton(h.xid), hton(h.proc), hton(h.clt_nonce), hton(h.srv_nonce), hton(h.xid_rep)}; }
+template<> inline reply_header hton(reply_header h) { return {hton(h.xid), hton(h.ret)}; }
+
+template <class T> inline T ntoh(T t) { return hton(t); }
+

 typedef int rpc_sz_t;
 
 typedef int rpc_sz_t;
 

-//size of initial buffer allocation 
+//size of initial buffer allocation

 #define DEFAULT_RPC_SZ 1024
 #define DEFAULT_RPC_SZ 1024

-#define RPC_HEADER_SZ (std::max(sizeof(req_header), sizeof(reply_header)) + sizeof(rpc_sz_t))
+#define RPC_HEADER_SZ (max(sizeof(request_header), sizeof(reply_header)) + sizeof(rpc_sz_t))

 
 

-struct pass {
-    template<typename... Args> inline pass(Args&&...) {}
-};
+struct pass { template <typename... Args> inline pass(Args&&...) {} };

 
 class marshall {
 
 class marshall {

-       private:
-               char *_buf;     // Base of the raw bytes buffer (dynamically readjusted)
-               int _capa;      // Capacity of the buffer
-               int _ind;       // Read/write head position
-
-       public:
-               marshall() {
-                       _buf = (char *) malloc(sizeof(char)*DEFAULT_RPC_SZ);
-                       VERIFY(_buf);
-                       _capa = DEFAULT_RPC_SZ;
-                       _ind = RPC_HEADER_SZ;
-               }
-
-        template <typename... Args> marshall(const Args&... args) : marshall() {
+    private:
+        char *buf_;     // Base of the raw bytes buffer (dynamically readjusted)
+        size_t capacity_;  // Capacity of the buffer
+        size_t index_;     // Read/write head position
+
+        inline void reserve(size_t n) {
+            if((index_+n) > capacity_){
+                capacity_ += max(capacity_, n);
+                VERIFY (buf_ != NULL);
+                buf_ = (char *)realloc(buf_, capacity_);
+                VERIFY(buf_);
+            }
+        }
+    public:
+        template <typename... Args>
+        marshall(const Args&... args) {
+            buf_ = (char *) malloc(sizeof(char)*DEFAULT_RPC_SZ);
+            VERIFY(buf_);
+            capacity_ = DEFAULT_RPC_SZ;
+            index_ = RPC_HEADER_SZ;

             (void)pass{(*this << args)...};
         }
 
             (void)pass{(*this << args)...};
         }
 

-               ~marshall() { 
-                       if (_buf) 
-                               free(_buf); 
-               }
-
-               int size() { return _ind;}
-               char *cstr() { return _buf;}
-
-               void rawbyte(unsigned char);
-               void rawbytes(const char *, int);
-
-               // Return the current content (excluding header) as a string
-               std::string get_content() { 
-                       return std::string(_buf+RPC_HEADER_SZ,_ind-RPC_HEADER_SZ);
-               }
-
-               // Return the current content (excluding header) as a string
-               std::string str() {
-                       return get_content();
-               }
-
-               void pack(int i);
-
-               void pack_req_header(const req_header &h) {
-                       int saved_sz = _ind;
-                       //leave the first 4-byte empty for channel to fill size of pdu
-                       _ind = sizeof(rpc_sz_t); 
-                       pack(h.xid);
-                       pack(h.proc);
-                       pack((int)h.clt_nonce);
-                       pack((int)h.srv_nonce);
-                       pack(h.xid_rep);
-                       _ind = saved_sz;
-               }
-
-               void pack_reply_header(const reply_header &h) {
-                       int saved_sz = _ind;
-                       //leave the first 4-byte empty for channel to fill size of pdu
-                       _ind = sizeof(rpc_sz_t); 
-                       pack(h.xid);
-                       pack(h.ret);
-                       _ind = saved_sz;
-               }
-
-               void take_buf(char **b, int *s) {
-                       *b = _buf;
-                       *s = _ind;
-                       _buf = NULL;
-                       _ind = 0;
-                       return;
-               }
+        ~marshall() {
+            if (buf_)
+                free(buf_);
+        }
+
+        size_t size() { return index_;}
+        char *cstr() { return buf_;}
+        const char *cstr() const { return buf_;}
+
+        void rawbyte(uint8_t x) {
+            reserve(1);
+            buf_[index_++] = (int8_t)x;
+        }
+
+        void rawbytes(const char *p, size_t n) {
+            reserve(n);
+            memcpy(buf_+index_, p, n);
+            index_ += n;
+        }
+
+        // Return the current content (excluding header) as a string
+        string get_content() {
+            return string(buf_+RPC_HEADER_SZ,index_-RPC_HEADER_SZ);
+        }
+
+        // Return the current content (excluding header) as a string
+        string str() {
+            return get_content();
+        }
+
+        void pack_req_header(const request_header &h);
+        void pack_reply_header(const reply_header &h);
+
+        void take_buf(char **b, size_t *s) {
+            *b = buf_;
+            *s = index_;
+            buf_ = NULL;
+            index_ = 0;
+            return;
+        }

 };
 
 marshall& operator<<(marshall &, bool);
 };
 
 marshall& operator<<(marshall &, bool);

-marshall& operator<<(marshall &, unsigned int);
-marshall& operator<<(marshall &, int);
-marshall& operator<<(marshall &, unsigned char);
-marshall& operator<<(marshall &, char);
-marshall& operator<<(marshall &, unsigned short);
-marshall& operator<<(marshall &, short);
-marshall& operator<<(marshall &, unsigned long long);
-marshall& operator<<(marshall &, const std::string &);
-
-template <class C> marshall &
-operator<<(marshall &m, std::vector<C> v)
-{
-       m << (unsigned int) v.size();
-       for(unsigned i = 0; i < v.size(); i++)
-               m << v[i];
-       return m;
+marshall& operator<<(marshall &, uint32_t);
+marshall& operator<<(marshall &, int32_t);
+marshall& operator<<(marshall &, uint8_t);
+marshall& operator<<(marshall &, int8_t);
+marshall& operator<<(marshall &, uint16_t);
+marshall& operator<<(marshall &, int16_t);
+marshall& operator<<(marshall &, uint64_t);
+marshall& operator<<(marshall &, const string &);
+
+template <class A> typename enable_if<is_iterable<A>::value, marshall>::type &
+operator<<(marshall &m, const A &x) {
+    m << (unsigned int) x.size();
+    for (const auto &a : x)
+        m << a;
+    return m;

 }
 
 template <class A, class B> marshall &
 }
 
 template <class A, class B> marshall &

-operator<<(marshall &m, const std::map<A,B> &d) {
-       typename std::map<A,B>::const_iterator i;
+operator<<(marshall &m, const pair<A,B> &d) {
+    return m << d.first << d.second;
+}

 
 

-       m << (unsigned int) d.size();
+template<typename E>
+using enum_type_t = typename enable_if<is_enum<E>::value, typename underlying_type<E>::type>::type;
+template<typename E> constexpr inline enum_type_t<E> from_enum(E e) noexcept { return (enum_type_t<E>)e; }
+template<typename E> constexpr inline E to_enum(enum_type_t<E> value) noexcept { return (E)value; }

 
 

-       for (i = d.begin(); i != d.end(); i++) {
-               m << i->first << i->second;
-       }
-       return m;
+template <class E> typename enable_if<is_enum<E>::value, marshall>::type &
+operator<<(marshall &m, E e) {
+    return m << from_enum(e);

 }
 
 }
 

-template <class A> marshall &
-operator<<(marshall &m, const std::list<A> &d) {
-    m << std::vector<A>(d.begin(), d.end());
-    return m;
-}
+class unmarshall;

 
 

-template <class A, class B> marshall &
-operator<<(marshall &m, const std::pair<A,B> &d) {
-    m << d.first;
-    m << d.second;
-    return m;
-}
+unmarshall& operator>>(unmarshall &, bool &);
+unmarshall& operator>>(unmarshall &, uint8_t &);
+unmarshall& operator>>(unmarshall &, int8_t &);
+unmarshall& operator>>(unmarshall &, uint16_t &);
+unmarshall& operator>>(unmarshall &, int16_t &);
+unmarshall& operator>>(unmarshall &, uint32_t &);
+unmarshall& operator>>(unmarshall &, int32_t &);
+unmarshall& operator>>(unmarshall &, size_t &);
+unmarshall& operator>>(unmarshall &, uint64_t &);
+unmarshall& operator>>(unmarshall &, int64_t &);
+unmarshall& operator>>(unmarshall &, string &);
+template <class E> typename enable_if<is_enum<E>::value, unmarshall>::type &
+operator>>(unmarshall &u, E &e);

 
 class unmarshall {
 
 class unmarshall {

-       private:
-               char *_buf;
-               int _sz;
-               int _ind;
-               bool _ok;
-       public:
-               unmarshall(): _buf(NULL),_sz(0),_ind(0),_ok(false) {}
-               unmarshall(char *b, int sz): _buf(b),_sz(sz),_ind(),_ok(true) {}
-               unmarshall(const std::string &s) : _buf(NULL),_sz(0),_ind(0),_ok(false) 
-               {
-                       //take the content which does not exclude a RPC header from a string
-                       take_content(s);
-               }
-               ~unmarshall() {
-                       if (_buf) free(_buf);
-               }
-
-               //take contents from another unmarshall object
-               void take_in(unmarshall &another);
-
-               //take the content which does not exclude a RPC header from a string
-               void take_content(const std::string &s) {
-                       _sz = s.size()+RPC_HEADER_SZ;
-                       _buf = (char *)realloc(_buf,_sz);
-                       VERIFY(_buf);
-                       _ind = RPC_HEADER_SZ;
-                       memcpy(_buf+_ind, s.data(), s.size());
-                       _ok = true;
-               }
-
-               bool ok() { return _ok; }
-               char *cstr() { return _buf;}
-               bool okdone();
-               unsigned int rawbyte();
-               void rawbytes(std::string &s, unsigned int n);
-
-               int ind() { return _ind;}
-               int size() { return _sz;}
-               void unpack(int *); //non-const ref
-               void take_buf(char **b, int *sz) {
-                       *b = _buf;
-                       *sz = _sz;
-                       _sz = _ind = 0;
-                       _buf = NULL;
-               }
-
-               void unpack_req_header(req_header *h) {
-                       //the first 4-byte is for channel to fill size of pdu
-                       _ind = sizeof(rpc_sz_t); 
-                       unpack(&h->xid);
-                       unpack(&h->proc);
-                       unpack((int *)&h->clt_nonce);
-                       unpack((int *)&h->srv_nonce);
-                       unpack(&h->xid_rep);
-                       _ind = RPC_HEADER_SZ;
-               }
-
-               void unpack_reply_header(reply_header *h) {
-                       //the first 4-byte is for channel to fill size of pdu
-                       _ind = sizeof(rpc_sz_t); 
-                       unpack(&h->xid);
-                       unpack(&h->ret);
-                       _ind = RPC_HEADER_SZ;
-               }
-
-        template <class OutputIterator>
-        void iterate(OutputIterator i, int n) {
-            while (n--) {
-                typename OutputIterator::value_type t;
-                *this >> t;
-                *i++ = t;
-            }
+    private:
+        char *buf_;
+        size_t sz_;
+        size_t index_;
+        bool ok_;
+
+        inline bool ensure(size_t n);
+    public:
+        unmarshall(): buf_(NULL),sz_(0),index_(0),ok_(false) {}
+        unmarshall(char *b, size_t sz): buf_(b),sz_(sz),index_(),ok_(true) {}
+        unmarshall(const string &s) : buf_(NULL),sz_(0),index_(0),ok_(false)
+        {
+            //take the content which does not exclude a RPC header from a string
+            take_content(s);
+        }
+        ~unmarshall() {
+            if (buf_) free(buf_);
+        }
+
+        //take contents from another unmarshall object
+        void take_in(unmarshall &another);
+
+        //take the content which does not exclude a RPC header from a string
+        void take_content(const string &s) {
+            sz_ = s.size()+RPC_HEADER_SZ;
+            buf_ = (char *)realloc(buf_,sz_);
+            VERIFY(buf_);
+            index_ = RPC_HEADER_SZ;
+            memcpy(buf_+index_, s.data(), s.size());
+            ok_ = true;
+        }
+
+        bool ok() const { return ok_; }
+        char *cstr() { return buf_;}
+        bool okdone() const { return ok_ && index_ == sz_; }
+
+        uint8_t rawbyte();
+        void rawbytes(string &s, size_t n);
+        template <class T> void rawbytes(T &t);
+
+        size_t ind() { return index_;}
+        size_t size() { return sz_;}
+        void take_buf(char **b, size_t *sz) {
+            *b = buf_;
+            *sz = sz_;
+            sz_ = index_ = 0;
+            buf_ = NULL;
+        }
+
+        void unpack_req_header(request_header *h) {
+            //the first 4-byte is for channel to fill size of pdu
+            index_ = sizeof(rpc_sz_t);
+            *this >> h->xid >> h->proc >> h->clt_nonce >> h->srv_nonce >> h->xid_rep;
+            index_ = RPC_HEADER_SZ;
+        }
+
+        void unpack_reply_header(reply_header *h) {
+            //the first 4-byte is for channel to fill size of pdu
+            index_ = sizeof(rpc_sz_t);
+            *this >> h->xid >> h->ret;
+            index_ = RPC_HEADER_SZ;
+        }
+
+        template <class A>
+        inline A grab() {
+            A a;
+            *this >> a;
+            return a;

         }
 };
 
         }
 };
 

-unmarshall& operator>>(unmarshall &, bool &);
-unmarshall& operator>>(unmarshall &, unsigned char &);
-unmarshall& operator>>(unmarshall &, char &);
-unmarshall& operator>>(unmarshall &, unsigned short &);
-unmarshall& operator>>(unmarshall &, short &);
-unmarshall& operator>>(unmarshall &, unsigned int &);
-unmarshall& operator>>(unmarshall &, int &);
-unmarshall& operator>>(unmarshall &, unsigned long long &);
-unmarshall& operator>>(unmarshall &, std::string &);
-
-template <class C> unmarshall &
-operator>>(unmarshall &u, std::vector<C> &v)
-{
-       unsigned n;
-       u >> n;
-    v.clear();
-    while (n--) {
-        C c;
-        u >> c;
-        v.push_back(c);
-    }
-       return u;
+template <class A> typename enable_if<is_iterable<A>::value, unmarshall>::type &
+operator>>(unmarshall &u, A &x) {
+    unsigned n = u.grab<unsigned>();
+    x.clear();
+    while (n--)
+        x.emplace_back(u.grab<typename A::value_type>());
+    return u;
+}
+
+template <class A, class B> unmarshall &
+operator>>(unmarshall &u, map<A,B> &x) {
+    unsigned n = u.grab<unsigned>();
+    x.clear();
+    while (n--)
+        x.emplace(u.grab<pair<A,B>>());
+    return u;

 }
 
 template <class A, class B> unmarshall &
 }
 
 template <class A, class B> unmarshall &

-operator>>(unmarshall &u, std::map<A,B> &d) {
-       unsigned n;
-       u >> n;
-       d.clear();
-    while (n--) {
-        A a;
-        B b;
-        u >> a >> b;
-        d[a] = b;
+operator>>(unmarshall &u, pair<A,B> &d) {
+    return u >> d.first >> d.second;
+}
+
+template <class E> typename enable_if<is_enum<E>::value, unmarshall>::type &
+operator>>(unmarshall &u, E &e) {
+    e = to_enum<E>(u.grab<enum_type_t<E>>());
+    return u;
+}
+
+typedef function<int(unmarshall &, marshall &)> handler;
+
+//
+// Automatic marshalling wrappers for RPC handlers
+//
+
+// PAI 2013/09/19
+// C++11 does neither of these two things for us:
+// 1) Declare variables using a parameter pack expansion, like so
+//      Args ...args;
+// 2) Call a function with a tuple of the arguments it expects
+//
+// We implement an 'invoke' function for functions of the RPC handler
+// signature, i.e. int(R & r, const Args...)
+//
+// One thing we need in order to accomplish this is a way to cause the compiler
+// to specialize 'invoke' with a parameter pack containing a list of indices
+// for the elements of the tuple.  This will allow us to call the underlying
+// function with the exploded contents of the tuple.  The empty type
+// tuple_indices<size_t...> accomplishes this.  It will be passed in to
+// 'invoke' as a parameter which will be ignored, but its type will force the
+// compiler to specialize 'invoke' appropriately.
+
+// The following implementation of tuple_indices is redistributed under the MIT
+// License as an insubstantial portion of the LLVM compiler infrastructure.
+
+template <size_t...> struct tuple_indices {};
+template <size_t S, class IntTuple, size_t E> struct make_indices_imp;
+template <size_t S, size_t ...Indices, size_t E> struct make_indices_imp<S, tuple_indices<Indices...>, E> {
+    typedef typename make_indices_imp<S+1, tuple_indices<Indices..., S>, E>::type type;
+};
+template <size_t E, size_t ...Indices> struct make_indices_imp<E, tuple_indices<Indices...>, E> {
+    typedef tuple_indices<Indices...> type;
+};
+template <size_t E, size_t S=0> struct make_tuple_indices {
+    typedef typename make_indices_imp<S, tuple_indices<>, E>::type type;
+};
+
+// This class encapsulates the default response to runtime unmarshalling
+// failures.  The templated wrappers below may optionally use a different
+// class.
+
+struct VerifyOnFailure {
+    static inline int unmarshall_args_failure() {
+        VERIFY(0);
+        return 0;

     }
     }

-       return u;
+};
+
+// Here's the implementation of 'invoke'.  It could be more general, but this
+// meets our needs.
+
+// One for function pointers...
+
+template <class F, class R, class RV, class args_type, size_t ...Indices>
+typename enable_if<!is_member_function_pointer<F>::value, RV>::type
+invoke(RV, F f, void *, R & r, args_type & t, tuple_indices<Indices...>) {
+    return f(r, move(get<Indices>(t))...);
+}
+
+// And one for pointers to member functions...
+
+template <class F, class C, class RV, class R, class args_type, size_t ...Indices>
+typename enable_if<is_member_function_pointer<F>::value, RV>::type
+invoke(RV, F f, C *c, R & r, args_type & t, tuple_indices<Indices...>) {
+    return (c->*f)(r, move(get<Indices>(t))...);

 }
 
 }
 

-template <class C> unmarshall &
-operator>>(unmarshall &u, std::list<C> &l) {
-    unsigned n;
-    u >> n;
-    l.clear();
-    while (n--) {
-        C c;
-        u >> c;
-        l.push_back(c);
+// The class marshalled_func_imp uses partial template specialization to
+// implement the ::wrap static function.  ::wrap takes a function pointer or a
+// pointer to a member function and returns a handler * object which
+// unmarshalls arguments, verifies successful unmarshalling, calls the supplied
+// function, and marshalls the response.
+
+template <class Functor, class Instance, class Signature,
+          class ErrorHandler=VerifyOnFailure> struct marshalled_func_imp;
+
+// Here we specialize on the Signature template parameter to obtain the list of
+// argument types.  Note that we do not assume that the Functor parameter has
+// the same pattern as Signature; this allows us to ignore the distinctions
+// between various types of callable objects at this level of abstraction.
+
+template <class F, class C, class ErrorHandler, class R, class RV, class... Args>
+struct marshalled_func_imp<F, C, RV(R&, Args...), ErrorHandler> {
+    static inline handler *wrap(F f, C *c=nullptr) {
+        // This type definition corresponds to an empty struct with
+        // template parameters running from 0 up to (# args) - 1.
+        using Indices = typename make_tuple_indices<sizeof...(Args)>::type;
+        // This type definition represents storage for f's unmarshalled
+        // arguments.  decay is (most notably) stripping off const
+        // qualifiers.
+        using ArgsStorage = tuple<typename decay<Args>::type...>;
+        // Allocate a handler (i.e. function) to hold the lambda
+        // which will unmarshall RPCs and call f.
+        return new handler([=](unmarshall &u, marshall &m) -> RV {
+            // Unmarshall each argument with the correct type and store the
+            // result in a tuple.
+            ArgsStorage t = {u.grab<typename decay<Args>::type>()...};
+            // Verify successful unmarshalling of the entire input stream.
+            if (!u.okdone())
+                return (RV)ErrorHandler::unmarshall_args_failure();
+            // Allocate space for the RPC response -- will be passed into the
+            // function as an lvalue reference.
+            R r;
+            // Perform the invocation.  Note that Indices() calls the default
+            // constructor of the empty struct with the special template
+            // parameters.
+            RV b = invoke(RV(), f, c, r, t, Indices());
+            // Marshall the response.
+            m << r;
+            // Make like a tree.
+            return b;
+        });

     }
     }

+};
+
+// More partial template specialization shenanigans to reduce the number of
+// parameters which must be provided explicitly and to support a few common
+// callable types.  C++11 doesn't allow partial function template
+// specialization, so we use classes (structs).
+
+template <class Functor, class ErrorHandler=VerifyOnFailure,
+    class Signature=Functor> struct marshalled_func;
+
+template <class F, class ErrorHandler, class RV, class... Args>
+struct marshalled_func<F, ErrorHandler, RV(*)(Args...)> :
+    public marshalled_func_imp<F, void, RV(Args...), ErrorHandler> {};
+
+template <class F, class ErrorHandler, class RV, class C, class... Args>
+struct marshalled_func<F, ErrorHandler, RV(C::*)(Args...)> :
+    public marshalled_func_imp<F, C, RV(Args...), ErrorHandler> {};
+
+template <class F, class ErrorHandler, class Signature>
+struct marshalled_func<F, ErrorHandler, function<Signature>> :
+    public marshalled_func_imp<F, void, Signature, ErrorHandler> {};
+
+template <class ...Args, size_t ...Indices> unmarshall &
+tuple_unmarshall_imp(unmarshall & u, tuple<Args &...> t, tuple_indices<Indices...>) {
+    (void)pass{(u >> get<Indices>(t))...};

     return u;
 }
 
     return u;
 }
 

-template <class A, class B> unmarshall &
-operator>>(unmarshall &u, std::pair<A,B> &d) {
-    return u >> d.first >> d.second;
+template <class... Args> unmarshall &
+operator>>(unmarshall & u, tuple<Args &...> && t) {
+    using Indices = typename make_tuple_indices<sizeof...(Args)>::type;
+    return tuple_unmarshall_imp(u, t, Indices());
+}
+
+template <class ...Args, size_t ...Indices> marshall &
+tuple_marshall_imp(marshall & m, tuple<Args...> & t, tuple_indices<Indices...>) {
+    (void)pass{(m << get<Indices>(t))...};
+    return m;

 }
 
 }
 

+template <class... Args> marshall &
+operator<<(marshall & m, tuple<Args...> && t) {
+    using Indices = typename make_tuple_indices<sizeof...(Args)>::type;
+    return tuple_marshall_imp(m, t, Indices());
+}
+
+// for structs or classes containing a MEMBERS declaration
+#define MARSHALLABLE(_c_) \
+inline unmarshall & operator>>(unmarshall &u, _c_ &a) { return u >> a._tuple_(); } \
+inline marshall & operator<<(marshall &m, _c_ a) { return m << a._tuple_(); }
+

 #endif
 #endif