Problem: unnecessarily complex inheritance hierarchy in decoders, warning C4355 with VS2010

Solution: make allocator a member of decoder_base_t

src/decoder.hpp

@@ -57,23 +57,23 @@ template <typename T, typename A = c_single_allocator>
 class decoder_base_t : public i_decoder
 {
   public:
-    explicit decoder_base_t (A *allocator_) :
+    explicit decoder_base_t (const size_t buf_size_) :
         next (NULL),
         read_pos (NULL),
         to_read (0),
-        allocator (allocator_)
+        allocator (buf_size_)
     {
-        buf = allocator->allocate ();
+        buf = allocator.allocate ();
     }
 
     //  The destructor doesn't have to be virtual. It is made virtual
     //  just to keep ICC and code checking tools from complaining.
-    virtual ~decoder_base_t () { allocator->deallocate (); }
+    virtual ~decoder_base_t () { allocator.deallocate (); }
 
     //  Returns a buffer to be filled with binary data.
     void get_buffer (unsigned char **data_, std::size_t *size_)
     {
-        buf = allocator->allocate ();
+        buf = allocator.allocate ();
 
         //  If we are expected to read large message, we'll opt for zero-
         //  copy, i.e. we'll ask caller to fill the data directly to the
@@ -83,14 +83,14 @@ class decoder_base_t : public i_decoder
         //  As a consequence, large messages being received won't block
         //  other engines running in the same I/O thread for excessive
         //  amounts of time.
-        if (to_read >= allocator->size ()) {
+        if (to_read >= allocator.size ()) {
             *data_ = read_pos;
             *size_ = to_read;
             return;
         }
 
         *data_ = buf;
-        *size_ = allocator->size ();
+        *size_ = allocator.size ();
     }
 
     //  Processes the data in the buffer previously allocated using
@@ -151,7 +151,7 @@ class decoder_base_t : public i_decoder
 
     virtual void resize_buffer (std::size_t new_size)
     {
-        allocator->resize (new_size);
+        allocator.resize (new_size);
     }
 
   protected:
@@ -168,6 +168,8 @@ class decoder_base_t : public i_decoder
         next = next_;
     }
 
+    A &get_allocator () { return allocator; }
+
   private:
     //  Next step. If set to NULL, it means that associated data stream
     //  is dead. Note that there can be still data in the process in such
@@ -181,7 +183,7 @@ class decoder_base_t : public i_decoder
     std::size_t to_read;
 
     //  The duffer for data to decode.
-    A *allocator;
+    A allocator;
     unsigned char *buf;
 
     decoder_base_t (const decoder_base_t &);

src/v1_decoder.cpp

@@ -39,8 +39,7 @@
 #include "err.hpp"
 
 zmq::v1_decoder_t::v1_decoder_t (size_t bufsize_, int64_t maxmsgsize_) :
-    c_single_allocator (bufsize_),
+    decoder_base_t<v1_decoder_t> (bufsize_),
-    decoder_base_t<v1_decoder_t> (this),
     maxmsgsize (maxmsgsize_)
 {
     int rc = in_progress.init ();

src/v1_decoder.hpp

@@ -36,8 +36,7 @@ namespace zmq
 {
 //  Decoder for ZMTP/1.0 protocol. Converts data batches into messages.
 
-class v1_decoder_t : public zmq::c_single_allocator,
+class v1_decoder_t : public decoder_base_t<v1_decoder_t>
-                     public decoder_base_t<v1_decoder_t>
 {
   public:
     v1_decoder_t (size_t bufsize_, int64_t maxmsgsize_);

src/v2_decoder.cpp

@@ -41,8 +41,7 @@
 zmq::v2_decoder_t::v2_decoder_t (size_t bufsize_,
                                  int64_t maxmsgsize_,
                                  bool zero_copy_) :
-    shared_message_memory_allocator (bufsize_),
+    decoder_base_t<v2_decoder_t, shared_message_memory_allocator> (bufsize_),
-    decoder_base_t<v2_decoder_t, shared_message_memory_allocator> (this),
     msg_flags (0),
     zero_copy (zero_copy_),
     maxmsgsize (maxmsgsize_)
@@ -114,9 +113,10 @@ int zmq::v2_decoder_t::size_ready (uint64_t msg_size,
     // the current message can exceed the current buffer. We have to copy the buffer
     // data into a new message and complete it in the next receive.
 
-    if (unlikely (
+    shared_message_memory_allocator &allocator = get_allocator ();
-          !zero_copy
+    if (unlikely (!zero_copy
-          || ((unsigned char *) read_pos + msg_size > (data () + size ())))) {
+                  || ((unsigned char *) read_pos + msg_size
+                      > (allocator.data () + allocator.size ())))) {
         // a new message has started, but the size would exceed the pre-allocated arena
         // this happens every time when a message does not fit completely into the buffer
         rc = in_progress.init_size (static_cast<size_t> (msg_size));
@@ -124,15 +124,16 @@ int zmq::v2_decoder_t::size_ready (uint64_t msg_size,
         // construct message using n bytes from the buffer as storage
         // increase buffer ref count
         // if the message will be a large message, pass a valid refcnt memory location as well
-        rc = in_progress.init (const_cast<unsigned char *> (read_pos),
+        rc =
-                               static_cast<size_t> (msg_size),
+          in_progress.init (const_cast<unsigned char *> (read_pos),
-                               shared_message_memory_allocator::call_dec_ref,
+                            static_cast<size_t> (msg_size),
-                               buffer (), provide_content ());
+                            shared_message_memory_allocator::call_dec_ref,
+                            allocator.buffer (), allocator.provide_content ());
 
         // For small messages, data has been copied and refcount does not have to be increased
         if (in_progress.is_zcmsg ()) {
-            advance_content ();
+            allocator.advance_content ();
-            inc_ref ();
+            allocator.inc_ref ();
         }
     }
 

src/v2_decoder.hpp

@@ -38,10 +38,8 @@ namespace zmq
 //  Decoder for ZMTP/2.x framing protocol. Converts data stream into messages.
 //  The class has to inherit from shared_message_memory_allocator because
 //  the base class calls allocate in its constructor.
-class v2_decoder_t :
+class v2_decoder_t
-  // inherit first from allocator to ensure that it is constructed before decoder_base_t
+    : public decoder_base_t<v2_decoder_t, shared_message_memory_allocator>
-  public shared_message_memory_allocator,
-  public decoder_base_t<v2_decoder_t, shared_message_memory_allocator>
 {
   public:
     v2_decoder_t (size_t bufsize_, int64_t maxmsgsize_, bool zero_copy_);