message flags added to zmq_msg_t strcuture

bindings/c/zmq.h

@@ -102,15 +102,19 @@ ZMQ_EXPORT const char *zmq_strerror (int errnum);
 #define ZMQ_DELIMITER 31
 #define ZMQ_VSM 32
 
-//  A message. If 'shared' is true, message content pointed to by 'content'
-//  is shared, i.e. reference counting is used to manage its lifetime
-//  rather than straighforward malloc/free. Not that 'content' is not a pointer
-//  to the raw data. Rather it is pointer to zmq::msg_content_t structure
+//  Message flags. ZMQ_MSG_SHARED is strictly speaking not a message flag
+//  (it has no equivalent in the wire format), however, making  it a flag
+//  allows us to pack the stucture tigher and thus improve performance.
+#define ZMQ_MSG_TBC 1
+#define ZMQ_MSG_SHARED 128
+
+//  A message. Note that 'content' is not a pointer to the raw data.
+//  Rather it is pointer to zmq::msg_content_t structure
 //  (see src/msg_content.hpp for its definition).
 typedef struct
 {
     void *content;
-    unsigned char shared;
+    unsigned char flags;
     unsigned char vsm_size;
     unsigned char vsm_data [ZMQ_MAX_VSM_SIZE];
 } zmq_msg_t;

src/pipe.cpp

@@ -174,7 +174,7 @@ void zmq::writer_t::term ()
     zmq_msg_t msg;
     const unsigned char *offset = 0;
     msg.content = (void*) (offset + ZMQ_DELIMITER);
-    msg.shared = false;
+    msg.flags = 0;
     pipe->write (msg);
     pipe->flush ();
 }

src/pub.cpp

@@ -121,11 +121,11 @@ int zmq::pub_t::xsend (zmq_msg_t *msg_, int flags_)
     //  There are at least 2 destinations for the message. That means we have
     //  to deal with reference counting. First add N-1 references to
     //  the content (we are holding one reference anyway, that's why -1).
-    if (msg_->shared)
+    if (msg_->flags & ZMQ_MSG_SHARED)
         content->refcnt.add (pipes_count - 1);
     else {
         content->refcnt.set (pipes_count);
-        msg_->shared = true;
+        msg_->flags |= ZMQ_MSG_SHARED;
     }
 
     //  Push the message to all destinations.

src/zmq.cpp

@@ -96,6 +96,7 @@ const char *zmq_strerror (int errnum_)
 int zmq_msg_init (zmq_msg_t *msg_)
 {
     msg_->content = (zmq::msg_content_t*) ZMQ_VSM;
+    msg_->flags = 0;
     msg_->vsm_size = 0;
     return 0;
 }
@@ -104,6 +105,7 @@ int zmq_msg_init_size (zmq_msg_t *msg_, size_t size_)
 {
     if (size_ <= ZMQ_MAX_VSM_SIZE) {
         msg_->content = (zmq::msg_content_t*) ZMQ_VSM;
+        msg_->flags = 0;
         msg_->vsm_size = (uint8_t) size_;
     }
     else {
@@ -113,8 +115,8 @@ int zmq_msg_init_size (zmq_msg_t *msg_, size_t size_)
             errno = ENOMEM;
             return -1;
         }
-        msg_->shared = 0;
-
+        msg_->flags = 0;
+        
         zmq::msg_content_t *content = (zmq::msg_content_t*) msg_->content;
         content->data = (void*) (content + 1);
         content->size = size_;
@@ -128,9 +130,9 @@ int zmq_msg_init_size (zmq_msg_t *msg_, size_t size_)
 int zmq_msg_init_data (zmq_msg_t *msg_, void *data_, size_t size_,
     zmq_free_fn *ffn_, void *hint_)
 {
-    msg_->shared = 0;
     msg_->content = (zmq::msg_content_t*) malloc (sizeof (zmq::msg_content_t));
     zmq_assert (msg_->content);
+    msg_->flags = 0;
     zmq::msg_content_t *content = (zmq::msg_content_t*) msg_->content;
     content->data = data_;
     content->size = size_;
@@ -150,7 +152,7 @@ int zmq_msg_close (zmq_msg_t *msg_)
     //  If the content is not shared, or if it is shared and the reference.
     //  count has dropped to zero, deallocate it.
     zmq::msg_content_t *content = (zmq::msg_content_t*) msg_->content;
-    if (!msg_->shared || !content->refcnt.sub (1)) {
+    if (!(msg_->flags & ZMQ_MSG_SHARED) || !content->refcnt.sub (1)) {
 
         //  We used "placement new" operator to initialize the reference.
         //  counter so we call its destructor now.
@@ -183,10 +185,10 @@ int zmq_msg_copy (zmq_msg_t *dest_, zmq_msg_t *src_)
         //  One reference is added to shared messages. Non-shared messages
         //  are turned into shared messages and reference count is set to 2.
         zmq::msg_content_t *content = (zmq::msg_content_t*) src_->content;
-        if (src_->shared)
+        if (src_->flags & ZMQ_MSG_SHARED)
             content->refcnt.add (1);
         else {
-            src_->shared = true;
+            src_->flags |= ZMQ_MSG_SHARED;
             content->refcnt.set (2);
         }
     }