Solution: if all peers of a socket are >= 3.1 use sub/cancel commands
instead of the old 0/1 messages.
For backward compatibility, move the handling of 0/1 or sub/cancel
command strings to the encoders, so that the right thing can be done
depending on the protocol version.
Do not set the command flag until the encoder, so that we can handle
the inproc case (which skips the encoder).
Solution: add some msg helpers to parse commands, and check for
subscribe or cancel commands and process them accordingly in the xpub
and xsub classes.
The shared reference count was not shared but copied. msg_t cannot
store the refcnt itsef but has to store a pointer to an externally
allocated (shared) refcnter. The changes to lmsg are reverted to
use content_t again. Howver, this introduces an allocation in v2_decoder
when creating the message which can be avoided. When allocating the reception
buffer, space is allocated for the maximum number of reference counts
(8192 / max_vsm_size = 8192/64 = 128 zmq:atomic_counter objects). This
increases the buffer by 128*sizeof(atomic_counter) = 128*4 = 512 bytes only.
When creating a message, the refcnt member is set to the address of one of the
pre-allocated atomic_counter_t objects. To do so, a new msg_t type zcmsg
is introduced because msg::copy must discriminate between the message types
when releasing memory.
With a msg_t size of 64 bytes, it becomes possible to embedd the content_t's members
struct for large messages directly in the msg_t. This saves the dynamic allocation
of content_t obejcts when using msg_t::init_data.
content_t contains a zmq::atomic_counter_t object which is not a POD in C++98
and thus it cannot be used as a member of the union u. To bypass this, C++11
is used which has relaxed rules for POD and atomic_counter is a C++11-POD. An
alternative would have been to make atomic_counter a classical POD by removing
constructors and all private member functions, i.e. have a struct and free functions
to manipulate it.
A new msg_t::init function is added which decides to either to copy the data for size<64 bytes
or use msg_t::init_data to do zero-copy initialization.
Of course people still "can" distributed the sources under the
LGPLv3. However we provide COPYING.LESSER with additional grants.
Solution: specify these grants in the header of each source file.
Increasing it would have at least two benefits -
* More messages would be 'VSM' messages, so it would reduce allocation
overhead a bit.
* Remove any chance of false sharing of things that are, by design,
pushed by value onto a ypipe_t<msg_t> which is shared between two threads.
The only downside I see is slightly increased memory consumption on memory
constrained applications.
- Full discussion of this rationale is part of issue #1295
- copy and move message operations are updated to maintain proper
reference count of properties object
- zmq_msg_gets updated to use i_properties interface to fetch property
value
- setter/getter added to msg_t class
The get_credential () member function returns
credential for the last peer we received message for.
The idea is that this function is used to implement user-level API.
* Command names changed from null terminated to length-specified
* Command frames use the correct flag (bit 2)
* test_stream acts as test case for command frames
* Some code cleanups
