Fix data loss for PUB/SUB and unidirectional transports (LIBZMQ-268)

With the introduction of subscription forwarding, the first message
sent on a PUB socket using a unidirectional transport (e.g. PGM) is
always lost due to the "subscribe to all" being done asynchronously.
This patch fixes the problem and also refactors the code to have a
single point where the "subscribe to all" is performed.

Signed-off-by: Martin Lucina <martin@lucina.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/xpub.cpp b/src/xpub.cpp
index bf73399..b4bc135 100644
--- a/src/xpub.cpp
+++ b/src/xpub.cpp
@@ -37,11 +37,16 @@ xs::xpub_t::~xpub_t ()
 {
 }
 
-void xs::xpub_t::xattach_pipe (pipe_t *pipe_)
+void xs::xpub_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
 {
     xs_assert (pipe_);
     dist.attach (pipe_);
 
+    // If icanhasall_ is specified, the caller would like to subscribe
+    // to all data on this pipe, implicitly.
+    if (icanhasall_)
+        subscriptions.add (NULL, 0, pipe_);
+
     //  The pipe is active when attached. Let's read the subscriptions from
     //  it, if any.
     xread_activated (pipe_);