Socket re-entrancy rewritten

The inspiration for this re-write came form John Skaller's
patch. Adding him to Credits section of the AUTHORS file.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

4 files changed, 89 insertions, 150 deletions

diff --git a/src/mutex.hpp b/src/mutex.hpp
index fc75bed..c0a2cc9 100644
--- a/src/mutex.hpp
+++ b/src/mutex.hpp
@@ -37,34 +37,28 @@ namespace xs
     class mutex_t
     {
     public:
-        inline mutex_t (bool fake_ = false) :
-            fake (fake_)
+        inline mutex_t ()
         {
-            if (!fake)
-                InitializeCriticalSection (&cs);
+            InitializeCriticalSection (&cs);
         }
 
         inline ~mutex_t ()
         {
-            if (!fake)
-                DeleteCriticalSection (&cs);
+            DeleteCriticalSection (&cs);
         }
 
         inline void lock ()
         {
-            if (!fake)
-                EnterCriticalSection (&cs);
+            EnterCriticalSection (&cs);
         }
 
         inline void unlock ()
         {
-            if (!fake)
-                LeaveCriticalSection (&cs);
+            LeaveCriticalSection (&cs);
         }
 
     private:
 
-        bool fake;
         CRITICAL_SECTION cs;
 
         //  Disable copy construction and assignment.
@@ -84,46 +78,36 @@ namespace xs
     class mutex_t
     {
     public:
-        inline mutex_t (bool fake_ = false) :
-            fake (fake_)
+        inline mutex_t ()
         {
-            if (!fake) {
-                int rc = pthread_mutex_init (&mutex, NULL);
-                if (rc)
-                    posix_assert (rc);
-            }
+            int rc = pthread_mutex_init (&mutex, NULL);
+            if (rc)
+                posix_assert (rc);
         }
  
         inline ~mutex_t ()
         {
-            if (!fake) {
-                int rc = pthread_mutex_destroy (&mutex);
-                if (rc)
-                    posix_assert (rc);
-            }
+            int rc = pthread_mutex_destroy (&mutex);
+            if (rc)
+                posix_assert (rc);
         }
  
         inline void lock ()
         {
-            if (!fake) {
-                int rc = pthread_mutex_lock (&mutex);
-                if (rc)
-                    posix_assert (rc);
-            }
+            int rc = pthread_mutex_lock (&mutex);
+            if (rc)
+                posix_assert (rc);
         }
  
         inline void unlock ()
         {
-            if (!fake) {
-                int rc = pthread_mutex_unlock (&mutex);
-                if (rc)
-                    posix_assert (rc);
-            }
+            int rc = pthread_mutex_unlock (&mutex);
+            if (rc)
+                posix_assert (rc);
         }
  
     private:
  
-        bool fake;
         pthread_mutex_t mutex;
  
         // Disable copy construction and assignment.
@@ -136,3 +120,4 @@ namespace xs
 #endif
 
 #endif
+
diff --git a/src/socket_base.cpp b/src/socket_base.cpp
index fb387db..97ac4b4 100644
--- a/src/socket_base.cpp
+++ b/src/socket_base.cpp
@@ -117,7 +117,7 @@ xs::socket_base_t *xs::socket_base_t::create (int type_, class ctx_t *parent_,
 xs::socket_base_t::socket_base_t (ctx_t *parent_, uint32_t tid_, int sid_) :
     own_t (parent_, tid_),
     tag (0xbaddecaf),
-    sync (!parent_->is_reentrant ()),
+    reentrant (parent_->is_reentrant ()),
     ctx_terminated (false),
     destroyed (false),
     last_tsc (0),
@@ -146,6 +146,18 @@ void xs::socket_base_t::stop ()
     send_stop ();
 }
 
+void xs::socket_base_t::lock ()
+{
+    if (reentrant)
+        sync.lock ();
+}
+
+void xs::socket_base_t::unlock ()
+{
+    if (reentrant)
+        sync.unlock ();
+}
+
 int xs::socket_base_t::parse_uri (const char *uri_,
                         std::string &protocol_, std::string &address_)
 {
@@ -227,74 +239,58 @@ void xs::socket_base_t::attach_pipe (pipe_t *pipe_, bool icanhasall_)
 int xs::socket_base_t::setsockopt (int option_, const void *optval_,
     size_t optvallen_)
 {
-    sync.lock ();
-
     if (unlikely (ctx_terminated)) {
-        sync.unlock ();
         errno = ETERM;
         return -1;
     }
 
     //  First, check whether specific socket type overloads the option.
     int rc = xsetsockopt (option_, optval_, optvallen_);
-    if (rc == 0 || errno != EINVAL) {
-        sync.unlock ();
+    if (rc == 0 || errno != EINVAL)
         return rc;
-    }
 
     //  If the socket type doesn't support the option, pass it to
     //  the generic option parser.
     rc = options.setsockopt (option_, optval_, optvallen_);
-    sync.unlock ();
     return rc;
 }
 
 int xs::socket_base_t::getsockopt (int option_, void *optval_,
     size_t *optvallen_)
 {
-    sync.lock ();
-
     if (unlikely (ctx_terminated)) {
-        sync.unlock ();
         errno = ETERM;
         return -1;
     }
 
     if (option_ == XS_RCVMORE) {
         if (*optvallen_ < sizeof (int)) {
-            sync.unlock ();
             errno = EINVAL;
             return -1;
         }
         *((int*) optval_) = rcvmore ? 1 : 0;
         *optvallen_ = sizeof (int);
-        sync.unlock ();
         return 0;
     }
 
     if (option_ == XS_FD) {
         if (*optvallen_ < sizeof (fd_t)) {
             errno = EINVAL;
-            sync.unlock ();
             return -1;
         }
         *((fd_t*) optval_) = mailbox.get_fd ();
         *optvallen_ = sizeof (fd_t);
-        sync.unlock ();
         return 0;
     }
 
     if (option_ == XS_EVENTS) {
         if (*optvallen_ < sizeof (int)) {
             errno = EINVAL;
-            sync.unlock ();
             return -1;
         }
         int rc = process_commands (0, false);
-        if (rc != 0 && (errno == EINTR || errno == ETERM)) {
-            sync.unlock ();
+        if (rc != 0 && (errno == EINTR || errno == ETERM))
             return -1;
-        }
         errno_assert (rc == 0);
         *((int*) optval_) = 0;
         if (has_out ())
@@ -302,7 +298,6 @@ int xs::socket_base_t::getsockopt (int option_, void *optval_,
         if (has_in ())
             *((int*) optval_) |= XS_POLLIN;
         *optvallen_ = sizeof (int);
-        sync.unlock ();
         return 0;
     }
 
@@ -311,10 +306,7 @@ int xs::socket_base_t::getsockopt (int option_, void *optval_,
 
 int xs::socket_base_t::bind (const char *addr_)
 {
-    sync.lock ();
-
     if (unlikely (ctx_terminated)) {
-        sync.unlock ();
         errno = ETERM;
         return -1;
     }
@@ -323,21 +315,16 @@ int xs::socket_base_t::bind (const char *addr_)
     std::string protocol;
     std::string address;
     int rc = parse_uri (addr_, protocol, address);
-    if (rc != 0) {
-        sync.unlock ();
+    if (rc != 0)
         return -1;
-    }
 
     rc = check_protocol (protocol);
-    if (rc != 0) {
-        sync.unlock ();
+    if (rc != 0)
         return -1;
-    }
 
     if (protocol == "inproc") {
         endpoint_t endpoint = {this, options};
         rc = register_endpoint (addr_, endpoint);
-        sync.unlock ();
         return rc;
     }
 
@@ -346,7 +333,6 @@ int xs::socket_base_t::bind (const char *addr_)
         //  For convenience's sake, bind can be used interchageable with
         //  connect for PGM and EPGM transports.
         rc = connect (addr_);
-        sync.unlock ();
         return rc;
     }
 
@@ -354,7 +340,6 @@ int xs::socket_base_t::bind (const char *addr_)
     //  point we'll choose one.
     io_thread_t *io_thread = choose_io_thread (options.affinity);
     if (!io_thread) {
-        sync.unlock ();
         errno = EMTHREAD;
         return -1;
     }
@@ -366,11 +351,9 @@ int xs::socket_base_t::bind (const char *addr_)
         int rc = listener->set_address (address.c_str ());
         if (rc != 0) {
             delete listener;
-            sync.unlock ();
             return -1;
         }
         launch_child (listener);
-        sync.unlock ();
         return 0;
     }
 
@@ -382,11 +365,9 @@ int xs::socket_base_t::bind (const char *addr_)
         int rc = listener->set_address (address.c_str ());
         if (rc != 0) {
             delete listener;
-            sync.unlock ();
             return -1;
         }
         launch_child (listener);
-        sync.unlock ();
         return 0;
     }
 #endif
@@ -397,10 +378,7 @@ int xs::socket_base_t::bind (const char *addr_)
 
 int xs::socket_base_t::connect (const char *addr_)
 {
-    sync.lock ();
-
     if (unlikely (ctx_terminated)) {
-        sync.unlock ();
         errno = ETERM;
         return -1;
     }
@@ -409,16 +387,12 @@ int xs::socket_base_t::connect (const char *addr_)
     std::string protocol;
     std::string address;
     int rc = parse_uri (addr_, protocol, address);
-    if (rc != 0) {
-        sync.unlock ();
+    if (rc != 0)
         return -1;
-    }
 
     rc = check_protocol (protocol);
-    if (rc != 0) {
-        sync.unlock ();
+    if (rc != 0)
         return -1;
-    }
 
     if (protocol == "inproc") {
 
@@ -428,10 +402,8 @@ int xs::socket_base_t::connect (const char *addr_)
 
         //  Find the peer endpoint.
         endpoint_t peer = find_endpoint (addr_);
-        if (!peer.socket) {
-            sync.unlock ();
+        if (!peer.socket)
             return -1;
-        }
 
         // The total HWM for an inproc connection should be the sum of
         // the binder's HWM and the connector's HWM.
@@ -473,14 +445,12 @@ int xs::socket_base_t::connect (const char *addr_)
         //  increased here.
         send_bind (peer.socket, pipes [1], false);
 
-        sync.unlock ();
         return 0;
     }
 
     //  Choose the I/O thread to run the session in.
     io_thread_t *io_thread = choose_io_thread (options.affinity);
     if (!io_thread) {
-        sync.unlock ();
         errno = EMTHREAD;
         return -1;
     }
@@ -513,34 +483,27 @@ int xs::socket_base_t::connect (const char *addr_)
     //  Activate the session. Make it a child of this socket.
     launch_child (session);
 
-    sync.unlock ();
     return 0;
 }
 
 int xs::socket_base_t::send (msg_t *msg_, int flags_)
 {
-    sync.lock ();
-
     //  Check whether the library haven't been shut down yet.
     if (unlikely (ctx_terminated)) {
-        sync.unlock ();
         errno = ETERM;
         return -1;
     }
 
     //  Check whether message passed to the function is valid.
     if (unlikely (!msg_ || !msg_->check ())) {
-        sync.unlock ();
         errno = EFAULT;
         return -1;
     }
 
     //  Process pending commands, if any.
     int rc = process_commands (0, true);
-    if (unlikely (rc != 0)) {
-        sync.unlock ();
+    if (unlikely (rc != 0))
         return -1;
-    }
 
     //  Clear any user-visible flags that are set on the message.
     msg_->reset_flags (msg_t::more);
@@ -551,21 +514,15 @@ int xs::socket_base_t::send (msg_t *msg_, int flags_)
 
     //  Try to send the message.
     rc = xsend (msg_, flags_);
-    if (rc == 0) {
-        sync.unlock ();
+    if (rc == 0)
         return 0;
-    }
-    if (unlikely (errno != EAGAIN)) {
-        sync.unlock ();
+    if (unlikely (errno != EAGAIN))
         return -1;
-    }
 
     //  In case of non-blocking send we'll simply propagate
     //  the error - including EAGAIN - up the stack.
-    if (flags_ & XS_DONTWAIT || options.sndtimeo == 0) {
-        sync.unlock ();
+    if (flags_ & XS_DONTWAIT || options.sndtimeo == 0)
         return -1;
-    }
 
     //  Compute the time when the timeout should occur.
     //  If the timeout is infite, don't care. 
@@ -577,55 +534,43 @@ int xs::socket_base_t::send (msg_t *msg_, int flags_)
     //  command, process it and try to send the message again.
     //  If timeout is reached in the meantime, return EAGAIN.
     while (true) {
-        if (unlikely (process_commands (timeout, false) != 0)) {
-            sync.unlock ();
+        if (unlikely (process_commands (timeout, false) != 0))
             return -1;
-        }
         rc = xsend (msg_, flags_);
         if (rc == 0)
             break;
-        if (unlikely (errno != EAGAIN)) {
-            sync.unlock ();
+        if (unlikely (errno != EAGAIN))
             return -1;
-        }
         if (timeout > 0) {
             timeout = (int) (end - clock.now_ms ());
             if (timeout <= 0) {
-                sync.unlock ();
                 errno = EAGAIN;
                 return -1;
             }
         }
     }
 
-    sync.unlock ();
     return 0;
 }
 
 int xs::socket_base_t::recv (msg_t *msg_, int flags_)
 {
-    sync.lock ();
-
     //  Check whether the library haven't been shut down yet.
     if (unlikely (ctx_terminated)) {
-        sync.unlock ();
         errno = ETERM;
         return -1;
     }
 
     //  Check whether message passed to the function is valid.
     if (unlikely (!msg_ || !msg_->check ())) {
-        sync.unlock ();
         errno = EFAULT;
         return -1;
     }
 
     //  Get the message.
     int rc = xrecv (msg_, flags_);
-    if (unlikely (rc != 0 && errno != EAGAIN)) {
-        sync.unlock ();
+    if (unlikely (rc != 0 && errno != EAGAIN))
         return -1;
-    }
 
     //  Once every inbound_poll_rate messages check for signals and process
     //  incoming commands. This happens only if we are not polling altogether
@@ -644,7 +589,6 @@ int xs::socket_base_t::recv (msg_t *msg_, int flags_)
     //  If we have the message, return immediately.
     if (rc == 0) {
         extract_flags (msg_);
-        sync.unlock ();
         return 0;
     }
 
@@ -653,20 +597,15 @@ int xs::socket_base_t::recv (msg_t *msg_, int flags_)
     //  activate_reader command already waiting int a command pipe.
     //  If it's not, return EAGAIN.
     if (flags_ & XS_DONTWAIT || options.rcvtimeo == 0) {
-        if (unlikely (process_commands (0, false) != 0)) {
-            sync.unlock ();
+        if (unlikely (process_commands (0, false) != 0))
             return -1;
-        }
         ticks = 0;
 
         rc = xrecv (msg_, flags_);
-        if (rc < 0) {
-            sync.unlock ();
+        if (rc < 0)
             return rc;
-        }
 
         extract_flags (msg_);
-        sync.unlock ();
         return 0;
     }
 
@@ -680,24 +619,19 @@ int xs::socket_base_t::recv (msg_t *msg_, int flags_)
     //  we are able to fetch a message.
     bool block = (ticks != 0);
     while (true) {
-        if (unlikely (process_commands (block ? timeout : 0, false) != 0)) {
-            sync.unlock ();
+        if (unlikely (process_commands (block ? timeout : 0, false) != 0))
             return -1;
-        }
         rc = xrecv (msg_, flags_);
         if (rc == 0) {
             ticks = 0;
             break;
         }
-        if (unlikely (errno != EAGAIN)) {
-            sync.unlock ();
+        if (unlikely (errno != EAGAIN))
             return -1;
-        }
         block = true;
         if (timeout > 0) {
             timeout = (int) (end - clock.now_ms ());
             if (timeout <= 0) {
-                sync.unlock ();
                 errno = EAGAIN;
                 return -1;
             }
@@ -705,7 +639,6 @@ int xs::socket_base_t::recv (msg_t *msg_, int flags_)
     }
 
     extract_flags (msg_);
-    sync.unlock ();
     return 0;
 }
 
@@ -724,17 +657,13 @@ int xs::socket_base_t::close ()
 
 bool xs::socket_base_t::has_in ()
 {
-    sync.lock ();
     bool ret = xhas_in ();
-    sync.unlock ();
     return ret;
 }
 
 bool xs::socket_base_t::has_out ()
 {
-    sync.lock ();
     bool ret = xhas_out ();
-    sync.unlock ();
     return ret;
 }
 
diff --git a/src/socket_base.hpp b/src/socket_base.hpp
index 850586e..8b9a948 100644
--- a/src/socket_base.hpp
+++ b/src/socket_base.hpp
@@ -65,6 +65,10 @@ namespace xs
         //  This function can be called from a different thread!
         void stop ();
 
+        //  Synchronise access of application threads to the socket.
+        void lock ();
+        void unlock ();
+
         //  Interface for communication with the API layer.
         int setsockopt (int option_, const void *optval_, size_t optvallen_);
         int getsockopt (int option_, void *optval_, size_t *optvallen_);
@@ -143,6 +147,7 @@ namespace xs
 
         //  Synchronisation of access to the socket. If Crossroads are running
         //  in non-reentrant mode, it is a dummy mutex-like object.
+        bool reentrant;
         mutex_t sync;
 
         //  If true, associated context was already terminated.
diff --git a/src/xs.cpp b/src/xs.cpp
index ad5bd97..7160da9 100644
--- a/src/xs.cpp
+++ b/src/xs.cpp
@@ -202,40 +202,54 @@ int xs_close (void *s_)
 int xs_setsockopt (void *s_, int option_, const void *optval_,
     size_t optvallen_)
 {
-    if (!s_ || !((xs::socket_base_t*) s_)->check_tag ()) {
+    xs::socket_base_t *s = (xs::socket_base_t*) s_;
+    if (!s || !s->check_tag ()) {
         errno = ENOTSOCK;
         return -1;
     }
-    return (((xs::socket_base_t*) s_)->setsockopt (option_, optval_,
-        optvallen_));
+    s->lock ();
+    int rc = s->setsockopt (option_, optval_, optvallen_);
+    s->unlock ();
+    return rc;
 }
 
 int xs_getsockopt (void *s_, int option_, void *optval_, size_t *optvallen_)
 {
-    if (!s_ || !((xs::socket_base_t*) s_)->check_tag ()) {
+    xs::socket_base_t *s = (xs::socket_base_t*) s_;
+    if (!s || !s->check_tag ()) {
         errno = ENOTSOCK;
         return -1;
     }
-    return (((xs::socket_base_t*) s_)->getsockopt (option_, optval_,
-        optvallen_));
+    s->lock ();
+    int rc = s->getsockopt (option_, optval_, optvallen_);
+    s->unlock ();
+    return rc;
 }
 
 int xs_bind (void *s_, const char *addr_)
 {
-    if (!s_ || !((xs::socket_base_t*) s_)->check_tag ()) {
+    xs::socket_base_t *s = (xs::socket_base_t*) s_;
+    if (!s || !s->check_tag ()) {
         errno = ENOTSOCK;
         return -1;
     }
-    return (((xs::socket_base_t*) s_)->bind (addr_));
+    s->lock ();
+    int rc = s->bind (addr_);
+    s->unlock ();
+    return rc;
 }
 
 int xs_connect (void *s_, const char *addr_)
 {
-    if (!s_ || !((xs::socket_base_t*) s_)->check_tag ()) {
+    xs::socket_base_t *s = (xs::socket_base_t*) s_;
+    if (!s || !s->check_tag ()) {
         errno = ENOTSOCK;
         return -1;
     }
-    return (((xs::socket_base_t*) s_)->connect (addr_));
+    s->lock ();
+    int rc = s->connect (addr_);
+    s->unlock ();
+    return rc;
 }
 
 int xs_send (void *s_, const void *buf_, size_t len_, int flags_)
@@ -288,12 +302,15 @@ int xs_recv (void *s_, void *buf_, size_t len_, int flags_)
 
 int xs_sendmsg (void *s_, xs_msg_t *msg_, int flags_)
 {
-    if (!s_ || !((xs::socket_base_t*) s_)->check_tag ()) {
+    xs::socket_base_t *s = (xs::socket_base_t*) s_;
+    if (!s || !s->check_tag ()) {
         errno = ENOTSOCK;
         return -1;
     }
     int sz = (int) xs_msg_size (msg_);
-    int rc = (((xs::socket_base_t*) s_)->send ((xs::msg_t*) msg_, flags_));
+    s->lock ();
+    int rc = s->send ((xs::msg_t*) msg_, flags_);
+    s->unlock ();
     if (unlikely (rc < 0))
         return -1;
     return sz;
@@ -301,11 +318,14 @@ int xs_sendmsg (void *s_, xs_msg_t *msg_, int flags_)
 
 int xs_recvmsg (void *s_, xs_msg_t *msg_, int flags_)
 {
-    if (!s_ || !((xs::socket_base_t*) s_)->check_tag ()) {
+    xs::socket_base_t *s = (xs::socket_base_t*) s_;
+    if (!s || !s->check_tag ()) {
         errno = ENOTSOCK;
         return -1;
     }
-    int rc = (((xs::socket_base_t*) s_)->recv ((xs::msg_t*) msg_, flags_));
+    s->lock ();
+    int rc = s->recv ((xs::msg_t*) msg_, flags_);
+    s->unlock ();
     if (unlikely (rc < 0))
         return -1;
     return (int) xs_msg_size (msg_);