3 files changed, 28 insertions, 3 deletions
diff --git a/gr-blocks/grc/blocks_delay.block.yml b/gr-blocks/grc/blocks_delay.block.yml
index ac9cb182b7..d5b43704c6 100644
--- a/gr-blocks/grc/blocks_delay.block.yml
+++ b/gr-blocks/grc/blocks_delay.block.yml
@@ -31,6 +31,9 @@ inputs:
     dtype: ${ type }
     vlen: ${ vlen }
     multiplicity: ${ num_ports }
+-   domain: message
+    id: dly
+    optional: true
 
 outputs:
 -   domain: stream
diff --git a/gr-blocks/lib/delay_impl.cc b/gr-blocks/lib/delay_impl.cc
index 6162c7b87a..97e3ecf92f 100644
--- a/gr-blocks/lib/delay_impl.cc
+++ b/gr-blocks/lib/delay_impl.cc
@@ -35,6 +35,9 @@ delay_impl::delay_impl(size_t itemsize, int delay)
     }
     set_dly(delay);
     d_delta = 0;
+
+    message_port_register_in(pmt::mp("dly"));
+    set_msg_handler(pmt::mp("dly"), [this](pmt::pmt_t msg) { this->handle_msg(msg); });
 }
 
 delay_impl::~delay_impl() {}
@@ -53,7 +56,7 @@ void delay_impl::set_dly(int d)
     // protects from quickly-repeated calls to this function that
     // would end with d_delta=0.
     if (d != dly()) {
-        gr::thread::scoped_lock l(d_mutex_delay);
+        gr::thread::scoped_lock l(d_setlock);
         int old = dly();
         set_history(d + 1);
         declare_sample_delay(history() - 1);
@@ -61,12 +64,31 @@ void delay_impl::set_dly(int d)
     }
 }
 
+void delay_impl::handle_msg(pmt::pmt_t msg)
+{
+    if (pmt::is_number(msg)) {
+        int value = pmt::to_long(msg);
+        set_dly(value);
+    } else {
+        if (pmt::is_pair(msg)) {
+            pmt::pmt_t data = pmt::cdr(msg);
+            if (pmt::is_number(data)) {
+                int value = pmt::to_long(data);
+                set_dly(value);
+            } else
+                GR_LOG_WARN(
+                    d_logger,
+                    "Delay message must be a number or a number pair.  Ignoring value.");
+        }
+    }
+}
+
 int delay_impl::general_work(int noutput_items,
                              gr_vector_int& ninput_items,
                              gr_vector_const_void_star& input_items,
                              gr_vector_void_star& output_items)
 {
-    gr::thread::scoped_lock l(d_mutex_delay);
+    gr::thread::scoped_lock l(d_setlock);
     assert(input_items.size() == output_items.size());
 
     const char* iptr;
diff --git a/gr-blocks/lib/delay_impl.h b/gr-blocks/lib/delay_impl.h
index c58de83668..2b39e64ce5 100644
--- a/gr-blocks/lib/delay_impl.h
+++ b/gr-blocks/lib/delay_impl.h
@@ -24,7 +24,7 @@ private:
 
     const size_t d_itemsize;
     int d_delta;
-    gr::thread::mutex d_mutex_delay;
+    void handle_msg(pmt::pmt_t msg);
 
 public:
     delay_impl(size_t itemsize, int delay);