Using CHANNEL_PRINTS to transfer printbuffers to stdout is now working.

luprex/cpp/core/drivenengine.cpp

@@ -168,10 +168,6 @@ void DrivenEngine::set_console_prompt(const eng::string &prompt) {
     console_prompt_ = prompt;
 }
 
-void DrivenEngine::rescan_lua_source(bool b) {
-    rescan_lua_source_ = b;
-}
-
 void DrivenEngine::set_visible_world_and_actor(World *w, int64_t id) {
     visible_world_ = w;
     visible_actor_id_ = id;
@@ -192,6 +188,7 @@ DrivenEngine::DrivenEngine() {
     channels_[0] = stdio_channel_;
     rescan_lua_source_ = false;
     clock_ = 0.0;
+    have_prints_ = false;
     stop_driver_ = false;
 }
 
@@ -381,6 +378,10 @@ double DrivenEngine::drv_get_clock() const {
     return clock_;
 }
 
+bool DrivenEngine::drv_get_have_prints() const {
+    return have_prints_;
+}
+
 bool DrivenEngine::drv_get_rescan_lua_source() const {
     return rescan_lua_source_;
 }
@@ -536,6 +537,10 @@ static double drv_get_clock(EngineWrapper *w) {
     return w->engine->drv_get_clock();
 }
 
+static bool drv_get_have_prints(EngineWrapper *w) {
+    return w->engine->drv_get_have_prints();
+}
+
 static bool drv_get_rescan_lua_source(EngineWrapper *w) {
     return w->engine->drv_get_rescan_lua_source();
 }
@@ -913,6 +918,7 @@ static void init_engine_wrapper_helper(EngineWrapper *w) {
     w->get_outgoing_empty = drv_get_outgoing_empty;
     w->get_console_prompt = drv_get_console_prompt;
     w->get_clock = drv_get_clock;
+    w->get_have_prints = drv_get_have_prints;
     w->get_rescan_lua_source = drv_get_rescan_lua_source;
     w->get_stop_driver = drv_get_stop_driver;
     w->get_actor_id = drv_get_actor_id;

luprex/cpp/core/drivenengine.hpp

@@ -218,7 +218,12 @@ public:
     // DRIVER: this merely sets a flag, which the driver will notice later,
     // causing the driver to update the lua source.
     //
-    void rescan_lua_source(bool b);
+    void rescan_lua_source(bool b) { rescan_lua_source_ = b; }
+
+    // Set the flag to indicate that you have something you want to
+    // print.  This will trigger the driver to access CHANNEL_PRINTS.
+    //
+    void set_have_prints(bool b) { have_prints_ = b; }
 
     // Set the world pointer and the actor ID.
     //
@@ -274,6 +279,7 @@ public:
     bool drv_get_outgoing_empty(uint32_t chid) const;
     void drv_get_console_prompt(uint32_t *len, const char **data) const;
     double drv_get_clock() const;
+    bool drv_get_have_prints() const;
     bool drv_get_rescan_lua_source() const;
     bool drv_get_stop_driver() const;
     int64_t drv_get_actor_id() const;
@@ -310,6 +316,7 @@ private:
     StreamBuffer call_function_retpk_;
     bool rescan_lua_source_;
     double clock_;
+    bool have_prints_;
     bool stop_driver_;
     eng::string console_prompt_;
     friend class Channel;

luprex/cpp/core/enginewrapper.hpp

@@ -115,6 +115,11 @@ struct EngineWrapper {
     //
     double (*get_clock)(EngineWrapper *w);
 
+    // Check the 'have prints' flag.  If true, then the engine
+    // wants the driver to use CHANNEL_PRINTS to obtain prints.
+    //
+    bool (*get_have_prints)(EngineWrapper *w);
+
     // Check the 'rescan_lua_source' flag.  If this flag is set, it means
     // that the engine wants the driver to rescan the lua source code.
     // When the driver sees this flag, it should rescan the source and call

luprex/cpp/core/lpxclient.cpp

@@ -276,6 +276,7 @@ public:
                 if (print_channeler_.channel(world_->get_printbuffer(actor_id_), retpk)) {
                     send_invocation(print_channeler_.invocation(actor_id_));
                 }
+                set_have_prints(false);
                 break;
             }
             default: {
@@ -313,6 +314,8 @@ public:
                 world_to_asynchronous();
             }
         }
+
+        set_have_prints(print_channeler_.have_prints(world_->get_printbuffer(actor_id_)));
     }
 };
 

luprex/cpp/core/lpxserver.cpp

@@ -202,6 +202,7 @@ public:
                 if (print_channeler_.channel(master_->get_printbuffer(admin_id_), retpk)) {
                     master_->invoke(print_channeler_.invocation(admin_id_));
                 }
+                set_have_prints(false);
                 break;
             }
             default: {
@@ -354,6 +355,9 @@ public:
             }
         }
         util::remove_marked_items(http_server_channels_);
+
+        // Notify the driver if there are any prints.
+        set_have_prints(print_channeler_.have_prints(master_->get_printbuffer(admin_id_)));
     }
 };
 

luprex/cpp/core/printbuffer.cpp

@@ -179,6 +179,13 @@ void PrintBuffer::patch(StreamBuffer *sb, DebugCollector *dbc) {
     }
 }
 
+bool PrintChanneler::have_prints(const PrintBuffer *printbuffer) const
+{
+    return ((printbuffer != nullptr) &&
+            (printbuffer->first_line() < printbuffer->first_unchecked()) &&
+            (line_ < printbuffer->first_unchecked()));
+}
+
 bool PrintChanneler::channel(const PrintBuffer *printbuffer, StreamBuffer *sb) {
     if (printbuffer == nullptr) return false;
     if (printbuffer->first_line() > line_) {

luprex/cpp/core/printbuffer.hpp

@@ -149,6 +149,9 @@ public:
     // Reset the print channeler.
     void reset() { line_ = 0; }
     
+    // Check if there's anything to channel.
+    bool have_prints(const PrintBuffer *pb) const;
+
     // Copy any new lines from the printbuffer to the stream buffer.
     // Update the current line number.  Return true if the printbuffer
     // contains any lines that have already been channeled.