From 2acbe5e19b6daf254adebc742926834220f4b27f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Tue, 7 Nov 2023 11:52:20 +0000
Subject: [PATCH 1/9] Initial test implementation of output message queuing.

---
 Makefile.am                  |   3 +-
 source/server/main.c         |  46 ++++++++-----
 source/server/output-queue.c | 129 +++++++++++++++++++++++++++++++++++
 source/server/output-queue.h |  61 +++++++++++++++++
 4 files changed, 220 insertions(+), 19 deletions(-)
 create mode 100644 source/server/output-queue.c
 create mode 100644 source/server/output-queue.h

diff --git a/Makefile.am b/Makefile.am
index 6f59a34..37985b6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -8,7 +8,8 @@ SilverMUDServer_SOURCES = \
 	source/server/player-data.c \
 	source/server/connections.c \
 	source/server/scheme-integration.c \
-	source/server/main.c 
+	source/server/output-queue.c \
+	source/server/main.c
 
 SilverMUDClient_SOURCES = \
 	source/messages.c \
diff --git a/source/server/main.c b/source/server/main.c
index a7bab43..23fac61 100644
--- a/source/server/main.c
+++ b/source/server/main.c
@@ -19,6 +19,7 @@
 #include <netinet/in.h>
 #include <gnutls/gnutls.h>
 
+#include "output-queue.h"
 #include "player-data.h"
 #include "connections.h"
 #include "../messages.h"
@@ -104,7 +105,7 @@ int main (int argc, char ** argv)
 
 	// Create some structures needed to store global state:
 	struct PlayerList * globalPlayerList = createPlayerList();
-	
+	struct OutputQueue * globalOutputQueue = createOutputQueue();
 	// Start a REPL thread:
 	//pthread_t schemeREPLThread;
 	//pthread_create(&schemeREPLThread, NULL, schemeREPLHandler, NULL);
@@ -213,23 +214,10 @@ int main (int argc, char ** argv)
 							continue;
 						}
 						// ONLY FOR DEMO
-						
-						struct ServerToClientMessage outputMessage;
-
-						// Copy the message to the output format:
-						outputMessage.type = LOCAL_CHAT;
-						
-						strncpy(outputMessage.name, connection->player->name, 64);
-						strncpy(outputMessage.content, message.content, MESSAGE_CONTENT_LENGTH);
-
-						// Echo the message into all other clients: (Temporary)
-						struct ClientConnectionNode * currentClient = clientConnections.head;
-						while (currentClient != NULL)
-						{
-							gnutls_record_send(*currentClient->connection->tlsSession, &outputMessage,
-											   sizeof(struct ServerToClientMessage));
-							currentClient = currentClient->next;
-						}					
+]					   
+						pushOutputMessage(globalOutputQueue, false, globalPlayerList, LOCAL_CHAT,
+										  connection->player->name, message.content,
+										  MESSAGE_NAME_LENGTH,  MESSAGE_CONTENT_LENGTH);						
 					}
 				}
 				else
@@ -241,7 +229,29 @@ int main (int argc, char ** argv)
 					close(events[index].data.fd);
 					removeConnectionByFileDescriptor(&clientConnections, events[index].data.fd);
 				}
+			} 
+		}
+
+		// Output the queue:
+		struct OutputMessage * currentMessage = NULL;
+		while (globalOutputQueue->count != 0)
+		{
+			currentMessage = popOutputMessage(globalOutputQueue);
+			struct PlayerListNode * currentPlayerNode = currentMessage->recepients->head;
+
+			while (currentPlayerNode != NULL)
+			{
+				gnutls_record_send(*currentPlayerNode->player->connection->tlsSession,
+								   currentMessage->message, sizeof(struct ServerToClientMessage));
+				currentPlayerNode = currentPlayerNode->next;
 			}
+
+			if (currentMessage->deallocatePlayerList == true)
+			{
+				deallocatePlayerList(&currentMessage->recepients);
+			}
+			
+			deallocateOutputMessage(&currentMessage);
 		}
 	}
 	
diff --git a/source/server/output-queue.c b/source/server/output-queue.c
new file mode 100644
index 0000000..906638f
--- /dev/null
+++ b/source/server/output-queue.c
@@ -0,0 +1,129 @@
+// =========================================
+// | SilverMUD Server - output-queue.c     |
+// | Copyright (C) 2023, Barra Ó Catháin   |
+// | See end of file for copyright notice. |
+// =========================================
+#include <string.h>
+#include <stdbool.h>
+#include <pthread.h>
+#include "output-queue.h"
+
+struct OutputQueue * const createOutputQueue()
+{
+	// Allocate a new queue:
+	struct OutputQueue * const newQueue = calloc(1, sizeof(struct OutputQueue));
+
+	// Initialize it:
+	pthread_mutex_init(&newQueue->mutex, NULL);
+	newQueue->count = 0;
+	newQueue->front = NULL;
+	newQueue->back = NULL;
+
+	// Return the new queue:
+	return newQueue;
+}
+
+size_t pushOutputMessage(struct OutputQueue * const queue,
+						 const bool deallocatePlayerList,
+						 struct PlayerList * const recepients,
+						 const enum MessageTypes type,
+						 const char const * name, const char const * content,
+						 const size_t nameLength, const size_t contentLength)
+{
+	// Allocate the appropriate memory for the queued message:
+	struct OutputMessage * newMessage = calloc(1, sizeof(struct OutputMessage));
+	newMessage->message = calloc(1, sizeof(struct ServerToClientMessage));
+
+	// Copy in the appropriate values to the ServerToClientMessage:
+	newMessage->message->type = type;
+	
+	strncpy(newMessage->message->name, name, (nameLength < MESSAGE_NAME_LENGTH) ?
+			nameLength : MESSAGE_NAME_LENGTH);
+	newMessage->message->name[MESSAGE_NAME_LENGTH - 1] = '\0';
+
+	strncpy(newMessage->message->content, content, (contentLength < MESSAGE_CONTENT_LENGTH) ?
+			contentLength : MESSAGE_CONTENT_LENGTH);
+	newMessage->message->content[MESSAGE_CONTENT_LENGTH - 1] = '\0';
+
+	// Copy in the appropriate values to the OutputMessage:
+	newMessage->deallocatePlayerList = deallocatePlayerList;
+	newMessage->recepients = recepients;
+
+	// Entering critical section - Lock the queue:
+	pthread_mutex_lock(&queue->mutex);
+
+	// Add it to the queue:
+	if (queue->back != NULL)
+	{
+		queue->back->next = newMessage;
+		queue->back = newMessage;
+	}
+	
+	if (queue->front == NULL)
+	{
+		queue->front = newMessage;
+		queue->back = newMessage;
+	}
+	
+	queue->count++;
+	
+	// Leaving critical section - Unlock the queue:
+	pthread_mutex_unlock(&queue->mutex);
+
+	return queue->count;
+}
+
+struct OutputMessage * popOutputMessage(struct OutputQueue * queue)
+{
+	if (queue->count == 0)
+	{
+		return NULL;
+	}
+	
+	// Entering the critical section - Lock the queue:
+	pthread_mutex_lock(&queue->mutex);
+
+	struct OutputMessage * message = queue->front;
+	queue->count--;
+
+	if(queue->count == 0)
+	{
+		queue->front = NULL;
+		queue->back = NULL;
+	}
+
+	else
+	{
+		queue->front = queue->front->next;
+	}
+
+	// Leaving the critical section - Unlock the queue:
+	pthread_mutex_unlock(&queue->mutex);
+
+	return message;
+}
+
+void deallocateOutputMessage(struct OutputMessage ** message)
+{
+	// Free and set the pointer to NULL:
+	free(*message);
+	message = NULL;
+}
+
+// ====================================================
+// | End of output-queue.c, copyright notice follows. |
+// ====================================================
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
diff --git a/source/server/output-queue.h b/source/server/output-queue.h
new file mode 100644
index 0000000..d2b1f9a
--- /dev/null
+++ b/source/server/output-queue.h
@@ -0,0 +1,61 @@
+// =========================================
+// | SilverMUD Server - output-queue.h     |
+// | Copyright (C) 2023, Barra Ó Catháin   |
+// | See end of file for copyright notice. |
+// =========================================
+#ifndef OUTPUT_QUEUE_H
+#define OUTPUT_QUEUE_H
+#include <stdbool.h>
+#include <pthread.h>
+
+#include "../messages.h"
+
+struct OutputMessage
+{
+	// Allows for easy reuse of existing player lists, such as the global list
+	// or an area's playerlist:	
+	bool deallocatePlayerList;
+	
+	struct OutputMessage * next;
+	struct PlayerList * recepients;
+	struct ServerToClientMessage * message;
+};
+
+struct OutputQueue
+{
+	pthread_mutex_t mutex;
+	size_t count;
+	struct OutputMessage * front, * back;	
+};
+
+struct OutputQueue * const createOutputQueue();
+
+size_t pushOutputMessage(struct OutputQueue * const queue,
+						 const bool deallocatePlayerList,
+						 struct PlayerList * const recepients,
+						 const enum MessageTypes type,
+						 const char const * name, const char const * content,
+						 const size_t nameLength, const size_t contentLength);
+	
+struct OutputMessage * popOutputMessage();
+
+void deallocateOutputMessage(struct OutputMessage ** message);
+
+#endif
+// ====================================================
+// | End of output-queue.h, copyright notice follows. |
+// ====================================================
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+

From e11a7b3a76d305c2bbbb1b103c299f46ac24f10b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Tue, 7 Nov 2023 22:46:15 +0000
Subject: [PATCH 2/9] Basic global messaging functions for Scheme

---
 source/server/main.c               |  9 +++++++--
 source/server/output-queue.h       |  6 +++---
 source/server/scheme-integration.c | 30 +++++++++++++++++++++++++++++-
 source/server/scheme-integration.h |  2 ++
 4 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/source/server/main.c b/source/server/main.c
index 23fac61..fdc4475 100644
--- a/source/server/main.c
+++ b/source/server/main.c
@@ -106,6 +106,11 @@ int main (int argc, char ** argv)
 	// Create some structures needed to store global state:
 	struct PlayerList * globalPlayerList = createPlayerList();
 	struct OutputQueue * globalOutputQueue = createOutputQueue();
+
+	scm_c_define_gsubr("push-output-message", 6, 0, 0, &push_output_message);
+	scm_c_define("*globalPlayerList*", scm_from_pointer(globalPlayerList, NULL));
+	scm_c_define("*globalOutputQueue*", scm_from_pointer(globalOutputQueue, NULL));
+	
 	// Start a REPL thread:
 	//pthread_t schemeREPLThread;
 	//pthread_create(&schemeREPLThread, NULL, schemeREPLHandler, NULL);
@@ -214,10 +219,10 @@ int main (int argc, char ** argv)
 							continue;
 						}
 						// ONLY FOR DEMO
-]					   
+
 						pushOutputMessage(globalOutputQueue, false, globalPlayerList, LOCAL_CHAT,
 										  connection->player->name, message.content,
-										  MESSAGE_NAME_LENGTH,  MESSAGE_CONTENT_LENGTH);						
+										  MESSAGE_NAME_LENGTH,  MESSAGE_CONTENT_LENGTH);
 					}
 				}
 				else
diff --git a/source/server/output-queue.h b/source/server/output-queue.h
index d2b1f9a..b988ba8 100644
--- a/source/server/output-queue.h
+++ b/source/server/output-queue.h
@@ -14,8 +14,8 @@ struct OutputMessage
 {
 	// Allows for easy reuse of existing player lists, such as the global list
 	// or an area's playerlist:	
-	bool deallocatePlayerList;
-	
+	bool deallocatePlayerList;	
+
 	struct OutputMessage * next;
 	struct PlayerList * recepients;
 	struct ServerToClientMessage * message;
@@ -37,7 +37,7 @@ size_t pushOutputMessage(struct OutputQueue * const queue,
 						 const char const * name, const char const * content,
 						 const size_t nameLength, const size_t contentLength);
 	
-struct OutputMessage * popOutputMessage();
+struct OutputMessage * popOutputMessage(struct OutputQueue * queue);
 
 void deallocateOutputMessage(struct OutputMessage ** message);
 
diff --git a/source/server/scheme-integration.c b/source/server/scheme-integration.c
index 56bd86d..ce61391 100644
--- a/source/server/scheme-integration.c
+++ b/source/server/scheme-integration.c
@@ -3,9 +3,37 @@
 // | Copyright (C) 2023, Barra Ó Catháin     |
 // | See end of file for copyright notice.   |
 // ===========================================
+#include <stdbool.h>
 #include <libguile.h>
 
-SCM scheme_get_player_by_name(SCM name);
+#include "../messages.h"
+#include "output-queue.h"
+
+SCM scheme_get_player_by_name(SCM name, SCM queue);
+
+SCM push_output_message(SCM queue, SCM deallocate_list, SCM recepients, SCM type, SCM name, SCM content)
+{
+	// Convert our scheme values into appropriate data types:
+	struct OutputQueue * queue_c = scm_to_pointer(queue);
+	bool deallocate_list_c = scm_to_bool(deallocate_list);
+	struct PlayerList * recepients_c = scm_to_pointer(recepients);
+	enum MessageTypes type_c = scm_to_int(type);
+
+	// Turn the Scheme strings into C strings:
+	size_t nameLength, contentLength;
+	char * name_c = scm_to_locale_stringn(name, &nameLength);
+	char * content_c = scm_to_locale_stringn(content, &contentLength);
+
+	// Call the C function:
+	pushOutputMessage(queue_c, deallocate_list_c, recepients_c, type_c, name_c, content_c,
+					  nameLength, contentLength);
+
+	// Free the created C strings:
+	free(name_c);
+	free(content_c);
+
+	return SCM_BOOL_T;
+}
 
 // ==========================================================
 // | End of scheme-integration.c, copyright notice follows. |
diff --git a/source/server/scheme-integration.h b/source/server/scheme-integration.h
index 9992bfb..41accfc 100644
--- a/source/server/scheme-integration.h
+++ b/source/server/scheme-integration.h
@@ -8,6 +8,8 @@
 
 SCM scheme_get_player_by_name(SCM name);
 
+SCM push_output_message(SCM queue, SCM deallocate_list, SCM recepients, SCM type, SCM name, SCM content);
+
 #endif
 // ==========================================================
 // | End of scheme-integration.h, copyright notice follows. |

From 2e813ae29c3bc0865d31a47296232ce0a62a72a1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Thu, 9 Nov 2023 23:51:50 +0000
Subject: [PATCH 3/9] Added independent output thread.

---
 .gitignore                   |  4 +++-
 Makefile.am                  |  2 ++
 configure.ac                 |  4 +---
 source/server/main.c         | 26 ++++----------------------
 source/server/output-queue.c | 31 +++++++++++++++++++++++++++++++
 source/server/output-queue.h |  2 ++
 6 files changed, 43 insertions(+), 26 deletions(-)

diff --git a/.gitignore b/.gitignore
index 7d9403b..c9e1630 100644
--- a/.gitignore
+++ b/.gitignore
@@ -108,4 +108,6 @@ SilverMUDServer
 SilverMUDClient
 config.h
 config.h.in
-stamp-h1
\ No newline at end of file
+stamp-h1
+
+build/
\ No newline at end of file
diff --git a/Makefile.am b/Makefile.am
index 37985b6..f239522 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,5 +1,7 @@
 bin_PROGRAMS = SilverMUDServer SilverMUDClient
 dist_doc_DATA = README.org
+schemedir = $(pkgdatadir)/scheme
+dist_scheme_DATA = lisp
 SilverMUDServer_CFLAGS = -lgnutls -g $(GUILE_CFLAGS) $(GUILE_LIBS)
 SilverMUDClient_CFLAGS = -lgnutls -g -lncurses $(GUILE_CFLAGS) $(GUILE_LIBS)
 
diff --git a/configure.ac b/configure.ac
index 1151bc2..9e4bdeb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,8 +2,6 @@ AC_INIT([SilverMUD], [0.0.1], [barra@ocathain.ie])
 AM_INIT_AUTOMAKE([-Wall -Werror foreign subdir-objects])
 AC_PROG_CC
 AC_CONFIG_HEADERS([source/config.h])
-AC_CONFIG_FILES([
-	Makefile
-])
+AC_CONFIG_FILES([Makefile])
 PKG_CHECK_MODULES([GUILE], [guile-3.0])
 AC_OUTPUT
diff --git a/source/server/main.c b/source/server/main.c
index fdc4475..50ca891 100644
--- a/source/server/main.c
+++ b/source/server/main.c
@@ -110,6 +110,10 @@ int main (int argc, char ** argv)
 	scm_c_define_gsubr("push-output-message", 6, 0, 0, &push_output_message);
 	scm_c_define("*globalPlayerList*", scm_from_pointer(globalPlayerList, NULL));
 	scm_c_define("*globalOutputQueue*", scm_from_pointer(globalOutputQueue, NULL));
+
+	// Start an output thread:
+	pthread_t outputThread;
+	pthread_create(&outputThread, NULL, outputThreadHandler, (void *)globalOutputQueue);
 	
 	// Start a REPL thread:
 	//pthread_t schemeREPLThread;
@@ -236,28 +240,6 @@ int main (int argc, char ** argv)
 				}
 			} 
 		}
-
-		// Output the queue:
-		struct OutputMessage * currentMessage = NULL;
-		while (globalOutputQueue->count != 0)
-		{
-			currentMessage = popOutputMessage(globalOutputQueue);
-			struct PlayerListNode * currentPlayerNode = currentMessage->recepients->head;
-
-			while (currentPlayerNode != NULL)
-			{
-				gnutls_record_send(*currentPlayerNode->player->connection->tlsSession,
-								   currentMessage->message, sizeof(struct ServerToClientMessage));
-				currentPlayerNode = currentPlayerNode->next;
-			}
-
-			if (currentMessage->deallocatePlayerList == true)
-			{
-				deallocatePlayerList(&currentMessage->recepients);
-			}
-			
-			deallocateOutputMessage(&currentMessage);
-		}
 	}
 	
 	// Wait for all other threads to terminate:
diff --git a/source/server/output-queue.c b/source/server/output-queue.c
index 906638f..5e565f9 100644
--- a/source/server/output-queue.c
+++ b/source/server/output-queue.c
@@ -6,8 +6,39 @@
 #include <string.h>
 #include <stdbool.h>
 #include <pthread.h>
+#include "player-data.h"
 #include "output-queue.h"
 
+// A thread handler for constantly outputting messages from an output queue:
+void * outputThreadHandler(void * outputQueue)
+{
+	struct OutputQueue * queue = (struct OutputQueue *)outputQueue;	
+	struct OutputMessage * currentMessage = NULL;
+	
+	while (true)
+	{
+			currentMessage = popOutputMessage(queue);
+			if (currentMessage != NULL)
+			{
+				struct PlayerListNode * currentPlayerNode = currentMessage->recepients->head;
+
+				while (currentPlayerNode != NULL)
+				{
+					gnutls_record_send(*currentPlayerNode->player->connection->tlsSession,
+									   currentMessage->message, sizeof(struct ServerToClientMessage));
+					currentPlayerNode = currentPlayerNode->next;
+				}
+
+				if (currentMessage->deallocatePlayerList == true)
+				{
+					deallocatePlayerList(&currentMessage->recepients);
+				}
+			
+				deallocateOutputMessage(&currentMessage);
+			}
+	}
+}
+
 struct OutputQueue * const createOutputQueue()
 {
 	// Allocate a new queue:
diff --git a/source/server/output-queue.h b/source/server/output-queue.h
index b988ba8..ebe7d51 100644
--- a/source/server/output-queue.h
+++ b/source/server/output-queue.h
@@ -28,6 +28,8 @@ struct OutputQueue
 	struct OutputMessage * front, * back;	
 };
 
+void * outputThreadHandler(void * outputQueue);
+
 struct OutputQueue * const createOutputQueue();
 
 size_t pushOutputMessage(struct OutputQueue * const queue,

From 3309c034c4cd2088c18d5a9483cfb8f8656d98f3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Mon, 20 Nov 2023 21:26:21 +0000
Subject: [PATCH 4/9] Update output queue to not pin the CPU (proper waiting)

---
 source/server/output-queue.c | 42 +++++++++++++++++++++---------------
 source/server/output-queue.h |  2 ++
 2 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/source/server/output-queue.c b/source/server/output-queue.c
index 5e565f9..ba97b69 100644
--- a/source/server/output-queue.c
+++ b/source/server/output-queue.c
@@ -17,25 +17,30 @@ void * outputThreadHandler(void * outputQueue)
 	
 	while (true)
 	{
-			currentMessage = popOutputMessage(queue);
-			if (currentMessage != NULL)
+		if (queue->count == 0)
+		{
+			pthread_cond_wait(&queue->updated, &queue->waitMutex);
+		}
+		
+		currentMessage = popOutputMessage(queue);		   
+		if (currentMessage != NULL)
+		{
+			struct PlayerListNode * currentPlayerNode = currentMessage->recepients->head;
+
+			while (currentPlayerNode != NULL)
 			{
-				struct PlayerListNode * currentPlayerNode = currentMessage->recepients->head;
-
-				while (currentPlayerNode != NULL)
-				{
-					gnutls_record_send(*currentPlayerNode->player->connection->tlsSession,
-									   currentMessage->message, sizeof(struct ServerToClientMessage));
-					currentPlayerNode = currentPlayerNode->next;
-				}
-
-				if (currentMessage->deallocatePlayerList == true)
-				{
-					deallocatePlayerList(&currentMessage->recepients);
-				}
-			
-				deallocateOutputMessage(&currentMessage);
+				gnutls_record_send(*currentPlayerNode->player->connection->tlsSession,
+								   currentMessage->message, sizeof(struct ServerToClientMessage));
+				currentPlayerNode = currentPlayerNode->next;
 			}
+
+			if (currentMessage->deallocatePlayerList == true)
+			{
+				deallocatePlayerList(&currentMessage->recepients);
+			}
+			
+			deallocateOutputMessage(&currentMessage);
+		}
 	}
 }
 
@@ -46,6 +51,7 @@ struct OutputQueue * const createOutputQueue()
 
 	// Initialize it:
 	pthread_mutex_init(&newQueue->mutex, NULL);
+	pthread_cond_init(&newQueue->updated, NULL);
 	newQueue->count = 0;
 	newQueue->front = NULL;
 	newQueue->back = NULL;
@@ -101,6 +107,8 @@ size_t pushOutputMessage(struct OutputQueue * const queue,
 	// Leaving critical section - Unlock the queue:
 	pthread_mutex_unlock(&queue->mutex);
 
+	pthread_cond_signal(&queue->updated);
+	
 	return queue->count;
 }
 
diff --git a/source/server/output-queue.h b/source/server/output-queue.h
index ebe7d51..2af4768 100644
--- a/source/server/output-queue.h
+++ b/source/server/output-queue.h
@@ -24,6 +24,8 @@ struct OutputMessage
 struct OutputQueue
 {
 	pthread_mutex_t mutex;
+	pthread_mutex_t waitMutex;
+	pthread_cond_t updated;
 	size_t count;
 	struct OutputMessage * front, * back;	
 };

From 4fa677c09a7925f54d06f4363c17ad1d165211ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Mon, 20 Nov 2023 21:30:30 +0000
Subject: [PATCH 5/9] Update C Codebase to use modules for Scheme primitives

---
 source/server/main.c               | 20 ++++++++++++--------
 source/server/scheme-integration.c | 12 +++++++++++-
 source/server/scheme-integration.h |  8 ++++++++
 3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/source/server/main.c b/source/server/main.c
index 50ca891..a7b5d5f 100644
--- a/source/server/main.c
+++ b/source/server/main.c
@@ -37,11 +37,6 @@ int main (int argc, char ** argv)
 	// Initialize Scheme:
 	scm_init_guile();
 
-	// Start the REPL server on a UNIX socket:
-	scm_c_eval_string("(begin (use-modules (system repl server))"
-					  "(if (file-exists? \"silvermud-repl\") (delete-file \"silvermud-repl\"))"
-					  "(spawn-server (make-unix-domain-server-socket #:path \"silvermud-repl\")))");
-
 	// Create a socket to listen for connections on:
 	int masterSocket = socket(AF_INET, SOCK_STREAM, 0);
 	if (masterSocket < 0)
@@ -107,10 +102,19 @@ int main (int argc, char ** argv)
 	struct PlayerList * globalPlayerList = createPlayerList();
 	struct OutputQueue * globalOutputQueue = createOutputQueue();
 
-	scm_c_define_gsubr("push-output-message", 6, 0, 0, &push_output_message);
-	scm_c_define("*globalPlayerList*", scm_from_pointer(globalPlayerList, NULL));
-	scm_c_define("*globalOutputQueue*", scm_from_pointer(globalOutputQueue, NULL));
+	// Define a module for use in the REPL containing our needed primitives:
+	SchemeModulePointers schemePointers;
+	schemePointers.globalPlayerList = globalPlayerList;
+	schemePointers.globalOutputQueue = globalOutputQueue;
+	
+	scm_c_define_module("silvermud primitives", initialize_silvermud_primitives, &schemePointers);
+	scm_c_use_module("silvermud primitives");
 
+	// Start the REPL server on a UNIX socket:
+	scm_c_eval_string("(begin (use-modules (system repl server))"
+					  "(if (file-exists? \"silvermud-repl\") (delete-file \"silvermud-repl\"))"
+					  "(spawn-server (make-unix-domain-server-socket #:path \"silvermud-repl\")))");
+	
 	// Start an output thread:
 	pthread_t outputThread;
 	pthread_create(&outputThread, NULL, outputThreadHandler, (void *)globalOutputQueue);
diff --git a/source/server/scheme-integration.c b/source/server/scheme-integration.c
index ce61391..de95aa2 100644
--- a/source/server/scheme-integration.c
+++ b/source/server/scheme-integration.c
@@ -8,8 +8,18 @@
 
 #include "../messages.h"
 #include "output-queue.h"
+#include "scheme-integration.h"
 
-SCM scheme_get_player_by_name(SCM name, SCM queue);
+void initialize_silvermud_primitives (void * gameState)
+{
+	SchemeModulePointers * pointers = (SchemeModulePointers *)gameState;
+	scm_c_define_gsubr("push-output-message", 6, 0, 0, &push_output_message);
+	scm_c_define("*global-player-list*", scm_from_pointer(pointers->globalPlayerList, NULL));
+	scm_c_define("*global-output-queue*", scm_from_pointer(pointers->globalOutputQueue, NULL));
+	scm_c_export("push-output-message", "*global-player-list*", "*global-output-queue*", NULL);
+}
+
+//SCM scheme_get_player_by_name(SCM name, SCM queue)
 
 SCM push_output_message(SCM queue, SCM deallocate_list, SCM recepients, SCM type, SCM name, SCM content)
 {
diff --git a/source/server/scheme-integration.h b/source/server/scheme-integration.h
index 41accfc..64d396a 100644
--- a/source/server/scheme-integration.h
+++ b/source/server/scheme-integration.h
@@ -6,6 +6,14 @@
 #ifndef SCHEME_INTEGRATION_H
 #define SCHEME_INTEGRATION_H
 
+typedef struct SchemeModulePointers
+{
+	struct PlayerList * globalPlayerList;
+	struct OutputQueue * globalOutputQueue;
+} SchemeModulePointers;
+
+void initialize_silvermud_primitives (void * gameState);
+
 SCM scheme_get_player_by_name(SCM name);
 
 SCM push_output_message(SCM queue, SCM deallocate_list, SCM recepients, SCM type, SCM name, SCM content);

From 3873192547f6544d9d58d143d62d7c0735401116 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Mon, 20 Nov 2023 21:32:53 +0000
Subject: [PATCH 6/9] Basic Scheme implementations of player structures and
 messaging.

---
 lisp/messaging.scm  | 18 ++++++++++++
 lisp/structures.scm | 67 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 lisp/messaging.scm
 create mode 100644 lisp/structures.scm

diff --git a/lisp/messaging.scm b/lisp/messaging.scm
new file mode 100644
index 0000000..fdf7dc4
--- /dev/null
+++ b/lisp/messaging.scm
@@ -0,0 +1,18 @@
+;;;; This file is part of SilverMUD.
+;;;; structures.scm defines various variables and functions used for interacting with the player's
+;;;; via chat output from the Scheme enviroment of SilverMUD.
+(define-module (silvermud messaging))
+(use-modules (silvermud primitives))
+
+(define message-everyone (lambda (name content)
+						   (push-output-message *global-output-queue* #f *global-player-list*
+												8 name content)))
+(define system-message (lambda (contennt)
+						 (push-output-message *global-output-queue* #f *global-player-list*
+											  0 "" content)))
+
+(define message-expression (lambda (expression)
+							 (system-message (format #f "~a" expression))))
+
+;; Export everything!
+(export message-everyone system-message message-expression)
diff --git a/lisp/structures.scm b/lisp/structures.scm
new file mode 100644
index 0000000..cc45cc1
--- /dev/null
+++ b/lisp/structures.scm
@@ -0,0 +1,67 @@
+;;;; This file is part of SilverMUD.
+;;;; structures.scm defines various variables and functions used for interacting with C structures
+;;;; from the Scheme enviroment of SilverMUD.
+(define-module (silvermud structures))
+(use-modules (system foreign)
+			 (silvermud primitives))
+
+;;; struct PlayerList:
+
+;; The layout of the struct PlayerList:
+(define *player-list-structure* (list size_t '* '*))
+
+;; Pretty-format the player list header:
+(define (player-list-header->string player-list-pointer)
+  "Format a struct PlayerList pointer into a string."
+  (if (not (null-pointer? player-list-pointer))
+	  (let ((structure (parse-c-struct player-list-pointer *player-list-structure*)))
+		(format #f
+				"Players in list: ~d.\nHead: ~a. \nTail: ~a.\n"
+				(list-ref structure 0) (list-ref structure 1) (list-ref structure 2)))))
+
+;; Create a list of strings representing all players in a list:
+(define (list-players player-list-pointer)
+  "List all players in a given C PlayerList as a list of strings."
+  (if (not (null-pointer? player-list-pointer)) ; Check we're not dereferencing a null pointer.
+	  (build-list-players
+	   (list-ref (parse-c-struct player-list-pointer *player-list-node-structure*) 2))))
+
+(define (build-list-players pointer)
+  (if (not (null-pointer? pointer))
+	  (let* ((node (parse-c-struct pointer *player-list-node-structure*))
+			(player (parse-c-struct (list-ref node 0) *player-structure*)))
+		(cons (pointer->string (list-ref player 1)) (build-list-players (list-ref node 1))))
+	  '()))
+
+;;; struct PlayerListNode:
+
+;; Used to interact with struct PlayerListNode:
+(define *player-list-node-structure* (list '* '* '*))
+
+;; Pretty-format the player list node:
+(define (player-list-node->string player-list-node-pointer)
+  "Format a struct PlayerListNode pointer into a string."
+  (if (not (null-pointer? player-list-node-pointer))
+	  (let ((structure (parse-c-struct player-list-node-pointer *player-list-node-structure*)))
+		(format #f
+				"Player pointer: ~a.\nNext: ~a. \nPrevious: ~a.\n"
+				(list-ref structure 0) (list-ref structure 1) (list-ref structure 2)))))
+
+;;; struct Player:
+
+; Used to interact with struct Player:
+(define *player-structure* (list '* '*))
+
+(define (player->string player-info-pointer)
+  "Format a struct Player pointer into a string."
+  (if (not (null-pointer? player-info-pointer))
+	  (let ((structure (parse-c-struct player-info-pointer *player-structure*)))
+		(display (null-pointer? (list-ref structure 1)))
+		(format #f
+				"Player Name: ~a\n" (if (null-pointer? (list-ref structure 1))	 
+										(pointer->bytevector (list-ref structure 1) 64)
+										#f)))))
+
+;; Export everything!
+(export *player-list-structure* *player-list-node-structure* *player-structure*
+		player->string player-list-header->string player-list-node->string list-players)

From 30e63d36b5911b20723410001ff4d7d34b6ccce2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Mon, 20 Nov 2023 21:33:45 +0000
Subject: [PATCH 7/9] Changed player names to allocated strings to be friendly
 to Scheme!

---
 source/server/player-data.c | 2 ++
 source/server/player-data.h | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/source/server/player-data.c b/source/server/player-data.c
index c3d530d..923546d 100644
--- a/source/server/player-data.c
+++ b/source/server/player-data.c
@@ -31,6 +31,7 @@ struct Player * createNewPlayer(struct ClientConnection * connection)
 {
 	struct Player * newPlayer = calloc(1, sizeof(struct Player));
 	newPlayer->connection = connection;
+	newPlayer->name = calloc(PLAYER_NAME_LENGTH, sizeof(char));
 	
 	return newPlayer;
 }
@@ -38,6 +39,7 @@ struct Player * createNewPlayer(struct ClientConnection * connection)
 // Deallocates a player:
 void deallocatePlayer(struct Player ** player)
 {
+	free((*player)->name);
 	free(*player);
 	*player = NULL;
 }
diff --git a/source/server/player-data.h b/source/server/player-data.h
index d908e5e..7547512 100644
--- a/source/server/player-data.h
+++ b/source/server/player-data.h
@@ -5,6 +5,7 @@
 // =========================================
 #ifndef PLAYER_DATA_H
 #define PLAYER_DATA_H
+#define PLAYER_NAME_LENGTH 64
 #include <stdbool.h>
 #include "connections.h"
 
@@ -14,7 +15,7 @@
 struct Player
 {
 	struct ClientConnection * connection;
-	char name[64];
+	char * name;
 };
 
 // Functions:

From 3c8ed9994bf68b8ebd547165e2f0f923122e9c3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Mon, 20 Nov 2023 21:34:06 +0000
Subject: [PATCH 8/9] Removed now unneeded placeholder.

---
 lisp/.placeholder | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 lisp/.placeholder

diff --git a/lisp/.placeholder b/lisp/.placeholder
deleted file mode 100644
index e69de29..0000000

From 7fa1fadc12f792f7218694f471f12581d8762b71 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barra=20=C3=93=20Cath=C3=A1in?= <barra@ocathain.ie>
Date: Tue, 21 Nov 2023 10:51:38 +0000
Subject: [PATCH 9/9] Accidental typo while moving around.

---
 lisp/messaging.scm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/messaging.scm b/lisp/messaging.scm
index fdf7dc4..2085bd8 100644
--- a/lisp/messaging.scm
+++ b/lisp/messaging.scm
@@ -7,7 +7,7 @@
 (define message-everyone (lambda (name content)
 						   (push-output-message *global-output-queue* #f *global-player-list*
 												8 name content)))
-(define system-message (lambda (contennt)
+(define system-message (lambda (content)
 						 (push-output-message *global-output-queue* #f *global-player-list*
 											  0 "" content)))