added cosmoM_addRoot & cosmoM_removeRoot

src/cmem.c

@@ -191,6 +191,16 @@ void sweep(CState *state) {
     }
 }
 
+void markUserRoots(CState *state) {
+    CObj *root = state->userRoots;
+
+    // traverse userRoots and mark all the object
+    while (root != NULL) {
+        markObject(state, root);
+        root = root->nextRoot;
+    }
+}
+
 void markRoots(CState *state) {
     // mark all values on the stack
     for (StkPtr value = state->stack; value < state->top; value++) {
@@ -213,6 +223,9 @@ void markRoots(CState *state) {
     for (int i = 0; i < ISTRING_MAX; i++)
         markObject(state, (CObj*)state->iStrings[i]);
 
+    // mark the user defined roots
+    markUserRoots(state);
+
     // mark our proto object
     markObject(state, (CObj*)state->protoObj);
     traceGrays(state);
@@ -234,7 +247,7 @@ COSMO_API void cosmoM_collectGarbage(CState *state) {
     // set our next GC event
     cosmoM_updateThreshhold(state);
 
-    cosmoM_unfreezeGC(state);
+    state->freezeGC--; // we don't want to use cosmoM_unfreezeGC because that might trigger a GC event
 #ifdef GC_DEBUG
     printf("-- GC end, reclaimed %ld bytes (started at %ld, ended at %ld), next garbage collection scheduled at %ld bytes\n",
             start - state->allocatedBytes, start, state->allocatedBytes, state->nextGC);
@@ -244,4 +257,43 @@ COSMO_API void cosmoM_collectGarbage(CState *state) {
 
 COSMO_API void cosmoM_updateThreshhold(CState *state) {
     state->nextGC = state->allocatedBytes * HEAP_GROW_FACTOR;
+}
+
+COSMO_API void cosmoM_addRoot(CState *state, CObj *newRoot) {
+    // first, check and make sure this root doesn't already exist in the list
+    CObj *root = state->userRoots;
+    while (root != NULL) {
+        if (root == newRoot) // found in the list, abort
+            return;
+        
+        root = root->nextRoot;
+    }
+    
+    // adds root to userRoot linked list
+    newRoot->nextRoot = state->userRoots;
+    state->userRoots = newRoot;
+}
+
+COSMO_API void cosmoM_removeRoot(CState *state, CObj *oldRoot) {
+    CObj *prev = NULL;
+    CObj *root = state->userRoots;
+
+    // traverse the userRoot linked list
+    while (root != NULL) {
+        if (root == oldRoot) { // found root in list
+
+            // remove from the linked list
+            if (prev == NULL) {
+                state->userRoots = root->nextRoot;
+            } else {
+                prev->nextRoot = root->nextRoot;
+            }
+
+            root->nextRoot = NULL;
+            break;
+        }
+
+        prev = root;
+        root = root->nextRoot;
+    }
 }

src/cmem.h

@@ -39,9 +39,12 @@
     printf("unfreezing state at %s:%d [%d]\n", __FILE__, __LINE__, state->freezeGC); \
     cosmoM_checkGarbage(state, 0)
 #else
+
+// freeze's the garbage collector until cosmoM_unfreezeGC is called
 #define cosmoM_freezeGC(state) \
     state->freezeGC++
 
+// unfreeze's the garbage collector and tries to run a garbage collection cycle
 #define cosmoM_unfreezeGC(state) \
     state->freezeGC--; \
     cosmoM_checkGarbage(state, 0)
@@ -53,9 +56,13 @@ COSMO_API bool cosmoM_checkGarbage(CState *state, size_t needed); // returns tru
 COSMO_API void cosmoM_collectGarbage(CState *state);
 COSMO_API void cosmoM_updateThreshhold(CState *state);
 
-/*
-    wrapper for cosmoM_reallocate so we can track our memory usage (it's also safer :P)
-*/
+// lets the VM know you are holding a reference to a CObj and to not free it
+COSMO_API void cosmoM_addRoot(CState *state, CObj *newRoot);
+
+// lets the VM know this root is no longer held in a reference and is able to be free'd
+COSMO_API void cosmoM_removeRoot(CState *state, CObj *oldRoot);
+
+// wrapper for cosmoM_reallocate so we can track our memory usage (it's also safer :P)
 static inline void *cosmoM_xmalloc(CState *state, size_t sz) {
     return cosmoM_reallocate(state, NULL, 0, sz);
 }

src/cobj.c

@@ -24,6 +24,8 @@ CObj *cosmoO_allocateBase(CState *state, size_t sz, CObjType type) {
 
     obj->next = state->objects;
     state->objects = obj;
+
+    obj->nextRoot = NULL;
 #ifdef GC_DEBUG
     printf("allocated %p with OBJ_TYPE %d\n", obj, type);
 #endif

src/cobj.h

@@ -31,6 +31,7 @@ typedef struct CObj {
     CObjType type;
     bool isMarked; // for the GC
     struct CObj *next;
+    struct CObj *nextRoot; // for the root linked list
 } CObj;
 
 typedef struct CObjString {

src/cstate.c

@@ -20,6 +20,7 @@ CState *cosmoV_newState() {
 
     // GC
     state->objects = NULL;
+    state->userRoots = NULL;
     state->grayStack.count = 0;
     state->grayStack.capacity = 2;
     state->grayStack.array = NULL;

src/cstate.h

@@ -32,6 +32,7 @@ typedef struct CState {
     bool panic;
     int freezeGC; // when > 0, GC events will be ignored (for internal use)
     CObj *objects; // tracks all of our allocated objects
+    CObj *userRoots; // user definable roots, this holds CObjs that should be considered "roots", lets the VM know you are holding a reference to a CObj in your code
     ArrayCObj grayStack; // keeps track of which objects *haven't yet* been traversed in our GC, but *have been* found
     size_t allocatedBytes;
     size_t nextGC; // when allocatedBytes reaches this threshhold, trigger a GC event

src/cvalue.h

@@ -18,13 +18,15 @@ typedef double cosmo_Number;
 
 #ifdef NAN_BOXXED
 /*
-        NaN box, this is great for performance on x86_64 or ARM64 architectures. If you don't know how this works please reference these
+        NaN box, this is great for fitting more in the cpu cache on x86_64 or ARM64 architectures. If you don't know how this works please reference these
     two articles:
 
     https://leonardschuetz.ch/blog/nan-boxing/ and https://piotrduperas.com/posts/nan-boxing/
 
     both are great resources :)
 
+    Performance notes: this can actually degrade performance, so only enable if you know what you're doing.
+
     TL;DR: we can store payloads in the NaN value in the IEEE 754 standard.
 */
 typedef union CValue {

src/main.c

@@ -30,7 +30,6 @@ CValue cosmoB_input(CState *state, int nargs, CValue *args) {
 }
 
 static void interpret(CState *state, const char* script) {
-    
     // cosmoP_compileString pushes the result onto the stack (NIL or COBJ_FUNCTION)
     CObjFunction* func = cosmoP_compileString(state, script);
     if (func != NULL) {