Add scratch memory API.

This should make it easier to write
code that does not leak memory on panics.

src/core/gc.c

@@ -39,6 +39,11 @@ JANET_THREAD_LOCAL Janet *janet_vm_roots;
 JANET_THREAD_LOCAL uint32_t janet_vm_root_count;
 JANET_THREAD_LOCAL uint32_t janet_vm_root_capacity;
 
+/* Scratch Memory */
+JANET_THREAD_LOCAL void **janet_scratch_mem;
+JANET_THREAD_LOCAL size_t janet_scratch_cap;
+JANET_THREAD_LOCAL size_t janet_scratch_len;
+
 /* Helpers for marking the various gc types */
 static void janet_mark_funcenv(JanetFuncEnv *env);
 static void janet_mark_funcdef(JanetFuncDef *def);
@@ -342,6 +347,13 @@ void *janet_gcalloc(enum JanetMemoryType type, size_t size) {
     return (void *)mem;
 }
 
+/* Free all allocated scratch memory */
+static void janet_free_all_scratch(void) {
+    for (size_t i = 0; i < janet_scratch_len; i++)
+        free(janet_scratch_mem[i]);
+    janet_scratch_len = 0;
+}
+
 /* Run garbage collection */
 void janet_collect(void) {
     uint32_t i;
@@ -356,6 +368,7 @@ void janet_collect(void) {
     }
     janet_sweep();
     janet_vm_next_collection = 0;
+    janet_free_all_scratch();
 }
 
 /* Add a root value to the GC. This prevents the GC from removing a value
@@ -429,6 +442,8 @@ void janet_clear_memory(void) {
         current = next;
     }
     janet_vm_blocks = NULL;
+    janet_free_all_scratch();
+    free(janet_scratch_mem);
 }
 
 /* Primitives for suspending GC. */
@@ -438,3 +453,56 @@ int janet_gclock(void) {
 void janet_gcunlock(int handle) {
     janet_vm_gc_suspend = handle;
 }
+
+/* Scratch memory API */
+
+void *janet_smalloc(size_t size) {
+    void *mem = malloc(size);
+    if (NULL == mem) {
+        JANET_OUT_OF_MEMORY;
+    }
+    if (janet_scratch_len == janet_scratch_cap) {
+        size_t newcap = 2 * janet_scratch_cap + 2;
+        void **newmem = (void **) realloc(janet_scratch_mem, newcap * sizeof(void *));
+        if (NULL == newmem) {
+            JANET_OUT_OF_MEMORY;
+        }
+        janet_scratch_cap = newcap;
+        janet_scratch_mem = newmem;
+    }
+    janet_scratch_mem[janet_scratch_len++] = mem;
+    return mem;
+}
+
+void *janet_srealloc(void *mem, size_t size) {
+    if (NULL == mem) return janet_smalloc(size);
+    if (janet_scratch_len) {
+        for (size_t i = janet_scratch_len - 1; ; i--) {
+            if (janet_scratch_mem[i] == mem) {
+                void *newmem = realloc(mem, size);
+                if (NULL == newmem) {
+                    JANET_OUT_OF_MEMORY;
+                }
+                janet_scratch_mem[i] = newmem;
+                return newmem;
+            }
+            if (i == 0) break;
+        }
+    }
+    janet_exit("invalid janet_srealloc");
+}
+
+void janet_sfree(void *mem) {
+    if (NULL == mem) return;
+    if (janet_scratch_len) {
+        for (size_t i = janet_scratch_len - 1; ; i--) {
+            if (janet_scratch_mem[i] == mem) {
+                janet_scratch_mem[i] = janet_scratch_mem[--janet_scratch_len];
+                free(mem);
+                return;
+            }
+            if (i == 0) break;
+        }
+    }
+    janet_exit("invalid janet_sfree");
+}

src/core/state.h

@@ -65,4 +65,9 @@ extern JANET_THREAD_LOCAL Janet *janet_vm_roots;
 extern JANET_THREAD_LOCAL uint32_t janet_vm_root_count;
 extern JANET_THREAD_LOCAL uint32_t janet_vm_root_capacity;
 
+/* Scratch memory */
+extern JANET_THREAD_LOCAL void **janet_scratch_mem;
+extern JANET_THREAD_LOCAL size_t janet_scratch_cap;
+extern JANET_THREAD_LOCAL size_t janet_scratch_len;
+
 #endif /* JANET_STATE_H_defined */

src/core/vector.c

@@ -30,17 +30,10 @@ void *janet_v_grow(void *v, int32_t increment, int32_t itemsize) {
     int32_t dbl_cur = (NULL != v) ? 2 * janet_v__cap(v) : 0;
     int32_t min_needed = janet_v_count(v) + increment;
     int32_t m = dbl_cur > min_needed ? dbl_cur : min_needed;
-    int32_t *p = (int32_t *) realloc(v ? janet_v__raw(v) : 0, itemsize * m + sizeof(int32_t) * 2);
-    if (NULL != p) {
-        if (!v) p[1] = 0;
-        p[0] = m;
-        return p + 2;
-    } else {
-        {
-            JANET_OUT_OF_MEMORY;
-        }
-        return (void *)(2 * sizeof(int32_t));
-    }
+    int32_t *p = (int32_t *) janet_srealloc(v ? janet_v__raw(v) : 0, itemsize * m + sizeof(int32_t) * 2);
+    if (!v) p[1] = 0;
+    p[0] = m;
+    return p + 2;
 }
 
 /* Convert a buffer to normal allocated memory (forget capacity) */

src/core/vector.h

@@ -33,16 +33,15 @@
 */
 
 /* This is mainly used code such as the assembler or compiler, which
- * need vector like data structures that are not garbage collected
- * and used only from C */
+ * need vector like data structures that are only garbage collected in case
+ * of an error, and normally rely on malloc/free. */
 
-#define janet_v_free(v)         (((v) != NULL) ? (free(janet_v__raw(v)), 0) : 0)
+#define janet_v_free(v)         (((v) != NULL) ? (janet_sfree(janet_v__raw(v)), 0) : 0)
 #define janet_v_push(v, x)      (janet_v__maybegrow(v, 1), (v)[janet_v__cnt(v)++] = (x))
 #define janet_v_pop(v)          (janet_v_count(v) ? janet_v__cnt(v)-- : 0)
 #define janet_v_count(v)        (((v) != NULL) ? janet_v__cnt(v) : 0)
 #define janet_v_last(v)         ((v)[janet_v__cnt(v) - 1])
 #define janet_v_empty(v)        (((v) != NULL) ? (janet_v__cnt(v) = 0) : 0)
-#define janet_v_copy(v)         (janet_v_copymem((v), sizeof(*(v))))
 #define janet_v_flatten(v)      (janet_v_flattenmem((v), sizeof(*(v))))
 
 #define janet_v__raw(v) ((int32_t *)(v) - 2)
@@ -55,7 +54,6 @@
 
 /* Actual functions defined in vector.c */
 void *janet_v_grow(void *v, int32_t increment, int32_t itemsize);
-void *janet_v_copymem(void *v, int32_t itemsize);
 void *janet_v_flattenmem(void *v, int32_t itemsize);
 
 #endif

src/core/vm.c

@@ -906,6 +906,10 @@ int janet_init(void) {
     janet_vm_roots = NULL;
     janet_vm_root_count = 0;
     janet_vm_root_capacity = 0;
+    /* Scratch memory */
+    janet_scratch_mem = NULL;
+    janet_scratch_len = 0;
+    janet_scratch_cap = 0;
     /* Initialize registry */
     janet_vm_registry = janet_table(0);
     janet_gcroot(janet_wrap_table(janet_vm_registry));

src/include/janet.h

@@ -1281,6 +1281,11 @@ JANET_API JanetSignal janet_pcall(JanetFunction *fun, int32_t argn, const Janet
 JANET_API Janet janet_call(JanetFunction *fun, int32_t argc, const Janet *argv);
 JANET_API void janet_stacktrace(JanetFiber *fiber, Janet err);
 
+/* Scratch Memory API */
+JANET_API void *janet_smalloc(size_t size);
+JANET_API void *janet_srealloc(void *mem, size_t size);
+JANET_API void janet_sfree(void *mem);
+
 /* C Library helpers */
 typedef enum {
     JANET_BINDING_NONE,