From 4fad0714e7ca32350c76081d1162a576da28ca00 Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Wed, 22 Jan 2020 20:52:35 -0600
Subject: [PATCH] Add janet_gcpressure. Address #269.

---
 src/core/buffer.c   | 6 +++---
 src/core/gc.c       | 5 +++++
 src/include/janet.h | 1 +
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/core/buffer.c b/src/core/buffer.c
index 39d774e8..9691a552 100644
--- a/src/core/buffer.c
+++ b/src/core/buffer.c
@@ -32,7 +32,7 @@
 JanetBuffer *janet_buffer_init(JanetBuffer *buffer, int32_t capacity) {
     uint8_t *data = NULL;
     if (capacity > 0) {
-        janet_vm_next_collection += capacity;
+        janet_gcpressure(capacity);
         data = malloc(sizeof(uint8_t) * (size_t) capacity);
         if (NULL == data) {
             JANET_OUT_OF_MEMORY;
@@ -62,7 +62,7 @@ void janet_buffer_ensure(JanetBuffer *buffer, int32_t capacity, int32_t growth)
     if (capacity <= buffer->capacity) return;
     int64_t big_capacity = ((int64_t) capacity) * growth;
     capacity = big_capacity > INT32_MAX ? INT32_MAX : (int32_t) big_capacity;
-    janet_vm_next_collection += capacity - buffer->capacity;
+    janet_gcpressure(capacity - buffer->capacity);
     new_data = realloc(old, (size_t) capacity * sizeof(uint8_t));
     if (NULL == new_data) {
         JANET_OUT_OF_MEMORY;
@@ -94,7 +94,7 @@ void janet_buffer_extra(JanetBuffer *buffer, int32_t n) {
     if (new_size > buffer->capacity) {
         int32_t new_capacity = new_size * 2;
         uint8_t *new_data = realloc(buffer->data, new_capacity * sizeof(uint8_t));
-        janet_vm_next_collection += new_capacity - buffer->capacity;
+        janet_gcpressure(new_capacity - buffer->capacity);
         if (NULL == new_data) {
             JANET_OUT_OF_MEMORY;
         }
diff --git a/src/core/gc.c b/src/core/gc.c
index 5201192c..b5d62ddd 100644
--- a/src/core/gc.c
+++ b/src/core/gc.c
@@ -69,6 +69,11 @@ static void janet_mark_abstract(void *adata);
 static JANET_THREAD_LOCAL uint32_t depth = JANET_RECURSION_GUARD;
 static JANET_THREAD_LOCAL size_t orig_rootcount;
 
+/* Hint to the GC that we may need to collect */
+void janet_gcpressure(size_t s) {
+    janet_vm_next_collection += s;
+}
+
 /* Mark a value */
 void janet_mark(Janet x) {
     if (depth) {
diff --git a/src/include/janet.h b/src/include/janet.h
index 612a08ef..b0742c0d 100644
--- a/src/include/janet.h
+++ b/src/include/janet.h
@@ -1312,6 +1312,7 @@ JANET_API int janet_gcunroot(Janet root);
 JANET_API int janet_gcunrootall(Janet root);
 JANET_API int janet_gclock(void);
 JANET_API void janet_gcunlock(int handle);
+JANET_API void janet_gcpressure(size_t s);
 
 /* Functions */
 JANET_API JanetFuncDef *janet_funcdef_alloc(void);