From 9604a3f491a08ea1576b4722212b83c6a6a8d2a4 Mon Sep 17 00:00:00 2001
From: Joe Conigliaro <joe@vlang.io>
Date: Mon, 9 Oct 2023 12:10:19 +1100
Subject: [PATCH] coroutines: get photonlib/coroutines working with GC

---
 thirdparty/photon/photonwrapper.h  |  6 ++++--
 vlib/builtin/builtin_d_gcboehm.c.v |  3 +++
 vlib/coroutines/coroutines.v       | 15 +++++++++++++++
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/thirdparty/photon/photonwrapper.h b/thirdparty/photon/photonwrapper.h
index 76123c6aa527f4..97833b01e38f1e 100644
--- a/thirdparty/photon/photonwrapper.h
+++ b/thirdparty/photon/photonwrapper.h
@@ -24,8 +24,10 @@ int photon_init_default();
 void photon_thread_create(void* (* f)(void*), void* arg);
 void photon_sleep_s(int n);
 void photon_sleep_ms(int n);
-
-
+void set_photon_thread_stack_allocator(
+    void* (*alloc_func)(void*, size_t),
+    void (*dealloc_func)(void*, void*, size_t)
+);
 
 #ifdef __cplusplus
 }
diff --git a/vlib/builtin/builtin_d_gcboehm.c.v b/vlib/builtin/builtin_d_gcboehm.c.v
index a2ff9efc484e32..9be092a57d4d92 100644
--- a/vlib/builtin/builtin_d_gcboehm.c.v
+++ b/vlib/builtin/builtin_d_gcboehm.c.v
@@ -139,3 +139,6 @@ pub fn gc_check_leaks() {
 
 fn C.GC_get_heap_usage_safe(pheap_size &usize, pfree_bytes &usize, punmapped_bytes &usize, pbytes_since_gc &usize, ptotal_bytes &usize)
 fn C.GC_get_memory_use() usize
+
+fn C.GC_add_roots(voidptr, voidptr)
+fn C.GC_remove_roots(voidptr, voidptr)
diff --git a/vlib/coroutines/coroutines.v b/vlib/coroutines/coroutines.v
index 0d50ad3a039612..98a79a39fece71 100644
--- a/vlib/coroutines/coroutines.v
+++ b/vlib/coroutines/coroutines.v
@@ -14,6 +14,7 @@ fn C.photon_init_default() int
 fn C.photon_thread_create(f voidptr, arg voidptr)
 fn C.photon_sleep_s(n int)
 fn C.photon_sleep_ms(n int)
+fn C.set_photon_thread_stack_allocator(fn (voidptr, int) voidptr, fn (voidptr, voidptr, int))
 
 // sleep is coroutine-safe version of time.sleep()
 pub fn sleep(duration time.Duration) {
@@ -21,6 +22,20 @@ pub fn sleep(duration time.Duration) {
 }
 
 fn init() {
+	alloc := fn (_ voidptr, stack_size int) voidptr {
+		unsafe {
+			stack_ptr := malloc(stack_size)
+			C.GC_add_roots(stack_ptr, charptr(stack_ptr) + stack_size)
+			return stack_ptr
+		}
+	}
+	dealloc := fn (_ voidptr, stack_ptr voidptr, stack_size int) {
+		unsafe {
+			C.GC_add_roots(stack_ptr, charptr(stack_ptr) + stack_size)
+			free(stack_ptr)
+		}
+	}
+	C.set_photon_thread_stack_allocator(alloc, dealloc)
 	ret := C.photon_init_default()
 	if ret < 0 {
 		panic('failed to initialize coroutines via photon (ret=${ret})')