Lua Add Emergency Garbage Collector

Derivative of work by RobertGabrielJakabosky
 http://lua-users.org/wiki/EmergencyGarbageCollector

I've only implemented the not enough memory part and
 expanded this idea to adding a mechanism to signal
 the OOM condition of the plugin buffer which allows us to only
 grab the playback buffer after garbage collection fails
 (SO THE MUSIC KEEPS PLAYING AS LONG AS POSSIBLE)

Change-Id: I684fb98b540ffc01f7ba324ab5b761ceb59b9f9b

1 files changed, 24 insertions, 0 deletions

diff --git a/apps/plugins/lua/lgc.h b/apps/plugins/lua/lgc.h
index 5123ccb479..115008d6be 100644
--- a/apps/plugins/lua/lgc.h
+++ b/apps/plugins/lua/lgc.h
@@ -37,12 +37,30 @@
 #define test2bits(x,b1,b2)      testbits(x, (bit2mask(b1, b2)))
 
 
+/*
+** Possible Garbage Collector flags.
+** Layout for bit use in 'gsflags' field in global_State structure.
+** bit 0 - Protect GC from recursive calls.
+** bit 1 - Don't try to shrink string table if EGC was called during a string table resize.
+*/
+#define GCFlagsNone          0
+#define GCBlockGCBit         0
+#define GCResizingStringsBit 1
+
+
+#define is_block_gc(L)    testbit(G(L)->gcflags, GCBlockGCBit)
+#define set_block_gc(L)   l_setbit(G(L)->gcflags, GCBlockGCBit)
+#define unset_block_gc(L) resetbit(G(L)->gcflags, GCBlockGCBit)
+#define is_resizing_strings_gc(L)    testbit(G(L)->gcflags, GCResizingStringsBit)
+#define set_resizing_strings_gc(L)   l_setbit(G(L)->gcflags, GCResizingStringsBit)
+#define unset_resizing_strings_gc(L) resetbit(G(L)->gcflags, GCResizingStringsBit)
 
 /*
 ** Layout for bit use in `marked' field:
 ** bit 0 - object is white (type 0)
 ** bit 1 - object is white (type 1)
 ** bit 2 - object is black
+** bit 3 - for thread: Don't resize thread's stack
 ** bit 3 - for userdata: has been finalized
 ** bit 3 - for tables: has weak keys
 ** bit 4 - for tables: has weak values
@@ -54,6 +72,7 @@
 #define WHITE0BIT       0
 #define WHITE1BIT       1
 #define BLACKBIT        2
+#define FIXEDSTACKBIT   3
 #define FINALIZEDBIT    3
 #define KEYWEAKBIT      3
 #define VALUEWEAKBIT    4
@@ -76,6 +95,9 @@
 
 #define luaC_white(g)   cast(lu_byte, (g)->currentwhite & WHITEBITS)
 
+#define isfixedstack(x) testbit((x)->marked, FIXEDSTACKBIT)
+#define fixedstack(x)   l_setbit((x)->marked, FIXEDSTACKBIT)
+#define unfixedstack(x) resetbit((x)->marked, FIXEDSTACKBIT)
 
 #define luaC_checkGC(L) { \
   condhardstacktests(luaD_reallocstack(L, L->stacksize - EXTRA_STACK - 1)); \
@@ -101,6 +123,8 @@ LUAI_FUNC void luaC_callGCTM (lua_State *L);
 LUAI_FUNC void luaC_freeall (lua_State *L);
 LUAI_FUNC void luaC_step (lua_State *L);
 LUAI_FUNC void luaC_fullgc (lua_State *L);
+LUAI_FUNC int luaC_sweepstrgc (lua_State *L);
+LUAI_FUNC void luaC_marknew (lua_State *L, GCObject *o);
 LUAI_FUNC void luaC_link (lua_State *L, GCObject *o, lu_byte tt);
 LUAI_FUNC void luaC_linkupval (lua_State *L, UpVal *uv);
 LUAI_FUNC void luaC_barrierf (lua_State *L, GCObject *o, GCObject *v);