From 45bd14b392622cb58e967a24e4652c510b3d43e4 Mon Sep 17 00:00:00 2001
From: William Wilgus <me.theuser@yahoo.com>
Date: Fri, 12 Jul 2019 05:23:52 -0500
Subject: 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
---
 apps/plugins/lua/lstring.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

(limited to 'apps/plugins/lua/lstring.c')

diff --git a/apps/plugins/lua/lstring.c b/apps/plugins/lua/lstring.c
index bf0536e..6d73f1e 100644
--- a/apps/plugins/lua/lstring.c
+++ b/apps/plugins/lua/lstring.c
@@ -22,30 +22,34 @@
 
 
 void luaS_resize (lua_State *L, int newsize) {
-  GCObject **newhash;
   stringtable *tb;
   int i;
-  if (G(L)->gcstate == GCSsweepstring)
-    return;  /* cannot resize during GC traverse */
-  newhash = luaM_newvector(L, newsize, GCObject *);
   tb = &G(L)->strt;
-  for (i=0; i<newsize; i++) newhash[i] = NULL;
+  if (luaC_sweepstrgc(L) || newsize == tb->size || is_resizing_strings_gc(L))
+    return;  /* cannot resize during GC traverse or doesn't need to be resized */
+  set_resizing_strings_gc(L);
+  if (newsize > tb->size) {
+    luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
+    for (i=tb->size; i<newsize; i++) tb->hash[i] = NULL;
+  }
   /* rehash */
   for (i=0; i<tb->size; i++) {
     GCObject *p = tb->hash[i];
+    tb->hash[i] = NULL;
     while (p) {  /* for each node in the list */
       GCObject *next = p->gch.next;  /* save next */
       unsigned int h = gco2ts(p)->hash;
       int h1 = lmod(h, newsize);  /* new position */
       lua_assert(cast_int(h%newsize) == lmod(h, newsize));
-      p->gch.next = newhash[h1];  /* chain it */
-      newhash[h1] = p;
+      p->gch.next = tb->hash[h1];  /* chain it */
+      tb->hash[h1] = p;
       p = next;
     }
   }
-  luaM_freearray(L, tb->hash, tb->size, TString *);
+  if (newsize < tb->size)
+    luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
   tb->size = newsize;
-  tb->hash = newhash;
+  unset_resizing_strings_gc(L);
 }
 
 
@@ -55,6 +59,9 @@ static TString *newlstr (lua_State *L, const char *str, size_t l,
   stringtable *tb;
   if (l > ((MAX_SIZET - sizeof(TString))/sizeof(char)) - sizeof(""))
     luaM_toobig(L);
+  tb = &G(L)->strt;
+  if ((tb->nuse + 1) > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
+    luaS_resize(L, tb->size*2);  /* too crowded */
   ts = cast(TString *, luaM_malloc(L, sizetstring(type, l)));
   ts->tsv.len = l;
   ts->tsv.hash = h;
@@ -70,13 +77,10 @@ static TString *newlstr (lua_State *L, const char *str, size_t l,
     memcpy(ts+1, str, l*sizeof(char));
     ((char *)(ts+1))[l] = '\0';  /* ending 0 */
   }
-  tb = &G(L)->strt;
   h = lmod(h, tb->size);
   ts->tsv.next = tb->hash[h];  /* chain new entry */
   tb->hash[h] = obj2gco(ts);
   tb->nuse++;
-  if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
-    luaS_resize(L, tb->size*2);  /* too crowded */
   return ts;
 }
 
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