#include "nasal.h"
#include "data.h"
+#include "code.h"
-#define MIN_BLOCK_SIZE 256
+#define MIN_BLOCK_SIZE 32
-// "type" for an object freed by the collector
-#define T_GCFREED 123 // DEBUG
+static void reap(struct naPool* p);
+static void mark(naRef r);
struct Block {
int size;
char* block;
+ struct Block* next;
};
-// Decremented every allocation. When it reaches zero, we do a
-// garbage collection. The value is reset to 1/2 of the total object
-// count each collection, which is sane: it ensures that no more than
-// 50% growth can happen between collections, and ensures that garbage
-// collection work is constant with allocation work (i.e. that O(N)
-// work is done only every O(1/2N) allocations).
-static int GlobalAllocCount = 256;
-
-static void appendfree(struct naPool*p, struct naObj* o)
-{
- // Need more space?
- if(p->freesz <= p->nfree) {
- int i, n = 1+((3*p->nfree)>>1);
- void** newf = naAlloc(n * sizeof(void*));
- for(i=0; i<p->nfree; i++)
- newf[i] = p->free[i];
- naFree(p->free);
- p->free = newf;
- p->freesz = n;
+// Must be called with the giant exclusive lock!
+static void freeDead()
+{
+ int i;
+ for(i=0; i<globals->ndead; i++)
+ naFree(globals->deadBlocks[i]);
+ globals->ndead = 0;
+}
+
+static void marktemps(struct Context* c)
+{
+ int i;
+ naRef r = naNil();
+ for(i=0; i<c->ntemps; i++) {
+ SETPTR(r, c->temps[i]);
+ mark(r);
}
+}
- p->free[p->nfree++] = o;
+// Must be called with the big lock!
+static void garbageCollect()
+{
+ int i;
+ struct Context* c;
+ globals->allocCount = 0;
+ c = globals->allContexts;
+ while(c) {
+ for(i=0; i<NUM_NASAL_TYPES; i++)
+ c->nfree[i] = 0;
+ for(i=0; i < c->fTop; i++) {
+ mark(c->fStack[i].func);
+ mark(c->fStack[i].locals);
+ }
+ for(i=0; i < c->opTop; i++)
+ mark(c->opStack[i]);
+ mark(c->dieArg);
+ marktemps(c);
+ c = c->nextAll;
+ }
+
+ mark(globals->save);
+ mark(globals->symbols);
+ mark(globals->meRef);
+ mark(globals->argRef);
+ mark(globals->parentsRef);
+
+ // Finally collect all the freed objects
+ for(i=0; i<NUM_NASAL_TYPES; i++)
+ reap(&(globals->pools[i]));
+
+ // Make enough space for the dead blocks we need to free during
+ // execution. This works out to 1 spot for every 2 live objects,
+ // which should be limit the number of bottleneck operations
+ // without imposing an undue burden of extra "freeable" memory.
+ if(globals->deadsz < globals->allocCount) {
+ globals->deadsz = globals->allocCount;
+ if(globals->deadsz < 256) globals->deadsz = 256;
+ naFree(globals->deadBlocks);
+ globals->deadBlocks = naAlloc(sizeof(void*) * globals->deadsz);
+ }
+ globals->needGC = 0;
+}
+
+void naModLock()
+{
+ LOCK();
+ globals->nThreads++;
+ UNLOCK();
+ naCheckBottleneck();
+}
+
+void naModUnlock()
+{
+ LOCK();
+ globals->nThreads--;
+ // We might be the "last" thread needed for collection. Since
+ // we're releasing our modlock to do something else for a while,
+ // wake someone else up to do it.
+ if(globals->waitCount == globals->nThreads)
+ naSemUp(globals->sem, 1);
+ UNLOCK();
+}
+
+// Must be called with the main lock. Engages the "bottleneck", where
+// all threads will block so that one (the last one to call this
+// function) can run alone. This is done for GC, and also to free the
+// list of "dead" blocks when it gets full (which is part of GC, if
+// you think about it).
+static void bottleneck()
+{
+ struct Globals* g = globals;
+ g->bottleneck = 1;
+ while(g->bottleneck && g->waitCount < g->nThreads - 1) {
+ g->waitCount++;
+ UNLOCK(); naSemDown(g->sem); LOCK();
+ g->waitCount--;
+ }
+ if(g->waitCount >= g->nThreads - 1) {
+ freeDead();
+ if(g->needGC) garbageCollect();
+ if(g->waitCount) naSemUp(g->sem, g->waitCount);
+ g->bottleneck = 0;
+ }
+}
+
+void naCheckBottleneck()
+{
+ if(globals->bottleneck) { LOCK(); bottleneck(); UNLOCK(); }
}
static void naCode_gcclean(struct naCode* o)
{
- naFree(o->byteCode); o->byteCode = 0;
- naFree(o->constants); o->constants = 0;
+ naFree(o->constants); o->constants = 0;
}
static void naGhost_gcclean(struct naGhost* g)
{
- if(g->ptr) g->gtype->destroy(g->ptr);
+ if(g->ptr && g->gtype->destroy) g->gtype->destroy(g->ptr);
g->ptr = 0;
}
static void freeelem(struct naPool* p, struct naObj* o)
{
- // Mark the object as "freed" for debugging purposes
- o->type = T_GCFREED; // DEBUG
-
- // Free any intrinsic (i.e. non-garbage collected) storage the
- // object might have
+ // Clean up any intrinsic storage the object might have...
switch(p->type) {
- case T_STR:
- naStr_gcclean((struct naStr*)o);
- break;
- case T_VEC:
- naVec_gcclean((struct naVec*)o);
- break;
- case T_HASH:
- naHash_gcclean((struct naHash*)o);
- break;
- case T_CODE:
- naCode_gcclean((struct naCode*)o);
- break;
- case T_GHOST:
- naGhost_gcclean((struct naGhost*)o);
- break;
+ case T_STR: naStr_gcclean ((struct naStr*) o); break;
+ case T_VEC: naVec_gcclean ((struct naVec*) o); break;
+ case T_HASH: naiGCHashClean ((struct naHash*) o); break;
+ case T_CODE: naCode_gcclean ((struct naCode*) o); break;
+ case T_GHOST: naGhost_gcclean((struct naGhost*)o); break;
}
-
- // And add it to the free list
- appendfree(p, o);
+ p->free[p->nfree++] = o; // ...and add it to the free list
}
static void newBlock(struct naPool* p, int need)
{
int i;
- char* buf;
- struct Block* newblocks;
+ struct Block* newb;
- if(need < MIN_BLOCK_SIZE)
- need = MIN_BLOCK_SIZE;
-
- newblocks = naAlloc((p->nblocks+1) * sizeof(struct Block));
- for(i=0; i<p->nblocks; i++) newblocks[i] = p->blocks[i];
- naFree(p->blocks);
- p->blocks = newblocks;
- buf = naAlloc(need * p->elemsz);
- naBZero(buf, need * p->elemsz);
- p->blocks[p->nblocks].size = need;
- p->blocks[p->nblocks].block = buf;
- p->nblocks++;
+ if(need < MIN_BLOCK_SIZE) need = MIN_BLOCK_SIZE;
+
+ newb = naAlloc(sizeof(struct Block));
+ newb->block = naAlloc(need * p->elemsz);
+ newb->size = need;
+ newb->next = p->blocks;
+ p->blocks = newb;
+ naBZero(newb->block, need * p->elemsz);
- for(i=0; i<need; i++) {
- struct naObj* o = (struct naObj*)(buf + i*p->elemsz);
+ if(need > p->freesz - p->freetop) need = p->freesz - p->freetop;
+ p->nfree = 0;
+ p->free = p->free0 + p->freetop;
+ for(i=0; i < need; i++) {
+ struct naObj* o = (struct naObj*)(newb->block + i*p->elemsz);
o->mark = 0;
- o->type = p->type;
- appendfree(p, o);
+ p->free[p->nfree++] = o;
}
+ p->freetop += need;
}
void naGC_init(struct naPool* p, int type)
{
p->type = type;
p->elemsz = naTypeSize(type);
- p->nblocks = 0;
p->blocks = 0;
- p->nfree = 0;
- p->freesz = 0;
- p->free = 0;
- naGC_reap(p);
+
+ p->free0 = p->free = 0;
+ p->nfree = p->freesz = p->freetop = 0;
+ reap(p);
}
-int naGC_size(struct naPool* p)
+static int poolsize(struct naPool* p)
{
- int i, total=0;
- for(i=0; i<p->nblocks; i++)
- total += ((struct Block*)(p->blocks + i))->size;
+ int total = 0;
+ struct Block* b = p->blocks;
+ while(b) { total += b->size; b = b->next; }
return total;
}
-struct naObj* naGC_get(struct naPool* p)
+struct naObj** naGC_get(struct naPool* p, int n, int* nout)
{
- // Collect every GlobalAllocCount allocations.
- // This gets set to ~50% of the total object count each
- // collection (it's incremented in naGC_reap()).
- if(--GlobalAllocCount < 0) {
- GlobalAllocCount = 0;
- naGarbageCollect();
+ struct naObj** result;
+ naCheckBottleneck();
+ LOCK();
+ while(globals->allocCount < 0 || (p->nfree == 0 && p->freetop >= p->freesz)) {
+ globals->needGC = 1;
+ bottleneck();
}
-
- // If we're out, then allocate an extra 12.5%
if(p->nfree == 0)
- newBlock(p, naGC_size(p)/8);
- return p->free[--p->nfree];
+ newBlock(p, poolsize(p)/8);
+ n = p->nfree < n ? p->nfree : n;
+ *nout = n;
+ p->nfree -= n;
+ globals->allocCount -= n;
+ result = (struct naObj**)(p->free + p->nfree);
+ UNLOCK();
+ return result;
+}
+
+static void markvec(naRef r)
+{
+ int i;
+ struct VecRec* vr = PTR(r).vec->rec;
+ if(!vr) return;
+ for(i=0; i<vr->size; i++)
+ mark(vr->array[i]);
}
// Sets the reference bit on the object, and recursively on all
-// objects reachable from it. Clumsy: uses C stack recursion, which
-// is slower than it need be and may cause problems on some platforms
-// due to the very large stack depths that result.
-void naGC_mark(naRef r)
+// objects reachable from it. Uses the processor stack for recursion...
+static void mark(naRef r)
{
int i;
if(IS_NUM(r) || IS_NIL(r))
return;
- if(r.ref.ptr.obj->mark == 1)
+ if(PTR(r).obj->mark == 1)
return;
- // Verify that the object hasn't been freed incorrectly:
- if(r.ref.ptr.obj->type == T_GCFREED) *(int*)0=0; // DEBUG
-
- r.ref.ptr.obj->mark = 1;
- switch(r.ref.ptr.obj->type) {
- case T_VEC:
- for(i=0; i<r.ref.ptr.vec->size; i++)
- naGC_mark(r.ref.ptr.vec->array[i]);
- break;
- case T_HASH:
- if(r.ref.ptr.hash->table == 0)
- break;
- for(i=0; i < (1<<r.ref.ptr.hash->lgalloced); i++) {
- struct HashNode* hn = r.ref.ptr.hash->table[i];
- while(hn) {
- naGC_mark(hn->key);
- naGC_mark(hn->val);
- hn = hn->next;
- }
- }
- break;
+ PTR(r).obj->mark = 1;
+ switch(PTR(r).obj->type) {
+ case T_VEC: markvec(r); break;
+ case T_HASH: naiGCMarkHash(r); break;
case T_CODE:
- naGC_mark(r.ref.ptr.code->srcFile);
- for(i=0; i<r.ref.ptr.code->nConstants; i++)
- naGC_mark(r.ref.ptr.code->constants[i]);
- break;
- case T_CLOSURE:
- naGC_mark(r.ref.ptr.closure->namespace);
- naGC_mark(r.ref.ptr.closure->next);
+ mark(PTR(r).code->srcFile);
+ for(i=0; i<PTR(r).code->nConstants; i++)
+ mark(PTR(r).code->constants[i]);
break;
case T_FUNC:
- naGC_mark(r.ref.ptr.func->code);
- naGC_mark(r.ref.ptr.func->closure);
+ mark(PTR(r).func->code);
+ mark(PTR(r).func->namespace);
+ mark(PTR(r).func->next);
break;
}
}
+void naiGCMark(naRef r)
+{
+ mark(r);
+}
+
// Collects all the unreachable objects into a free list, and
// allocates more space if needed.
-void naGC_reap(struct naPool* p)
+static void reap(struct naPool* p)
{
- int i, elem, total = 0;
+ struct Block* b;
+ int elem, freesz, total = poolsize(p);
+ freesz = total < MIN_BLOCK_SIZE ? MIN_BLOCK_SIZE : total;
+ freesz = (3 * freesz / 2) + (globals->nThreads * OBJ_CACHE_SZ);
+ if(p->freesz < freesz) {
+ naFree(p->free0);
+ p->freesz = freesz;
+ p->free = p->free0 = naAlloc(sizeof(void*) * p->freesz);
+ }
+
p->nfree = 0;
- for(i=0; i<p->nblocks; i++) {
- struct Block* b = p->blocks + i;
- total += b->size;
+ p->free = p->free0;
+
+ for(b = p->blocks; b; b = b->next)
for(elem=0; elem < b->size; elem++) {
struct naObj* o = (struct naObj*)(b->block + elem * p->elemsz);
if(o->mark == 0)
freeelem(p, o);
o->mark = 0;
}
- }
- // Add 50% of our total to the global count
- GlobalAllocCount += total/2;
+ p->freetop = p->nfree;
+
+ // allocs of this type until the next collection
+ globals->allocCount += total/2;
// Allocate more if necessary (try to keep 25-50% of the objects
// available)
}
}
+// Does the swap, returning the old value
+static void* doswap(void** target, void* val)
+{
+ void* old = *target;
+ *target = val;
+ return old;
+}
+
+// Atomically replaces target with a new pointer, and adds the old one
+// to the list of blocks to free the next time something holds the
+// giant lock.
+void naGC_swapfree(void** target, void* val)
+{
+ void* old;
+ LOCK();
+ old = doswap(target, val);
+ while(globals->ndead >= globals->deadsz)
+ bottleneck();
+ globals->deadBlocks[globals->ndead++] = old;
+ UNLOCK();
+}
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