Thomas Geymayer
bb82b9d168
These new functions are meant to replace the gcSave/gcRelease methods of the NasalSystem class in FlightGear, as passing an adapter to SimGear from FlightGear is quite a lot of useless work just for being able to save objects.
336 lines
8.3 KiB
C
336 lines
8.3 KiB
C
#include "nasal.h"
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#include "data.h"
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#include "code.h"
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#define MIN_BLOCK_SIZE 32
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static void reap(struct naPool* p);
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static void mark(naRef r);
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struct Block {
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int size;
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char* block;
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struct Block* next;
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};
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// Must be called with the giant exclusive lock!
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static void freeDead()
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{
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int i;
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for(i=0; i<globals->ndead; i++)
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naFree(globals->deadBlocks[i]);
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globals->ndead = 0;
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}
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static void marktemps(struct Context* c)
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{
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int i;
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naRef r = naNil();
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for(i=0; i<c->ntemps; i++) {
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SETPTR(r, c->temps[i]);
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mark(r);
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}
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}
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// Must be called with the big lock!
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static void garbageCollect()
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{
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int i;
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struct Context* c;
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globals->allocCount = 0;
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c = globals->allContexts;
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while(c) {
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for(i=0; i<NUM_NASAL_TYPES; i++)
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c->nfree[i] = 0;
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for(i=0; i < c->fTop; i++) {
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mark(c->fStack[i].func);
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mark(c->fStack[i].locals);
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}
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for(i=0; i < c->opTop; i++)
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mark(c->opStack[i]);
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mark(c->dieArg);
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marktemps(c);
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c = c->nextAll;
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}
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mark(globals->save);
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mark(globals->save_hash);
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mark(globals->symbols);
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mark(globals->meRef);
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mark(globals->argRef);
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mark(globals->parentsRef);
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// Finally collect all the freed objects
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for(i=0; i<NUM_NASAL_TYPES; i++)
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reap(&(globals->pools[i]));
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// Make enough space for the dead blocks we need to free during
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// execution. This works out to 1 spot for every 2 live objects,
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// which should be limit the number of bottleneck operations
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// without imposing an undue burden of extra "freeable" memory.
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if(globals->deadsz < globals->allocCount) {
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globals->deadsz = globals->allocCount;
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if(globals->deadsz < 256) globals->deadsz = 256;
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naFree(globals->deadBlocks);
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globals->deadBlocks = naAlloc(sizeof(void*) * globals->deadsz);
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}
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globals->needGC = 0;
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}
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void naModLock()
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{
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LOCK();
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globals->nThreads++;
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UNLOCK();
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naCheckBottleneck();
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}
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void naModUnlock()
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{
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LOCK();
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globals->nThreads--;
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// We might be the "last" thread needed for collection. Since
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// we're releasing our modlock to do something else for a while,
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// wake someone else up to do it.
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if(globals->waitCount == globals->nThreads)
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naSemUp(globals->sem, 1);
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UNLOCK();
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}
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// Must be called with the main lock. Engages the "bottleneck", where
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// all threads will block so that one (the last one to call this
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// function) can run alone. This is done for GC, and also to free the
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// list of "dead" blocks when it gets full (which is part of GC, if
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// you think about it).
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static void bottleneck()
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{
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struct Globals* g = globals;
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g->bottleneck = 1;
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while(g->bottleneck && g->waitCount < g->nThreads - 1) {
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g->waitCount++;
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UNLOCK(); naSemDown(g->sem); LOCK();
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g->waitCount--;
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}
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if(g->waitCount >= g->nThreads - 1) {
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freeDead();
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if(g->needGC) garbageCollect();
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if(g->waitCount) naSemUp(g->sem, g->waitCount);
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g->bottleneck = 0;
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}
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}
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void naGC()
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{
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LOCK();
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globals->needGC = 1;
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bottleneck();
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UNLOCK();
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naCheckBottleneck();
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}
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void naCheckBottleneck()
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{
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if(globals->bottleneck) { LOCK(); bottleneck(); UNLOCK(); }
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}
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static void naCode_gcclean(struct naCode* o)
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{
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naFree(o->constants); o->constants = 0;
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}
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static void naCCode_gcclean(struct naCCode* c)
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{
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if(c->fptru && c->user_data && c->destroy) c->destroy(c->user_data);
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c->user_data = 0;
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}
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static void naGhost_gcclean(struct naGhost* g)
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{
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if(g->ptr && g->gtype->destroy) g->gtype->destroy(g->ptr);
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g->ptr = 0;
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}
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static void freeelem(struct naPool* p, struct naObj* o)
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{
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// Clean up any intrinsic storage the object might have...
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switch(p->type) {
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case T_STR: naStr_gcclean ((struct naStr*) o); break;
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case T_VEC: naVec_gcclean ((struct naVec*) o); break;
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case T_HASH: naiGCHashClean ((struct naHash*) o); break;
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case T_CODE: naCode_gcclean ((struct naCode*) o); break;
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case T_CCODE: naCCode_gcclean((struct naCCode*)o); break;
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case T_GHOST: naGhost_gcclean((struct naGhost*)o); break;
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}
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p->free[p->nfree++] = o; // ...and add it to the free list
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}
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static void newBlock(struct naPool* p, int need)
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{
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int i;
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struct Block* newb;
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if(need < MIN_BLOCK_SIZE) need = MIN_BLOCK_SIZE;
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newb = naAlloc(sizeof(struct Block));
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newb->block = naAlloc(need * p->elemsz);
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newb->size = need;
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newb->next = p->blocks;
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p->blocks = newb;
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naBZero(newb->block, need * p->elemsz);
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if(need > p->freesz - p->freetop) need = p->freesz - p->freetop;
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p->nfree = 0;
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p->free = p->free0 + p->freetop;
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for(i=0; i < need; i++) {
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struct naObj* o = (struct naObj*)(newb->block + i*p->elemsz);
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o->mark = 0;
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p->free[p->nfree++] = o;
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}
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p->freetop += need;
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}
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void naGC_init(struct naPool* p, int type)
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{
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p->type = type;
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p->elemsz = naTypeSize(type);
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p->blocks = 0;
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p->free0 = p->free = 0;
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p->nfree = p->freesz = p->freetop = 0;
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reap(p);
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}
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static int poolsize(struct naPool* p)
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{
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int total = 0;
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struct Block* b = p->blocks;
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while(b) { total += b->size; b = b->next; }
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return total;
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}
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struct naObj** naGC_get(struct naPool* p, int n, int* nout)
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{
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struct naObj** result;
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naCheckBottleneck();
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LOCK();
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while(globals->allocCount < 0 || (p->nfree == 0 && p->freetop >= p->freesz)) {
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globals->needGC = 1;
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bottleneck();
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}
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if(p->nfree == 0)
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newBlock(p, poolsize(p)/8);
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n = p->nfree < n ? p->nfree : n;
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*nout = n;
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p->nfree -= n;
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globals->allocCount -= n;
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result = (struct naObj**)(p->free + p->nfree);
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UNLOCK();
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return result;
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}
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static void markvec(naRef r)
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{
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int i;
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struct VecRec* vr = PTR(r).vec->rec;
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if(!vr) return;
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for(i=0; i<vr->size; i++)
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mark(vr->array[i]);
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}
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// Sets the reference bit on the object, and recursively on all
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// objects reachable from it. Uses the processor stack for recursion...
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static void mark(naRef r)
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{
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int i;
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if(IS_NUM(r) || IS_NIL(r))
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return;
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if(PTR(r).obj->mark == 1)
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return;
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PTR(r).obj->mark = 1;
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switch(PTR(r).obj->type) {
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case T_VEC: markvec(r); break;
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case T_HASH: naiGCMarkHash(r); break;
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case T_CODE:
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mark(PTR(r).code->srcFile);
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for(i=0; i<PTR(r).code->nConstants; i++)
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mark(PTR(r).code->constants[i]);
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break;
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case T_FUNC:
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mark(PTR(r).func->code);
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mark(PTR(r).func->namespace);
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mark(PTR(r).func->next);
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break;
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}
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}
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void naiGCMark(naRef r)
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{
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mark(r);
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}
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// Collects all the unreachable objects into a free list, and
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// allocates more space if needed.
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static void reap(struct naPool* p)
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{
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struct Block* b;
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int elem, freesz, total = poolsize(p);
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freesz = total < MIN_BLOCK_SIZE ? MIN_BLOCK_SIZE : total;
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freesz = (3 * freesz / 2) + (globals->nThreads * OBJ_CACHE_SZ);
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if(p->freesz < freesz) {
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naFree(p->free0);
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p->freesz = freesz;
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p->free = p->free0 = naAlloc(sizeof(void*) * p->freesz);
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}
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p->nfree = 0;
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p->free = p->free0;
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for(b = p->blocks; b; b = b->next)
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for(elem=0; elem < b->size; elem++) {
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struct naObj* o = (struct naObj*)(b->block + elem * p->elemsz);
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if(o->mark == 0)
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freeelem(p, o);
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o->mark = 0;
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}
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p->freetop = p->nfree;
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// allocs of this type until the next collection
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globals->allocCount += total/2;
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// Allocate more if necessary (try to keep 25-50% of the objects
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// available)
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if(p->nfree < total/4) {
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int used = total - p->nfree;
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int avail = total - used;
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int need = used/2 - avail;
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if(need > 0)
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newBlock(p, need);
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}
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}
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// Does the swap, returning the old value
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static void* doswap(void** target, void* val)
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{
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void* old = *target;
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*target = val;
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return old;
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}
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// Atomically replaces target with a new pointer, and adds the old one
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// to the list of blocks to free the next time something holds the
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// giant lock.
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void naGC_swapfree(void** target, void* val)
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{
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void* old;
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LOCK();
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old = doswap(target, val);
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while(globals->ndead >= globals->deadsz)
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bottleneck();
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globals->deadBlocks[globals->ndead++] = old;
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UNLOCK();
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}
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