ref: dfd53a7c1835c5caa8a56bbe74f8f9977bb08add
dir: /snap.c/
#include <u.h> #include <libc.h> #include <fcall.h> #include <avl.h> #include "dat.h" #include "fns.h" uvlong inc64(uvlong *v, uvlong dv) { vlong ov, nv; while(1){ ov = *v; nv = ov + dv; if(cas64((u64int*)v, ov, nv)) return ov; } } Tree* openlabel(char *name) { char *p, buf[Keymax]; Kvp kv; Key k; if((p = packlabel(buf, sizeof(buf), name)) == nil) return nil; k.k = buf; k.nk = p - buf; if(btlookup(&fs->snap, &k, &kv, buf, sizeof(buf)) != nil) return nil; if(kv.nv != Snapsz) return nil; return opensnap(GBIT64(kv.v + 1)); } Tree* opensnap(vlong id) { char *p, buf[Kvmax]; Tree *t; Kvp kv; Key k; qlock(&fs->snaplk); for(t = fs->osnap; t != nil; t = t->snext){ if(t->gen == id){ ainc(&t->memref); qunlock(&fs->snaplk); return t; } } if((t = mallocz(sizeof(Tree), 1)) == nil) goto Error; memset(&t->lk, 0, sizeof(t->lk)); if((p = packsnap(buf, sizeof(buf), id)) == nil) goto Error; k.k = buf; k.nk = p - buf; if(btlookup(&fs->snap, &k, &kv, buf, sizeof(buf)) != nil) goto Error; if(unpacktree(t, kv.v, kv.nv) == nil) goto Error; t->memref = 1; t->snext = fs->osnap; fs->osnap = t; qunlock(&fs->snaplk); return t; Error: qunlock(&fs->snaplk); return nil; } void closesnap(Tree *t) { Tree *te, **p; int i; if(adec(&t->memref) != 0) return; for(i = Ndead-1; i >= 0; i--){ if(t->dead[i].tail == nil) continue; finalize(t->dead[i].tail); syncblk(t->dead[i].tail); //FIXME: putblk(t->dead[i].tail); } p = &fs->osnap; for(te = fs->osnap; te != nil; te = te->snext){ if(te == t) break; p = &te->snext; } assert(te != nil); *p = te->snext; free(te); } char* modifysnap(int op, Tree *t) { char kbuf[Snapsz], vbuf[Treesz]; char *p, *e; Msg m; int i; for(i = 0; i < Ndead; i++){ if(t->dead[i].tail != nil){ finalize(t->dead[i].tail); syncblk(t->dead[i].tail); } } m.op = op; if((p = packsnap(kbuf, sizeof(kbuf), t->gen)) == nil) return Elength; m.k = kbuf; m.nk = p - kbuf; if(op == Oinsert){ if((p = packtree(vbuf, sizeof(vbuf), t)) == nil) return Elength; m.v = vbuf; m.nv = p - vbuf; }else{ m.v = nil; m.nv = 0; } if((e = btupsert(&fs->snap, &m, 1)) != nil) return e; return nil; } static char* modifylabel(int op, char *name, vlong id) { char *p, *e, kbuf[Keymax], vbuf[Snapsz]; Msg m; if(op == Oinsert) e = refsnap(id); else e = unrefsnap(id, -1); if(e != nil) return e; m.op = op; if((p = packlabel(kbuf, sizeof(kbuf), name)) == nil) return Elength; m.k = kbuf; m.nk = p - kbuf; if((p = packsnap(vbuf, sizeof(vbuf), id)) == nil) return Elength; m.v = vbuf; m.nv = p - vbuf; if((e = btupsert(&fs->snap, &m, 1)) != nil) return e; return nil; } char* labelsnap(char *name, vlong gen) { return modifylabel(Oinsert, name, gen); } char* unlabelsnap(vlong gen, char *name) { return modifylabel(Odelete, name, gen); } char* refsnap(vlong id) { Tree *t; char *e; t = opensnap(id); t->ref++; if((e = modifysnap(Oinsert, t)) != nil) return e; closesnap(t); return nil; } char* unrefsnap(vlong id, vlong succ) { Tree *t, *u; char *e; if((t = opensnap(id)) == nil) return Eexist; if(--t->ref == 0){ if((u = opensnap(succ)) == nil) return Eexist; if((e = freesnap(t, u)) != nil) return e; if((e = modifysnap(Odelete, t)) != nil) return e; if((e = modifysnap(Oinsert, u)) != nil) return e; closesnap(u); closesnap(t); }else{ if((e = modifysnap(Oinsert, t)) != nil) return e; closesnap(t); } return nil; } void freedead(Bptr bp, void *) { dprint("reclaimed deadlist: %B\n", bp); reclaimblk(bp); } void redeadlist(Bptr bp, void *pt) { killblk(pt, bp); } char* freesnap(Tree *snap, Tree *next) { Oplog dl; int i; assert(snap->gen != next->gen); assert(next->prev[0] == snap->gen); dl = next->dead[Ndead-1]; scandead(&next->dead[0], freedead, nil); for(i = 0; i < Ndead-2; i++){ if(graft(&snap->dead[i], &next->dead[i+1]) == -1) return Efs; next->prev[i] = snap->prev[i]; next->dead[i] = snap->dead[i]; } for(; i < Ndead; i++){ next->prev[i] = snap->prev[i]; next->dead[i] = snap->dead[i]; } scandead(&dl, redeadlist, next); return nil; } Tree* newsnap(Tree *t) { vlong gen; Tree *r; int i; if(modifysnap(Oinsert, t) != nil) return nil; if((r = malloc(sizeof(Tree))) == nil) return nil; gen = inc64(&fs->nextgen, 1); memset(&r->lk, 0, sizeof(r->lk)); r->snext = fs->osnap; r->memref = 1; r->ref = 0; r->ht = t->ht; r->bp = t->bp; r->gen = gen; r->dirty = 0; /* shift deadlist down */ for(i = Ndead-1; i >= 0; i--){ r->prev[i] = i == 0 ? t->gen : t->prev[i-1]; r->dead[i].head.addr = -1; r->dead[i].head.hash = -1; r->dead[i].head.gen = -1; r->dead[i].tail = nil; } fs->osnap = r; return r; }