Initial stab at Venti.

src/cmd/venti/lump.c

@@ -0,0 +1,206 @@
+#include "stdinc.h"
+#include "dat.h"
+#include "fns.h"
+
+int			queuewrites = 0;
+
+static Packet		*readilump(Lump *u, IAddr *ia, u8int *score, int rac);
+
+Packet*
+readlump(u8int *score, int type, u32int size)
+{
+	Lump *u;
+	Packet *p;
+	IAddr ia;
+	u32int n;
+	int rac;
+
+	qlock(&stats.lock);
+	stats.lumpreads++;
+	qunlock(&stats.lock);
+	u = lookuplump(score, type);
+	if(u->data != nil){
+		n = packetsize(u->data);
+		if(n > size){
+			seterr(EOk, "read too small: asked for %d need at least %d", size, n);
+			putlump(u);
+
+			return nil;
+		}
+		p = packetdup(u->data, 0, n);
+		putlump(u);
+
+		return p;
+	}
+
+	if(lookupscore(score, type, &ia, &rac) < 0){
+		//ZZZ place to check for someone trying to guess scores
+		seterr(EOk, "no block with that score exists");
+
+		putlump(u);
+		return nil;
+	}
+	if(ia.size > size){
+		seterr(EOk, "read too small 1: asked for %d need at least %d", size, ia.size);
+
+		putlump(u);
+		return nil;
+	}
+
+	p = readilump(u, &ia, score, rac);
+	putlump(u);
+
+	return p;
+}
+
+/*
+ * save away a lump, and return it's score.
+ * doesn't store duplicates, but checks that the data is really the same.
+ */
+int
+writelump(Packet *p, u8int *score, int type, u32int creator)
+{
+	Lump *u;
+	int ok;
+
+	qlock(&stats.lock);
+	stats.lumpwrites++;
+	qunlock(&stats.lock);
+
+	packetsha1(p, score);
+
+	u = lookuplump(score, type);
+	if(u->data != nil){
+		ok = 0;
+		if(packetcmp(p, u->data) != 0){
+			seterr(EStrange, "score collision");
+			ok = -1;
+		}
+		packetfree(p);
+		putlump(u);
+		return ok;
+	}
+
+print("writelump %08x\n", mainindex->arenas[0]);
+	if(queuewrites)
+		return queuewrite(u, p, creator);
+
+	ok = writeqlump(u, p, creator);
+
+	putlump(u);
+	return ok;
+}
+
+int
+writeqlump(Lump *u, Packet *p, int creator)
+{
+	ZBlock *flat;
+	Packet *old;
+	IAddr ia;
+	int ok;
+	int rac;
+
+	if(lookupscore(u->score, u->type, &ia, &rac) == 0){
+		/*
+		 * if the read fails,
+		 * assume it was corrupted data and store the block again
+		 */
+		old = readilump(u, &ia, u->score, rac);
+		if(old != nil){
+			ok = 0;
+			if(packetcmp(p, old) != 0){
+				seterr(EStrange, "score collision");
+				ok = -1;
+			}
+			packetfree(p);
+			packetfree(old);
+
+			return ok;
+		}
+		logerr(EAdmin, "writelump: read %V failed, rewriting: %r\n", u->score);
+	}
+
+	flat = packet2zblock(p, packetsize(p));
+	ok = storeclump(mainindex, flat, u->score, u->type, creator, &ia);
+	freezblock(flat);
+	if(ok == 0)
+		ok = insertscore(u->score, &ia, 1);
+	if(ok == 0)
+		insertlump(u, p);
+	else
+		packetfree(p);
+
+	return ok;
+}
+
+static void
+readahead(u64int a, Arena *arena, u64int aa, int n)
+{	
+	u8int buf[ClumpSize];
+	Clump cl;
+	IAddr ia;
+
+	while(n > 0) {
+		if (aa >= arena->used)
+			break;
+		if(readarena(arena, aa, buf, ClumpSize) < ClumpSize)
+			break;
+		if(unpackclump(&cl, buf) < 0)
+			break;
+		ia.addr = a;
+		ia.type = cl.info.type;
+		ia.size = cl.info.uncsize;
+		ia.blocks = (cl.info.size + ClumpSize + (1 << ABlockLog) - 1) >> ABlockLog;
+		insertscore(cl.info.score, &ia, 0);
+		a += ClumpSize + cl.info.size;
+		aa += ClumpSize + cl.info.size;
+		n--;
+	}
+}
+
+static Packet*
+readilump(Lump *u, IAddr *ia, u8int *score, int rac)
+{
+	Arena *arena;
+	ZBlock *zb;
+	Packet *p, *pp;
+	Clump cl;
+	u64int a, aa;
+	u8int sc[VtScoreSize];
+
+	arena = amapitoa(mainindex, ia->addr, &aa);
+	if(arena == nil)
+		return nil;
+
+	zb = loadclump(arena, aa, ia->blocks, &cl, sc, paranoid);
+	if(zb == nil)
+		return nil;
+
+	if(ia->size != cl.info.uncsize){
+		seterr(EInconsist, "index and clump size mismatch");
+		freezblock(zb);
+		return nil;
+	}
+	if(ia->type != cl.info.type){
+		seterr(EInconsist, "index and clump type mismatch");
+		freezblock(zb);
+		return nil;
+	}
+	if(scorecmp(score, sc) != 0){
+		seterr(ECrash, "score mismatch");
+		freezblock(zb);
+		return nil;
+	}
+
+	if(rac == 0) {
+		a = ia->addr + ClumpSize + cl.info.size;
+		aa += ClumpSize + cl.info.size;
+		readahead(a, arena, aa, 20);
+	}
+
+	p = zblock2packet(zb, cl.info.uncsize);
+	freezblock(zb);
+	pp = packetdup(p, 0, packetsize(p));
+	insertlump(u, pp);
+	return p;
+}