git/send: smaller packfiles when pushing

When pushing to a remote repository, we would
pack at least all objects in one commit, even
if the remote repository had most of them.

This change prunes out all objects from the
last commit that they have, which should drop
the size of the generated pack file noticably
for the common case of pushing a commit or
that changes a small percentage of files
in a larger repository.

git.h

@@ -248,7 +248,7 @@ Object	*readobject(Hash);
 Object	*clearedobject(Hash, int);
 void	parseobject(Object *);
 int	indexpack(char *, char *, Hash);
-int	writepack(int, Object **, int, Hash*);
+int	writepack(int, Hash*, int, Hash*, int, Hash*);
 int	hasheq(Hash *, Hash *);
 Object	*ref(Object *);
 void	unref(Object *);

pack.c

@@ -1167,10 +1167,15 @@ writeordercmp(void *pa, void *pb)
 }
 
 static void
-addmeta(Objmeta ***meta, int *nmeta, Object *o, char *path, vlong mtime)
+addmeta(Objmeta ***meta, int *nmeta, Objset *has, Object *o, char *path, vlong mtime)
 {
 	Objmeta *m;
 
+	if(oshas(has, o->hash))
+		return;
+	osadd(has, o);
+	if(meta == nil)
+		return;
 	m = emalloc(sizeof(Objmeta));
 	m->obj = o;
 	m->path = estrdup(path);
@@ -1201,8 +1206,7 @@ loadtree(Objmeta ***m, int *nm, Objset *has, Hash tree, char *dpath, vlong mtime
 		return 0;
 	if((t = readobject(tree)) == nil)
 		return -1;
-	osadd(has, t);
-	addmeta(m, nm, t, dpath, mtime);
+	addmeta(m, nm, has, t, dpath, mtime);
 	for(i = 0; i < t->tree->nent; i++){
 		e = &t->tree->ent[i];
 		if(oshas(has, e->h))
@@ -1212,10 +1216,9 @@ loadtree(Objmeta ***m, int *nm, Objset *has, Hash tree, char *dpath, vlong mtime
 		k = (e->mode & DMDIR) ? GTree : GBlob;
 		o = clearedobject(e->h, k);
 		p = smprint("%s/%s", dpath, e->name);
-		if(k == GBlob){
-			osadd(has, o);
-			addmeta(m, nm, o, p, mtime);
-		}else if(loadtree(m, nm, has, e->h, p, mtime) == -1){
+		if(k == GBlob)
+			addmeta(m, nm, has, o, p, mtime);
+		else if(loadtree(m, nm, has, e->h, p, mtime) == -1){
 			free(p);
 			return -1;
 		}
@@ -1235,31 +1238,39 @@ loadcommit(Objmeta ***m, int *nm, Objset *has, Hash h)
 		return 0;
 	if((c = readobject(h)) == nil)
 		return -1;
-	osadd(has, c);
-	addmeta(m, nm, c, "", c->commit->ctime);
+	addmeta(m, nm, has, c, "", c->commit->ctime);
 	r = loadtree(m, nm, has, c->commit->tree, "", c->commit->ctime);
 	unref(c);
 	return r;
 }
 
 static int
-readmeta(Object **commits, int ncommits, Objmeta ***m)
+readmeta(Hash *theirs, int ntheirs, Hash *ours, int nours, Objmeta ***m)
 {
+	Object **obj;
 	Objset has;
-	int i, nm;
+	int i, nm, nobj;
 
 	*m = nil;
 	nm = 0;
 	osinit(&has);
-	for(i = 0; i < ncommits; i++){
-		dprint(2, "loading commit %H\n", commits[i]->hash);
-		if(loadcommit(m, &nm, &has, commits[i]->hash) == -1){
-			free(*m);
-			return -1;
-		}
-	}
+	if(findtwixt(theirs, ntheirs, ours, nours, &obj, &nobj) == -1)
+		sysfatal("load twixt: %r");
+	if(nobj == 0)
+		return 0;
+	for(i = 0; i < nours; i++)
+		if(!hasheq(&ours[i], &Zhash))
+			if(loadcommit(nil, nil, &has, ours[i]) == -1)
+				goto out;
+	for(i = 0; i < nobj; i++)
+		if(loadcommit(m, &nm, &has, obj[i]->hash) == -1)
+			goto out;
 	osclear(&has);
 	return nm;
+out:
+	osclear(&has);
+	free(*m);
+	return -1;
 }
 
 static int
@@ -1281,12 +1292,14 @@ pickdeltas(Objmeta **meta, int nmeta)
 	int i, j, x, nd, sz, pcnt, best;
 
 	pcnt = 0;
-	fprint(2, "deltifying %d objects:   0%%", nmeta);
+	dprint(1, "picking deltas\n");
+	if(interactive)
+		fprint(2, "deltifying %d objects:   0%%", nmeta);
 	qsort(meta, nmeta, sizeof(Objmeta*), deltaordercmp);
 	for(i = 0; i < nmeta; i++){
 		m = meta[i];
 		x = (i*100) / nmeta;
-		if(x > pcnt){
+		if(interactive && x > pcnt){
 			pcnt = x;
 			if(pcnt%10 == 0)
 				fprint(2, "\b\b\b\b%3d%%", pcnt);
@@ -1561,15 +1574,15 @@ genpack(int fd, Objmeta **meta, int nmeta, Hash *h, int odelta)
 }
 
 int
-writepack(int fd, Object **obj, int nobj, Hash *h)
+writepack(int fd, Hash *theirs, int ntheirs, Hash *ours, int nours, Hash *h)
 {
 	Objmeta **meta;
 	int i, r, nmeta;
 
-	dprint(1, "reading meta\n");
-	if((nmeta = readmeta(obj, nobj, &meta)) == -1)
+	if((nmeta = readmeta(theirs, ntheirs, ours, nours, &meta)) == -1)
 		return -1;
-	dprint(1, "picking deltas\n");
+	if(nmeta == 0)
+		return 0;
 	pickdeltas(meta, nmeta);
 	dprint(1, "generating pack\n");
 	r = genpack(fd, meta, nmeta, h, 0);

repack.c

@@ -47,9 +47,8 @@ void
 main(int argc, char **argv)
 {
 	char path[128], **names;
-	int fd, nobj, nrefs;
+	int fd, nrefs;
 	Hash *refs, h;
-	Object **obj;
 	Dir rn;
 
 	ARGBEGIN{
@@ -64,13 +63,10 @@ main(int argc, char **argv)
 	refs = nil;
 	if((nrefs = listrefs(&refs, &names)) == -1)
 		sysfatal("load refs: %r");
-	if(findtwixt(refs, nrefs, nil, 0, &obj, &nobj) == -1)
-		sysfatal("load twixt: %r");
 	if((fd = create(TMPPATH("pack.tmp"), OWRITE, 0644)) == -1)
 		sysfatal("open %s: %r", TMPPATH("pack.tmp"));
-	if(writepack(fd, obj, nobj, &h) == -1)
+	if(writepack(fd, refs, nrefs, nil, 0, &h) == -1)
 		sysfatal("writepack: %r");
-	free(obj);
 	if(indexpack(TMPPATH("pack.tmp"), TMPPATH("idx.tmp"), h) == -1)
 		sysfatal("indexpack: %r");
 	close(fd);

send.c

@@ -99,10 +99,10 @@ parsecaps(char *caps, Capset *cs)
 int
 sendpack(Conn *c)
 {
-	int i, n, r, idx, nupd, nobj, nsp, send, first;
+	int i, n, r, idx, nupd, nsp, send, first;
 	char buf[Pktmax], *sp[3];
 	Hash h, *theirs, *ours;
-	Object *a, *b, *p, **obj;
+	Object *a, *b, *p;
 	char **refs;
 	Capset cs;
 
@@ -187,9 +187,7 @@ sendpack(Conn *c)
 	if(!send)
 		print("nothing to send\n");
 	if(send){
-		if(findtwixt(ours, nupd, theirs, nupd, &obj, &nobj) == -1)
-			return -1;
-		if(writepack(c->wfd, obj, nobj, &h) == -1)
+		if(writepack(c->wfd, ours, nupd, theirs, nupd, &h) == -1)
 			return -1;
 		if(cs.report && readphase(c) == -1)
 			return -1;

serve.c

@@ -138,17 +138,13 @@ int
 servpack(Conn *c)
 {
 	Hash *head, *tail, h;
-	Object **obj;
-	int nhead, ntail, nobj;
+	int nhead, ntail;
 
 	dprint(1, "negotiating pack\n");
 	if(servnegotiate(c, &head, &nhead, &tail, &ntail) == -1)
 		sysfatal("negotiate: %r");
-	dprint(1, "finding twixt\n");
-	if(findtwixt(head, nhead, tail, ntail, &obj, &nobj) == -1)
-		sysfatal("twixt: %r");
 	dprint(1, "writing pack\n");
-	if(nobj > 0 && writepack(c->wfd, obj, nobj, &h) == -1)
+	if(writepack(c->wfd, head, nhead, tail, ntail, &h) == -1)
 		sysfatal("send: %r");
 	return 0;
 }