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hgfs: various improvements

lazily close revlog files and keep up to 8
revlogs arround. also cache the latest extracted
file descriptor of a revision in the revlog.
this avoids the quite expensive reextracting/patching
when we reopen the same file revision.

dont use the racy mktemp()/create, instead create
a uniqueue name and create with OEXCL. this also
avoids a bunch of access() calls.

fix eof case and use pread() in fcopy() to avoid the
seeks.

dont modify changelog temp file but simulate trailing
newline instead.

--- a/sys/src/cmd/hgfs/dat.h

+++ b/sys/src/cmd/hgfs/dat.h

@@ -46,6 +46,9 @@

 	int	nmap;

 	Revmap	*map;

+

+	int	tfd;

+	int	tid;

 };

 struct Revnode

--- a/sys/src/cmd/hgfs/fns.h

+++ b/sys/src/cmd/hgfs/fns.h

@@ -6,6 +6,7 @@

 int readhash(char *path, char *name, uchar hash[]);

 /* patch */

+int fcopy(int dfd, int sfd, vlong off, vlong len);

 int fpatchmark(int pfd, char *mark);

 int fpatch(int ofd, int bfd, int pfd);

--- a/sys/src/cmd/hgfs/fs.c

+++ b/sys/src/cmd/hgfs/fs.c

@@ -43,6 +43,7 @@

 static Revlog changelog;

 static Revlog manifest;

 static Revlog *revlogs;

+static int nfreerevlogs = 0;

 static char workdir[MAXPATH];

 static int mangle = 0;

@@ -51,7 +52,7 @@

 getrevlog(Revnode *nd)

 {

 	char buf[MAXPATH];

-	Revlog *rl;

+	Revlog *rl, **link;

 	int mang;

 	mang = mangle;

@@ -58,9 +59,21 @@

 Again:

 	nodepath(seprint(buf, buf+sizeof(buf), "%s/.hg/store/data", workdir),

 		buf+sizeof(buf), nd, mang);

-	for(rl = revlogs; rl; rl = rl->next)

-		if(strcmp(buf, rl->path) == 0)

+	link = &revlogs;

+	while(rl = *link){

+		if(strcmp(buf, rl->path) == 0){

+			if(rl->ref == 0) nfreerevlogs--;

 			break;

+		}

+		if(nfreerevlogs > 8 && rl->ref == 0){

+			*link = rl->next;

+			nfreerevlogs--;

+			revlogclose(rl);

+			free(rl);

+			continue;

+		}

+		link = &rl->next;

+	}

 	if(rl == nil){

 		rl = emalloc9p(sizeof(*rl));

 		memset(rl, 0, sizeof(*rl));

@@ -83,18 +96,8 @@

 static void

 closerevlog(Revlog *rl)

 {

-	Revlog **pp;

-

-	if(rl == nil || decref(rl))

-		return;

-	for(pp = &revlogs; *pp; pp = &((*pp)->next)){

-		if(*pp == rl){

-			*pp = rl->next;

-			break;

-		}

-	}

-	revlogclose(rl);

-	free(rl);

+	if(rl != nil && decref(rl) == 0)

+		nfreerevlogs++;

 }

 static Revinfo*

--- a/sys/src/cmd/hgfs/info.c

+++ b/sys/src/cmd/hgfs/info.c

@@ -8,7 +8,7 @@

 loadrevinfo(Revlog *changelog, int rev)

 {

 	char buf[BUFSZ], *p, *e;

-	int fd, line, inmsg, n;

+	int fd, line, eof, inmsg, n;

 	Revinfo *ri;

 	vlong off;

@@ -15,9 +15,6 @@

 	if((fd = revlogopentemp(changelog, rev)) < 0)

 		return nil;

-	seek(fd, 0, 2);

-	write(fd, "\n", 1);

-

 	off = fmetaheader(fd);

 	seek(fd, off, 0);

@@ -26,11 +23,19 @@

 	memmove(ri->chash, changelog->map[rev].hash, HASHSZ);

+	eof = 0;

 	line = 0;

 	inmsg = 0;

 	p = buf;

 	e = buf + BUFSZ;

-	while((n = read(fd, p, e - p)) > 0){

+	while(eof == 0){

+		if((n = read(fd, p, e - p)) < 0)

+			break;

+		if(n == 0){

+			eof = 1;

+			*p = '\n';

+			n++;

+		}

 		p += n;

 		while((p > buf) && (e = memchr(buf, '\n', p - buf))){

 			*e++ = 0;

--- a/sys/src/cmd/hgfs/patch.c

+++ b/sys/src/cmd/hgfs/patch.c

@@ -5,19 +5,25 @@

 #include "fns.h"

 int

-fcopy(int dfd, int sfd, vlong len)

+fcopy(int dfd, int sfd, vlong off, vlong len)

 {

 	uchar buf[BUFSZ];

 	int n;

-	while(len > 0){

-		if((n = BUFSZ) > len)

+	while(len != 0){

+		n = BUFSZ;

+		if(len > 0 && n > len)

 			n = len;

-		if((n = read(sfd, buf, n)) < 0)

+		if((n = pread(sfd, buf, n, off)) < 0)

 			return -1;

+		if(n == 0)

+			return len > 0 ? -1 : 0;

 		if(write(dfd, buf, n) != n)

 			return -1;

-		len -= n;

+		if(off >= 0)

+			off += n;

+		if(len > 0)

+			len -= n;

 	}

 	return 0;

 }

@@ -58,6 +64,8 @@

 	if(bfd >= 0){

 		h = malloc(sizeof(Frag));

+		if(h == nil)

+			goto errout;

 		h->next = nil;

 		h->off = 0;

 		h->fd = bfd;

@@ -101,6 +109,8 @@

 			back = end < fend;

 			if(front && back){

 				p = malloc(sizeof(Frag));

+				if(p == nil)

+					goto errout;

 				*p = *f;

 				f->next = p;

 				f->len = start - fstart;

@@ -123,6 +133,8 @@

 			fstart += f->len;

 		f = malloc(sizeof(Frag));

+		if(f == nil)

+			goto errout;

 		f->fd = pfd;

 		f->len = len;

 		f->off = seek(f->fd, 0, 1);

@@ -141,12 +153,9 @@

 			goto errout;

 	}

-	for(f = h; f; f = f->next){

-		if(seek(f->fd, f->off, 0) < 0)

+	for(f = h; f; f = f->next)

+		if(fcopy(ofd, f->fd, f->off, f->len) < 0)

 			goto errout;

-		if(fcopy(ofd, f->fd, f->len) < 0)

-			goto errout;

-	}

 	err = 0;

 errout:

--- a/sys/src/cmd/hgfs/revlog.c

+++ b/sys/src/cmd/hgfs/revlog.c

@@ -7,10 +7,10 @@

 int

 fmktemp(void)

 {

-	char temp[MAXPATH];

-

-	snprint(temp, sizeof(temp), "/tmp/hgXXXXXXXXXXX");

-	return create(mktemp(temp), OTRUNC|ORCLOSE|ORDWR, 0666);

+	static ulong id = 1;

+	char path[MAXPATH];

+	snprint(path, sizeof(path), "/tmp/hg%.12d%.8lux", getpid(), id++);

+	return create(path, OEXCL|OTRUNC|ORDWR|ORCLOSE, 0600);

 }

 void

@@ -65,6 +65,8 @@

 {

 	r->ifd = -1;

 	r->dfd = -1;

+	r->tfd = -1;

+	r->tid = -1;

 	path = smprint("%s.i", path);

 	if((r->ifd = open(path, mode)) < 0){

 		free(path);

@@ -94,6 +96,11 @@

 		close(r->dfd);

 		r->dfd = -1;

 	}

+	if(r->tfd >= 0){

+		close(r->tfd);

+		r->tfd = -1;

+	}

+	r->tid = -1;

 	free(r->map);

 	r->map = nil;

 	r->nmap = 0;

@@ -269,12 +276,19 @@

 {

 	int fd;

-	if((fd = fmktemp()) < 0)

-		return -1;

-	if(revlogextract(r, rev, fd) < 0){

-		close(fd);

-		return -1;

+	if(r->tfd < 0 || rev != r->tid){

+		if((fd = fmktemp()) < 0)

+			return -1;

+		if(revlogextract(r, rev, fd) < 0){

+			close(fd);

+			return -1;

+		}

+		if(r->tfd >= 0)

+			close(r->tfd);

+		r->tfd = fd;

+		r->tid = rev;

 	}

+	fd = dup(r->tfd, -1);

 	if(seek(fd, 0, 0) < 0){

 		close(fd);

 		return -1;

-- 

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