From 92baf59b693e2f2a624e6f4fc7262c438103664d Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@swtch.com>
Date: Thu, 23 Aug 2007 11:01:20 -0400
Subject: venti: add -s flag to disable redundant SHA1 in mirrorarenas

---
 src/cmd/venti/srv/mirrorarenas.c | 44 +++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/src/cmd/venti/srv/mirrorarenas.c b/src/cmd/venti/srv/mirrorarenas.c
index 55142054..b16472bb 100644
--- a/src/cmd/venti/srv/mirrorarenas.c
+++ b/src/cmd/venti/srv/mirrorarenas.c
@@ -22,13 +22,14 @@ Part *src;
 Part *dst;
 int force;
 int verbose;
+int dosha1 = 1;
 char *status;
 uvlong astart, aend;
 
 void
 usage(void)
 {
-	fprint(2, "usage: mirrorarenas [-v] src dst [ranges]\n");
+	fprint(2, "usage: mirrorarenas [-sv] src dst [ranges]\n");
 	threadexitsall("usage");
 }
 
@@ -240,7 +241,7 @@ void
 mirror(Arena *sa, Arena *da)
 {
 	vlong v, si, di, end;
-	int clumpmax, blocksize;
+	int clumpmax, blocksize, sealed;
 	static uchar buf[MaxIoSize];
 	ArenaHead h;
 	DigestState xds, *ds;
@@ -305,7 +306,8 @@ mirror(Arena *sa, Arena *da)
 
 	shaoff = 0;
 	ds = nil;
-	if(sa->diskstats.sealed && scorecmp(sa->score, zeroscore) != 0){
+	sealed = sa->diskstats.sealed && scorecmp(sa->score, zeroscore) != 0;
+	if(sealed && dosha1){
 		/* start sha1 state with header */
 		memset(&xds, 0, sizeof xds);
 		ds = &xds;
@@ -362,7 +364,7 @@ mirror(Arena *sa, Arena *da)
 	if(ewritepart(dst, end, buf, blocksize) < 0)
 		return;
 
-	if(ds){
+	if(sealed){
 		/*
 		 * ... but on the final pass, copy the encoding
 		 * of the tail information from the source
@@ -375,20 +377,27 @@ mirror(Arena *sa, Arena *da)
 		if(asha1(dst, shaoff, end, ds) < 0
 		|| copy(end, end+blocksize-VtScoreSize, "tail", ds) < 0)
 			return;
-		memset(buf, 0, VtScoreSize);
-		sha1(buf, VtScoreSize, da->score, ds);
-		if(scorecmp(sa->score, da->score) == 0){
+		if(dosha1){
+			memset(buf, 0, VtScoreSize);
+			sha1(buf, VtScoreSize, da->score, ds);
+			if(scorecmp(sa->score, da->score) == 0){
+				if(verbose)
+					chat("%T %s: %V sealed mirrored\n", sa->name, sa->score);
+				if(ewritepart(dst, end+blocksize-VtScoreSize, da->score, VtScoreSize) < 0)
+					return;
+			}else{
+				chat("%T %s: sealing dst: score mismatch: %V vs %V\n", sa->name, sa->score, da->score);
+				memset(&xds, 0, sizeof xds);
+				asha1(dst, base-blocksize, end+blocksize-VtScoreSize, &xds);
+				sha1(buf, VtScoreSize, 0, &xds);
+				chat("%T   reseal: %V\n", da->score);
+				status = "errors";
+			}
+		}else{
 			if(verbose)
-				chat("%T %s: %V sealed mirrored\n", sa->name, sa->score);
-			if(ewritepart(dst, end+blocksize-VtScoreSize, da->score, VtScoreSize) < 0)
+				chat("%T %s: %V mirrored\n", sa->name, sa->score);
+			if(ewritepart(dst, end+blocksize-VtScoreSize, sa->score, VtScoreSize) < 0)
 				return;
-		}else{
-			chat("%T %s: sealing dst: score mismatch: %V vs %V\n", sa->name, sa->score, da->score);
-			memset(&xds, 0, sizeof xds);
-			asha1(dst, base-blocksize, end+blocksize-VtScoreSize, &xds);
-			sha1(buf, VtScoreSize, 0, &xds);
-			chat("%T   reseal: %V\n", da->score);
-			status = "errors";
 		}
 	}else{
 		chat("%T %s: %,lld used mirrored\n",
@@ -462,6 +471,9 @@ threadmain(int argc, char **argv)
 	case 'v':
 		verbose++;
 		break;
+	case 's':
+		dosha1 = 0;
+		break;
 	default:
 		usage();
 	}ARGEND
-- 
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