X-Git-Url: https://mattmccutchen.net/rsync/rsync.git/blobdiff_plain/c64ca7ef58bf3b2eb41cd0d1cd809fe934be4d8a..fdd10da6f7995296f6bb5ee3dd7231d6dbc20b5e:/match.c

diff --git a/match.c b/match.c
index 300e2ba0..72947d0a 100644
--- a/match.c
+++ b/match.c
@@ -1,21 +1,24 @@
 /*
-   Copyright (C) Andrew Tridgell 1996
-   Copyright (C) Paul Mackerras 1996
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-*/
+ * Block matching used by the file-transfer code.
+ *
+ * Copyright (C) 1996 Andrew Tridgell
+ * Copyright (C) 1996 Paul Mackerras
+ * Copyright (C) 2003, 2004, 2005, 2006 Wayne Davison
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
+ */
 
 #include "rsync.h"
 
@@ -37,35 +40,29 @@ static int total_matches;
 
 extern struct stats stats;
 
-static uint32 tablesize;
-static int32 *sum_table;
+#define TABLESIZE (1<<16)
+
+static int32 *hash_table;
 
-#define GETTAG(sum) ((sum)%tablesize)
+#define SUM2HASH2(s1,s2) (((s1) + (s2)) & 0xFFFF)
+#define SUM2HASH(sum) SUM2HASH2((sum)&0xFFFF,(sum)>>16)
 
 static void build_hash_table(struct sum_struct *s)
 {
 	int32 i;
-	uint32 prior_size = tablesize;
-
-	/* Dynamically calculate the hash table size so that the hash load
-	 * for big files is about 80%.  This number must be odd or s2 will
-	 * not be able to span the entire set. */
-	tablesize = (uint32)(s->count/8) * 10 + 11;
-	if (tablesize < 65537)
-		tablesize = 65537; /* a prime number */
-	if (tablesize != prior_size) {
-		free(sum_table);
-		sum_table = new_array(int32, tablesize);
-		if (!sum_table)
+
+	if (!hash_table) {
+		hash_table = new_array(int32, TABLESIZE);
+		if (!hash_table)
 			out_of_memory("build_hash_table");
 	}
 
-	memset(sum_table, 0xFF, tablesize * sizeof sum_table[0]);
+	memset(hash_table, 0xFF, TABLESIZE * sizeof hash_table[0]);
 
 	for (i = 0; i < s->count; i++) {
-		uint32 t = GETTAG(s->sums[i].sum1);
-		s->sums[i].chain = sum_table[t];
-		sum_table[t] = i;
+		uint32 t = SUM2HASH(s->sums[i].sum1);
+		s->sums[i].chain = hash_table[t];
+		hash_table[t] = i;
 	}
 }
 
@@ -163,13 +160,16 @@ static void hash_search(int f,struct sum_struct *s,
 		int done_csum2 = 0;
 		int32 i;
 
-		if (verbose > 4)
-			rprintf(FINFO,"offset=%.0f sum=%08x\n",(double)offset,sum);
+		if (verbose > 4) {
+			rprintf(FINFO, "offset=%.0f sum=%04x%04x\n",
+				(double)offset, s2 & 0xFFFF, s1 & 0xFFFF);
+		}
 
-		i = sum_table[GETTAG(sum)];
+		i = hash_table[SUM2HASH2(s1,s2)];
 		if (i < 0)
 			goto null_hash;
 
+		sum = (s1 & 0xffff) | (s2 << 16);
 		hash_hits++;
 		do {
 			int32 l;
@@ -272,7 +272,6 @@ static void hash_search(int f,struct sum_struct *s,
 			s2 += s1;
 		} else
 			--k;
-		sum = (s1 & 0xffff) | (s2 << 16);
 
 		/* By matching early we avoid re-reading the
 		   data 3 times in the case where a token