From fed962f059461f64b1017836599c9aa51285d026 Mon Sep 17 00:00:00 2001
From: Panu Matilainen <pmatilai@redhat.com>
Date: Thu, 1 Apr 2010 15:28:45 +0300
Subject: [PATCH] Generate package database statistics on close & make use of
 it on open - Turn dbiStat() into more useful: return the number of keys in
 the   index, hiding away the BDB internal access method stuff into the
 backend - Force statistics gathering at Packages db close, take advantage of 
  that when its opened to get a fairly accurate count of packages for  
 initial "header verified" bitmap allocation. Previously DB_FAST_STAT   was
 used on open but it never returns anything when no stats have   been
 previously collected, hence the need for the expensive slow stat. - The
 performance hit from stat generation is hardly worth it for   the bitmap
 allocation alone, but lets see if there are other uses... - Also gets rid of
 dbi_stats member, this is not particularly useful

---
 lib/backend/db3.c      | 28 +++++++++++++++++-----------
 lib/backend/dbconfig.c |  1 -
 lib/backend/dbi.h      |  9 ++++-----
 lib/rpmdb.c            | 22 ++++++++++++----------
 4 files changed, 33 insertions(+), 27 deletions(-)

diff --git a/lib/backend/db3.c b/lib/backend/db3.c
index ed6815c79..4b5500ed0 100644
--- a/lib/backend/db3.c
+++ b/lib/backend/db3.c
@@ -350,21 +350,27 @@ dbiIndexType dbiType(dbiIndex dbi)
     return dbi->dbi_type;
 }
 
-int dbiStat(dbiIndex dbi, unsigned int flags)
+int dbiNumKeys(dbiIndex dbi, int fast)
 {
     DB * db = dbi->dbi_db;
-    DB_TXN * txnid = NULL;
-    int rc = 0;
+    int rc, nkeys = -1;
+    void *sp = NULL;
 
-    assert(db != NULL);
-    if (flags)
-	flags = DB_FAST_STAT;
-    else
-	flags = 0;
-    dbi->dbi_stats = _free(dbi->dbi_stats);
-    rc = db->stat(db, txnid, &dbi->dbi_stats, flags);
+    rc = db->stat(db, dbi->dbi_txnid, &sp, fast ? DB_FAST_STAT : 0);
     rc = cvtdberr(dbi, "db->stat", rc, _debug);
-    return rc;
+
+    if (rc == 0 && sp) {
+	if (dbi->dbi_dbtype == DB_HASH) {
+	    DB_HASH_STAT *hash = sp;
+	    nkeys = hash->hash_nkeys;
+	} else if (dbi->dbi_dbtype == DB_BTREE) {
+	    DB_BTREE_STAT *btree = sp;
+	    nkeys = btree->bt_nkeys;
+	}
+	free(sp);
+    }
+
+    return nkeys;
 }
 
 int dbiVerify(dbiIndex dbi, unsigned int flags)
diff --git a/lib/backend/dbconfig.c b/lib/backend/dbconfig.c
index 750c67a5c..aaa5cef6d 100644
--- a/lib/backend/dbconfig.c
+++ b/lib/backend/dbconfig.c
@@ -119,7 +119,6 @@ static const struct poptOption rdbOptions[] = {
 dbiIndex dbiFree(dbiIndex dbi)
 {
     if (dbi) {
-	dbi->dbi_stats = _free(dbi->dbi_stats);
 	dbi = _free(dbi);
     }
     return dbi;
diff --git a/lib/backend/dbi.h b/lib/backend/dbi.h
index 4990cfad5..3bae2a425 100644
--- a/lib/backend/dbi.h
+++ b/lib/backend/dbi.h
@@ -49,7 +49,6 @@ struct _dbiIndex {
 
     DB * dbi_db;		/*!< Berkeley DB * handle */
     DB_TXN * dbi_txnid;		/*!< Bekerley DB_TXN * transaction id */
-    void * dbi_stats;		/*!< Berkeley db statistics */
 };
 
 /** \ingroup dbi
@@ -197,13 +196,13 @@ RPM_GNUC_INTERNAL
 int dbiByteSwapped(dbiIndex dbi);
 
 /** \ingroup dbi
- * Is database byte swapped?
+ * Return number of keys in index
  * @param dbi		index database handle
- * @param flags		DB_FAST_STAT or 0
- * @return		0 on success
+ * @param fast		fast, cached estimate or slow but accurate?
+ * @return		number of keys in index, -1 on error
  */
 RPM_GNUC_INTERNAL
-int dbiStat(dbiIndex dbi, unsigned int flags);
+int dbiNumKeys(dbiIndex dbi, int fast);
 
 /** \ingroup dbi
  * Type of dbi (primary data / index)
diff --git a/lib/rpmdb.c b/lib/rpmdb.c
index e324667eb..d15403ab8 100644
--- a/lib/rpmdb.c
+++ b/lib/rpmdb.c
@@ -178,20 +178,15 @@ static dbiIndex rpmdbOpenIndex(rpmdb db, rpmTag rpmtag, unsigned int flags)
 
     if (dbi != NULL && rc == 0) {
 	db->_dbi[dbix] = dbi;
+	/* Grab a fast estimate of package count for allocation */
 	if (rpmtag == RPMDBI_PACKAGES && db->db_bits == NULL) {
-	    db->db_nbits = 1024;
-	    if (!dbiStat(dbi, DB_FAST_STAT)) {
-		DB_HASH_STAT * hash = (DB_HASH_STAT *)dbi->dbi_stats;
-		if (hash)
-		    db->db_nbits += hash->hash_nkeys;
-	    }
+	    int nkeys = dbiNumKeys(dbi, 1);
+	    db->db_nbits = 1024 + (nkeys > 0 ? nkeys : 0);
 	    db->db_bits = PBM_ALLOC(db->db_nbits);
 	}
-    }
-#ifdef HAVE_DB_H
-      else
+    } else {
 	dbi = dbiFree(dbi);
-#endif
+    }
 
 /* FIX: db->_dbi may be NULL */
     return dbi;
@@ -687,6 +682,13 @@ int rpmdbClose(rpmdb db)
 	int xx;
 	if (db->_dbi[dbix] == NULL)
 	    continue;
+
+	/* Force full statistics generation at package db close */
+	if (dbiTags[dbix] == RPMDBI_PACKAGES && 
+		    (db->db_mode & O_ACCMODE) != O_RDONLY) {
+	    (void) dbiNumKeys(db->_dbi[dbix], 0);
+	}
+
     	xx = dbiClose(db->_dbi[dbix], 0);
 	if (xx && rc == 0) rc = xx;
     	db->_dbi[dbix] = NULL;