ndb: only invalidate the database cache if we must

We now only invalidate the cache if the cached entry gets written
or deleted. This is needed for the code in rpmdbNextIterator()
which first reads the next header and then writes the modified
old header to the database. Therefore we must not free the cached
entry if a modified header with a different id is written.

lib/backend/ndb/glue.c

@@ -311,12 +311,13 @@ static void setdata(dbiCursor dbc,  unsigned int hdrNum, unsigned char *hdrBlob,
 
 static rpmRC ndb_pkgdbPut(dbiIndex dbi, dbiCursor dbc,  unsigned int *hdrNum, unsigned char *hdrBlob, unsigned int hdrLen)
 {
+    struct ndbEnv_s *ndbenv = dbc->dbi->dbi_rpmdb->db_dbenv;
     unsigned int hnum = *hdrNum;
     int rc = RPMRC_OK;
 
     if (hnum == 0) {
 	rc = rpmpkgNextPkgIdx(dbc->dbi->dbi_db, &hnum);
-	if (!rc)
+	if (!rc && ndbenv->hdrNum == hnum)
 	    setdata(dbc, hnum, 0, 0);
     }
 
@@ -325,16 +326,19 @@ static rpmRC ndb_pkgdbPut(dbiIndex dbi, dbiCursor dbc,  unsigned int *hdrNum, un
 
     if (!rc) {
 	dbc->hdrNum = hnum;
-	setdata(dbc, hnum, 0, 0);
+	if (ndbenv->hdrNum == hnum)
+	    setdata(dbc, hnum, 0, 0);
 	*hdrNum = hnum;
     }
     return rc;
 }
 
 static rpmRC ndb_pkgdbDel(dbiIndex dbi, dbiCursor dbc,  unsigned int hdrNum)
 {
+    struct ndbEnv_s *ndbenv = dbc->dbi->dbi_rpmdb->db_dbenv;
     dbc->hdrNum = 0;
-    setdata(dbc, 0, 0, 0);
+    if (ndbenv->hdrNum == hdrNum)
+	setdata(dbc, 0, 0, 0);
     return rpmpkgDel(dbc->dbi->dbi_db, hdrNum);
 }