WT-3575 ASCII statistics log printing (#3652)

* WT-3575 ASCII statistics log printing

Add a test for JSON configuration before logging the table name in
JSON format.

Minor KNF/whitespace.

* When logging statistics, log them in JSON format, that's our default now.

When logging statistics, log them when closing down the system.

src/conn/conn_stat.c

@@ -271,6 +271,9 @@ __statlog_print_table_name(
 
 	conn = S2C(session);
 
+	if (!FLD_ISSET(conn->stat_flags, WT_STAT_JSON))
+		return (0);
+
 	/*
 	 * If printing the connection stats, write that header and we are done.
 	 */
@@ -282,8 +285,8 @@ __statlog_print_table_name(
 
 	/*
 	 * If this is the first table we are printing stats for print the header
-	 * for the wiredTigerTables section. Otherwise print a comma as this
-	 * is a subsequent table.
+	 * for the wiredTigerTables section. Otherwise print a comma as this is
+	 * a subsequent table.
 	 */
 	if (conn->stat_json_tables)
 		WT_RET(__wt_fprintf(session, conn->stat_fs,","));
@@ -386,11 +389,10 @@ __statlog_dump(WT_SESSION_IMPL *session, const char *name, bool conn_stats)
 			    "%s\"%s\":%" PRId64,
 			    groupfirst ? "" : ",", endprefix + 2, val));
 			groupfirst = false;
-		} else {
+		} else
 			WT_ERR(__wt_fprintf(session, conn->stat_fs,
 			    "%s %" PRId64 " %s %s\n",
 			    conn->stat_stamp, val, name, desc));
-		}
 	}
 	WT_ERR_NOTFOUND_OK(ret);
 	if (FLD_ISSET(conn->stat_flags, WT_STAT_JSON))

test/format/wts.c

@@ -224,11 +224,12 @@ wts_open(const char *home, bool set_api, WT_CONNECTION **connp)
 		if (mmrand(NULL, 0, 5) == 1 &&
 		    memcmp(g.uri, "file:", strlen("file:")) == 0)
 			CONFIG_APPEND(p,
-			    ",statistics=(fast)"
-			    ",statistics_log=(wait=5,sources=(\"file:\"))");
+			    ",statistics=(fast),statistics_log="
+			    "(json,on_close,wait=5,sources=(\"file:\"))");
 		else
 			CONFIG_APPEND(p,
-			    ",statistics=(fast),statistics_log=(wait=5)");
+			    ",statistics=(fast),statistics_log="
+			    "(json,on_close,wait=5)");
 	} else
 		CONFIG_APPEND(p,
 		    ",statistics=(%s)", g.c_statistics ? "fast" : "none");