Add bandwidth limit feature --bw-limit

cmdline/bw.c

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2016 Andrea Mazzoleni
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "portable.h"
+
+#include "bw.h"
+
+void bw_init(struct snapraid_bw* bw, uint64_t limit)
+{
+	bw->limit = limit;
+	bw->total = 0;
+	bw->start = tick_ms();
+}
+
+void bw_limit(struct snapraid_bw* bw, uint64_t bytes)
+{
+	if (!bw || bw->limit == 0)
+		return;
+
+	uint64_t elapsed = tick_ms() - bw->start;
+	uint64_t done;
+	uint64_t eta;
+
+	done = __atomic_add_fetch(&bw->total, bytes, __ATOMIC_SEQ_CST);
+
+	eta = done * 1000 / bw->limit;
+
+	if (eta > elapsed) {
+		eta -= elapsed;
+		usleep(eta * 1000);
+	}
+}