vendor: Add dependencies for discosrv

vendor/github.com/cznic/fileutil/storage/probe.go

@@ -0,0 +1,74 @@
+// Copyright (c) 2011 CZ.NIC z.s.p.o. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// blame: jnml, labs.nic.cz
+
+package storage
+
+import "sync/atomic"
+
+// Probe collects usage statistics of the embeded Accessor.
+// Probe itself IS an Accessor.
+type Probe struct {
+	Accessor
+	Chain     *Probe
+	OpsRd     int64
+	OpsWr     int64
+	BytesRd   int64
+	BytesWr   int64
+	SectorsRd int64 // Assuming 512 byte sector size
+	SectorsWr int64
+}
+
+// NewProbe returns a newly created probe which embedes the src Accessor.
+// The retuned *Probe satisfies Accessor. if chain != nil then Reset()
+// is cascaded down the chained Probes.
+func NewProbe(src Accessor, chain *Probe) *Probe {
+	return &Probe{Accessor: src, Chain: chain}
+}
+
+func reset(n *int64) {
+	atomic.AddInt64(n, -atomic.AddInt64(n, 0))
+}
+
+// Reset zeroes the collected statistics of p.
+func (p *Probe) Reset() {
+	if p.Chain != nil {
+		p.Chain.Reset()
+	}
+	reset(&p.OpsRd)
+	reset(&p.OpsWr)
+	reset(&p.BytesRd)
+	reset(&p.BytesWr)
+	reset(&p.SectorsRd)
+	reset(&p.SectorsWr)
+}
+
+func (p *Probe) ReadAt(b []byte, off int64) (n int, err error) {
+	n, err = p.Accessor.ReadAt(b, off)
+	atomic.AddInt64(&p.OpsRd, 1)
+	atomic.AddInt64(&p.BytesRd, int64(n))
+	if n <= 0 {
+		return
+	}
+
+	sectorFirst := off >> 9
+	sectorLast := (off + int64(n) - 1) >> 9
+	atomic.AddInt64(&p.SectorsRd, sectorLast-sectorFirst+1)
+	return
+}
+
+func (p *Probe) WriteAt(b []byte, off int64) (n int, err error) {
+	n, err = p.Accessor.WriteAt(b, off)
+	atomic.AddInt64(&p.OpsWr, 1)
+	atomic.AddInt64(&p.BytesWr, int64(n))
+	if n <= 0 {
+		return
+	}
+
+	sectorFirst := off >> 9
+	sectorLast := (off + int64(n) - 1) >> 9
+	atomic.AddInt64(&p.SectorsWr, sectorLast-sectorFirst+1)
+	return
+}