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// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package devicemapper
import (
"bufio"
"bytes"
"fmt"
"os/exec"
"strconv"
"strings"
"k8s.io/klog/v2"
)
// thinLsClient knows how to run a thin_ls very specific to CoW usage for
// containers.
type thinLsClient interface {
// ThinLs runs a thin ls on the given device, which is expected to be a
// metadata device. The caller must hold the metadata snapshot for the
// device.
ThinLs(deviceName string) (map[string]uint64, error)
}
// newThinLsClient returns a thinLsClient or an error if the thin_ls binary
// couldn't be located.
func newThinLsClient() (thinLsClient, error) {
thinLsPath, err := ThinLsBinaryPresent()
if err != nil {
return nil, fmt.Errorf("error creating thin_ls client: %v", err)
}
return &defaultThinLsClient{thinLsPath}, nil
}
// defaultThinLsClient is a functional thinLsClient
type defaultThinLsClient struct {
thinLsPath string
}
var _ thinLsClient = &defaultThinLsClient{}
func (c *defaultThinLsClient) ThinLs(deviceName string) (map[string]uint64, error) {
args := []string{"--no-headers", "-m", "-o", "DEV,EXCLUSIVE_BYTES", deviceName}
klog.V(4).Infof("running command: thin_ls %v", strings.Join(args, " "))
output, err := exec.Command(c.thinLsPath, args...).Output()
if err != nil {
return nil, fmt.Errorf("Error running command `thin_ls %v`: %v\noutput:\n\n%v", strings.Join(args, " "), err, string(output))
}
return parseThinLsOutput(output), nil
}
// parseThinLsOutput parses the output returned by thin_ls to build a map of
// device id -> usage.
func parseThinLsOutput(output []byte) map[string]uint64 {
cache := map[string]uint64{}
// parse output
scanner := bufio.NewScanner(bytes.NewReader(output))
for scanner.Scan() {
output := scanner.Text()
fields := strings.Fields(output)
if len(fields) != 2 {
continue
}
deviceID := fields[0]
usage, err := strconv.ParseUint(fields[1], 10, 64)
if err != nil {
klog.Warningf("unexpected error parsing thin_ls output: %v", err)
continue
}
cache[deviceID] = usage
}
return cache
}
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