github.com/alibaba/sealer@v0.8.6-0.20220430115802-37a2bdaa8173/pkg/image/imageprobe.go (about)

     1  // Copyright © 2021 Alibaba Group Holding Ltd.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package image
    16  
    17  import (
    18  	"fmt"
    19  
    20  	"github.com/opencontainers/go-digest"
    21  
    22  	"github.com/alibaba/sealer/logger"
    23  	"github.com/alibaba/sealer/pkg/image/cache"
    24  )
    25  
    26  type Prober interface {
    27  	Reset()
    28  	Probe(parentID string, layer *cache.Layer) (cacheID digest.Digest, err error)
    29  }
    30  
    31  type imageProber struct {
    32  	cache       Cache
    33  	reset       func() Cache
    34  	cacheBusted bool
    35  }
    36  
    37  func NewImageProber(cacheBuilder CacheBuilder, noCache bool) Prober {
    38  	if noCache {
    39  		return &nopProber{}
    40  	}
    41  
    42  	reset := func() Cache {
    43  		c, err := cacheBuilder.BuildImageCache()
    44  		if err != nil {
    45  			logger.Info("failed to init image cache, err: %s", err)
    46  			return &cache.NopImageCache{}
    47  		}
    48  		return c
    49  	}
    50  
    51  	return &imageProber{cache: reset(), reset: reset}
    52  }
    53  
    54  func (c *imageProber) Reset() {
    55  	c.cache = c.reset()
    56  	c.cacheBusted = false
    57  }
    58  
    59  func (c *imageProber) Probe(parentID string, layer *cache.Layer) (cacheID digest.Digest, err error) {
    60  	if c.cacheBusted {
    61  		return "", nil
    62  	}
    63  
    64  	cacheID, err = c.cache.GetCache(parentID, layer)
    65  	if err != nil {
    66  		return "", err
    67  	}
    68  
    69  	return cacheID, nil
    70  }
    71  
    72  type nopProber struct{}
    73  
    74  func (c *nopProber) Reset() {}
    75  
    76  func (c *nopProber) Probe(_ string, _ *cache.Layer) (digest.Digest, error) {
    77  	return "", fmt.Errorf("nop prober")
    78  }