cache_test.go

Documentation: github.com/google/go-containerregistry/pkg/v1/cache

     1  // Copyright 2021 Google LLC All Rights Reserved.
     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 cache
    16  
    17  import (
    18  	"errors"
    19  	"io"
    20  	"testing"
    21  
    22  	v1 "github.com/google/go-containerregistry/pkg/v1"
    23  	"github.com/google/go-containerregistry/pkg/v1/mutate"
    24  	"github.com/google/go-containerregistry/pkg/v1/random"
    25  	"github.com/google/go-containerregistry/pkg/v1/validate"
    26  )
    27  
    28  func TestImage(t *testing.T) {
    29  	img, err := random.Image(1024, 5)
    30  	if err != nil {
    31  		t.Fatalf("random.Image: %v", err)
    32  	}
    33  	m := &memcache{map[v1.Hash]v1.Layer{}}
    34  	img = Image(img, m)
    35  
    36  	// Validate twice to hit the cache.
    37  	if err := validate.Image(img); err != nil {
    38  		t.Errorf("Validate: %v", err)
    39  	}
    40  	if err := validate.Image(img); err != nil {
    41  		t.Errorf("Validate: %v", err)
    42  	}
    43  }
    44  
    45  func TestImageIndex(t *testing.T) {
    46  	// ImageIndex with child Image and ImageIndex manifests.
    47  	ii, err := random.Index(1024, 5, 2)
    48  	if err != nil {
    49  		t.Fatalf("random.Index: %v", err)
    50  	}
    51  	iiChild, err := random.Index(1024, 5, 2)
    52  	if err != nil {
    53  		t.Fatalf("random.Index: %v", err)
    54  	}
    55  	ii = mutate.AppendManifests(ii, mutate.IndexAddendum{Add: iiChild})
    56  
    57  	m := &memcache{map[v1.Hash]v1.Layer{}}
    58  	ii = ImageIndex(ii, m)
    59  
    60  	// Validate twice to hit the cache.
    61  	if err := validate.Index(ii); err != nil {
    62  		t.Errorf("Validate: %v", err)
    63  	}
    64  	if err := validate.Index(ii); err != nil {
    65  		t.Errorf("Validate: %v", err)
    66  	}
    67  }
    68  
    69  func TestLayersLazy(t *testing.T) {
    70  	img, err := random.Image(1024, 5)
    71  	if err != nil {
    72  		t.Fatalf("random.Image: %v", err)
    73  	}
    74  	m := &memcache{map[v1.Hash]v1.Layer{}}
    75  	img = Image(img, m)
    76  
    77  	layers, err := img.Layers()
    78  	if err != nil {
    79  		t.Fatalf("img.Layers: %v", err)
    80  	}
    81  
    82  	// After calling Layers, nothing is cached.
    83  	if got, want := len(m.m), 0; got != want {
    84  		t.Errorf("Cache has %d entries, want %d", got, want)
    85  	}
    86  
    87  	rc, err := layers[0].Uncompressed()
    88  	if err != nil {
    89  		t.Fatalf("layer.Uncompressed: %v", err)
    90  	}
    91  	io.Copy(io.Discard, rc)
    92  
    93  	if got, expected := len(m.m), 1; got != expected {
    94  		t.Errorf("expected %v layers in cache after reading, got %v", expected, got)
    95  	}
    96  }
    97  
    98  // TestCacheShortCircuit tests that if a layer is found in the cache,
    99  // LayerByDigest is not called in the underlying Image implementation.
   100  func TestCacheShortCircuit(t *testing.T) {
   101  	l := &fakeLayer{}
   102  	m := &memcache{map[v1.Hash]v1.Layer{
   103  		fakeHash: l,
   104  	}}
   105  	img := Image(&fakeImage{}, m)
   106  
   107  	for i := 0; i < 10; i++ {
   108  		if _, err := img.LayerByDigest(fakeHash); err != nil {
   109  			t.Errorf("LayerByDigest[%d]: %v", i, err)
   110  		}
   111  	}
   112  }
   113  
   114  var fakeHash = v1.Hash{Algorithm: "fake", Hex: "data"}
   115  
   116  type fakeLayer struct{ v1.Layer }
   117  type fakeImage struct{ v1.Image }
   118  
   119  func (f *fakeImage) LayerByDigest(v1.Hash) (v1.Layer, error) {
   120  	return nil, errors.New("LayerByDigest was called")
   121  }
   122  
   123  // memcache is an in-memory Cache implementation.
   124  //
   125  // It doesn't intend to actually write layer data, it just keeps a reference
   126  // to the original Layer.
   127  //
   128  // It only assumes/considers compressed layers, and so only writes layers by
   129  // digest.
   130  type memcache struct {
   131  	m map[v1.Hash]v1.Layer
   132  }
   133  
   134  func (m *memcache) Put(l v1.Layer) (v1.Layer, error) {
   135  	digest, err := l.Digest()
   136  	if err != nil {
   137  		return nil, err
   138  	}
   139  	m.m[digest] = l
   140  	return l, nil
   141  }
   142  
   143  func (m *memcache) Get(h v1.Hash) (v1.Layer, error) {
   144  	l, found := m.m[h]
   145  	if !found {
   146  		return nil, ErrNotFound
   147  	}
   148  	return l, nil
   149  }
   150  
   151  func (m *memcache) Delete(h v1.Hash) error {
   152  	delete(m.m, h)
   153  	return nil
   154  }
   155
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