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Support for a local filesystem cache (#41)
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* Draft support for a local filesystem cache

* Checkpoint on hash interface

* Remove unused function

* Adjust gitignore so that test fixture is versioned

* Use SetEnvKeyReplacer so that ZIM_CACHE_PATH is usable

Co-authored-by: Curtis Myzie <curtis.myzie@snyk.io>
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@curtis-fugue @curtis-snyk
curtis-fugue and curtis-snyk committed Jun 23, 2022
1 parent b0c7304 commit 4b06ad4
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Showing 27 changed files with 730 additions and 281 deletions.
1 change: 1 addition & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -9,3 +9,4 @@ auth.zip
samconfig.toml
venv
coverage.out
store/filesystem/tmp*.txt
220 changes: 42 additions & 178 deletions cache/cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
// 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 cache

import (
Expand All @@ -19,12 +20,11 @@ import (
"encoding/hex"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"sort"

"github.com/fugue/zim/hash"
"github.com/fugue/zim/project"
"github.com/fugue/zim/store"
)
Expand All @@ -48,108 +48,36 @@ func (e Error) Error() string { return string(e) }
// CacheMiss indicates the cache did not contain a match
const CacheMiss = Error("Item not found in cache")

// Entry carries the name and hash for one item within a Key
type Entry struct {
Name string `json:"name"`
Hash string `json:"hash"`
}

// command is the contribution to a cache key from a rule command
type command struct {
Kind string `json:"kind"`
Argument string `json:"argument,omitempty"`
Attributes map[string]interface{} `json:"attributes,omitempty"`
}

func newEntry(name, hash string) *Entry {
return &Entry{Name: name, Hash: hash}
// Opts defines options for initializing a Cache
type Opts struct {
Store store.Store
Hasher hash.Hasher
User string
Mode string
}

// Key contains information used to build a key
type Key struct {
Project string `json:"project"`
Component string `json:"component"`
Rule string `json:"rule"`
Image string `json:"image"`
OutputCount int `json:"output_count"`
Inputs []*Entry `json:"inputs"`
Deps []*Entry `json:"deps"`
Env []*Entry `json:"env"`
Toolchain []*Entry `json:"toolchain"`
Version string `json:"version"`
Commands []string `json:"commands"`
Native bool `json:"native,omitempty"`
hex string
// Cache for rule outputs
type Cache struct {
store store.Store
hasher hash.Hasher
user string
mode string
}

// String returns the key as a hexadecimal string
func (k *Key) String() string {
return k.hex
}
// New returns a Cache
func New(opts Opts) *Cache {

// Compute determines the hash for this key
func (k *Key) Compute() error {
h := sha1.New()
if err := json.NewEncoder(h).Encode(k); err != nil {
return err
if opts.Hasher == nil {
opts.Hasher = hash.SHA1()
}
k.hex = hex.EncodeToString(h.Sum(nil))
return nil
}

// NewMiddleware returns caching middleware
func NewMiddleware(s store.Store, user, mode string) project.RunnerBuilder {

c := New(s)
c.user = user
c.mode = mode

return project.RunnerBuilder(func(runner project.Runner) project.Runner {
return project.RunnerFunc(func(ctx context.Context, r *project.Rule, opts project.RunOpts) (project.Code, error) {

// Caching is only applicable for rules that have cacheable
// outputs. If this is not the case, run the rule normally.
outputs := r.Outputs()
if len(outputs) == 0 || !outputs[0].Cacheable() {
return runner.Run(ctx, r, opts)
}

if mode != WriteOnly {
// Download matching outputs from the cache if they exist
_, err := c.Read(ctx, r)
if err == nil {
return project.Cached, nil // Cache hit
}
if err != CacheMiss {
return project.Error, err // Cache error
}
}

// At this point, the outputs were not cached so build the rule
code, err := runner.Run(ctx, r, opts)

// Code "OK" indicates the rule was built which means we can
// store its outputs in the cache
if code == project.OK {
if _, err := c.Write(ctx, r); err != nil {
return project.Error, err
}
}
return code, err
})
})
}

// Cache used to determine rule keys
type Cache struct {
store store.Store
user string
mode string
}

// New returns a cache
func New(s store.Store) *Cache {
return &Cache{store: s}
c := &Cache{
store: opts.Store,
hasher: opts.Hasher,
user: opts.User,
mode: opts.Mode,
}
return c
}

// Write rule outputs to the cache
Expand All @@ -159,7 +87,7 @@ func (c *Cache) Write(ctx context.Context, r *project.Rule) ([]string, error) {

// If the rule has no outputs then there is nothing to cache
if len(outputs) == 0 {
return nil, fmt.Errorf("Rule has no outputs: %s", r.NodeID())
return nil, fmt.Errorf("rule has no outputs: %s", r.NodeID())
}

key, err := c.Key(ctx, r)
Expand Down Expand Up @@ -207,7 +135,7 @@ func (c *Cache) Read(ctx context.Context, r *project.Rule) ([]string, error) {

// If the rule has no outputs then there is nothing to read from the cache
if len(outputs) == 0 {
return nil, fmt.Errorf("Rule has no outputs: %s", r.NodeID())
return nil, fmt.Errorf("rule has no outputs: %s", r.NodeID())
}

key, err := c.Key(ctx, r)
Expand Down Expand Up @@ -237,7 +165,7 @@ func (c *Cache) Read(ctx context.Context, r *project.Rule) ([]string, error) {
func (c *Cache) put(ctx context.Context, key, src string) error {

// The file hash will be added to the cache item metadata
hash, err := HashFile(src)
hash, err := c.hasher.File(src)
if err != nil {
return err
}
Expand All @@ -264,11 +192,12 @@ func (c *Cache) get(ctx context.Context, key, dst string) error {

// If a local file exists that is identical to the one in the cache,
// then there is nothing to do
if localHash, err := HashFile(dst); err == nil {
if localHash, err := c.hasher.File(dst); err == nil {
if remoteHash == localHash {
return nil
}
}

// Download the file from the cache
return c.store.Get(ctx, key, dst)
}
Expand Down Expand Up @@ -328,7 +257,7 @@ func (c *Cache) buildKey(ctx context.Context, r *project.Rule) (*Key, error) {

// Include the hash of every input file in the key
for _, input := range inputs.Paths() {
hash, err := c.hashFile(input)
hash, err := c.hasher.File(input)
if err != nil {
return nil, err
}
Expand All @@ -342,7 +271,7 @@ func (c *Cache) buildKey(ctx context.Context, r *project.Rule) (*Key, error) {

// Include rule environment variables in the key
for _, k := range MapKeys(env) {
hash, err := c.hashString(env[k])
hash, err := c.hasher.String(env[k])
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -374,7 +303,7 @@ func (c *Cache) buildKey(ctx context.Context, r *project.Rule) (*Key, error) {
// For new built-in commands, reduce the command to a hash.
hashStr, err := HashCommand(cmd)
if err != nil {
return nil, fmt.Errorf("Failed to hash command: %s", err)
return nil, fmt.Errorf("failed to hash command: %s", err)
}
key.Commands = append(key.Commands, hashStr)
}
Expand All @@ -387,55 +316,6 @@ func (c *Cache) buildKey(ctx context.Context, r *project.Rule) (*Key, error) {
return key, nil
}

// hashFile returns the SHA1 hash of a given file
func (c *Cache) hashFile(p string) (string, error) {
// No caching for now
return HashFile(p)
}

// hashString returns the SHA1 hash of a given string
func (c *Cache) hashString(s string) (string, error) {
// No caching for now
return HashString(s)
}

// HashCommand returns a SHA1 hash of the command configuration
func HashCommand(cmd *project.Command) (string, error) {
entry := &command{
Kind: cmd.Kind,
Argument: cmd.Argument,
Attributes: cmd.Attributes,
}
h := sha1.New()
if err := json.NewEncoder(h).Encode(entry); err != nil {
return "", err
}
return hex.EncodeToString(h.Sum(nil)), nil
}

// HashFile returns the SHA1 hash of file contents
func HashFile(filePath string) (string, error) {
file, err := os.Open(filePath)
if err != nil {
return "", err
}
defer file.Close()
h := sha1.New()
if _, err := io.Copy(h, file); err != nil {
return "", err
}
return hex.EncodeToString(h.Sum(nil)), nil
}

// HashString returns the SHA1 hash of a string
func HashString(s string) (string, error) {
h := sha1.New()
if _, err := h.Write([]byte(s)); err != nil {
return "", err
}
return hex.EncodeToString(h.Sum(nil)), nil
}

// MapKeys returns a sorted slice containing all keys from the given map
func MapKeys(m map[string]string) (result []string) {
result = make([]string, 0, len(m))
Expand All @@ -446,32 +326,16 @@ func MapKeys(m map[string]string) (result []string) {
return
}

func writeJSON(key *Key) (string, error) {
js, err := json.Marshal(key)
if err != nil {
return "", err
}
f, err := ioutil.TempFile("", "zim-key-")
if err != nil {
return "", err
// Command returns a SHA1 hash of the command configuration
func HashCommand(cmd *project.Command) (string, error) {
entry := &command{
Kind: cmd.Kind,
Argument: cmd.Argument,
Attributes: cmd.Attributes,
}
defer f.Close()
if _, err := f.Write(js); err != nil {
h := sha1.New()
if err := json.NewEncoder(h).Encode(entry); err != nil {
return "", err
}
return f.Name(), nil
}

func writeKey(path string, key *Key) error {
js, err := json.Marshal(key)
if err != nil {
return err
}
f, err := os.Create(path)
if err != nil {
return err
}
defer f.Close()
_, err = f.Write(js)
return err
return hex.EncodeToString(h.Sum(nil)), nil
}
10 changes: 5 additions & 5 deletions cache/cache_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -65,14 +65,14 @@ func TestCacheKey(t *testing.T) {
Path: cPath("component.yaml"),
Docker: definitions.Docker{Image: "repo/img:1.2.3"},
Rules: map[string]definitions.Rule{
"test": definitions.Rule{
"test": {
Description: "test it!",
Inputs: []string{"${NAME}_test.go", "go.mod"},
Ignore: []string{"exclude_me.go"},
Outputs: []string{"test_results"},
Command: "go test -v",
},
"build": definitions.Rule{
"build": {
Description: "build it!",
Inputs: []string{"${NAME}.go", "go.mod"},
Ignore: []string{"exclude_me.go"},
Expand Down Expand Up @@ -110,7 +110,7 @@ func TestCacheKey(t *testing.T) {
buildDeps := buildRule.Dependencies()
require.Len(t, buildDeps, 1)

cache := New(nil)
cache := New(Opts{})

key1, err := cache.Key(ctx, testRule)
require.Nil(t, err, "Error getting cache key")
Expand Down Expand Up @@ -149,7 +149,7 @@ func TestCacheKeyNonDocker(t *testing.T) {
Name: "my-component",
Path: path.Join(cDir, "component.yaml"),
Rules: map[string]definitions.Rule{
"test": definitions.Rule{
"test": {
Inputs: []string{"main.go"},
Outputs: []string{"my-exe"},
Command: "touch my-exe",
Expand All @@ -170,7 +170,7 @@ func TestCacheKeyNonDocker(t *testing.T) {
require.NotNil(t, c)
testRule := c.MustRule("test")

cache := New(nil)
cache := New(Opts{})

key, err := cache.Key(ctx, testRule)
require.Nil(t, err, "Error getting cache key")
Expand Down
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