distribution/registry/storage/cache/redis/redis.go
Derek McGowan 31a448a628 Update to provide small and clear interfaces
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
2015-10-09 16:05:49 -07:00

268 lines
8.4 KiB
Go

package redis
import (
"fmt"
"github.com/docker/distribution"
"github.com/docker/distribution/context"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/reference"
"github.com/docker/distribution/registry/storage/cache"
"github.com/garyburd/redigo/redis"
)
// redisBlobStatService provides an implementation of
// BlobDescriptorCacheProvider based on redis. Blob descriptors are stored in
// two parts. The first provide fast access to repository membership through a
// redis set for each repo. The second is a redis hash keyed by the digest of
// the layer, providing path, length and mediatype information. There is also
// a per-repository redis hash of the blob descriptor, allowing override of
// data. This is currently used to override the mediatype on a per-repository
// basis.
//
// Note that there is no implied relationship between these two caches. The
// layer may exist in one, both or none and the code must be written this way.
type redisBlobDescriptorService struct {
pool *redis.Pool
// TODO(stevvooe): We use a pool because we don't have great control over
// the cache lifecycle to manage connections. A new connection if fetched
// for each operation. Once we have better lifecycle management of the
// request objects, we can change this to a connection.
}
// NewRedisBlobDescriptorCacheProvider returns a new redis-based
// BlobDescriptorCacheProvider using the provided redis connection pool.
func NewRedisBlobDescriptorCacheProvider(pool *redis.Pool) cache.BlobDescriptorCacheProvider {
return &redisBlobDescriptorService{
pool: pool,
}
}
// RepositoryScoped returns the scoped cache.
func (rbds *redisBlobDescriptorService) RepositoryScoped(repo string) (distribution.BlobDescriptorService, error) {
if _, err := reference.ParseNamed(repo); err != nil {
return nil, err
}
return &repositoryScopedRedisBlobDescriptorService{
repo: repo,
upstream: rbds,
}, nil
}
// Stat retrieves the descriptor data from the redis hash entry.
func (rbds *redisBlobDescriptorService) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
if err := dgst.Validate(); err != nil {
return distribution.Descriptor{}, err
}
conn := rbds.pool.Get()
defer conn.Close()
return rbds.stat(ctx, conn, dgst)
}
func (rbds *redisBlobDescriptorService) Clear(ctx context.Context, dgst digest.Digest) error {
if err := dgst.Validate(); err != nil {
return err
}
conn := rbds.pool.Get()
defer conn.Close()
// Not atomic in redis <= 2.3
reply, err := conn.Do("HDEL", rbds.blobDescriptorHashKey(dgst), "digest", "length", "mediatype")
if err != nil {
return err
}
if reply == 0 {
return distribution.ErrBlobUnknown
}
return nil
}
// stat provides an internal stat call that takes a connection parameter. This
// allows some internal management of the connection scope.
func (rbds *redisBlobDescriptorService) stat(ctx context.Context, conn redis.Conn, dgst digest.Digest) (distribution.Descriptor, error) {
reply, err := redis.Values(conn.Do("HMGET", rbds.blobDescriptorHashKey(dgst), "digest", "size", "mediatype"))
if err != nil {
return distribution.Descriptor{}, err
}
// NOTE(stevvooe): The "size" field used to be "length". We treat a
// missing "size" field here as an unknown blob, which causes a cache
// miss, effectively migrating the field.
if len(reply) < 3 || reply[0] == nil || reply[1] == nil { // don't care if mediatype is nil
return distribution.Descriptor{}, distribution.ErrBlobUnknown
}
var desc distribution.Descriptor
if _, err := redis.Scan(reply, &desc.Digest, &desc.Size, &desc.MediaType); err != nil {
return distribution.Descriptor{}, err
}
return desc, nil
}
// SetDescriptor sets the descriptor data for the given digest using a redis
// hash. A hash is used here since we may store unrelated fields about a layer
// in the future.
func (rbds *redisBlobDescriptorService) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
if err := dgst.Validate(); err != nil {
return err
}
if err := cache.ValidateDescriptor(desc); err != nil {
return err
}
conn := rbds.pool.Get()
defer conn.Close()
return rbds.setDescriptor(ctx, conn, dgst, desc)
}
func (rbds *redisBlobDescriptorService) setDescriptor(ctx context.Context, conn redis.Conn, dgst digest.Digest, desc distribution.Descriptor) error {
if _, err := conn.Do("HMSET", rbds.blobDescriptorHashKey(dgst),
"digest", desc.Digest,
"size", desc.Size); err != nil {
return err
}
// Only set mediatype if not already set.
if _, err := conn.Do("HSETNX", rbds.blobDescriptorHashKey(dgst),
"mediatype", desc.MediaType); err != nil {
return err
}
return nil
}
func (rbds *redisBlobDescriptorService) blobDescriptorHashKey(dgst digest.Digest) string {
return "blobs::" + dgst.String()
}
type repositoryScopedRedisBlobDescriptorService struct {
repo string
upstream *redisBlobDescriptorService
}
var _ distribution.BlobDescriptorService = &repositoryScopedRedisBlobDescriptorService{}
// Stat ensures that the digest is a member of the specified repository and
// forwards the descriptor request to the global blob store. If the media type
// differs for the repository, we override it.
func (rsrbds *repositoryScopedRedisBlobDescriptorService) Stat(ctx context.Context, dgst digest.Digest) (distribution.Descriptor, error) {
if err := dgst.Validate(); err != nil {
return distribution.Descriptor{}, err
}
conn := rsrbds.upstream.pool.Get()
defer conn.Close()
// Check membership to repository first
member, err := redis.Bool(conn.Do("SISMEMBER", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst))
if err != nil {
return distribution.Descriptor{}, err
}
if !member {
return distribution.Descriptor{}, distribution.ErrBlobUnknown
}
upstream, err := rsrbds.upstream.stat(ctx, conn, dgst)
if err != nil {
return distribution.Descriptor{}, err
}
// We allow a per repository mediatype, let's look it up here.
mediatype, err := redis.String(conn.Do("HGET", rsrbds.blobDescriptorHashKey(dgst), "mediatype"))
if err != nil {
return distribution.Descriptor{}, err
}
if mediatype != "" {
upstream.MediaType = mediatype
}
return upstream, nil
}
// Clear removes the descriptor from the cache and forwards to the upstream descriptor store
func (rsrbds *repositoryScopedRedisBlobDescriptorService) Clear(ctx context.Context, dgst digest.Digest) error {
if err := dgst.Validate(); err != nil {
return err
}
conn := rsrbds.upstream.pool.Get()
defer conn.Close()
// Check membership to repository first
member, err := redis.Bool(conn.Do("SISMEMBER", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst))
if err != nil {
return err
}
if !member {
return distribution.ErrBlobUnknown
}
return rsrbds.upstream.Clear(ctx, dgst)
}
func (rsrbds *repositoryScopedRedisBlobDescriptorService) SetDescriptor(ctx context.Context, dgst digest.Digest, desc distribution.Descriptor) error {
if err := dgst.Validate(); err != nil {
return err
}
if err := cache.ValidateDescriptor(desc); err != nil {
return err
}
if dgst != desc.Digest {
if dgst.Algorithm() == desc.Digest.Algorithm() {
return fmt.Errorf("redis cache: digest for descriptors differ but algorthim does not: %q != %q", dgst, desc.Digest)
}
}
conn := rsrbds.upstream.pool.Get()
defer conn.Close()
return rsrbds.setDescriptor(ctx, conn, dgst, desc)
}
func (rsrbds *repositoryScopedRedisBlobDescriptorService) setDescriptor(ctx context.Context, conn redis.Conn, dgst digest.Digest, desc distribution.Descriptor) error {
if _, err := conn.Do("SADD", rsrbds.repositoryBlobSetKey(rsrbds.repo), dgst); err != nil {
return err
}
if err := rsrbds.upstream.setDescriptor(ctx, conn, dgst, desc); err != nil {
return err
}
// Override repository mediatype.
if _, err := conn.Do("HSET", rsrbds.blobDescriptorHashKey(dgst), "mediatype", desc.MediaType); err != nil {
return err
}
// Also set the values for the primary descriptor, if they differ by
// algorithm (ie sha256 vs tarsum).
if desc.Digest != "" && dgst != desc.Digest && dgst.Algorithm() != desc.Digest.Algorithm() {
if err := rsrbds.setDescriptor(ctx, conn, desc.Digest, desc); err != nil {
return err
}
}
return nil
}
func (rsrbds *repositoryScopedRedisBlobDescriptorService) blobDescriptorHashKey(dgst digest.Digest) string {
return "repository::" + rsrbds.repo + "::blobs::" + dgst.String()
}
func (rsrbds *repositoryScopedRedisBlobDescriptorService) repositoryBlobSetKey(repo string) string {
return "repository::" + rsrbds.repo + "::blobs"
}