go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/appengine/gaemiddleware/cache.go (about)

     1  // Copyright 2017 The LUCI Authors.
     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 gaemiddleware
    16  
    17  import (
    18  	"context"
    19  	"time"
    20  
    21  	"go.chromium.org/luci/gae/service/info"
    22  	"go.chromium.org/luci/gae/service/memcache"
    23  
    24  	"go.chromium.org/luci/common/retry/transient"
    25  	"go.chromium.org/luci/server/caching"
    26  )
    27  
    28  // blobCacheProvider returns caching.BlobCache implemented on top of luci/gae.
    29  func blobCacheProvider(namespace string) caching.BlobCache {
    30  	return &gaeBlobCache{namespace}
    31  }
    32  
    33  // gaeBlobCache implements caching.BlobCache.
    34  type gaeBlobCache struct {
    35  	ns string
    36  }
    37  
    38  func (g gaeBlobCache) Get(ctx context.Context, key string) ([]byte, error) {
    39  	switch itm, err := memcache.GetKey(info.MustNamespace(ctx, g.ns), key); {
    40  	case err == memcache.ErrCacheMiss:
    41  		return nil, caching.ErrCacheMiss
    42  	case err != nil:
    43  		return nil, transient.Tag.Apply(err)
    44  	default:
    45  		return itm.Value(), nil
    46  	}
    47  }
    48  
    49  func (g gaeBlobCache) Set(ctx context.Context, key string, value []byte, exp time.Duration) error {
    50  	ctx = info.MustNamespace(ctx, g.ns)
    51  	item := memcache.NewItem(ctx, key).SetValue(value).SetExpiration(exp)
    52  	if err := memcache.Set(ctx, item); err != nil {
    53  		return transient.Tag.Apply(err)
    54  	}
    55  	return nil
    56  }