mirror of https://github.com/perkeep/perkeep.git
57 lines
1.4 KiB
Go
57 lines
1.4 KiB
Go
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/*
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Copyright 2011 Google Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package main
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import (
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"camli/blobref"
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"camli/blobserver"
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"os"
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)
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func NewCachingFetcher(cacheTarget blobserver.Cache, sfetcher blobref.StreamingFetcher) blobref.Fetcher {
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return &CachingFetcher{cacheTarget, sfetcher}
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}
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type CachingFetcher struct {
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c blobserver.Cache
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sf blobref.StreamingFetcher
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}
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func (cf *CachingFetcher) Fetch(br *blobref.BlobRef) (file blobref.ReadSeekCloser, size int64, err os.Error) {
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file, size, err = cf.c.Fetch(br)
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if err == nil {
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return
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}
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// TODO: let fetches some in real-time with stream in the
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// common case, only blocking if a Seek-forward is encountered
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// mid-download. But for now we're lazy and first copy the
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// whole thing to cache.
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sblob, size, err := cf.sf.FetchStreaming(br)
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if err != nil {
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return nil, 0, err
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}
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_, err = cf.c.ReceiveBlob(br, sblob, nil)
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if err != nil {
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return nil, 0, err
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}
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return cf.c.Fetch(br)
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}
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