mirror of https://github.com/perkeep/perkeep.git
85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
/*
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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 client
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import (
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"camli/blobref"
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)
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// TODO: use Generics if/when available
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type chanPeeker struct {
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ch chan blobref.SizedBlobRef
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peek *blobref.SizedBlobRef
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Closed bool
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}
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func (cp *chanPeeker) Peek() *blobref.SizedBlobRef {
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if cp.Closed {
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return nil
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}
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if cp.peek != nil {
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return cp.peek
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}
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v, ok := <-cp.ch
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if !ok {
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cp.Closed = true
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return nil
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}
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cp.peek = &v
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return cp.peek
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}
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func (cp *chanPeeker) Take() *blobref.SizedBlobRef {
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v := cp.Peek()
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cp.peek = nil
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return v
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}
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// ListMissingDestinationBlobs reads from 'srcch' and 'dstch' (sorted
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// enumerations of blobs from two blob servers) and sends to
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// 'destMissing' any blobs which appear on the source but not at the
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// destination. destMissing is closed at the end.
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func ListMissingDestinationBlobs(destMissing, srcch, dstch chan blobref.SizedBlobRef) {
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defer close(destMissing)
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src := &chanPeeker{ch: srcch}
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dst := &chanPeeker{ch: dstch}
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for src.Peek() != nil {
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// If the destination has reached its end, anything
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// remaining in the source is needed.
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if dst.Peek() == nil {
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destMissing <- *(src.Take())
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continue
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}
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srcStr := src.Peek().BlobRef.String()
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dstStr := dst.Peek().BlobRef.String()
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switch {
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case srcStr == dstStr:
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// Skip both
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src.Take()
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dst.Take()
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case srcStr < dstStr:
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destMissing <- *(src.Take())
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case srcStr > dstStr:
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dst.Take()
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}
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}
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}
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