Browse code
Fix panic on network timeout during push
`Upload` already closes the reader returned by `compress` and the
progressreader passed into it, before returning. But even so, the
io.Copy inside compress' goroutine needs to attempt a read from the
progressreader to notice that it's closed, and this read has a side
effect of outputting a progress message. If this happens after `Upload`
returns, it can result in a write to a closed channel. Change `compress`
to return a channel that allows the caller to wait for its goroutine to
finish before freeing any resources connected to the reader that was
passed to it.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Aaron Lehmann authored on 2016/01/30 07:34:50Showing 2 changed files
| ... | ... |
@@ -170,7 +170,14 @@ func Push(ctx context.Context, ref reference.Named, imagePushConfig *ImagePushCo |
| 170 | 170 |
// argument so that it can be used with httpBlobWriter's ReadFrom method. |
| 171 | 171 |
// Using httpBlobWriter's Write method would send a PATCH request for every |
| 172 | 172 |
// Write call. |
| 173 |
-func compress(in io.Reader) io.ReadCloser {
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+// |
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+// The second return value is a channel that gets closed when the goroutine |
|
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+// is finished. This allows the caller to make sure the goroutine finishes |
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+// before it releases any resources connected with the reader that was |
|
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+// passed in. |
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+func compress(in io.Reader) (io.ReadCloser, chan struct{}) {
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+ compressionDone := make(chan struct{})
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+ |
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| 174 | 181 |
pipeReader, pipeWriter := io.Pipe() |
| 175 | 182 |
// Use a bufio.Writer to avoid excessive chunking in HTTP request. |
| 176 | 183 |
bufWriter := bufio.NewWriterSize(pipeWriter, compressionBufSize) |
| ... | ... |
@@ -189,7 +196,8 @@ func compress(in io.Reader) io.ReadCloser {
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| 189 | 189 |
} else {
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| 190 | 190 |
pipeWriter.Close() |
| 191 | 191 |
} |
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+ close(compressionDone) |
|
| 192 | 193 |
}() |
| 193 | 194 |
|
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- return pipeReader |
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+ return pipeReader, compressionDone |
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| 195 | 196 |
} |
| ... | ... |
@@ -345,8 +345,11 @@ func (pd *v2PushDescriptor) Upload(ctx context.Context, progressOutput progress. |
| 345 | 345 |
size, _ := pd.layer.DiffSize() |
| 346 | 346 |
|
| 347 | 347 |
reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, arch), progressOutput, size, pd.ID(), "Pushing") |
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- defer reader.Close() |
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- compressedReader := compress(reader) |
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+ compressedReader, compressionDone := compress(reader) |
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+ defer func() {
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+ reader.Close() |
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+ <-compressionDone |
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+ }() |
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| 350 | 353 |
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| 351 | 354 |
digester := digest.Canonical.New() |
| 352 | 355 |
tee := io.TeeReader(compressedReader, digester.Hash()) |