54 lines
1.2 KiB
Go
54 lines
1.2 KiB
Go
package cache
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import (
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"os"
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"path/filepath"
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)
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func (c *Cache) getStream(relPath string) (*inFlight, *os.File, error) {
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// lock the map
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c.inFlightMu.Lock()
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defer c.inFlightMu.Unlock()
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// download in progress connect new stream to existing download
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if flight, ok := c.inFlight[relPath]; ok {
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f, err := c.cr.Open(flight.tmpPath)
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if err != nil {
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return nil, nil, err
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}
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return flight, f, nil
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}
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// download not in progress, setup new download and stream
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// make sure the dir structure exists
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if err := c.cr.MkdirAll(filepath.Dir(relPath), 0750); err != nil {
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return nil, nil, err
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}
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// use a tmp file for the initial fetch in case it fails
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tmpPath := relPath + ".tmp"
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tmpFile, err := c.cr.Create(tmpPath)
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if err != nil {
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return nil, nil, err
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}
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flight := &inFlight{
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contentLength: 0,
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headerReady: make(chan struct{}),
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tmpPath: tmpPath,
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done: make(chan struct{}),
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}
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c.inFlight[relPath] = flight
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// spin off a downloading func so we can return the file handler
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// downloadWrangle takes ownership of tmpFile and closes it.
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go c.downloadWrangle(relPath, flight, tmpFile)
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f, err := c.cr.Open(flight.tmpPath)
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if err != nil {
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return nil, nil, err
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}
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return flight, f, nil
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}
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