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webapi: Add cancellation channel to FileStartReader. Add convenience function FileReadAll.

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This commit is contained in:
Kleissner
2021-11-01 22:36:10 +01:00
parent 0f546caed0
commit 4704b5194f
1 changed files with 34 additions and 6 deletions
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40
webapi/File IO.go
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@@ -80,8 +80,8 @@ func apiFileRead(w http.ResponseWriter, r *http.Request) {
return
}
// start the reader
reader, fileSize, transferSize, err := FileStartReader(peer, fileHash, uint64(offset), uint64(limit))
// Start the reader. If this HTTP request is canceled, r.Context().Done() acts as cancellation signal to the underlying UDT connection.
reader, fileSize, transferSize, err := FileStartReader(peer, fileHash, uint64(offset), uint64(limit), r.Context().Done())
if reader != nil {
defer reader.Close()
}
@@ -98,7 +98,7 @@ func apiFileRead(w http.ResponseWriter, r *http.Request) {
}
/*
apiFileView is similar to /file/read but but provides a format parameter. It set the Content-Type header and may manipulate the content on the fly.
apiFileView is similar to /file/read but but provides a format parameter. It sets the Content-Type and Accept-Ranges headers.
This endpoint supports the Range, Content-Range and Content-Length headers. Multipart ranges are not supported and result in HTTP 400.
Instead of providing the node ID, the peer ID is also accepted in the &node= parameter.
The default timeout for connecting to the peer is 10 seconds.
@@ -162,7 +162,7 @@ func apiFileView(w http.ResponseWriter, r *http.Request) {
}
// start the reader
reader, fileSize, transferSize, err := FileStartReader(peer, fileHash, uint64(offset), uint64(limit))
reader, fileSize, transferSize, err := FileStartReader(peer, fileHash, uint64(offset), uint64(limit), r.Context().Done())
if reader != nil {
defer reader.Close()
}
@@ -222,9 +222,10 @@ func PeerConnectNode(nodeID []byte, timeout time.Duration) (peer *core.PeerInfo,
}
// FileStartReader providers a reader to a remote file. The reader must be closed by the caller.
// File Size is the full file size, regardless of the requested offset and limit.
// File Size is the full file size reported by the remote peer, regardless of the requested offset and limit.
// Transfer Size is the size in bytes that is actually going to be transferred. The reader should be closed after reading that amount.
func FileStartReader(peer *core.PeerInfo, hash []byte, offset, limit uint64) (reader io.ReadCloser, fileSize, transferSize uint64, err error) {
// The optional cancelChan can be used to stop the file transfer at any point.
func FileStartReader(peer *core.PeerInfo, hash []byte, offset, limit uint64, cancelChan <-chan struct{}) (reader io.ReadCloser, fileSize, transferSize uint64, err error) {
if peer == nil {
return nil, 0, 0, errors.New("peer not provided")
} else if !peer.IsConnectionActive() {
@@ -236,6 +237,13 @@ func FileStartReader(peer *core.PeerInfo, hash []byte, offset, limit uint64) (re
return nil, 0, 0, err
}
if cancelChan != nil {
go func() {
<-cancelChan
udtConn.Close()
}()
}
fileSize, transferSize, err = core.FileTransferReadHeaderUDT(udtConn)
if err != nil {
udtConn.Close()
@@ -244,3 +252,23 @@ func FileStartReader(peer *core.PeerInfo, hash []byte, offset, limit uint64) (re
return udtConn, fileSize, transferSize, nil
}
// FileReadAll downloads the file from the peer.
// This function should only be used for testing or as a basis to fork. The caller should develop a custom download function that handles timeouts and excessive file sizes.
// It allocates whatever size is reported by the remote peer. This could lead to an out of memory crash.
// This function is blocking and may take a long time depending on the remote peer and the network connection.
func FileReadAll(peer *core.PeerInfo, hash []byte) (data []byte, err error) {
reader, _, transferSize, err := FileStartReader(peer, hash, 0, 0, nil)
if err != nil {
return nil, err
}
defer reader.Close()
// read all data
data = make([]byte, transferSize) // Warning: This could lead to an out of memory crash.
_, err = reader.Read(data)
// Note: This function does not verify if the returned data matches the hash and expected size.
return data, err
}