2e3ecdca37
We are change the the rpc call for WriteStream to not require the size argument, opting to drive the process with io.Reader. The main issue was that io.Reader may return io.EOF before reaching size, making the error handling around this condition for callers more complex. To complement this, WriteStream now returns the number of successfully written bytes. The method no longer requires an io.ReadCloser, opting to require just an io.Reader. This keeps the reader under the control of the caller, which provides more flexibility. This also begins to address some of the problems described in #791.
93 lines
3.1 KiB
Go
93 lines
3.1 KiB
Go
package storagedriver
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import (
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"fmt"
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"io"
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"strconv"
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"strings"
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)
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// Version is a string representing the storage driver version, of the form
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// Major.Minor.
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// The registry must accept storage drivers with equal major version and greater
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// minor version, but may not be compatible with older storage driver versions.
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type Version string
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// Major returns the major (primary) component of a version.
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func (version Version) Major() uint {
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majorPart := strings.Split(string(version), ".")[0]
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major, _ := strconv.ParseUint(majorPart, 10, 0)
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return uint(major)
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}
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// Minor returns the minor (secondary) component of a version.
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func (version Version) Minor() uint {
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minorPart := strings.Split(string(version), ".")[1]
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minor, _ := strconv.ParseUint(minorPart, 10, 0)
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return uint(minor)
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}
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// CurrentVersion is the current storage driver Version.
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const CurrentVersion Version = "0.1"
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// StorageDriver defines methods that a Storage Driver must implement for a
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// filesystem-like key/value object storage.
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type StorageDriver interface {
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// GetContent retrieves the content stored at "path" as a []byte.
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// This should primarily be used for small objects.
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GetContent(path string) ([]byte, error)
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// PutContent stores the []byte content at a location designated by "path".
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// This should primarily be used for small objects.
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PutContent(path string, content []byte) error
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// ReadStream retrieves an io.ReadCloser for the content stored at "path"
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// with a given byte offset.
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// May be used to resume reading a stream by providing a nonzero offset.
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ReadStream(path string, offset int64) (io.ReadCloser, error)
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// WriteStream stores the contents of the provided io.ReadCloser at a
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// location designated by the given path.
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// The driver will know it has received the full contents when it has read
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// "size" bytes.
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// May be used to resume writing a stream by providing a nonzero offset.
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// The offset must be no larger than the CurrentSize for this path.
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WriteStream(path string, offset int64, reader io.Reader) (nn int64, err error)
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// Stat retrieves the FileInfo for the given path, including the current
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// size in bytes and the creation time.
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Stat(path string) (FileInfo, error)
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// List returns a list of the objects that are direct descendants of the
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//given path.
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List(path string) ([]string, error)
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// Move moves an object stored at sourcePath to destPath, removing the
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// original object.
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// Note: This may be no more efficient than a copy followed by a delete for
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// many implementations.
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Move(sourcePath string, destPath string) error
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// Delete recursively deletes all objects stored at "path" and its subpaths.
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Delete(path string) error
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}
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// PathNotFoundError is returned when operating on a nonexistent path.
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type PathNotFoundError struct {
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Path string
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}
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func (err PathNotFoundError) Error() string {
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return fmt.Sprintf("Path not found: %s", err.Path)
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}
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// InvalidOffsetError is returned when attempting to read or write from an
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// invalid offset.
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type InvalidOffsetError struct {
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Path string
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Offset int64
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}
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func (err InvalidOffsetError) Error() string {
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return fmt.Sprintf("Invalid offset: %d for path: %s", err.Offset, err.Path)
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}
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