137 lines
4.5 KiB
Go
137 lines
4.5 KiB
Go
package swift
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import (
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"os"
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)
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// DynamicLargeObjectCreateFile represents an open static large object
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type DynamicLargeObjectCreateFile struct {
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largeObjectCreateFile
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}
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// DynamicLargeObjectCreateFile creates a dynamic large object
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// returning an object which satisfies io.Writer, io.Seeker, io.Closer
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// and io.ReaderFrom. The flags are as passes to the
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// largeObjectCreate method.
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func (c *Connection) DynamicLargeObjectCreateFile(opts *LargeObjectOpts) (LargeObjectFile, error) {
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lo, err := c.largeObjectCreate(opts)
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if err != nil {
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return nil, err
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}
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return withBuffer(opts, &DynamicLargeObjectCreateFile{
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largeObjectCreateFile: *lo,
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}), nil
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}
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// DynamicLargeObjectCreate creates or truncates an existing dynamic
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// large object returning a writeable object. This sets opts.Flags to
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// an appropriate value before calling DynamicLargeObjectCreateFile
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func (c *Connection) DynamicLargeObjectCreate(opts *LargeObjectOpts) (LargeObjectFile, error) {
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opts.Flags = os.O_TRUNC | os.O_CREATE
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return c.DynamicLargeObjectCreateFile(opts)
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}
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// DynamicLargeObjectDelete deletes a dynamic large object and all of its segments.
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func (c *Connection) DynamicLargeObjectDelete(container string, path string) error {
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return c.LargeObjectDelete(container, path)
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}
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// DynamicLargeObjectMove moves a dynamic large object from srcContainer, srcObjectName to dstContainer, dstObjectName
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func (c *Connection) DynamicLargeObjectMove(srcContainer string, srcObjectName string, dstContainer string, dstObjectName string) error {
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info, headers, err := c.Object(dstContainer, srcObjectName)
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if err != nil {
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return err
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}
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segmentContainer, segmentPath := parseFullPath(headers["X-Object-Manifest"])
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if err := c.createDLOManifest(dstContainer, dstObjectName, segmentContainer+"/"+segmentPath, info.ContentType); err != nil {
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return err
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}
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if err := c.ObjectDelete(srcContainer, srcObjectName); err != nil {
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return err
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}
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return nil
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}
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// createDLOManifest creates a dynamic large object manifest
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func (c *Connection) createDLOManifest(container string, objectName string, prefix string, contentType string) error {
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headers := make(Headers)
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headers["X-Object-Manifest"] = prefix
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manifest, err := c.ObjectCreate(container, objectName, false, "", contentType, headers)
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if err != nil {
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return err
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}
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if err := manifest.Close(); err != nil {
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return err
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}
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return nil
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}
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// Close satisfies the io.Closer interface
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func (file *DynamicLargeObjectCreateFile) Close() error {
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return file.Flush()
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}
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func (file *DynamicLargeObjectCreateFile) Flush() error {
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err := file.conn.createDLOManifest(file.container, file.objectName, file.segmentContainer+"/"+file.prefix, file.contentType)
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if err != nil {
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return err
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}
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return file.conn.waitForSegmentsToShowUp(file.container, file.objectName, file.Size())
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}
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func (c *Connection) getAllDLOSegments(segmentContainer, segmentPath string) ([]Object, error) {
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//a simple container listing works 99.9% of the time
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segments, err := c.ObjectsAll(segmentContainer, &ObjectsOpts{Prefix: segmentPath})
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if err != nil {
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return nil, err
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}
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hasObjectName := make(map[string]struct{})
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for _, segment := range segments {
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hasObjectName[segment.Name] = struct{}{}
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}
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//The container listing might be outdated (i.e. not contain all existing
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//segment objects yet) because of temporary inconsistency (Swift is only
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//eventually consistent!). Check its completeness.
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segmentNumber := 0
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for {
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segmentNumber++
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segmentName := getSegment(segmentPath, segmentNumber)
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if _, seen := hasObjectName[segmentName]; seen {
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continue
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}
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//This segment is missing in the container listing. Use a more reliable
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//request to check its existence. (HEAD requests on segments are
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//guaranteed to return the correct metadata, except for the pathological
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//case of an outage of large parts of the Swift cluster or its network,
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//since every segment is only written once.)
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segment, _, err := c.Object(segmentContainer, segmentName)
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switch err {
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case nil:
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//found new segment -> add it in the correct position and keep
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//going, more might be missing
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if segmentNumber <= len(segments) {
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segments = append(segments[:segmentNumber], segments[segmentNumber-1:]...)
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segments[segmentNumber-1] = segment
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} else {
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segments = append(segments, segment)
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}
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continue
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case ObjectNotFound:
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//This segment is missing. Since we upload segments sequentially,
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//there won't be any more segments after it.
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return segments, nil
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default:
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return nil, err //unexpected error
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}
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}
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}
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