XL: Bring in support for object versions written during writeQuorum. (#1762)
Erasure is initialized as needed depending on the quorum and onlineDisks. This way we can manage the quorum at the object layer.master
Harshavardhana
9 years ago
committed by
Harshavardhana
parent
cae4782973
commit
553fdb9211
@ -0,0 +1,180 @@ |
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package main |
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import ( |
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"path" |
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"sync" |
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) |
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// Get the highest integer from a given integer slice.
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func highestInt(intSlice []int64) (highestInteger int64) { |
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highestInteger = int64(1) |
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for _, integer := range intSlice { |
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if highestInteger < integer { |
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highestInteger = integer |
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} |
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} |
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return highestInteger |
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} |
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// Extracts objects versions from xlMetaV1 slice and returns version slice.
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func listObjectVersions(partsMetadata []xlMetaV1, errs []error) (versions []int64) { |
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versions = make([]int64, len(partsMetadata)) |
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for index, metadata := range partsMetadata { |
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if errs[index] == nil { |
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versions[index] = metadata.Stat.Version |
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} else { |
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versions[index] = -1 |
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} |
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} |
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return versions |
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} |
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// Reads all `xl.json` metadata as a xlMetaV1 slice.
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// Returns error slice indicating the failed metadata reads.
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func (xl xlObjects) readAllXLMetadata(bucket, object string) ([]xlMetaV1, []error) { |
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errs := make([]error, len(xl.storageDisks)) |
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metadataArray := make([]xlMetaV1, len(xl.storageDisks)) |
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xlMetaPath := path.Join(object, xlMetaJSONFile) |
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var wg = &sync.WaitGroup{} |
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for index, disk := range xl.storageDisks { |
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wg.Add(1) |
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go func(index int, disk StorageAPI) { |
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defer wg.Done() |
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offset := int64(0) |
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metadataReader, err := disk.ReadFile(bucket, xlMetaPath, offset) |
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if err != nil { |
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errs[index] = err |
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return |
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} |
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defer metadataReader.Close() |
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_, err = metadataArray[index].ReadFrom(metadataReader) |
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if err != nil { |
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// Unable to parse xl.json, set error.
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errs[index] = err |
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return |
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} |
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}(index, disk) |
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} |
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// Wait for all the routines to finish.
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wg.Wait() |
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// Return all the metadata.
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return metadataArray, errs |
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} |
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// error based on total errors and read quorum.
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func (xl xlObjects) reduceError(errs []error) error { |
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fileNotFoundCount := 0 |
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longNameCount := 0 |
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diskNotFoundCount := 0 |
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volumeNotFoundCount := 0 |
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diskAccessDeniedCount := 0 |
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for _, err := range errs { |
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if err == errFileNotFound { |
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fileNotFoundCount++ |
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} else if err == errFileNameTooLong { |
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longNameCount++ |
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} else if err == errDiskNotFound { |
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diskNotFoundCount++ |
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} else if err == errVolumeAccessDenied { |
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diskAccessDeniedCount++ |
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} else if err == errVolumeNotFound { |
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volumeNotFoundCount++ |
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} |
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} |
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// If we have errors with 'file not found' greater than
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// readQuorum, return as errFileNotFound.
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// else if we have errors with 'volume not found'
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// greater than readQuorum, return as errVolumeNotFound.
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if fileNotFoundCount > len(xl.storageDisks)-xl.readQuorum { |
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return errFileNotFound |
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} else if longNameCount > len(xl.storageDisks)-xl.readQuorum { |
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return errFileNameTooLong |
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} else if volumeNotFoundCount > len(xl.storageDisks)-xl.readQuorum { |
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return errVolumeNotFound |
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} |
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// If we have errors with disk not found equal to the
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// number of disks, return as errDiskNotFound.
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if diskNotFoundCount == len(xl.storageDisks) { |
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return errDiskNotFound |
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} else if diskNotFoundCount > len(xl.storageDisks)-xl.readQuorum { |
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// If we have errors with 'disk not found'
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// greater than readQuorum, return as errFileNotFound.
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return errFileNotFound |
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} |
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// If we have errors with disk not found equal to the
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// number of disks, return as errDiskNotFound.
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if diskAccessDeniedCount == len(xl.storageDisks) { |
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return errVolumeAccessDenied |
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} |
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return nil |
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} |
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// Similar to 'len(slice)' but returns the actualelements count
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// skipping the unallocated elements.
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func diskCount(disks []StorageAPI) int { |
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diskCount := 0 |
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for _, disk := range disks { |
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if disk == nil { |
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continue |
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} |
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diskCount++ |
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} |
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return diskCount |
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} |
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func (xl xlObjects) shouldHeal(onlineDisks []StorageAPI) (heal bool) { |
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onlineDiskCount := diskCount(onlineDisks) |
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// If online disks count is lesser than configured disks, most
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// probably we need to heal the file, additionally verify if the
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// count is lesser than readQuorum, if not we throw an error.
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if onlineDiskCount < len(xl.storageDisks) { |
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// Online disks lesser than total storage disks, needs to be
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// healed. unless we do not have readQuorum.
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heal = true |
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// Verify if online disks count are lesser than readQuorum
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// threshold, return an error.
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if onlineDiskCount < xl.readQuorum { |
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errorIf(errReadQuorum, "Unable to establish read quorum, disks are offline.") |
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return false |
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} |
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} |
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return heal |
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} |
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// Returns slice of online disks needed.
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// - slice returing readable disks.
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// - xlMetaV1
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// - bool value indicating if healing is needed.
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// - error if any.
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func (xl xlObjects) listOnlineDisks(bucket, object string) (onlineDisks []StorageAPI, version int64, err error) { |
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onlineDisks = make([]StorageAPI, len(xl.storageDisks)) |
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partsMetadata, errs := xl.readAllXLMetadata(bucket, object) |
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if err = xl.reduceError(errs); err != nil { |
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if err == errFileNotFound { |
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// For file not found, treat as if disks are available
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// return all the configured ones.
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onlineDisks = xl.storageDisks |
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return onlineDisks, 1, nil |
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} |
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return nil, 0, err |
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} |
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highestVersion := int64(0) |
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// List all the file versions from partsMetadata list.
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versions := listObjectVersions(partsMetadata, errs) |
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// Get highest object version.
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highestVersion = highestInt(versions) |
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// Pick online disks with version set to highestVersion.
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for index, version := range versions { |
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if version == highestVersion { |
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onlineDisks[index] = xl.storageDisks[index] |
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} else { |
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onlineDisks[index] = nil |
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} |
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} |
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return onlineDisks, highestVersion, nil |
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} |
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@ -0,0 +1,85 @@ |
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package main |
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import ( |
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"path" |
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"sync" |
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) |
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// This function does the following check, suppose
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// object is "a/b/c/d", stat makes sure that objects ""a/b/c""
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// "a/b" and "a" do not exist.
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func (xl xlObjects) parentDirIsObject(bucket, parent string) bool { |
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var isParentDirObject func(string) bool |
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isParentDirObject = func(p string) bool { |
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if p == "." { |
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return false |
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} |
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if xl.isObject(bucket, p) { |
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// If there is already a file at prefix "p" return error.
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return true |
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} |
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// Check if there is a file as one of the parent paths.
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return isParentDirObject(path.Dir(p)) |
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} |
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return isParentDirObject(parent) |
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} |
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func (xl xlObjects) isObject(bucket, prefix string) bool { |
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// Create errs and volInfo slices of storageDisks size.
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var errs = make([]error, len(xl.storageDisks)) |
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// Allocate a new waitgroup.
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var wg = &sync.WaitGroup{} |
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for index, disk := range xl.storageDisks { |
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wg.Add(1) |
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// Stat file on all the disks in a routine.
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go func(index int, disk StorageAPI) { |
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defer wg.Done() |
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_, err := disk.StatFile(bucket, path.Join(prefix, xlMetaJSONFile)) |
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if err != nil { |
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errs[index] = err |
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return |
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} |
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errs[index] = nil |
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}(index, disk) |
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} |
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// Wait for all the Stat operations to finish.
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wg.Wait() |
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var errFileNotFoundCount int |
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for _, err := range errs { |
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if err != nil { |
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if err == errFileNotFound { |
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errFileNotFoundCount++ |
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// If we have errors with file not found greater than allowed read
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// quorum we return err as errFileNotFound.
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if errFileNotFoundCount > len(xl.storageDisks)-xl.readQuorum { |
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return false |
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} |
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continue |
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} |
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errorIf(err, "Unable to access file "+path.Join(bucket, prefix)) |
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return false |
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} |
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} |
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return true |
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} |
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// statPart - stat a part file.
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func (xl xlObjects) statPart(bucket, objectPart string) (fileInfo FileInfo, err error) { |
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// Count for errors encountered.
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var xlJSONErrCount = 0 |
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// Return the first success entry based on the selected random disk.
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for xlJSONErrCount < len(xl.storageDisks) { |
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// Choose a random disk on each attempt, do not hit the same disk all the time.
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disk := xl.getRandomDisk() // Pick a random disk.
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fileInfo, err = disk.StatFile(bucket, objectPart) |
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if err == nil { |
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return fileInfo, nil |
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} |
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xlJSONErrCount++ // Update error count.
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} |
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return FileInfo{}, err |
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} |
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