XL: Cleanup and add more comments. (#1807)
Harshavardhana
9 years ago
parent
ffc2b3c304
commit
445dc22118
@ -0,0 +1,112 @@ |
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/* |
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* Minio Cloud Storage, (C) 2016 Minio, Inc. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package main |
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import ( |
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"math/rand" |
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"path" |
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"sync" |
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"time" |
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) |
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// getRandomDisk - gives a random disk at any point in time from the
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// available pool of disks.
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func (xl xlObjects) getRandomDisk() (disk StorageAPI) { |
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rand.Seed(time.Now().UTC().UnixNano()) // Seed with current time.
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randIndex := rand.Intn(len(xl.storageDisks) - 1) |
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disk = xl.storageDisks[randIndex] // Pick a random disk.
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return disk |
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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.
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disk := xl.getRandomDisk() |
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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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@ -1,85 +1,59 @@ |
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/* |
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* Minio Cloud Storage, (C) 2016 Minio, Inc. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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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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"bytes" |
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"io" |
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"math/rand" |
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"time" |
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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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// randInts - uses Knuth Fisher-Yates shuffle algorithm for generating uniform shuffling.
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func randInts(count int) []int { |
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rand.Seed(time.Now().UTC().UnixNano()) // Seed with current time.
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ints := make([]int, count) |
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for i := 0; i < count; i++ { |
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ints[i] = i + 1 |
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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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for i := 0; i < count; i++ { |
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// Choose index uniformly in [i, count-1]
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r := i + rand.Intn(count-i) |
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ints[r], ints[i] = ints[i], ints[r] |
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} |
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return isParentDirObject(parent) |
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return ints |
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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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// readAll reads from bucket, object until an error or returns the data it read until io.EOF.
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func readAll(disk StorageAPI, bucket, object string) ([]byte, error) { |
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var writer = new(bytes.Buffer) |
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startOffset := int64(0) |
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// Read until io.EOF.
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for { |
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buf := make([]byte, blockSizeV1) |
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n, err := disk.ReadFile(bucket, object, startOffset, buf) |
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if err == io.EOF { |
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break |
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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.
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disk := xl.getRandomDisk() |
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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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if err != nil && err != io.EOF { |
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return nil, err |
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} |
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xlJSONErrCount++ // Update error count.
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writer.Write(buf[:n]) |
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startOffset += n |
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} |
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return FileInfo{}, err |
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return writer.Bytes(), nil |
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} |
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