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Make FsBlobContainer Listing Resilient to Concurrent Modifications #49142

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Merged
merged 3 commits into from
Nov 15, 2019
Merged

Make FsBlobContainer Listing Resilient to Concurrent Modifications #49142

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Make FsBlobContainer Listing Resilient to Concurrent Modifications
original-brownbear Nov 15, 2019
28325f8
Merge remote-tracking branch 'elastic/master' into fix-concurrency-fs…
original-brownbear Nov 15, 2019
65087f4
more catching and comment
original-brownbear Nov 15, 2019
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8 changes: 7 additions & 1 deletion server/src/main/java/org/elasticsearch/common/blobstore/fs/FsBlobContainer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -97,7 +97,13 @@ public Map<String, BlobMetaData> listBlobsByPrefix(String blobNamePrefix) throws
blobNamePrefix = blobNamePrefix == null ? "" : blobNamePrefix;
try (DirectoryStream<Path> stream = Files.newDirectoryStream(path, blobNamePrefix + "*")) {
for (Path file : stream) {
final BasicFileAttributes attrs = Files.readAttributes(file, BasicFileAttributes.class);
final BasicFileAttributes attrs;
try {
attrs = Files.readAttributes(file, BasicFileAttributes.class);
} catch (FileNotFoundException | NoSuchFileException e) {
// The file was concurrently deleted between listing files and trying to get its attributes so we skip it here
continue;
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can you add a comment here saying why it's ok to ignore?

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Done :)

}
if (attrs.isRegularFile()) {
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perhaps easier as the two suggestions above is to use Files.isRegularFile(file) here which takes care of all this.

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This won't help us I think? We still want the file size two lines below where we'd have to make another call to the FS that we'd have to guard against "file not found".

builder.put(file.getFileName().toString(), new PlainBlobMetaData(file.getFileName().toString(), attrs.size()));
}
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