BsoBird commented on code in PR #9546:
URL: https://github.com/apache/iceberg/pull/9546#discussion_r1476118577
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core/src/main/java/org/apache/iceberg/hadoop/HadoopTableOperations.java:
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@@ -289,23 +341,58 @@ Path versionHintFile() {
return metadataPath(Util.VERSION_HINT_FILENAME);
}
- private void writeVersionHint(int versionToWrite) {
- Path versionHintFile = versionHintFile();
- FileSystem fs = getFileSystem(versionHintFile, conf);
-
+ @VisibleForTesting
+ boolean writeVersionHint(Integer versionToWrite, Path finalMetadataFile) {
+ boolean deleteSuccess = false;
try {
- Path tempVersionHintFile = metadataPath(UUID.randomUUID().toString() +
"-version-hint.temp");
+ Path versionHintFile = versionHintFile();
+ FileSystem fs = getFileSystem(versionHintFile, conf);
+ Path tempVersionHintFile = metadataPath(UUID.randomUUID() +
"-version-hint.temp");
writeVersionToPath(fs, tempVersionHintFile, versionToWrite);
- fs.delete(versionHintFile, false /* recursive delete */);
- fs.rename(tempVersionHintFile, versionHintFile);
- } catch (IOException e) {
- LOG.warn("Failed to update version hint", e);
+ deleteSuccess = dropOldVersionHint(fs, versionHintFile);
+ if (!deleteSuccess) {
+ throw new RuntimeException("Can't delete version Hint, something wrong
with File System?");
+ }
+ return renameVersionHint(fs, tempVersionHintFile, versionHintFile);
+ } catch (Exception e) {
+ // This is the most dangerous scenario. There are two possibilities:
+ // 1. We wrote to metadata-v+1.json, but didn't have time to change the
versionHint, the
+ // content in VersionHint is old. If we do nothing, then all commits
after this table will
+ // fail because versionHint points to the old version, but
metadata-v+1.json exists and rename
+ // will fail.
+ // 2. We deleted the versionHint, but did not have time to write a new
versionHint. At this
+ // point, because VersionHint is lost, all clients can only traverse the
metadata-json to find
+ // the latest version, that is: as long as the versionHint is deleted,
then in fact, commit
+ // will be succeeded.
+ // For case 1, we'd better clean up the metadata-v+1.json to ensure that
the next commit will
+ // be successful.
+ // For case 2, Since the commit was successful, we can't clean up the
data files associated
+ // with this commit.we need to throw a CommitStateUnknownException to
skip the data file
+ // cleanup.
+ if (!deleteSuccess) {
+ io().deleteFile(finalMetadataFile.toString());
Review Comment:
@RussellSpitzer
Perhaps we should change the order of execution from ```writeMeta ->
deleteHint -> writeHite``` to ```deleteHint -> writeMeta -> writeHint```. This
is because in reality the versionHint is just an index, and by the time the
metaData write succeeds, the commit has actually succeeded. By changing the
order of execution, we can eliminate the UnknowCommitStateException. Make the
HadoopCatalog implementation conform to Spec.
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