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https://issues.apache.org/jira/browse/HADOOP-13712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15568300#comment-15568300
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Steve Loughran commented on HADOOP-13712:
-----------------------------------------
Pseudo-code
{code}
OutputStream open(path) {
if (!path.endsWith."/") {
try {
return GET path
} catch (404) {
// not a file
}
}
// either no file or looking for "/", fallback for exception
// this will raise the FNFE if the path isn't there
S3AFileStatus status = getFileStatus(path);
if (status.isDirectory()) {
throw new PathIsDirectoryException(path);
} else {
// we could only get here if there wasn't a file before, but there is now.
// Race condition? And how to react? Recursion?
}
}
{code}
> S3A open to avoid needless HEAD on the successful execution path
> ----------------------------------------------------------------
>
> Key: HADOOP-13712
> URL: https://issues.apache.org/jira/browse/HADOOP-13712
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.7.3
> Reporter: Steve Loughran
>
> S3A's open() operation does a {{getFileStatus()}} check to see if a file is
> not a directory before opening with a GET. That initial check will take up at
> least one HEAD request if the file is present, more if it isn't.
> As the GET itself performs the existence check, it is needless. A successful
> GET of a path which doesn't end in "/" means a file was there. The only
> reason a getFileStatus call is needed is to choose which error message to
> display if the path isn't there: is it an FNFE or is it path-is-directory.
> Proposed: reorder the code to do the GET; only if that fails fallback to
> getFileStatus()
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