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Steve Loughran commented on HADOOP-15691: ----------------------------------------- Sorry, missed that I'd pulled this back as part of some of the dir marker work. > Add PathCapabilities to FS and FC to complement StreamCapabilities > ------------------------------------------------------------------ > > Key: HADOOP-15691 > URL: https://issues.apache.org/jira/browse/HADOOP-15691 > Project: Hadoop Common > Issue Type: New Feature > Reporter: Steve Loughran > Assignee: Steve Loughran > Priority: Major > Fix For: 3.3.0, 3.2.2, 3.2.3 > > Attachments: HADOOP-15691-001.patch, HADOOP-15691-002.patch, > HADOOP-15691-003.patch, HADOOP-15691-004.patch > > > This complements the {{StreamCapabilities}} interface by allowing > applications > to probe for a specific path on a specific instance of a {{FileSystem}} > or {{FileContext}} offering a specific feature. > This is intended to allow applications to determine > * Whether a method is implemented before calling it and dealing with > any subsequent UnsupportedOperationException. > * Whether a specific feature is believed to be available in the remote store. > As well as a common set of capabilities defined in CommonPathCapabilities, > file systems are free to add their own capabilities, prefixed with > fs. + schema + . > > The plan is to identify and document more capabilities -and for file systems > which add new features, for a declaration of the availability of the feature > to > always be available. > The interface may be offered by other classes too; there is no restriction > here. > Note > * The remote store is not expected to be checked for the feature; > It is more a check of client API and the client's configuration/knowledge > of the state of the remote system. > * Permissions are not checked. > This is needed for > * HADOOP-14707: declare that a dest FS supports permissions > * object stores to declare that they offer PUT-in-place alongside > (slow-rename) > * Anything else where the implementation semantics of an FS is so different > caller apps would benefit from probing for the underlying semantics > I know, we want all filesystem to work *exactly* the same. But it doesn't > hold, especially for object stores —and to efficiently use them, callers need > to be able to ask for specific features. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: common-issues-h...@hadoop.apache.org