org.apache.hadoop.fs.PathCapabilities Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.fs;
import java.io.IOException;
/**
* The Path counterpoint to {@link StreamCapabilities}; a query to see if,
* a FileSystem/FileContext instance has a specific capability under the given
* path.
* Other classes may also implement the interface, as desired.
*
* See {@link CommonPathCapabilities} for the well-known capabilities.
*/
public interface PathCapabilities {
/**
* Probe for a specific capability under the given path.
* If the function returns {@code true}, this instance is explicitly
* declaring that the capability is available.
* If the function returns {@code false}, it can mean one of:
*
* - The capability is not known.
* - The capability is known but it is not supported.
* - The capability is known but the filesystem does not know if it
* is supported under the supplied path.
*
* The core guarantee which a caller can rely on is: if the predicate
* returns true, then the specific operation/behavior can be expected to be
* supported. However a specific call may be rejected for permission reasons,
* the actual file/directory not being present, or some other failure during
* the attempted execution of the operation.
*
* Implementors: {@link org.apache.hadoop.fs.impl.PathCapabilitiesSupport}
* can be used to help implement this method.
* @param path path to query the capability of.
* @param capability non-null, non-empty string to query the path for support.
* @return true if the capability is supported under that part of the FS.
* @throws IOException this should not be raised, except on problems
* resolving paths or relaying the call.
* @throws IllegalArgumentException invalid arguments
*/
boolean hasPathCapability(Path path, String capability)
throws IOException;
}