org.eclipse.aether.spi.connector.checksum.ChecksumPolicy Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
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*/
package org.eclipse.aether.spi.connector.checksum;
import org.eclipse.aether.transfer.ChecksumFailureException;
/**
* A checksum policy gets employed by repository connectors to validate the integrity of a downloaded file. For each
* downloaded file, a checksum policy instance is obtained and presented with the available checksums to conclude
* whether the download is valid or not. The following pseudo-code illustrates the usage of a checksum policy by a
* repository connector in some more detail (the retry logic has been omitted for the sake of brevity):
*
*
* void validateChecksums() throws ChecksumFailureException {
* for (checksum : checksums) {
* switch (checksum.state) {
* case MATCH:
* if (policy.onChecksumMatch(...)) {
* return;
* }
* break;
* case MISMATCH:
* policy.onChecksumMismatch(...);
* break;
* case ERROR:
* policy.onChecksumError(...);
* break;
* }
* }
* policy.onNoMoreChecksums();
* }
*
* void downloadFile() throws Exception {
* ...
* policy = newChecksumPolicy();
* try {
* validateChecksums();
* } catch (ChecksumFailureException e) {
* if (!policy.onTransferChecksumFailure(...)) {
* throw e;
* }
* }
* }
*
*
* Checksum policies might be stateful and are generally not thread-safe.
*/
public interface ChecksumPolicy {
/**
* Enum denoting origin of checksum.
*
* @since 1.8.0
*/
enum ChecksumKind {
/**
* Remote external kind of checksum are retrieved from remote doing extra transport round-trip (usually by
* getting "file.jar.sha1" for corresponding "file.jar" file). This kind of checksum is part of layout, and
* was from beginning the "official" (and one and only) checksum used by resolver. If no external checksum
* present, {@link #onNoMoreChecksums()} method is invoked that (by default) fails retrieval.
*/
REMOTE_EXTERNAL,
/**
* Included checksums may be received from remote repository during the retrieval of the main file, for example
* from response headers in case of HTTP transport. They may be set with
* {@link org.eclipse.aether.spi.connector.transport.GetTask#setChecksum(String, String)}. If no included
* checksum present, {@link #REMOTE_EXTERNAL} is tried for.
*/
REMOTE_INCLUDED,
/**
* Provided checksums may be provided by {@link ProvidedChecksumsSource} components, ahead of artifact
* retrieval. If no provided checksum present, {@link #REMOTE_INCLUDED} is tried for.
*/
PROVIDED
}
/**
* Signals a match between the locally computed checksum value and the checksum value declared by the remote
* repository.
*
* @param algorithm The name of the checksum algorithm being used, must not be {@code null}.
* @param kind A field providing further details about the checksum.
* @return {@code true} to accept the download as valid and stop further validation, {@code false} to continue
* validation with the next checksum.
*/
boolean onChecksumMatch(String algorithm, ChecksumKind kind);
/**
* Signals a mismatch between the locally computed checksum value and the checksum value declared by the remote
* repository. A simple policy would just rethrow the provided exception. More sophisticated policies could update
* their internal state and defer a conclusion until all available checksums have been processed.
*
* @param algorithm The name of the checksum algorithm being used, must not be {@code null}.
* @param kind A field providing further details about the checksum.
* @param exception The exception describing the checksum mismatch, must not be {@code null}.
* @throws ChecksumFailureException If the checksum validation is to be failed. If the method returns normally,
* validation continues with the next checksum.
*/
void onChecksumMismatch(String algorithm, ChecksumKind kind, ChecksumFailureException exception)
throws ChecksumFailureException;
/**
* Signals an error while computing the local checksum value or retrieving the checksum value from the remote
* repository.
*
* @param algorithm The name of the checksum algorithm being used, must not be {@code null}.
* @param kind A field providing further details about the checksum.
* @param exception The exception describing the checksum error, must not be {@code null}.
* @throws ChecksumFailureException If the checksum validation is to be failed. If the method returns normally,
* validation continues with the next checksum.
*/
void onChecksumError(String algorithm, ChecksumKind kind, ChecksumFailureException exception)
throws ChecksumFailureException;
/**
* Signals that all available checksums have been processed.
*
* @throws ChecksumFailureException If the checksum validation is to be failed. If the method returns normally, the
* download is assumed to be valid.
*/
void onNoMoreChecksums() throws ChecksumFailureException;
/**
* Signals that the download is being retried after a previously thrown {@link ChecksumFailureException} that is
* {@link ChecksumFailureException#isRetryWorthy() retry-worthy}. Policies that maintain internal state will usually
* have to reset some of this state at this point to prepare for a new round of validation.
*/
void onTransferRetry();
/**
* Signals that (even after a potential retry) checksum validation has failed. A policy could opt to merely log this
* issue or insist on rejecting the downloaded file as unusable.
*
* @param exception The exception that was thrown from a prior call to
* {@link #onChecksumMismatch(String, ChecksumKind, ChecksumFailureException)},
* {@link #onChecksumError(String, ChecksumKind, ChecksumFailureException)} or {@link
* #onNoMoreChecksums()}.
* @return {@code true} to accept the download nevertheless and let artifact resolution succeed, {@code false} to
* reject the transferred file as unusable.
*/
boolean onTransferChecksumFailure(ChecksumFailureException exception);
}