org.eclipse.jgit/org.eclipse.jgit/5.5.0.201909110433-r : org/eclipse/jgit/transport/FetchConnection.java

FetchConnection
http://www.eclipse.org/jgit//org.eclipse.jgit: Repository access and algorithms (Eclipse JGit Project)
Eclipse Distribution License (New BSD License)
Andrey Loskutov
Christian Halstrick
Dave Borowitz
David Pursehouse
Gunnar Wagenknecht
Jonathan Nieder
Jonathan Tan
Matthias Sohn
Sasa Zivkov
Terry Parker
Thomas Wolf
/*
 * Copyright (C) 2008-2009, Google Inc.
 * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
 * Copyright (C) 2008, Mike Ralphson <mike@abacus.co.uk>
 * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.transport;

import java.io.OutputStream;
import java.util.Collection;
import java.util.Set;

import org.eclipse.jgit.errors.TransportException;
import org.eclipse.jgit.internal.storage.file.PackLock;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.lib.Ref;

Lists known refs from the remote and copies objects of selected refs.

A fetch connection typically connects to the git-upload-pack
service running where the remote repository is stored. This provides a
one-way object transfer service to copy objects from the remote repository
into this local repository.
 Instances of a FetchConnection must be created by a Transport that implements a specific object transfer protocol that both sides of the connection understand. 

FetchConnection instances are not thread safe and may be accessed by only one
thread at a time.
See Also: Transport/**
 * Lists known refs from the remote and copies objects of selected refs.
 * <p>
 * A fetch connection typically connects to the <code>git-upload-pack</code>
 * service running where the remote repository is stored. This provides a
 * one-way object transfer service to copy objects from the remote repository
 * into this local repository.
 * <p>
 * Instances of a FetchConnection must be created by a
 * {@link org.eclipse.jgit.transport.Transport} that implements a specific
 * object transfer protocol that both sides of the connection understand.
 * <p>
 * FetchConnection instances are not thread safe and may be accessed by only one
 * thread at a time.
 *
 * @see Transport
 */
public interface FetchConnection extends Connection {
	Fetch objects we don't have but that are reachable from advertised refs.
 Only one call per connection is allowed. Subsequent calls will result in TransportException. 
 Implementations are free to use network connections as necessary to efficiently (for both client and server) transfer objects from the remote repository into this repository. When possible implementations should avoid replacing/overwriting/duplicating an object already available in the local destination repository. Locally available objects and packs should always be preferred over remotely available objects and packs. Transport.isFetchThin() should be honored if applicable. 
Params: monitor – 
           progress monitor to inform the end-user about the amount of
           work completed, or to indicate cancellation. Implementations
           should poll the monitor at regular intervals to look for
           cancellation requests from the user.
want – 
           one or more refs advertised by this connection that the caller
           wants to store locally.
have – 
           additional objects known to exist in the destination
           repository, especially if they aren't yet reachable by the ref
           database. Connections should take this set as an addition to
           what is reachable through all Refs, not in replace of it.
Throws: TransportException – 
            objects could not be copied due to a network failure,
            protocol error, or error on remote side, or connection was
            already used for fetch./**
	 * Fetch objects we don't have but that are reachable from advertised refs.
	 * <p>
	 * Only one call per connection is allowed. Subsequent calls will result in
	 * {@link org.eclipse.jgit.errors.TransportException}.
	 * </p>
	 * <p>
	 * Implementations are free to use network connections as necessary to
	 * efficiently (for both client and server) transfer objects from the remote
	 * repository into this repository. When possible implementations should
	 * avoid replacing/overwriting/duplicating an object already available in
	 * the local destination repository. Locally available objects and packs
	 * should always be preferred over remotely available objects and packs.
	 * {@link org.eclipse.jgit.transport.Transport#isFetchThin()} should be
	 * honored if applicable.
	 * </p>
	 *
	 * @param monitor
	 *            progress monitor to inform the end-user about the amount of
	 *            work completed, or to indicate cancellation. Implementations
	 *            should poll the monitor at regular intervals to look for
	 *            cancellation requests from the user.
	 * @param want
	 *            one or more refs advertised by this connection that the caller
	 *            wants to store locally.
	 * @param have
	 *            additional objects known to exist in the destination
	 *            repository, especially if they aren't yet reachable by the ref
	 *            database. Connections should take this set as an addition to
	 *            what is reachable through all Refs, not in replace of it.
	 * @throws org.eclipse.jgit.errors.TransportException
	 *             objects could not be copied due to a network failure,
	 *             protocol error, or error on remote side, or connection was
	 *             already used for fetch.
	 */
	void fetch(final ProgressMonitor monitor,
			final Collection<Ref> want, final Set<ObjectId> have)
			throws TransportException;

	Fetch objects we don't have but that are reachable from advertised refs.
 Only one call per connection is allowed. Subsequent calls will result in TransportException. 
 Implementations are free to use network connections as necessary to efficiently (for both client and server) transfer objects from the remote repository into this repository. When possible implementations should avoid replacing/overwriting/duplicating an object already available in the local destination repository. Locally available objects and packs should always be preferred over remotely available objects and packs. Transport.isFetchThin() should be honored if applicable. 
Params: monitor – 
           progress monitor to inform the end-user about the amount of
           work completed, or to indicate cancellation. Implementations
           should poll the monitor at regular intervals to look for
           cancellation requests from the user.
want – 
           one or more refs advertised by this connection that the caller
           wants to store locally.
have – 
           additional objects known to exist in the destination
           repository, especially if they aren't yet reachable by the ref
           database. Connections should take this set as an addition to
           what is reachable through all Refs, not in replace of it.
out – 
           OutputStream to write sideband messages to
Throws: TransportException – 
            objects could not be copied due to a network failure,
            protocol error, or error on remote side, or connection was
            already used for fetch.
Since: 3.0/**
	 * Fetch objects we don't have but that are reachable from advertised refs.
	 * <p>
	 * Only one call per connection is allowed. Subsequent calls will result in
	 * {@link org.eclipse.jgit.errors.TransportException}.
	 * </p>
	 * <p>
	 * Implementations are free to use network connections as necessary to
	 * efficiently (for both client and server) transfer objects from the remote
	 * repository into this repository. When possible implementations should
	 * avoid replacing/overwriting/duplicating an object already available in
	 * the local destination repository. Locally available objects and packs
	 * should always be preferred over remotely available objects and packs.
	 * {@link org.eclipse.jgit.transport.Transport#isFetchThin()} should be
	 * honored if applicable.
	 * </p>
	 *
	 * @param monitor
	 *            progress monitor to inform the end-user about the amount of
	 *            work completed, or to indicate cancellation. Implementations
	 *            should poll the monitor at regular intervals to look for
	 *            cancellation requests from the user.
	 * @param want
	 *            one or more refs advertised by this connection that the caller
	 *            wants to store locally.
	 * @param have
	 *            additional objects known to exist in the destination
	 *            repository, especially if they aren't yet reachable by the ref
	 *            database. Connections should take this set as an addition to
	 *            what is reachable through all Refs, not in replace of it.
	 * @param out
	 *            OutputStream to write sideband messages to
	 * @throws org.eclipse.jgit.errors.TransportException
	 *             objects could not be copied due to a network failure,
	 *             protocol error, or error on remote side, or connection was
	 *             already used for fetch.
	 * @since 3.0
	 */
	void fetch(final ProgressMonitor monitor,
			final Collection<Ref> want, final Set<ObjectId> have,
			OutputStream out) throws TransportException;

	Did the last fetch(ProgressMonitor, Collection<Ref>, Set<ObjectId>) get tags?  Some Git aware transports are able to implicitly grab an annotated tag if TagOpt.AUTO_FOLLOW or TagOpt.FETCH_TAGS was selected and the object the tag peels to (references) was transferred as part of the last fetch(ProgressMonitor, Collection<Ref>, Set<ObjectId>) call. If it is possible for such tags to have been included in the transfer this method returns true, allowing the caller to attempt tag discovery. 

By returning only true/false (and not the actual list of tags obtained)
the transport itself does not need to be aware of whether or not tags
were included in the transfer.
Returns: true if the last fetch call implicitly included tag objects;
        false if tags were not implicitly obtained./**
	 * Did the last {@link #fetch(ProgressMonitor, Collection, Set)} get tags?
	 * <p>
	 * Some Git aware transports are able to implicitly grab an annotated tag if
	 * {@link org.eclipse.jgit.transport.TagOpt#AUTO_FOLLOW} or
	 * {@link org.eclipse.jgit.transport.TagOpt#FETCH_TAGS} was selected and the
	 * object the tag peels to (references) was transferred as part of the last
	 * {@link #fetch(ProgressMonitor, Collection, Set)} call. If it is possible
	 * for such tags to have been included in the transfer this method returns
	 * true, allowing the caller to attempt tag discovery.
	 * <p>
	 * By returning only true/false (and not the actual list of tags obtained)
	 * the transport itself does not need to be aware of whether or not tags
	 * were included in the transfer.
	 *
	 * @return true if the last fetch call implicitly included tag objects;
	 *         false if tags were not implicitly obtained.
	 */
	boolean didFetchIncludeTags();

	Did the last fetch(ProgressMonitor, Collection<Ref>, Set<ObjectId>) validate graph? 
Some transports walk the object graph on the client side, with the client
looking for what objects it is missing and requesting them individually
from the remote peer. By virtue of completing the fetch call the client
implicitly tested the object connectivity, as every object in the graph
was either already local or was requested successfully from the peer. In
such transports this method returns true.

Some transports assume the remote peer knows the Git object graph and is
able to supply a fully connected graph to the client (although it may
only be transferring the parts the client does not yet have). Its faster
to assume such remote peers are well behaved and send the correct
response to the client. In such transports this method returns false.
Returns: true if the last fetch had to perform a connectivity check on the
        client side in order to succeed; false if the last fetch assumed
        the remote peer supplied a complete graph./**
	 * Did the last {@link #fetch(ProgressMonitor, Collection, Set)} validate
	 * graph?
	 * <p>
	 * Some transports walk the object graph on the client side, with the client
	 * looking for what objects it is missing and requesting them individually
	 * from the remote peer. By virtue of completing the fetch call the client
	 * implicitly tested the object connectivity, as every object in the graph
	 * was either already local or was requested successfully from the peer. In
	 * such transports this method returns true.
	 * <p>
	 * Some transports assume the remote peer knows the Git object graph and is
	 * able to supply a fully connected graph to the client (although it may
	 * only be transferring the parts the client does not yet have). Its faster
	 * to assume such remote peers are well behaved and send the correct
	 * response to the client. In such transports this method returns false.
	 *
	 * @return true if the last fetch had to perform a connectivity check on the
	 *         client side in order to succeed; false if the last fetch assumed
	 *         the remote peer supplied a complete graph.
	 */
	boolean didFetchTestConnectivity();

	Set the lock message used when holding a pack out of garbage collection.

Callers that set a lock message must ensure they call getPackLocks() after fetch(ProgressMonitor, Collection<Ref>, Set<ObjectId>), even if an exception was thrown, and release the locks that are held. 
Params: message – message to use when holding a pack in place./**
	 * Set the lock message used when holding a pack out of garbage collection.
	 * <p>
	 * Callers that set a lock message <b>must</b> ensure they call
	 * {@link #getPackLocks()} after
	 * {@link #fetch(ProgressMonitor, Collection, Set)}, even if an exception
	 * was thrown, and release the locks that are held.
	 *
	 * @param message message to use when holding a pack in place.
	 */
	void setPackLockMessage(String message);

	All locks created by the last fetch(ProgressMonitor, Collection<Ref>, Set<ObjectId>) call. 
Returns: collection (possibly empty) of locks created by the last call to
        fetch. The caller must release these after refs are updated in
        order to safely permit garbage collection./**
	 * All locks created by the last
	 * {@link #fetch(ProgressMonitor, Collection, Set)} call.
	 *
	 * @return collection (possibly empty) of locks created by the last call to
	 *         fetch. The caller must release these after refs are updated in
	 *         order to safely permit garbage collection.
	 */
	Collection<PackLock> getPackLocks();
}
Params:	monitor – progress monitor to inform the end-user about the amount of work completed, or to indicate cancellation. Implementations should poll the monitor at regular intervals to look for cancellation requests from the user. want – one or more refs advertised by this connection that the caller wants to store locally. have – additional objects known to exist in the destination repository, especially if they aren't yet reachable by the ref database. Connections should take this set as an addition to what is reachable through all Refs, not in replace of it. out – OutputStream to write sideband messages to
Throws:	TransportException – objects could not be copied due to a network failure, protocol error, or error on remote side, or connection was already used for fetch.
Since:	3.0
/

org.eclipse.jgit/ org.eclipse.jgit/ 5.5.0.201909110433-r/ org/eclipse/jgit/transport/FetchConnection.java
