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/*
* 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 others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
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.
* <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.
* <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.
* <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 {@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 {@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.
* <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
* {@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();
}
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