org.spearce.jgit/src/org/spearce/jgit/transport/FetchConnection.java

   1 /*
   2  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
   3  *
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or
   7  * without modification, are permitted provided that the following
   8  * conditions are met:
   9  *
  10  * - Redistributions of source code must retain the above copyright
  11  *   notice, this list of conditions and the following disclaimer.
  12  *
  13  * - Redistributions in binary form must reproduce the above
  14  *   copyright notice, this list of conditions and the following
  15  *   disclaimer in the documentation and/or other materials provided
  16  *   with the distribution.
  17  *
  18  * - Neither the name of the Git Development Community nor the
  19  *   names of its contributors may be used to endorse or promote
  20  *   products derived from this software without specific prior
  21  *   written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  24  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  25  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  28  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  31  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  32  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  33  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  35  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 package org.spearce.jgit.transport;
  39
  40 import java.util.Collection;
  41
  42 import org.spearce.jgit.errors.TransportException;
  43 import org.spearce.jgit.lib.ProgressMonitor;
  44 import org.spearce.jgit.lib.Ref;
  45
  46 /**
  47  * Lists known refs from the remote and copies objects of selected refs.
  48  * <p>
  49  * A fetch connection typically connects to the <code>git-upload-pack</code>
  50  * service running where the remote repository is stored. This provides a
  51  * one-way object transfer service to copy objects from the remote repository
  52  * into this local repository.
  53  * <p>
  54  * Instances of a FetchConnection must be created by a {@link Transport} that
  55  * implements a specific object transfer protocol that both sides of the
  56  * connection understand.
  57  * <p>
  58  * FetchConnection instances are not thread safe and may be accessed by only one
  59  * thread at a time.
  60  *
  61  * @see Transport
  62  */
  63 public interface FetchConnection extends Connection {
  64         /**
  65          * Fetch objects we don't have but that are reachable from advertised refs.
  66          * <p>
  67          * Only one call per connection is allowed. Subsequent calls will result in
  68          * {@link TransportException}.
  69          * </p>
  70          * <p>
  71          * Implementations are free to use network connections as necessary to
  72          * efficiently (for both client and server) transfer objects from the remote
  73          * repository into this repository. When possible implementations should
  74          * avoid replacing/overwriting/duplicating an object already available in
  75          * the local destination repository. Locally available objects and packs
  76          * should always be preferred over remotely available objects and packs.
  77          * {@link Transport#isFetchThin()} should be honored if applicable.
  78          * </p>
  79          *
  80          * @param monitor
  81          *            progress monitor to inform the end-user about the amount of
  82          *            work completed, or to indicate cancellation. Implementations
  83          *            should poll the monitor at regular intervals to look for
  84          *            cancellation requests from the user.
  85          * @param want
  86          *            one or more refs advertised by this connection that the caller
  87          *            wants to store locally.
  88          * @throws TransportException
  89          *             objects could not be copied due to a network failure,
  90          *             protocol error, or error on remote side, or connection was
  91          *             already used for fetch.
  92          */
  93         public void fetch(final ProgressMonitor monitor, final Collection<Ref> want)
  94                         throws TransportException;
  95
  96         /**
  97          * Did the last {@link #fetch(ProgressMonitor, Collection)} get tags?
  98          * <p>
  99          * Some Git aware transports are able to implicitly grab an annotated tag if
 100          * {@link TagOpt#AUTO_FOLLOW} or {@link TagOpt#FETCH_TAGS} was selected and
 101          * the object the tag peels to (references) was transferred as part of the
 102          * last {@link #fetch(ProgressMonitor, Collection)} call. If it is possible
 103          * for such tags to have been included in the transfer this method returns
 104          * true, allowing the caller to attempt tag discovery.
 105          * <p>
 106          * By returning only true/false (and not the actual list of tags obtained)
 107          * the transport itself does not need to be aware of whether or not tags
 108          * were included in the transfer.
 109          *
 110          * @return true if the last fetch call implicitly included tag objects;
 111          *         false if tags were not implicitly obtained.
 112          */
 113         public boolean didFetchIncludeTags();
 114 }