Package org.eclipse.jgit.transport

Class BasePackFetchConnection

  • All Implemented Interfaces:
    AutoCloseable, Connection, FetchConnection
    public abstract class BasePackFetchConnection
extends BaseConnection
implements FetchConnection
    Fetch implementation using the native Git pack transfer service.

    This is the canonical implementation for transferring objects from the remote repository to the local repository by talking to the 'git-upload-pack' service. Objects are packed on the remote side into a pack file and then sent down the pipe to us.

    This connection requires only a bi-directional pipe or socket, and thus is easily wrapped up into a local process pipe, anonymous TCP socket, or a command executed through an SSH tunnel.

    If BasePackConnection.statelessRPC is true, this connection can be tunneled over a request-response style RPC system like HTTP. The RPC call boundary is determined by this class switching from writing to the OutputStream to reading from the InputStream.

    Concrete implementations should just call init(java.io.InputStream, java.io.OutputStream) and readAdvertisedRefs() methods in constructor or before any use. They should also handle resources releasing in close() method if needed.

    • Field Detail

      • MIN_CLIENT_BUFFER

        protected static final int MIN_CLIENT_BUFFER
        Amount of data the client sends before starting to read.

        Any output stream given to the client must be able to buffer this many bytes before the client will stop writing and start reading from the input stream. If the output stream blocks before this many bytes are in the send queue, the system will deadlock.

        See Also:
        Constant Field Values

      • OPTION_INCLUDE_TAG

        public static final String OPTION_INCLUDE_TAG
        Include tags if we are also including the referenced objects.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_MULTI_ACK

        public static final String OPTION_MULTI_ACK
        Multi-ACK support for improved negotiation.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_MULTI_ACK_DETAILED

        public static final String OPTION_MULTI_ACK_DETAILED
        Multi-ACK detailed support for improved negotiation.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_THIN_PACK

        public static final String OPTION_THIN_PACK
        The client supports packs with deltas but not their bases.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_SIDE_BAND

        public static final String OPTION_SIDE_BAND
        The client supports using the side-band for progress messages.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_SIDE_BAND_64K

        public static final String OPTION_SIDE_BAND_64K
        The client supports using the 64K side-band for progress messages.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_OFS_DELTA

        public static final String OPTION_OFS_DELTA
        The client supports packs with OFS deltas.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_SHALLOW

        public static final String OPTION_SHALLOW
        The client supports shallow fetches.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_NO_PROGRESS

        public static final String OPTION_NO_PROGRESS
        The client does not want progress messages and will ignore them.
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_NO_DONE

        public static final String OPTION_NO_DONE
        The client supports receiving a pack before it has sent "done".
        Since:
        2.0
        See Also:
        Constant Field Values

      • OPTION_ALLOW_TIP_SHA1_IN_WANT

        public static final String OPTION_ALLOW_TIP_SHA1_IN_WANT
        The client supports fetching objects at the tip of any ref, even if not advertised.
        Since:
        3.1
        See Also:
        Constant Field Values

      • OPTION_ALLOW_REACHABLE_SHA1_IN_WANT

        public static final String OPTION_ALLOW_REACHABLE_SHA1_IN_WANT
        The client supports fetching objects that are reachable from a tip of a ref that is allowed to fetch.
        Since:
        4.1
        See Also:
        Constant Field Values

      • OPTION_FILTER

        public static final String OPTION_FILTER
        The client specified a filter expression.
        Since:
        5.0
        See Also:
        Constant Field Values

      • local

        protected final Repository local
        The repository this transport fetches into, or pushes out of.

      • uri

        protected final URIish uri
        Remote repository location.

      • transport

        protected final Transport transport
        A transport connected to uri.

      • timeoutIn

        protected TimeoutInputStream timeoutIn
        Low-level input stream, if a timeout was configured.

      • timeoutOut

        protected TimeoutOutputStream timeoutOut
        Low-level output stream, if a timeout was configured.

      • in

        protected InputStream in
        Input stream reading from the remote.

      • out

        protected OutputStream out
        Output stream sending to the remote.

      • statelessRPC

        protected boolean statelessRPC
        True if this is a stateless RPC connection.

      • additionalHaves

        protected final Set<ObjectId> additionalHaves
        Extra objects the remote has, but which aren't offered as refs.

    • Constructor Detail

      • BasePackFetchConnection

        public BasePackFetchConnection​(PackTransport packTransport)
        Create a new connection to fetch using the native git transport.
        Parameters:
        packTransport - the transport.

    • Method Detail

      • fetch

        public final void fetch​(ProgressMonitor monitor,
                        Collection<Ref> want,
                        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.

        Specified by:
        fetch in interface FetchConnection
        Parameters:
        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

        public final void fetch​(ProgressMonitor monitor,
                        Collection<Ref> want,
                        Set<ObjectId> have,
                        OutputStream outputStream)
                 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.

        Specified by:
        fetch in interface FetchConnection
        Parameters:
        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.
        outputStream - 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.

      • didFetchIncludeTags

        public boolean didFetchIncludeTags()
        Did the last FetchConnection.fetch(ProgressMonitor, Collection, Set) 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 FetchConnection.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.

        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.

        Specified by:
        didFetchIncludeTags in interface FetchConnection
        Returns:
        true if the last fetch call implicitly included tag objects; false if tags were not implicitly obtained.

      • didFetchTestConnectivity

        public boolean didFetchTestConnectivity()
        Did the last FetchConnection.fetch(ProgressMonitor, Collection, Set) 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.

        Specified by:
        didFetchTestConnectivity in interface FetchConnection
        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.

      • doFetch

        protected void doFetch​(ProgressMonitor monitor,
                       Collection<Ref> want,
                       Set<ObjectId> have,
                       OutputStream outputStream)
                throws TransportException
        Execute common ancestor negotiation and fetch the objects.
        Parameters:
        monitor - progress monitor to receive status updates. If the monitor is the NullProgressMonitor.INSTANCE, then the no-progress option enabled.
        want - the advertised remote references the caller wants to fetch.
        have - additional objects to assume that already exist locally. This will be added to the set of objects reachable from the destination repository's references.
        outputStream - ouputStream to write sideband messages to
        Throws:
        TransportException - if any exception occurs.
        Since:
        3.0

      • close

        public void close()

        Close any resources used by this connection.

        If the remote repository is contacted by a network socket this method must close that network socket, disconnecting the two peers. If the remote repository is actually local (same system) this method must close any open file handles used to read the "remote" repository.

        If additional messages were produced by the remote peer, these should still be retained in the connection instance for Connection.getMessages().

        AutoClosable.close() declares that it throws Exception. Implementers shouldn't throw checked exceptions. This override narrows the signature to prevent them from doing so.

        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Connection

      • onReceivePack

        protected void onReceivePack()
        Notification event delivered just before the pack is received from the network. This event can be used by RPC such as TransportHttp to disable its request magic and ensure the pack stream is read correctly.
        Since:
        2.0

      • init

        protected final void init​(InputStream myIn,
                          OutputStream myOut)
        Configure this connection with the directional pipes.
        Parameters:
        myIn - input stream to receive data from the peer. Caller must ensure the input is buffered, otherwise read performance may suffer.
        myOut - output stream to transmit data to the peer. Caller must ensure the output is buffered, otherwise write performance may suffer.

      • lsRefs

        protected void lsRefs​(Collection<RefSpec> refSpecs,
                      String... additionalPatterns)
               throws TransportException
        Issue a protocol V2 ls-refs command and read its response.
        Parameters:
        refSpecs - to produce ref prefixes from if the server supports git protocol V2
        additionalPatterns - to use for ref prefixes if the server supports git protocol V2
        Throws:
        TransportException - if the command could not be run or its output not be read

      • noRepository

        protected TransportException noRepository​(Throwable cause)
        Create an exception to indicate problems finding a remote repository. The caller is expected to throw the returned exception. Subclasses may override this method to provide better diagnostics.
        Parameters:
        cause - root cause exception
        Returns:
        a TransportException saying a repository cannot be found and possibly why.

      • isCapableOf

        protected boolean isCapableOf​(String option)
        Whether this option is supported
        Parameters:
        option - option string
        Returns:
        whether this option is supported

      • wantCapability

        protected boolean wantCapability​(StringBuilder b,
                                 String option)
        Request capability
        Parameters:
        b - buffer
        option - option we want
        Returns:
        true if the requested option is supported

      • getCapability

        protected String getCapability​(String option)
        Return a capability value.
        Parameters:
        option - to get
        Returns:
        the value stored, if any.

      • addUserAgentCapability

        protected void addUserAgentCapability​(StringBuilder b)
        Add user agent capability
        Parameters:
        b - a StringBuilder object.

      • getPeerUserAgent

        public String getPeerUserAgent()
        User agent advertised by the remote server. User agent advertised by the remote server.
        Specified by:
        getPeerUserAgent in interface Connection
        Overrides:
        getPeerUserAgent in class BaseConnection
        Returns:
        agent (version of Git) running on the remote server. Null if the server does not advertise this version.

      • endOut

        protected void endOut()
        Tell the peer we are disconnecting, if it cares to know.