Module org.eclipse.jgit
Package org.eclipse.jgit.transport

Class BasePackFetchConnection

java.lang.Object
org.eclipse.jgit.transport.BaseConnection
org.eclipse.jgit.transport.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 Details

    • 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:

    • 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:

    • OPTION_MULTI_ACK

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

    • OPTION_MULTI_ACK_DETAILED

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

    • 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:

    • 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:

    • 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:

    • OPTION_OFS_DELTA

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

    • OPTION_SHALLOW

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

    • 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:

    • 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:

    • 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:

    • 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:

    • OPTION_FILTER

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

    • CAPABILITY_SYMREF_PREFIX

      protected static final String CAPABILITY_SYMREF_PREFIX
      See Also:

    • 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.

    • pckIn

      protected PacketLineIn pckIn
      Packet line decoder around in.

    • pckOut

      protected PacketLineOut pckOut
      Packet line encoder around out.

    • outNeedsEnd

      protected boolean outNeedsEnd
      Send PacketLineOut.end() before closing out?

    • 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 Details

    • BasePackFetchConnection

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

  • Method Details

    • 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.

    • setPackLockMessage

      public void setPackLockMessage(String message)
      Set the lock message used when holding a pack out of garbage collection.

      Callers that set a lock message must ensure they call FetchConnection.getPackLocks() after FetchConnection.fetch(ProgressMonitor, Collection, Set), even if an exception was thrown, and release the locks that are held.

      Specified by:
      setPackLockMessage in interface FetchConnection
      Parameters:
      message - message to use when holding a pack in place.

    • getPackLocks

      public Collection<PackLock> getPackLocks()
      All locks created by the last FetchConnection.fetch(ProgressMonitor, Collection, Set) call.
      Specified by:
      getPackLocks in interface FetchConnection
      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.

    • 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.

    • readAdvertisedRefs

      protected boolean readAdvertisedRefs() throws TransportException
      Reads the advertised references through the initialized stream.

      Subclass implementations may call this method only after setting up the input and output streams with init(InputStream, OutputStream).

      If any errors occur, this connection is automatically closed by invoking BaseConnection.close() and the exception is wrapped (if necessary) and thrown as a TransportException.

      Returns:
      true if the refs were read; false otherwise indicating that lsRefs(java.util.Collection<org.eclipse.jgit.transport.RefSpec>, java.lang.String...) must be called
      Throws:
      TransportException - the reference list could not be scanned.

    • 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.