org.eclipse.jgit.transport
Class BasePackFetchConnection

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

All Implemented Interfaces:

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 Summary

protected Set<ObjectId>	additionalHaves Extra objects the remote has, but which aren't offered as refs.
protected InputStream	in Input stream reading from the remote.
protected Repository	local The repository this transport fetches into, or pushes out of.
protected static int	MIN_CLIENT_BUFFER Amount of data the client sends before starting to read.
static String	OPTION_INCLUDE_TAG Include tags if we are also including the referenced objects.
static String	OPTION_MULTI_ACK Mutli-ACK support for improved negotiation.
static String	OPTION_MULTI_ACK_DETAILED Mutli-ACK detailed support for improved negotiation.
static String	OPTION_NO_DONE The client supports receiving a pack before it has sent "done".
static String	OPTION_NO_PROGRESS The client does not want progress messages and will ignore them.
static String	OPTION_OFS_DELTA The client supports packs with OFS deltas.
static String	OPTION_SHALLOW The client supports shallow fetches.
static String	OPTION_SIDE_BAND The client supports using the side-band for progress messages.
static String	OPTION_SIDE_BAND_64K The client supports using the 64K side-band for progress messages.
static String	OPTION_THIN_PACK The client supports packs with deltas but not their bases.
protected OutputStream	out Output stream sending to the remote.
protected boolean	outNeedsEnd Send PacketLineOut.end() before closing out?
protected PacketLineIn	pckIn Packet line decoder around in.
protected PacketLineOut	pckOut Packet line encoder around out.
protected boolean	statelessRPC True if this is a stateless RPC connection.
protected TimeoutInputStream	timeoutIn Low-level input stream, if a timeout was configured.
protected TimeoutOutputStream	timeoutOut Low-level output stream, if a timeout was configured.
protected Transport	transport A transport connected to uri.
protected URIish	uri Remote repository location.

Constructor Summary

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

Method Summary

void	close() Close any resources used by this connection.
boolean	didFetchIncludeTags() Did the last FetchConnection.fetch(ProgressMonitor, Collection, Set) get tags?
boolean	didFetchTestConnectivity() Did the last FetchConnection.fetch(ProgressMonitor, Collection, Set) validate graph?
protected void	doFetch(ProgressMonitor monitor, Collection<Ref> want, Set<ObjectId> have) Execute common ancestor negotiation and fetch the objects.
protected void	endOut() Tell the peer we are disconnecting, if it cares to know.
void	fetch(ProgressMonitor monitor, Collection<Ref> want, Set<ObjectId> have) Fetch objects we don't have but that are reachable from advertised refs.
Collection<PackLock>	getPackLocks() All locks created by the last FetchConnection.fetch(ProgressMonitor, Collection, Set) call.
protected void	init(InputStream myIn, OutputStream myOut) Configure this connection with the directional pipes.
protected boolean	isCapableOf(String option)
protected TransportException	noRepository() Create an exception to indicate problems finding a remote repository.
protected void	onReceivePack() Notification event delivered just before the pack is received from the network.
protected void	readAdvertisedRefs() Reads the advertised references through the initialized stream.
void	setPackLockMessage(String message) Set the lock message used when holding a pack out of garbage collection.
protected boolean	wantCapability(StringBuilder b, String option)

Methods inherited from class org.eclipse.jgit.transport.BaseConnection

available, getMessages, getMessageWriter, getRef, getRefs, getRefsMap, markStartedOperation, setMessageWriter

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.eclipse.jgit.transport.Connection

getMessages, getRef, getRefs, getRefsMap

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

Mutli-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

Mutli-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

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 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

Description copied from interface: FetchConnection

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.

didFetchIncludeTags

public boolean didFetchIncludeTags()

Description copied from interface: FetchConnection

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()

Description copied from interface: FetchConnection

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)

Description copied from interface: FetchConnection

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()

Description copied from interface: FetchConnection

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)
                throws TransportException

Execute common ancestor negotiation and fetch the objects.

Parameters:

monitor - progress monitor to receive status updates.

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.

Throws:

TransportException - if any exception occurs.

close

public void close()

Description copied from interface: Connection

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().

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 void 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 close() and the exception is wrapped (if necessary) and thrown as a TransportException.

Throws:

TransportException - the reference list could not be scanned.

noRepository

protected TransportException noRepository()

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.

Returns:

a TransportException saying a repository cannot be found and possibly why.

isCapableOf

protected boolean isCapableOf(String option)

wantCapability

protected boolean wantCapability(StringBuilder b,
                                 String option)

endOut

protected void endOut()

Tell the peer we are disconnecting, if it cares to know.