Class DfsReader
- java.lang.Object
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- org.eclipse.jgit.lib.ObjectReader
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- org.eclipse.jgit.internal.storage.dfs.DfsReader
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- All Implemented Interfaces:
AutoCloseable
,ObjectReuseAsIs
public class DfsReader extends ObjectReader implements ObjectReuseAsIs
Reader to access repository content through.See the base
ObjectReader
documentation for details. Notably, a reader is not thread safe.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.eclipse.jgit.lib.ObjectReader
ObjectReader.Filter
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Field Summary
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Fields inherited from class org.eclipse.jgit.lib.ObjectReader
OBJ_ANY, streamFileThreshold
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Constructor Summary
Constructors Modifier Constructor Description protected
DfsReader(DfsObjDatabase db)
Initialize a new DfsReader
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
void
copyObjectAsIs(PackOutputStream out, ObjectToPack otp, boolean validate)
Output a previously selected representation.void
copyPackAsIs(PackOutputStream out, CachedPack pack)
Append an entire pack's contents onto the output stream.BitmapIndex
getBitmapIndex()
An index that can be used to speed up ObjectWalks.Collection<CachedPack>
getCachedPacksAndUpdate(BitmapIndex.BitmapBuilder needBitmap)
Obtain the available cached packs that match the bitmap and update the bitmap by removing the items that are in the CachedPack.DfsReaderIoStats
getIoStats()
Get IO statistics accumulated by this reader.<T extends ObjectId>
AsyncObjectSizeQueue<T>getObjectSize(Iterable<T> objectIds, boolean reportMissing)
Asynchronous object size lookup.long
getObjectSize(AnyObjectId objectId, int typeHint)
Get only the size of an object.Set<ObjectId>
getShallowCommits()
Returns IDs for those commits which should be considered as shallow.boolean
has(AnyObjectId objectId)
Does the requested object exist in this database?org.eclipse.jgit.internal.storage.dfs.DfsObjectToPack
newObjectToPack(AnyObjectId objectId, int type)
Allocate a newPackWriter
state structure for an object.ObjectReader
newReader()
Construct a new reader from the same data.<T extends ObjectId>
AsyncObjectLoaderQueue<T>open(Iterable<T> objectIds, boolean reportMissing)
Asynchronous object opening.ObjectLoader
open(AnyObjectId objectId, int typeHint)
Open an object from this database.Collection<ObjectId>
resolve(AbbreviatedObjectId id)
Resolve an abbreviated ObjectId to its full form.void
selectObjectRepresentation(PackWriter packer, ProgressMonitor monitor, Iterable<ObjectToPack> objects)
Select the best object representation for a packer.void
setAvoidUnreachableObjects(boolean avoid)
Advise the reader to avoid unreachable objects.void
writeObjects(PackOutputStream out, List<ObjectToPack> list)
Write objects to the pack stream in roughly the order given.-
Methods inherited from class org.eclipse.jgit.lib.ObjectReader
abbreviate, abbreviate, createObjectReachabilityChecker, createReachabilityChecker, getCreatedFromInserter, getStreamFileThreshold, has, open, setStreamFileThreshold
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Constructor Detail
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DfsReader
protected DfsReader(DfsObjDatabase db)
Initialize a new DfsReader- Parameters:
db
- parent DfsObjDatabase.
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Method Detail
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newReader
public ObjectReader newReader()
Construct a new reader from the same data.Applications can use this method to build a new reader from the same data source, but for an different thread.
- Specified by:
newReader
in classObjectReader
- Returns:
- a brand new reader, using the same data source.
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setAvoidUnreachableObjects
public void setAvoidUnreachableObjects(boolean avoid)
Advise the reader to avoid unreachable objects.While enabled the reader will skip over anything previously proven to be unreachable. This may be dangerous in the face of concurrent writes.
- Overrides:
setAvoidUnreachableObjects
in classObjectReader
- Parameters:
avoid
- true to avoid unreachable objects.
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getBitmapIndex
public BitmapIndex getBitmapIndex() throws IOException
An index that can be used to speed up ObjectWalks.- Overrides:
getBitmapIndex
in classObjectReader
- Returns:
- the index or null if one does not exist.
- Throws:
IOException
- when the index fails to load
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getCachedPacksAndUpdate
public Collection<CachedPack> getCachedPacksAndUpdate(BitmapIndex.BitmapBuilder needBitmap) throws IOException
Obtain the available cached packs that match the bitmap and update the bitmap by removing the items that are in the CachedPack.A cached pack has known starting points and may be sent entirely as-is, with almost no effort on the sender's part.
- Specified by:
getCachedPacksAndUpdate
in interfaceObjectReuseAsIs
- Parameters:
needBitmap
- the bitmap that contains all of the objects the client wants.- Returns:
- the available cached packs.
- Throws:
IOException
- the cached packs cannot be listed from the repository. Callers may choose to ignore this and continue as-if there were no cached packs.
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resolve
public Collection<ObjectId> resolve(AbbreviatedObjectId id) throws IOException
Resolve an abbreviated ObjectId to its full form. This method searches for an ObjectId that begins with the abbreviation, and returns at least some matching candidates. If the returned collection is empty, no objects start with this abbreviation. The abbreviation doesn't belong to this repository, or the repository lacks the necessary objects to complete it. If the collection contains exactly one member, the abbreviation is (currently) unique within this database. There is a reasonably high probability that the returned id is what was previously abbreviated. If the collection contains 2 or more members, the abbreviation is not unique. In this case the implementation is only required to return at least 2 candidates to signal the abbreviation has conflicts. User friendly implementations should return as many candidates as reasonably possible, as the caller may be able to disambiguate further based on context. However since databases can be very large (e.g. 10 million objects) returning 625,000 candidates for the abbreviation "0" is simply unreasonable, so implementors should draw the line at around 256 matches.- Specified by:
resolve
in classObjectReader
- Parameters:
id
- abbreviated id to resolve to a complete identity. The abbreviation must have a length of at least 2.- Returns:
- candidates that begin with the abbreviated identity.
- Throws:
IOException
- the object store cannot be read.
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has
public boolean has(AnyObjectId objectId) throws IOException
Does the requested object exist in this database?- Overrides:
has
in classObjectReader
- Parameters:
objectId
- identity of the object to test for existence of.- Returns:
- true if the specified object is stored in this database.
- Throws:
IOException
- the object store cannot be accessed.
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open
public ObjectLoader open(AnyObjectId objectId, int typeHint) throws MissingObjectException, IncorrectObjectTypeException, IOException
Open an object from this database.- Specified by:
open
in classObjectReader
- Parameters:
objectId
- identity of the object to open.typeHint
- hint about the type of object being requested, e.g.Constants.OBJ_BLOB
;ObjectReader.OBJ_ANY
if the object type is not known, or does not matter to the caller.- Returns:
- a
ObjectLoader
for accessing the object. - Throws:
MissingObjectException
- the object does not exist.IncorrectObjectTypeException
- typeHint was not OBJ_ANY, and the object's actual type does not match typeHint.IOException
- the object store cannot be accessed.
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getShallowCommits
public Set<ObjectId> getShallowCommits()
Returns IDs for those commits which should be considered as shallow.- Specified by:
getShallowCommits
in classObjectReader
- Returns:
- IDs of shallow commits
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open
public <T extends ObjectId> AsyncObjectLoaderQueue<T> open(Iterable<T> objectIds, boolean reportMissing)
Asynchronous object opening.- Overrides:
open
in classObjectReader
- Parameters:
objectIds
- objects to open from the object store. The supplied collection must not be modified until the queue has finished.reportMissing
- if true missing objects are reported by calling failure with a MissingObjectException. This may be more expensive for the implementation to guarantee. If false the implementation may choose to report MissingObjectException, or silently skip over the object with no warning.- Returns:
- queue to read the objects from.
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getObjectSize
public <T extends ObjectId> AsyncObjectSizeQueue<T> getObjectSize(Iterable<T> objectIds, boolean reportMissing)
Asynchronous object size lookup.- Overrides:
getObjectSize
in classObjectReader
- Parameters:
objectIds
- objects to get the size of from the object store. The supplied collection must not be modified until the queue has finished.reportMissing
- if true missing objects are reported by calling failure with a MissingObjectException. This may be more expensive for the implementation to guarantee. If false the implementation may choose to report MissingObjectException, or silently skip over the object with no warning.- Returns:
- queue to read object sizes from.
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getObjectSize
public long getObjectSize(AnyObjectId objectId, int typeHint) throws MissingObjectException, IncorrectObjectTypeException, IOException
Get only the size of an object.The default implementation of this method opens an ObjectLoader. Databases are encouraged to override this if a faster access method is available to them.
- Overrides:
getObjectSize
in classObjectReader
- Parameters:
objectId
- identity of the object to open.typeHint
- hint about the type of object being requested, e.g.Constants.OBJ_BLOB
;ObjectReader.OBJ_ANY
if the object type is not known, or does not matter to the caller.- Returns:
- size of object in bytes.
- Throws:
MissingObjectException
- the object does not exist.IncorrectObjectTypeException
- typeHint was not OBJ_ANY, and the object's actual type does not match typeHint.IOException
- the object store cannot be accessed.
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newObjectToPack
public org.eclipse.jgit.internal.storage.dfs.DfsObjectToPack newObjectToPack(AnyObjectId objectId, int type)
Allocate a newPackWriter
state structure for an object.PackWriter
allocates these objects to keep track of the per-object state, and how to load the objects efficiently into the generated stream. Implementers may subclass this type with additional object state, such as to remember what file and offset contains the object's pack encoded data.- Specified by:
newObjectToPack
in interfaceObjectReuseAsIs
- Parameters:
objectId
- the id of the object that will be packed.type
- the Git type of the object that will be packed.- Returns:
- a new instance for this object.
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selectObjectRepresentation
public void selectObjectRepresentation(PackWriter packer, ProgressMonitor monitor, Iterable<ObjectToPack> objects) throws IOException, MissingObjectException
Description copied from interface:ObjectReuseAsIs
Select the best object representation for a packer.Implementations should iterate through all available representations of an object, and pass them in turn to the PackWriter though
PackWriter.select(ObjectToPack, StoredObjectRepresentation)
so the writer can select the most suitable representation to reuse into the output stream.If the implementation returns CachedPack from
ObjectReuseAsIs.getCachedPacksAndUpdate(BitmapBuilder)
it must consider the representation of any object that is stored in any of the offered CachedPacks. PackWriter relies on this behavior to prune duplicate objects out of the pack stream when it selects a CachedPack and the object was also reached through the thin-pack enumeration.The implementation may choose to consider multiple objects at once on concurrent threads, but must evaluate all representations of an object within the same thread.
- Specified by:
selectObjectRepresentation
in interfaceObjectReuseAsIs
- Parameters:
packer
- the packer that will write the object in the near future.monitor
- progress monitor, implementation should update the monitor once for each item in the iteration when selection is done.objects
- the objects that are being packed.- Throws:
MissingObjectException
- there is no representation available for the object, as it is no longer in the repository. Packing will abort.IOException
- the repository cannot be accessed. Packing will abort.
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copyObjectAsIs
public void copyObjectAsIs(PackOutputStream out, ObjectToPack otp, boolean validate) throws IOException, StoredObjectRepresentationNotAvailableException
Output a previously selected representation.PackWriter
invokes this method only if a representation previously given to it byselectObjectRepresentation
was chosen for reuse into the output stream. Theotp
argument is an instance created by this reader's ownnewObjectToPack
, and the representation data saved within it also originated from this reader.Implementors must write the object header before copying the raw data to the output stream. The typical implementation is like:
MyToPack mtp = (MyToPack) otp; byte[] raw; if (validate) raw = validate(mtp); // throw SORNAE here, if at all else raw = readFast(mtp); out.writeHeader(mtp, mtp.inflatedSize); out.write(raw);
- Specified by:
copyObjectAsIs
in interfaceObjectReuseAsIs
- Parameters:
out
- stream the object should be written to.otp
- the object's saved representation information.validate
- if true the representation must be validated and not be corrupt before being reused. If false, validation may be skipped as it will be performed elsewhere in the processing pipeline.- Throws:
IOException
- the stream's write method threw an exception. Packing will abort.StoredObjectRepresentationNotAvailableException
- the previously selected representation is no longer available. If thrown beforeout.writeHeader
the pack writer will try to find another representation, and write that one instead. If throw afterout.writeHeader
, packing will abort.
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writeObjects
public void writeObjects(PackOutputStream out, List<ObjectToPack> list) throws IOException
Write objects to the pack stream in roughly the order given.PackWriter
invokes this method to write out one or more objects, in approximately the order specified by the iteration over the list. A simple implementation of this method would just iterate the list and output each object:for (ObjectToPack obj : list) out.writeObject(obj)
However more sophisticated implementors may try to perform some (small) reordering to access objects that are stored close to each other at roughly the same time. Implementations may choose to write objects out of order, but this may increase pack file size due to using a larger header format to reach a delta base that is later in the stream. It may also reduce data locality for the reader, slowing down data access. InvokingPackOutputStream.writeObject(ObjectToPack)
will causeObjectReuseAsIs.copyObjectAsIs(PackOutputStream, ObjectToPack, boolean)
to be invoked recursively onthis
if the current object is scheduled for reuse.- Specified by:
writeObjects
in interfaceObjectReuseAsIs
- Parameters:
out
- the stream to write each object to.list
- the list of objects to write. Objects should be written in approximately this order. Implementors may resort the list elements in-place during writing if desired.- Throws:
IOException
- the stream cannot be written to, or one or more required objects cannot be accessed from the object database.
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copyPackAsIs
public void copyPackAsIs(PackOutputStream out, CachedPack pack) throws IOException
Append an entire pack's contents onto the output stream.The entire pack, excluding its header and trailing footer is sent.
- Specified by:
copyPackAsIs
in interfaceObjectReuseAsIs
- Parameters:
out
- stream to append the pack onto.pack
- the cached pack to send.- Throws:
IOException
- the pack cannot be read, or stream did not accept a write.
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getIoStats
public DfsReaderIoStats getIoStats()
Get IO statistics accumulated by this reader.- Returns:
- IO statistics accumulated by this reader.
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close
public void close()
Release any resources used by this reader.
A reader that has been released can be used again, but may need to be released after the subsequent usage.
Release the current window cursor.
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in classObjectReader
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