JGit 7.2.0.202503040940-r · org.eclipse.jgit.internal.storage.file.BasePackIndexWriter

Modifier and Type	Field and Description
protected List<? extends PackedObjectInfo>	entries The entries this writer must pack.
protected final DigestOutputStream	out The index data stream we are responsible for creating.
protected byte[]	packChecksum SHA-1 checksum for the entire pack data.
protected final byte[]	tmp A temporary buffer for use during IO to {link #out}.
protected static final byte[]	TOC Magic constant indicating post-version 1 format.

Access	Constructor and Description
protected	BasePackIndexWriter(OutputStream the stream this instance outputs to. If not already buffered it will be automatically wrapped in a buffered stream. dst) Create a new writer instance.

Method Summary

Modifier and Type	Method and Description
public static PackIndexWriter	Returns: a new writer to output an index file of the requested format to the supplied stream. createOldestPossible(final OutputStream the stream the index data will be written to. If not already buffered it will be automatically wrapped in a buffered stream. Callers are always responsible for closing the stream. dst, final List<? extends PackedObjectInfo> the objects the caller needs to store in the index. Entries will be examined until a format can be conclusively selected. objs) Create a new writer for the oldest (most widely understood) format.
public static PackIndexWriter	Returns: a new writer to output an index file of the requested format to the supplied stream. createVersion(final OutputStream the stream the index data will be written to. If not already buffered it will be automatically wrapped in a buffered stream. Callers are always responsible for closing the stream. dst, final int index format version number required by the caller. Exactly this formatted version will be written. version) Create a new writer instance for a specific index format version.
public static int	Returns: the index format. oldestPossibleFormat(final List<? extends PackedObjectInfo> the objects the caller needs to store in the index. Entries will be examined until a format can be conclusively selected. objs) Return the oldest (most widely understood) index format.
public void	write(final List<? extends PackedObjectInfo> sorted list of objects to store in the index. The caller must have previously sorted the list using `org.eclipse.jgit.transport.PackedObjectInfo`'s native `java.lang.Comparable` implementation. toStore, final byte[] checksum signature of the entire pack data content. This is traditionally the last 20 bytes of the pack file's own stream. packDataChecksum) Implements org.eclipse.jgit.internal.storage.pack.PackIndexWriter.write. Write all object entries to the index stream.
protected void	writeChecksumFooter() Output the standard two-checksum index footer.
protected void	writeFanOutTable() Output the standard 256 entry first-level fan-out table.
protected abstract void	writeImpl() Writes the index file to `out`.
protected void	writeTOC(int version number of this index format being written. version) Output the version 2 (and later) TOC header, with version number.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

entries	back to summary
protected List<? extends PackedObjectInfo> entries The entries this writer must pack.

out	back to summary
protected final DigestOutputStream out The index data stream we are responsible for creating.

packChecksum	back to summary
protected byte[] packChecksum SHA-1 checksum for the entire pack data.

tmp	back to summary
protected final byte[] tmp A temporary buffer for use during IO to {link #out}.

TOC	back to summary
protected static final byte[] TOC Magic constant indicating post-version 1 format.

BasePackIndexWriter	back to summary
protected BasePackIndexWriter(OutputStream dst) Create a new writer instance. Parameters dst:OutputStream the stream this instance outputs to. If not already buffered it will be automatically wrapped in a buffered stream.

Method Detail

createOldestPossible back to summary

createOldestPossible	back to summary
public static PackIndexWriter createOldestPossible(final OutputStream dst, final List<? extends PackedObjectInfo> objs) Create a new writer for the oldest (most widely understood) format. This method selects an index format that can accurate describe the supplied objects and that will be the most compatible format with older Git implementations. Index version 1 is widely recognized by all Git implementations, but index version 2 (and later) is not as well recognized as it was introduced more than a year later. Index version 1 can only be used if the resulting pack file is under 4 gigabytes in size; packs larger than that limit must use index version 2. Parameters dst:OutputStream the stream the index data will be written to. If not already buffered it will be automatically wrapped in a buffered stream. Callers are always responsible for closing the stream. objs:List<? extends PackedObjectInfo> the objects the caller needs to store in the index. Entries will be examined until a format can be conclusively selected. Returns:PackIndexWriter a new writer to output an index file of the requested format to the supplied stream. Exceptions IllegalArgumentException: no recognized pack index version can support the supplied objects. This is likely a bug in the implementation. See Also `oldestPossibleFormat(List)`

public static PackIndexWriter createOldestPossible(final OutputStream dst, final List<? extends PackedObjectInfo> objs)

Create a new writer for the oldest (most widely understood) format.

This method selects an index format that can accurate describe the supplied objects and that will be the most compatible format with older Git implementations.

Index version 1 is widely recognized by all Git implementations, but index version 2 (and later) is not as well recognized as it was introduced more than a year later. Index version 1 can only be used if the resulting pack file is under 4 gigabytes in size; packs larger than that limit must use index version 2.

Parameters

dst:OutputStream: the stream the index data will be written to. If not already buffered it will be automatically wrapped in a buffered stream. Callers are always responsible for closing the stream.
objs:List<? extends PackedObjectInfo>: the objects the caller needs to store in the index. Entries will be examined until a format can be conclusively selected.

Returns:PackIndexWriter

a new writer to output an index file of the requested format to the supplied stream.

Exceptions

IllegalArgumentException:: no recognized pack index version can support the supplied objects. This is likely a bug in the implementation.

See Also

oldestPossibleFormat(List)

createVersion	back to summary
public static PackIndexWriter createVersion(final OutputStream dst, final int version) Create a new writer instance for a specific index format version. Parameters dst:OutputStream the stream the index data will be written to. If not already buffered it will be automatically wrapped in a buffered stream. Callers are always responsible for closing the stream. version:int index format version number required by the caller. Exactly this formatted version will be written. Returns:PackIndexWriter a new writer to output an index file of the requested format to the supplied stream. Exceptions IllegalArgumentException: the version requested is not supported by this implementation.

createVersion

back to summary

public static PackIndexWriter createVersion(final OutputStream dst, final int version)

Create a new writer instance for a specific index format version.

Parameters

dst:OutputStream: the stream the index data will be written to. If not already buffered it will be automatically wrapped in a buffered stream. Callers are always responsible for closing the stream.
version:int: index format version number required by the caller. Exactly this formatted version will be written.

Returns:PackIndexWriter

a new writer to output an index file of the requested format to the supplied stream.

Exceptions

IllegalArgumentException:: the version requested is not supported by this implementation.

oldestPossibleFormat	back to summary
public static int oldestPossibleFormat(final List<? extends PackedObjectInfo> objs) Return the oldest (most widely understood) index format. This method selects an index format that can accurate describe the supplied objects and that will be the most compatible format with older Git implementations. Index version 1 is widely recognized by all Git implementations, but index version 2 (and later) is not as well recognized as it was introduced more than a year later. Index version 1 can only be used if the resulting pack file is under 4 gigabytes in size; packs larger than that limit must use index version 2. Parameters objs:List<? extends PackedObjectInfo> the objects the caller needs to store in the index. Entries will be examined until a format can be conclusively selected. Returns:int the index format. Exceptions IllegalArgumentException: no recognized pack index version can support the supplied objects. This is likely a bug in the implementation.

oldestPossibleFormat

back to summary

public static int oldestPossibleFormat(final List<? extends PackedObjectInfo> objs)

Return the oldest (most widely understood) index format.

This method selects an index format that can accurate describe the supplied objects and that will be the most compatible format with older Git implementations.

Parameters

objs:List<? extends PackedObjectInfo>: the objects the caller needs to store in the index. Entries will be examined until a format can be conclusively selected.

Returns:int

the index format.

Exceptions

IllegalArgumentException:: no recognized pack index version can support the supplied objects. This is likely a bug in the implementation.

write back to summary

write	back to summary
public void write(final List<? extends PackedObjectInfo> toStore, final byte[] packDataChecksum) throws IOException Implements org.eclipse.jgit.internal.storage.pack.PackIndexWriter.write. Write all object entries to the index stream. After writing the stream passed to the factory is flushed but remains open. Callers are always responsible for closing the output stream. Parameters toStore:List<? extends PackedObjectInfo> sorted list of objects to store in the index. The caller must have previously sorted the list using `org.eclipse.jgit.transport.PackedObjectInfo`'s native `java.lang.Comparable` implementation. packDataChecksum:byte[] checksum signature of the entire pack data content. This is traditionally the last 20 bytes of the pack file's own stream. Annotations @Override Exceptions IOException: an error occurred while writing to the output stream, or this index format cannot store the object data supplied.

public void write(final List<? extends PackedObjectInfo> toStore, final byte[] packDataChecksum) throws IOException

Implements org.eclipse.jgit.internal.storage.pack.PackIndexWriter.write.

Write all object entries to the index stream.

After writing the stream passed to the factory is flushed but remains open. Callers are always responsible for closing the output stream.

Parameters

toStore:List<? extends PackedObjectInfo>: sorted list of objects to store in the index. The caller must have previously sorted the list using org.eclipse.jgit.transport.PackedObjectInfo's native java.lang.Comparable implementation.
packDataChecksum:byte[]: checksum signature of the entire pack data content. This is traditionally the last 20 bytes of the pack file's own stream.

Annotations

@Override

Exceptions

IOException:: an error occurred while writing to the output stream, or this index format cannot store the object data supplied.

writeChecksumFooter	back to summary
protected void writeChecksumFooter() throws IOException Output the standard two-checksum index footer. The standard footer contains two checksums (20 byte SHA-1 values): Pack data checksum - taken from the last 20 bytes of the pack file. Index data checksum - checksum of all index bytes written, including the pack data checksum above. Exceptions IOException: an error occurred while writing to the output stream.

writeChecksumFooter

back to summary

protected void writeChecksumFooter() throws IOException

Output the standard two-checksum index footer.

The standard footer contains two checksums (20 byte SHA-1 values):

Pack data checksum - taken from the last 20 bytes of the pack file.
Index data checksum - checksum of all index bytes written, including the pack data checksum above.

Exceptions

IOException:: an error occurred while writing to the output stream.

writeFanOutTable back to summary

writeFanOutTable	back to summary
protected void writeFanOutTable() throws IOException Output the standard 256 entry first-level fan-out table. The fan-out table is 4 KB in size, holding 256 32-bit unsigned integer counts. Each count represents the number of objects within this index whose `org.eclipse.jgit.lib.ObjectId#getFirstByte()` matches the count's position in the fan-out table. Exceptions IOException: an error occurred while writing to the output stream.

protected void writeFanOutTable() throws IOException

Output the standard 256 entry first-level fan-out table.

The fan-out table is 4 KB in size, holding 256 32-bit unsigned integer counts. Each count represents the number of objects within this index whose org.eclipse.jgit.lib.ObjectId#getFirstByte() matches the count's position in the fan-out table.

Exceptions

IOException:: an error occurred while writing to the output stream.

writeImpl back to summary

writeImpl	back to summary
protected abstract void writeImpl() throws IOException Writes the index file to `out`. Implementations should go something like: writeFanOutTable(); for (final PackedObjectInfo po : entries) writeOneEntry(po); writeChecksumFooter(); Where the logic for `writeOneEntry` is specific to the index format in use. Additional headers/footers may be used if necessary and the `entries` collection may be iterated over more than once if necessary. Implementors therefore have complete control over the data. Exceptions IOException: an error occurred while writing to the output stream, or this index format cannot store the object data supplied.

protected abstract void writeImpl() throws IOException

Writes the index file to out.

Implementations should go something like:

writeFanOutTable();
for (final PackedObjectInfo po : entries)
	writeOneEntry(po);
writeChecksumFooter();

Where the logic for writeOneEntry is specific to the index format in use. Additional headers/footers may be used if necessary and the entries collection may be iterated over more than once if necessary. Implementors therefore have complete control over the data.

Exceptions

IOException:: an error occurred while writing to the output stream, or this index format cannot store the object data supplied.

writeTOC	back to summary
protected void writeTOC(int version) throws IOException Output the version 2 (and later) TOC header, with version number. Post version 1 all index files start with a TOC header that makes the file an invalid version 1 file, and then includes the version number. This header is necessary to recognize a version 1 from a version 2 formatted index. Parameters version:int version number of this index format being written. Exceptions IOException: an error occurred while writing to the output stream.

writeTOC

back to summary

protected void writeTOC(int version) throws IOException

Output the version 2 (and later) TOC header, with version number.

Post version 1 all index files start with a TOC header that makes the file an invalid version 1 file, and then includes the version number. This header is necessary to recognize a version 1 from a version 2 formatted index.

Parameters

version:int: version number of this index format being written.

Exceptions

IOException:: an error occurred while writing to the output stream.

public abstract Class BasePackIndexWriter

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