org.eclipse.jgit.internal.storage.dfs

Class DfsReftableDatabase

java.lang.Object

org.eclipse.jgit.lib.RefDatabase

org.eclipse.jgit.internal.storage.dfs.DfsRefDatabase

org.eclipse.jgit.internal.storage.dfs.DfsReftableDatabase

Direct Known Subclasses:

InMemoryRepository.MemRefDatabase

public class DfsReftableDatabase
extends DfsRefDatabase

A DfsRefDatabase that uses reftable for storage.

A DfsRefDatabase instance is thread-safe.

Implementors may wish to use DfsPackDescription.getMaxUpdateIndex() as the primary key identifier for a PackExt.REFTABLE only pack description, ensuring that when there are competing transactions one wins, and one will fail.

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.jgit.internal.storage.dfs.DfsRefDatabase

DfsRefDatabase.RefCache

Field Summary

Fields inherited from class org.eclipse.jgit.lib.RefDatabase

ALL, MAX_SYMBOLIC_REF_DEPTH, SEARCH_PATH

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DfsReftableDatabase(DfsRepository repo) Initialize the reference database for a repository.

Method Summary

Modifier and Type	Method and Description
protected void	cachePeeledState(Ref oldLeaf, Ref newLeaf) Update the cached peeled state of a reference
protected boolean	compactDuringCommit() Whether to compact reftable instead of extending the stack depth.
protected boolean	compareAndPut(Ref oldRef, Ref newRef) Compare a reference, and put if it matches.
protected boolean	compareAndRemove(Ref oldRef) Compare a reference, and delete if it matches.
Ref	exactRef(String name) Read a single reference.
protected ReentrantLock	getLock() Get the lock protecting this instance's state.
Map<String,Ref>	getRefs(String prefix) Get a section of the reference namespace.
List<Ref>	getRefsByPrefix(String prefix) Returns refs whose names start with a given prefix.
ReftableConfig	getReftableConfig() Get configuration to write new reftables with.
boolean	hasVersioning() With versioning, each reference has a version number that increases on update.
boolean	isNameConflicting(String refName) Determine if a proposed reference name overlaps with an existing one.
BatchRefUpdate	newBatchUpdate() Create a new batch update to attempt on this database.
Ref	peel(Ref ref) Peel a possibly unpeeled reference by traversing the annotated tags.
boolean	performsAtomicTransactions() Whether the database is capable of performing batch updates as atomic transactions.
protected Reftable	reader() Obtain a handle to the merged reader.
protected DfsRefDatabase.RefCache	scanAllRefs() Read all known references in the repository.
protected ReftableStack	stack() Obtain a handle to the stack of reftables.

Methods inherited from class org.eclipse.jgit.internal.storage.dfs.DfsRefDatabase

close, create, getAdditionalRefs, getRepository, newRename, newUpdate, refresh

Methods inherited from class org.eclipse.jgit.lib.RefDatabase

exactRef, findRef, findRef, firstExactRef, getConflictingNames, getRef, getRefs, getRefsByPrefix, hasRefs

Methods inherited from class java.lang.Object

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

Constructor Detail

DfsReftableDatabase

protected DfsReftableDatabase(DfsRepository repo)

Initialize the reference database for a repository.

Parameters:

repo - the repository this database instance manages references for.

Method Detail

hasVersioning

public boolean hasVersioning()

With versioning, each reference has a version number that increases on update. See Ref.getUpdateIndex().

Overrides:

hasVersioning in class RefDatabase

Returns:

true if the implementation assigns update indices to references.

performsAtomicTransactions

public boolean performsAtomicTransactions()

Whether the database is capable of performing batch updates as atomic transactions.

If true, by default BatchRefUpdate instances will perform updates atomically, meaning either all updates will succeed, or all updates will fail. It is still possible to turn off this behavior on a per-batch basis by calling update.setAtomic(false).

If false, BatchRefUpdate instances will never perform updates atomically, and calling update.setAtomic(true) will cause the entire batch to fail with REJECTED_OTHER_REASON.

This definition of atomicity is stronger than what is provided by ReceivePack. ReceivePack will attempt to reject all commands if it knows in advance some commands may fail, even if the storage layer does not support atomic transactions. Here, atomicity applies even in the case of unforeseeable errors.

Overrides:

performsAtomicTransactions in class RefDatabase

Returns:

whether transactions are atomic by default.

newBatchUpdate

public BatchRefUpdate newBatchUpdate()

Create a new batch update to attempt on this database.

The default implementation performs a sequential update of each command.

Overrides:

newBatchUpdate in class RefDatabase

Returns:

a new batch update object.

getReftableConfig

public ReftableConfig getReftableConfig()

Get configuration to write new reftables with.

Returns:

configuration to write new reftables with.

getLock

protected ReentrantLock getLock()

Get the lock protecting this instance's state.

Returns:

the lock protecting this instance's state.

compactDuringCommit

protected boolean compactDuringCommit()

Whether to compact reftable instead of extending the stack depth.

Returns:

true if commit of a new small reftable should try to replace a prior small reftable by performing a compaction, instead of extending the stack depth.

reader

protected Reftable reader()
                   throws IOException

Obtain a handle to the merged reader.

Returns:

(possibly cached) handle to the merged reader.

Throws:

IOException - if tables cannot be opened.

stack

protected ReftableStack stack()
                       throws IOException

Obtain a handle to the stack of reftables.

Returns:

(possibly cached) handle to the stack.

Throws:

IOException - if tables cannot be opened.

isNameConflicting

public boolean isNameConflicting(String refName)
                          throws IOException

Determine if a proposed reference name overlaps with an existing one.

Reference names use '/' as a component separator, and may be stored in a hierarchical storage such as a directory on the local filesystem.

If the reference "refs/heads/foo" exists then "refs/heads/foo/bar" must not exist, as a reference cannot have a value and also be a container for other references at the same time.

If the reference "refs/heads/foo/bar" exists than the reference "refs/heads/foo" cannot exist, for the same reason.

Overrides:

isNameConflicting in class DfsRefDatabase

Parameters:

refName - proposed name.

Returns:

true if the name overlaps with an existing reference; false if using this name right now would be safe.

Throws:

IOException - the database could not be read to check for conflicts.

See Also:

RefDatabase.getConflictingNames(String)

exactRef

public Ref exactRef(String name)
             throws IOException

Read a single reference.

Unlike RefDatabase.findRef(java.lang.String), this method expects an unshortened reference name and does not search using the standard RefDatabase.SEARCH_PATH.

Overrides:

exactRef in class DfsRefDatabase

Parameters:

name - the unabbreviated name of the reference.

Returns:

the reference (if it exists); else null.

Throws:

IOException - the reference space cannot be accessed.

getRefs

public Map<String,Ref> getRefs(String prefix)
                        throws IOException

Get a section of the reference namespace.

Overrides:

getRefs in class DfsRefDatabase

Parameters:

prefix - prefix to search the namespace with; must end with /. If the empty string (RefDatabase.ALL), obtain a complete snapshot of all references.

Returns:

modifiable map that is a complete snapshot of the current reference namespace, with prefix removed from the start of each key. The map can be an unsorted map.

Throws:

IOException - the reference space cannot be accessed.

getRefsByPrefix

public List<Ref> getRefsByPrefix(String prefix)
                          throws IOException

Returns refs whose names start with a given prefix.

The default implementation uses RefDatabase.getRefs(String). Implementors of RefDatabase should override this method directly if a better implementation is possible.

Overrides:

getRefsByPrefix in class RefDatabase

Parameters:

prefix - string that names of refs should start with; may be empty (to return all refs).

Returns:

immutable list of refs whose names start with prefix.

Throws:

IOException - the reference space cannot be accessed.

peel

public Ref peel(Ref ref)
         throws IOException

Peel a possibly unpeeled reference by traversing the annotated tags.

If the reference cannot be peeled (as it does not refer to an annotated tag) the peeled id stays null, but Ref.isPeeled() will be true.

Implementors should check Ref.isPeeled() before performing any additional work effort.

Overrides:

peel in class DfsRefDatabase

Parameters:

ref - The reference to peel

Returns:

ref if ref.isPeeled() is true; otherwise a new Ref object representing the same data as Ref, but isPeeled() will be true and getPeeledObjectId() will contain the peeled object (or null).

Throws:

IOException - the reference space or object space cannot be accessed.

compareAndPut

protected boolean compareAndPut(Ref oldRef,
                                @Nullable
                                Ref newRef)
                         throws IOException

Compare a reference, and put if it matches.

Two reference match if and only if they satisfy the following:

• If one reference is a symbolic ref, the other one should be a symbolic ref.
• If both are symbolic refs, the target names should be same.
• If both are object ID refs, the object IDs should be same.

Specified by:

compareAndPut in class DfsRefDatabase

Parameters:

oldRef - old value to compare to. If the reference is expected to not exist the old value has a storage of Ref.Storage.NEW and an ObjectId value of null.

newRef - new reference to store.

Returns:

true if the put was successful; false otherwise.

Throws:

IOException - the reference cannot be put due to a system error.

compareAndRemove

protected boolean compareAndRemove(Ref oldRef)
                            throws IOException

Compare a reference, and delete if it matches.

Specified by:

compareAndRemove in class DfsRefDatabase

Parameters:

oldRef - the old reference information that was previously read.

Returns:

true if the remove was successful; false otherwise.

Throws:

IOException - the reference could not be removed due to a system error.

scanAllRefs

protected DfsRefDatabase.RefCache scanAllRefs()
                                       throws IOException

Read all known references in the repository.

Specified by:

scanAllRefs in class DfsRefDatabase

Returns:

all current references of the repository.

Throws:

IOException - references cannot be accessed.

cachePeeledState

protected void cachePeeledState(Ref oldLeaf,
                                Ref newLeaf)

Update the cached peeled state of a reference

The ref database invokes this method after it peels a reference that had not been peeled before. This allows the storage to cache the peel state of the reference, and if it is actually peelable, the target that it peels to, so that on-the-fly peeling doesn't have to happen on the next reference read.

Overrides:

cachePeeledState in class DfsRefDatabase

Parameters:

oldLeaf - the old reference.

newLeaf - the new reference, with peel information.