Class RefDirectory
RefDatabase
.
This is the classical reference database representation for a Git repository. References are stored in two formats: loose, and packed.
Loose references are stored as individual files within the refs/
directory. The file name matches the reference name and the file contents is
the current ObjectId
in string form.
Packed references are stored in a single text file named packed-refs
.
In the packed format, each reference is stored on its own line. This file
reduces the number of files needed for large reference spaces, reducing the
overall size of a Git repository on disk.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprivate static final class
private static final class
private static interface
private class
private static final class
private static final class
(package private) static class
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final String[]
The names of the additional refs supported by this classprivate final File
(package private) final ReentrantLock
Lock for coordinating operations within a single process that may contend on thepacked-refs
file.private final AtomicInteger
LastmodCnt
that we sent to listeners.private static final org.slf4j.Logger
(package private) final File
(package private) final File
private final AtomicReference
<RefList<RefDirectory.LooseRef>> Immutable sorted list of loose references.private final AtomicInteger
Number of modifications made to this database.private static final RefDirectory.PackedRefList
static final String
Magic string denoting the header of a packed-refs file.static final String
If in the header, denotes the file has peeled data.(package private) final AtomicReference
<RefDirectory.PackedRefList> Immutable sorted list of packed references.(package private) final File
private final FileRepository
(package private) final File
static final String
Magic string denoting the start of a symbolic reference file.Fields inherited from class org.eclipse.jgit.lib.RefDatabase
ALL, MAX_SYMBOLIC_REF_DEPTH, SEARCH_PATH
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate void
void
close()
Close any resources held by this database.(package private) RefDirectory.PackedRefList
commitPackedRefs
(LockFile lck, RefList<Ref> refs, RefDirectory.PackedRefList oldPackedList, boolean changed) private static String
void
create()
Initialize a new reference database at this location.(package private) static void
private static void
(package private) void
delete
(RefDirectoryUpdate update) private ObjectIdRef
Read a single reference.Read the specified references.(package private) File
Locate the file on disk for a single reference name.(package private) void
If the parent should fire listeners, fires them.firstExactRef
(String... refs) Find the first named reference.Get the additional reference-like entities from the repository.private RefList
<RefDirectory.LooseRef> (package private) RefDirectory.PackedRefList
Get a section of the reference namespace.(package private) Repository
Get times to sleep while retrying a possibly contentious operation.private boolean
private boolean
(package private) boolean
Detect if we are in a clone command executionboolean
isNameConflicting
(String name) Determine if a proposed reference name overlaps with an existing one.private static boolean
isSymRef
(byte[] buf, int n) (package private) static int
(package private) LockFile
private LockFile
(package private) void
Locate the log file on disk for a single reference name.Create a new batch update to attempt on this database.(package private) ReflogWriter
newLogWriter
(boolean force) Create a new update command to rename a reference.private static RefDirectory.LooseSymbolicRef
newSymbolicRef
(FileSnapshot snapshot, String name, String target) (package private) RefDirectoryUpdate
Create a reference update to write a temporary reference.Create a new update command to create, modify or delete a reference.private RefDirectory.PackedRefList
void
Adds a set of refs to the set of packed-refs.(package private) RefDirectory.PackedRefList
Peel a possibly unpeeled reference by traversing the annotated tags.private Ref
Make sure a ref is peeled and has the Storage PACKED.boolean
Whether the database is capable of performing batch updates as atomic transactions.private void
private Ref
readAndResolve
(String name, RefList<Ref> packed) private RefDirectory.PackedRefList
private Ref
private static Ref
recreate
(Ref old, ObjectIdRef leaf) void
refresh()
Triggers a refresh of all internal data structures.private Ref
resolve
(Ref ref, int depth, String prefix, RefList<RefDirectory.LooseRef> loose, RefList<Ref> packed) (package private) RefDirectory.LooseRef
scanRef
(RefDirectory.LooseRef ref, String name) (package private) void
setRetrySleepMs
(List<Integer> retrySleepMs) (package private) static void
sleep
(long ms) (package private) void
stored
(RefDirectoryUpdate update, FileSnapshot snapshot) (package private) void
storedSymbolicRef
(RefDirectoryUpdate u, FileSnapshot snapshot, String target) Methods inherited from class org.eclipse.jgit.lib.RefDatabase
findRef, findRef, getConflictingNames, getRef, getRefs, getRefsByPrefix, getRefsByPrefix, getRefsByPrefixWithExclusions, getTipsWithSha1, hasFastTipsWithSha1, hasRefs, hasVersioning
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Field Details
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LOG
private static final org.slf4j.Logger LOG -
SYMREF
Magic string denoting the start of a symbolic reference file.- See Also:
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PACKED_REFS_HEADER
Magic string denoting the header of a packed-refs file.- See Also:
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PACKED_REFS_PEELED
If in the header, denotes the file has peeled data.- See Also:
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additionalRefsNames
The names of the additional refs supported by this class -
RETRY_SLEEP_MS
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parent
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gitDir
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refsDir
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packedRefsFile
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logsDir
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logsRefsDir
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looseRefs
Immutable sorted list of loose references.Symbolic references in this collection are stored unresolved, that is their target appears to be a new reference with no ObjectId. These are converted into resolved references during a get operation, ensuring the live value is always returned.
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packedRefs
Immutable sorted list of packed references. -
inProcessPackedRefsLock
Lock for coordinating operations within a single process that may contend on thepacked-refs
file.All operations that write
packed-refs
must still acquire aLockFile
onpackedRefsFile
, even after they have acquired this lock, since there may be multipleRefDirectory
instances or other processes operating on the same repo on disk.This lock exists so multiple threads in the same process can wait in a fair queue without trying, failing, and retrying to acquire the on-disk lock. If
RepositoryCache
is used, this lock instance will be used by all threads. -
modCnt
Number of modifications made to this database.This counter is incremented when a change is made, or detected from the filesystem during a read operation.
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lastNotifiedModCnt
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retrySleepMs
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NO_PACKED_REFS
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Constructor Details
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RefDirectory
RefDirectory(FileRepository db)
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Method Details
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getRepository
Repository getRepository() -
newLogWriter
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logFor
Locate the log file on disk for a single reference name.- Parameters:
name
- name of the ref, relative to the Git repository top level directory (so typically starts with refs/).- Returns:
- the log file location.
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create
Initialize a new reference database at this location.- Specified by:
create
in classRefDatabase
- Throws:
IOException
- the database could not be created.
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close
public void close()Close any resources held by this database.- Specified by:
close
in classRefDatabase
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clearReferences
private void clearReferences() -
refresh
public void refresh()Triggers a refresh of all internal data structures.In case the RefDatabase implementation has internal caches this method will trigger that all these caches are cleared.
Implementors should overwrite this method if they use any kind of caches.
- Overrides:
refresh
in classRefDatabase
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isNameConflicting
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.
- Specified by:
isNameConflicting
in classRefDatabase
- Parameters:
name
- 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:
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getLooseRefs
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readAndResolve
- Throws:
IOException
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exactRef
Read a single reference.Unlike
RefDatabase.findRef(java.lang.String)
, this method expects an unshortened reference name and does not search using the standardRefDatabase.SEARCH_PATH
.- Specified by:
exactRef
in classRefDatabase
- Parameters:
name
- the unabbreviated name of the reference.- Returns:
- the reference (if it exists); else
null
. - Throws:
IOException
- the reference space cannot be accessed.
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exactRef
Read the specified references.This method expects a list of unshortened reference names and returns a map from reference names to refs. Any named references that do not exist will not be included in the returned map.
- Overrides:
exactRef
in classRefDatabase
- Parameters:
refs
- the unabbreviated names of references to look up.- Returns:
- modifiable map describing any refs that exist among the ref ref names supplied. The map can be an unsorted map.
- Throws:
IOException
- the reference space cannot be accessed.
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firstExactRef
Find the first named reference.This method expects a list of unshortened reference names and returns the first that exists.
- Overrides:
firstExactRef
in classRefDatabase
- Parameters:
refs
- the unabbreviated names of references to look up.- Returns:
- the first named reference that exists (if any); else
null
. - Throws:
IOException
- the reference space cannot be accessed.
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getRefs
Get a section of the reference namespace.- Specified by:
getRefs
in classRefDatabase
- 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.
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getAdditionalRefs
Get the additional reference-like entities from the repository.The result list includes non-ref items such as MERGE_HEAD and FETCH_RESULT cast to be refs. The names of these refs are not returned by
getRefs()
but are accepted byRefDatabase.findRef(String)
andRefDatabase.exactRef(String)
.- Specified by:
getAdditionalRefs
in classRefDatabase
- Returns:
- a list of additional refs
- Throws:
IOException
- the reference space cannot be accessed.
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upcast
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peel
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.- Specified by:
peel
in classRefDatabase
- Parameters:
ref
- The reference to peel- Returns:
ref
ifref.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 (ornull
).- Throws:
IOException
- the reference space or object space cannot be accessed.
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doPeel
- Throws:
MissingObjectException
IOException
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recreate
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storedSymbolicRef
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newUpdate
Create a new update command to create, modify or delete a reference.- Specified by:
newUpdate
in classRefDatabase
- Parameters:
name
- the name of the reference.detach
- iftrue
andname
is currently aSymbolicRef
, the update will replace it with anObjectIdRef
. Otherwise, the update will recursively traverseSymbolicRef
s and operate on the leafObjectIdRef
.- Returns:
- a new update for the requested name; never null.
- Throws:
IOException
- the reference space cannot be accessed.
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newRename
Create a new update command to rename a reference.- Specified by:
newRename
in classRefDatabase
- Parameters:
fromName
- name of reference to rename fromtoName
- name of reference to rename to- Returns:
- an update command that knows how to rename a branch to another.
- Throws:
IOException
- the reference space cannot be accessed.
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newBatchUpdate
Create a new batch update to attempt on this database.The default implementation performs a sequential update of each command.
- Overrides:
newBatchUpdate
in classRefDatabase
- Returns:
- a new batch update object.
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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 callingupdate.setAtomic(false)
.If false,
BatchRefUpdate
instances will never perform updates atomically, and callingupdate.setAtomic(true)
will cause the entire batch to fail withREJECTED_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 classRefDatabase
- Returns:
- whether transactions are atomic by default.
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stored
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putLooseRef
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delete
- Throws:
IOException
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pack
Adds a set of refs to the set of packed-refs. Only non-symbolic refs are added. If a ref with the given name already existed in packed-refs it is updated with the new value. Each loose ref which was added to the packed-ref file is deleted. If a given ref can't be locked it will not be added to the pack file.- Parameters:
refs
- the refs to be added. Must be fully qualified.- Throws:
IOException
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pack
- Throws:
IOException
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pack
private RefDirectory.PackedRefList pack(Collection<String> refs, Map<String, LockFile> heldLocks) throws IOException- Throws:
IOException
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lockPackedRefs
- Throws:
IOException
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lockPackedRefsOrThrow
- Throws:
IOException
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peeledPackedRef
Make sure a ref is peeled and has the Storage PACKED. If the given ref has this attributes simply return it. Otherwise create a new peeledObjectIdRef
where Storage is set to PACKED.- Parameters:
f
-- Returns:
- a ref for Storage PACKED having the same name, id, peeledId as f
- Throws:
MissingObjectException
IOException
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log
- Throws:
IOException
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resolve
private Ref resolve(Ref ref, int depth, String prefix, RefList<RefDirectory.LooseRef> loose, RefList<Ref> packed) throws IOException - Throws:
IOException
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getPackedRefs
- Throws:
IOException
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readPackedRefs
- Throws:
IOException
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parsePackedRefs
- Throws:
IOException
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copy
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commitPackedRefs
RefDirectory.PackedRefList commitPackedRefs(LockFile lck, RefList<Ref> refs, RefDirectory.PackedRefList oldPackedList, boolean changed) throws IOException - Throws:
IOException
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readRef
- Throws:
IOException
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scanRef
- Throws:
IOException
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isSymRef
private static boolean isSymRef(byte[] buf, int n) -
isInClone
Detect if we are in a clone command execution- Returns:
true
if we are currently cloning a repository- Throws:
IOException
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hasDanglingHead
- Throws:
IOException
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hasLooseRef
- Throws:
IOException
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fireRefsChanged
void fireRefsChanged()If the parent should fire listeners, fires them. -
newTemporaryUpdate
Create a reference update to write a temporary reference.- Returns:
- an update for a new temporary reference.
- Throws:
IOException
- a temporary name cannot be allocated.
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fileFor
Locate the file on disk for a single reference name.- Parameters:
name
- name of the ref, relative to the Git repository top level directory (so typically starts with refs/).- Returns:
- the loose file location.
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levelsIn
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delete
- Throws:
IOException
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delete
- Throws:
IOException
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getRetrySleepMs
Get times to sleep while retrying a possibly contentious operation.For retrying an operation that might have high contention, such as locking the
packed-refs
file, the caller may implement a retry loop using the returned values:for (int toSleepMs : getRetrySleepMs()) { sleep(toSleepMs); if (isSuccessful(doSomething())) { return success; } } return failure;
The first value in the returned iterable is 0, and the caller should treat a fully-consumed iterator as a timeout.- Returns:
- iterable of times, in milliseconds, that the caller should sleep before attempting an operation.
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setRetrySleepMs
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sleep
- Parameters:
ms
- time to sleep, in milliseconds; zero or negative is a no-op.- Throws:
InterruptedIOException
- if sleeping was interrupted.
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newSymbolicRef
private static RefDirectory.LooseSymbolicRef newSymbolicRef(FileSnapshot snapshot, String name, String target)
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