We no longer need an ObjectLoader to be lazy and try to delay
the materialization of the object content. That was done only
to support PackWriter searching for a good reuse candidate.
Instead, simplify the code base by doing the materialization
immediately when the loader asks for it, because any caller
asking for the loader is going to need the content.
Change-Id: Id867b1004529744f234ab8f9cfab3d2c52ca3bd0
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These were only used by PackWriter to help it filter object
representations. Their only user disappeared when we rewrote the
object selection code path to use the new representation type.
Change-Id: I9ed676bfe4f87fcf94aa21e53bda43115912e145
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This move isolates all of the local file specific implementation code
into a single package, where their package-private methods and support
classes are properly hidden away from the rest of the core library.
Because of the sheer number of files impacted, I have limited this
change to only the renames and the updated imports.
Change-Id: Icca4884e1a418f83f8b617d0c4c78b73d8a4bd17
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Only the ObjectDirectory type of database knows where to find the
objects directory on the local filesystem, so defer to it whenever
we need to know where the objects reside. Since this is the type
returned by FileRepository's getObjectDatabase() method, we mostly
don't have to do much other than use a slightly longer invocation.
Change-Id: Ie5f58132a6411b56c3acad73646ad169d78a0654
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This better matches with the name used in the environment
(GIT_WORK_TREE), in the configuration file (core.worktree),
and in our builder object.
Since we are already breaking a good chunk of other code
related to repository access, and this fairly easy to fix
in an application's code base, I'm not going to offer the
wrapper getWorkDir() method.
Change-Id: Ib698ba4bbc213c48114f342378cecfe377e37bb7
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The new FileRepositoryBuilder class helps applications to construct
a properly configured FileRepository, with properties assumed based
upon the standard Git rules for the local filesystem.
To better support simple command line applications, environment
variable handling and repository searching was moved into this
builder class.
The change gets rid of the ever-growing FileRepository constructor
variants, and the multitude of java.io.File typed parameters,
by using simple named setter methods.
Change-Id: I17e8e0392ad1dbf6a90a7eb49a6d809388d27e4c
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Not every type of Repository will be able to map an ObjectId into
a local file system path that stores that object's file contents.
Heck, its not even true for the FileRepository, as an object can
be stored in a pack file and not in its loose format.
Remove this from our public API, it was a mistake to publish it.
Change-Id: I20d1b8c39104023936e6d46a5b0d7ef39ff118e8
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The WindowCache is an implementation detail of PackFile and how its
used by ObjectDirectory. Lets start to hide it and replace the public
API with a more generic concept, ObjectReader.
Because PackedObjectLoader is also considered a private detail of
PackFile, we have to make PackWriter temporarily dependent upon the
WindowCursor and thus FileRepository and ObjectDirectory in order to
just start the refactoring. In later changes we will clean up the
APIs more, exposing sufficient support to PackWriter without needing
the file specific implementation details.
Change-Id: I676be12b57f3534f1285854ee5de1aa483895398
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Some newer style APIs are updated to use the newer ObjectInserter
interface instead of the now deprecated ObjectWriter. In many of
the unit tests we don't bother to release the inserter, these are
typically using the file backend which doesn't need a release,
but in the future should use an in-memory HashMap based store,
which really wouldn't need it either.
Change-Id: I91a15e1dc42da68e6715397814e30fbd87fa2e73
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The ObjectInserter API permits ObjectDatabase implementations to
control their own object insertion behavior, rather than forcing
it to always be a new loose file created in the local filesystem.
Inserted objects can also be queued and written asynchronously to
the main application, such as by appending into a pack file that
is later closed and added to the repository.
This change also starts to open the door to non-file based object
storage, such as an in-memory HashMap for unit testing, or a more
complex system built on top of a distributed hash table.
To help existing application code port to the newer interface we
are keeping ObjectWriter as a delegation wrapper to the new API.
Each ObjectWriter instances holds a reference to an ObjectInserter
for the Repository's top-level ObjectDatabase, and it flushes and
releases that instance on each object processed.
Change-Id: I413224fb95563e7330c82748deb0aada4e0d6ace
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
When the surrounding code is already heavily based upon the
assumption that we have a FileRepository (e.g. because it
created that type of repository) keep the type around and
use it directly. This permits us to continue to do things
like save the configuration file.
Change-Id: Ib783f0f6a11acd6aa305c16d61ccc368b46beecc
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
To support other storage models other than just the local filesystem,
we split the Repository class into a nearly abstract interface and
then create a concrete subclass called FileRepository with the file
based IO implementation.
We are using an abstract class for Repository rather than the much
more generic interface, as implementers will want to inherit a large
array of utility functions, such as resolve(String). Having these in
a base class makes it easy to inherit them.
This isn't the final home for lib.FileRepository. Future changes
will rename it into storage.file.FileRepository, but to do that we
need to also move a number of other related class, which we aren't
quite ready to do.
Change-Id: I1bd54ea0500337799a8e792874c272eb14d555f7
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Rather than relying on the helpers in RepositoryConfig to get
these objects, obtain them directly through the Config API.
Its only slightly more verbose, but permits us to work with the
base Config class, which is more flexible than the highly file
specific RepositoryConfig.
This is what I really meant to do when I added the section parser
and caching support to Config, we just failed to finish updating
all of the call sites.
Change-Id: I481cb365aa00bfa8c21e5ad0cd367ddd9c6c0edd
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We don't have to assume/depend on RepositoryConfig here, these
two tests can use higher level versions of the class and still
come up with the same test. That frees us up to do some changes
to the RepositoryConfig API.
Change-Id: Ia7b263c8c5efa3fae1054416d39c546867288132
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Long ago we stopped supporting the core.legacyHeaders variable,
as JGit (like C Git) stopped creating the new pack-style loose
objects, rendering this variable pointless. The test is still
valid, it proves we write the standard loose object format for
a commit, but the variable assignment has no impact on the test
so drop it from the code.
Change-Id: I051336ada23033c05e86bbff73ae5d78a37b1640
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This stream was used only to determine how many bytes had been
written thus far. Except we're always dumping it into a simple
ByteArrayOutputStream, which also knows that. Drop the dependency
on the pack stream and use ByteArrayOutputStream directly.
This lets us later move this test into the new storage.file
package without dragging along the pack stream that is an internal
implementation detail of PackWriter, which is more general than
just the file storage layer.
Change-Id: I291689c0b1ed799270c213ee73b710b2637fb238
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Setting this value is pointless, because its automatically set
by the refs.newUpdate call that created the update operation.
The API is protected by default, because application level code,
including this test, should not be calling it.
Change-Id: I8867a4e8007892e2bd44a05d7dec619081081943
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If a repository is "bare", it currently still returns a working directory.
This conflicts with the specification of "bare"-ness.
Bug: 311902
Change-Id: Ib54b31ddc80b9032e6e7bf013948bb83e12cfd88
Signed-off-by: Mathias Kinzler <mathias.kinzler@sap.com>
Currently, there is no way to read the content
of the Git Configuration in a way that would
allow to list all configured values generically.
This change extends the Config class in such a
way as to being able to get a list of sections and
to get a list of names for any given section or
subsection.
This is required in able to implement proper
configuration handling in EGit (show all the
content of a given configuration similar to
"git config -l").
Change-Id: Idd4bc47be18ed0e36b11be8c23c9c707159dc830
Signed-off-by: Mathias Kinzler <mathias.kinzler@sap.com>
On Windows, FS_Win32_Cygwin has been used if a Cygwin Git installation
is present in the PATH. Assuming that the user works with the Cygwin
Git installation may result in unnecessary overhead if he actually
does not.
Applications built on top of jgit may have more knowledge on the
actually used Git client (Cygwin or not) and hence should be able to
configure which FS to use accordingly.
Change-Id: Ifc4278078b298781d55cf5421e9647a21fa5db24
A Change-Id helps tools like Gerrit Code Review to keeps different
versions of a patch together. The Change-Id is computed as a SHA-1
hash of some of the same basic information as a commit id on the first
commit intended to solve a particular problem and then reused for
updated solutions.
Change-Id: I04334f84e76e83a4185283cb72ea0308b1cb4182
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
ReadTreeTest contains a lot of useful tests for "checkout"
implementations. But ReadTreeTest was hardcoded to test only
WorkDirCheckout. This change doesn't add/modify any tests semantically
but refactors ReadTreeTest so that a different implementations of
checkout can be tested. This was done to allow DirCacheCheckout to be
tested without rewriting all these tests.
Change-Id: I36e34264482b855ed22c9dde98824f573cf8ae22
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Merges the current head with one other commit.
In this first iteration the merge command supports
only fast forward and already up-to-date.
Change-Id: I0db480f061e01b343570cf7da02cac13a0cbdf8f
Signed-off-by: Stefan Lay <stefan.lay@sap.com>
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>
The CommitCommand should take care to create a merge commit if the file
$GIT_DIR/MERGE_HEAD exists. It should then read the parents for the merge
commit out of this file. It should also take care that when commiting
a merge and no commit message was specified to read the message from
$GIT_DIR/MERGE_MSG.
Finally the CommitCommand should remove these files if the commit
succeeded.
Change-Id: I4e292115085099d5b86546d2021680cb1454266c
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
The strings are externalized into the root resource bundles.
The resource bundles are stored under the new "resources" source
folder to get proper maven build.
Strings from tests are, in general, not externalized. Only in
cases where it was necessary to make the test pass the strings
were externalized. This was typically necessary in cases where
e.getMessage() was used in assert and the exception message was
slightly changed due to reuse of the externalized strings.
Change-Id: Ic0f29c80b9a54fcec8320d8539a3e112852a1f7b
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>
Rather than keep track of both the position of the object, and the
position of its data, just keep track of the number of bytes used
by the object's header in the pack. This shaves 4 bytes out of the
size of the PackedObjectLoader instances.
We also can defer the addition instruction to the materialize()
operation, avoiding it entirely if the caller never actually uses
the loader. This may be relevant for PackWriter invocations,
where only 1 loader gets chosen for a given object, even though
the object may appear on disk in more than one pack file.
Error reporting is now simplified, as we can rely on the object
offset rather than its data offset. This is the value displayed
by pack debugging tools like `git verify-pack -v`, so its better
to use that in our own errors.
Because nobody needs getDataOffset() now, we can drop that from
the public API.
Change-Id: Ic639c0d5a722315f4f5c8ffda6e26643d90e5f42
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Added a new package org.eclipse.jgit.api and a builder-style API for
jgit. Added also the first implementation for two git commands: Commit
and Log.
This API is intended to be used by external components when
functionalities of the standard git commands are required. It will also
help to ease writing JGit tests.
For internal usages this API may often not be optimal because the git
commands are doing much more than required or they expect parameters of
an unappropriate type.
Change-Id: I71ac4839ab9d2f848307eba9252090c586b4146b
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
The repository state tells in which state the repo is and also which actions
are currently allowed. The state MERGING is telling that a commit is not
possible. But this is only true in the case of unmerged paths in the index.
When we are merging but have resolved all conflicts then we are in a special
state: We are still merging (means the next commit should have multiple
parents) but a commit is now allowed.
Since the MERGING state "canCommit()" cannot be enhanced to return true/false
based on the index state (MERGING is an enum value which does not have a
reference to the repository its state it is representing) I had to introduce a new
state MERGING_RESOLVED. This new state will report that a commit is possible.
CAUTION: there might be the chance that users of jgit previously blindly did a
plain commit (with only one parent) when the RepositoryState allowed them to
do so. With this change these users will now be confronted with a RepositoryState
which says a commit is possible but before they can commit they'll have to
check the MERGE_MESSAGE and MERGE_HEAD files and use the info from these
files.
Change-Id: I0a885e2fe8c85049fb23722351ab89cf2c81a431
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
If two keys are the same length, but don't share the same sequence
of characters, we were incorrectly claiming they still matched due
to a bug in the for loop condition. I used the wrong variable and
the loop never executed, resulting in equality anytime the two keys
being compared were the same length.
Use the proper local variable to loop through the arrays, and add
a JUnit test to verify equality works as expected.
Change-Id: I4a02400e65a9b2e0da925b05a2cc4b579e1dd33a
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The pack files were left open after the test ended, which meant
we could not delete them automatically when the test was over.
Make sure we close the repositories (and thus their underlying packs)
before the tear down finishes.
Bug: 310367
Change-Id: I4d2703efa4b2e0c347ea4f4475777899cf71073e
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This option was mis-named from day 1. Its not checking that the
objects provided by the client are reachable, its actually doing
a scan to prove that objects referenced by the client are already
reachable through another reference on the server, or were sent
as part of the pack from the client.
Rename it checkReferencedObjectsAreReachable, since we really are
trying to validate that objects referenced by the client's actions
are reachable to the client.
We also need to ensure we run checkConnectivity() anytime this is
enabled, even if the caller didn't turn on fsck for object formats.
Otherwise the check would be completely bypassed.
Change-Id: Ic352ddb0ca8464d407c6da5c83573093e018af19
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If ensureProvidedObjectsVisible is enabled we expected any trees or
blobs directly reachable from an advertised reference to be marked
with UNINTERESTING. Unfortunately ObjectWalk doesn't bother setting
this until the traversal is complete. Even then it won't necessarily
set it on every tree if the corresponding commit wasn't popped.
When we are going to check the base objects for the received pack,
ensure the UNINTERESTING flag gets carried into every immediately
reachable tree or blob, because these are the ones that the client
might try to use as delta bases in a thin pack.
Change-Id: I5d5fdcf07e25ac9fc360e79a25dff491925e4101
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If we need to append less than 20 bytes in order to fix a thin pack
and make it complete, we need to set the length of our file back to
the actual number of bytes used because the original SHA-1 footer was
not completely overwritten. That extra data will confuse the header
and footer fixup logic when it tries to read to the end of the file.
This isn't a very common case to occur, which is why we've never
seen it before. Getting a delta that requires a whole object which
uses less than 20 bytes in pack representation is really hard.
Generally a delta generator won't make these, because the delta
would be bigger than simply deflating the whole object. I only
managed to do this with a hand-crafted pack file where a 1 byte
delta was pointed to a 1 byte whole object.
Normally we try really hard to avoid truncating, because its
typically not safe across network filesystems. But the odds of
this occurring are very low. This truncation is done on a file
we have open for writing, will append more content onto, and is
a temporary file that we won't move into position for others to
see until we've validated its SHA-1 is sane. I don't think the
truncate on NFS issue is something we need to worry about here.
Change-Id: I102b9637dfd048dc833c050890d142f43c1e75ae
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Some transports actually provide stream buffering on their own,
without needing to be wrapped up inside of a BufferedInputStream in
order to smooth out system calls to read or write. A great example
of this is the JSch SSH client, or the Apache MINA SSHD server.
Both use custom buffering to packetize the streams into the encrypted
SSH channel, and wrapping them up inside of a BufferedInputStream
or BufferedOutputStream is relatively pointless.
Our SideBandOutputStream implementation also provides some fairly
large buffering, equal to one complete side-band packet on the main
data channel. Wrapping that inside of a BufferedOutputStream just to
smooth out small writes from PackWriter causes extra data copies, and
provides no advantage. We can save some memory and some CPU cycles
by letting PackWriter dump directly into the SideBandOutputStream's
internal buffer array.
Instead we push the buffering streams down to be as close to the
network socket (or operating system pipe) as possible. This allows
us to smooth out the smaller reads/writes from pkt-line messages
during advertisement and negotation, but avoid copying altogether
when the stream switches to larger writes over a side band channel.
Change-Id: I2f6f16caee64783c77d3dd1b2a41b3cc0c64c159
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Instead of relying on our callers to wrap us up inside of a
BufferedOutputStream and using the proper block sizing, do the
buffering directly inside of SideBandOutputStream. This ensures
we don't get large write-throughs from BufferedOutputStream that
might overflow the configured packet size.
The constructor of SideBandOutputStream is also beefed up to check
its arguments and ensure they are within acceptable ranges for the
current side-band protocol.
Change-Id: Ic14567327d03c9e972f9734b8228178bc448867d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The tests were using a Locale.ROOT constant which was introduced
in Java 6. However, we need to retain Java 5 support.
Change-Id: I75c5648fcfc728a9aea2e839d2ad0320f5cf742f
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Sasa Zivkov <sasa.zivkov@sap.com>
The support for NLS relies on java.util API to load a standard
ResourceBundle and then uses java reflection API to inject localized
strings into public String fields of the corresponding instance
of TranslationBundle.
Locale setting is supported per thread to enable concurrent threads
to use different locales. This is useful when JGit runs in a server
context where (error) messages might need to differ per-request to
suit the user's preference.
Change-Id: Ie0e63a0d7bb74eaad495dbe8248595d8a3a76883
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>
If the build server is really busy, we might wait longer than 250 ms
before being interrupted, simply because one of our threads couldn't
be scheduled onto a CPU. Don't make that cause a test failure.
Instead tolerate longer than expected waits, but not shorter waits.
Change-Id: I64511eec24b49e33928451e4c8b8c124eddaf0c2
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
A 0 file mode in a DirCacheEntry is not a valid mode. To C git
such a value indicates the record should not be present. We already
were catching this bad state and exceptioning out when writing tree
objects to disk, but we did not fail when writing the dircache back
to disk. This allowed JGit applications to create a dircache file
which C git would not like to read.
Instead of checking the mode during writes, we now check during
mutation. This allows application bugs to be detected sooner and
closer to the cause site. It also allows us to avoid checking most
of the records which we read in from disk, as we can assume these
are formatted correctly.
Some of our unit tests were not setting the FileMode on their test
entry, so they had to be updated to use REGULAR_FILE.
Change-Id: Ie412053c390b737c0ece57b8e063e4355ee32437
Originally: http://thread.gmane.org/gmane.comp.version-control.git/128214/focus=128213
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Adam W. Hawks <awhawks@writeme.com>
The supplied test case comes out of the example tree identified by
Robert de Wilde and Ilari on #git:
$ git ls-tree -rt a54f1a85ebf6a7f53aa60a45a1be33f8b078fb7e
040000 tree bfe058ad536cdb12e127cde63b01472c960ea105 A
040000 tree 4b825dc642 A/A
040000 tree 4b825dc642 A/B
100644 blob abbbfafe3129f85747aba7bfac992af77134c607 B
In this tree, "B" was being skipped because "A/A" as an empty tree
was immediately followed by "A/B", also an empty tree, but the
ObjectWalk broke out too early and never visited "B".
Bug: 286653
Change-Id: I25bcb0bc99d0cbbbdd9c2bd625ad6a691a6d0335
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We didn't skip the correct number of bytes when we skipped over an
unrecognized but optional dircache extension. We missed skipping
the 8 byte header that makes up the extension's name and length.
We also didn't include the skipped extension's payload as part of
our index checksum, resuting in a checksum failure when the index
was done reading. So ensure we always scan through a skipped
section and include it in the checksum computation.
Add a test case for a currently unsupported index extension, 'ZZZZ',
to verify we can still read the DirCache object even though we
don't know what 'ZZZZ' is supposed to mean.
Bug: 301287
Change-Id: I4bdde94576fffe826d0782483fd98cab1ea628fa
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This test doesn't actually depend upon the large data set we have
in the RepositoryTestCase, so drop that from the dependency and
use the more simple LocalDiskRepositoryTestCase instead.
Change-Id: I0fd4affe1dd5ec86e8c3253db42df11d3b612e36
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The unsetSection method can be used to delete an entire configuration
block, such as a [branch ""] or [remote ""] section in a file.
Change-Id: I93390c9b2187eb1b0d51353518feaed83bed2aad
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
Config was confusing the following two variables when writing the
file back to text format:
[my]
empty =
enabled
When parsed, we say that my.empty has 1 value, null, and my.enabled
is an empty string value that in boolean context should be evaluated
as true.
Saving this configuration file back to text format was ignoring the
null value for my.empty, producing a completely different file than
what Config read:
[my]
empty
enabled
Instead handle the writing differently to ensure the original format
is output. New tests cases cover the expected behavior and return
values from accessor methods.
Change-Id: Id37379ce20cb27e3330923cf989444dd9f2bdd96
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Annotated tags created with C Git versions before the introduction
of c818566 ([PATCH] Update tags to record who made them, 2005-07-14),
do not have a "tagger" line present in the object header. This line
did not appear in C Git until v0.99.1~9.
Ancient projects such as the Linux kernel contain such tags, for
example Linux 2.6.12 is older than when this feature first appeared
in C Git. Linux v2.6.13-rc4 in late July 2005 is the first kernel
version tag to actually contain a tagger line.
It is therefore acceptable for the header to be missing, and for
the RevTag.getTaggerIdent() method to return null.
Since the Javadoc for getTaggerIdent() already explained that the
identity may be null, we just need to test that this is true when
the header is missing, and allow the ObjectChecker to pass anyway.
Change-Id: I34ba82e0624a0d1a7edcf62ffba72260af6f7e5d
See: http://code.google.com/p/gerrit/issues/detail?id=399
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
By using RefUpdate for symbolic reference creation we can reuse
the logic related to updating the reflog with the event, without
needing to expose something such as the legacy ReflogWriter class
(which we no longer have).
Applications using writeSymref must update their code to use the
new pattern of changing the reference through the updateRef method:
String refName = "refs/heads/master";
RefUpdate u = repository.updateRef(Constants.HEAD);
u.setRefLogMessage("checkout: moving to " + refName, false);
switch (u.link(refName)) {
case NEW:
case FORCED:
case NO_CHANGE:
// A successful update of the reference
break;
default:
// Handle the failure, e.g. for older behavior
throw new IOException(u.getResult());
}
Change-Id: I1093e1ec2970147978a786cfdd0a75d0aebf8010
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This commit actually does three major changes to the way references
are handled within JGit. Unfortunately they were easier to do as
a single massive commit than to break them up into smaller units.
Disambiguate symbolic references:
---------------------------------
Reporting a symbolic reference such as HEAD as though it were
any other normal reference like refs/heads/master causes subtle
programming errors. We have been bitten by this error on several
occasions, as have some downstream applications written by myself.
Instead of reporting HEAD as a reference whose name differs from
its "original name", report it as an actual SymbolicRef object
that the application can test the type and examine the target of.
With this change, Ref is now an abstract type with different
subclasses for the different types.
In the classical example of "HEAD" being a symbolic reference to
branch "refs/heads/master", the Repository.getAllRefs() method
will now return:
Map<String, Ref> all = repository.getAllRefs();
SymbolicRef HEAD = (SymbolicRef) all.get("HEAD");
ObjectIdRef master = (ObjectIdRef) all.get("refs/heads/master");
assertSame(master, HEAD.getTarget());
assertSame(master.getObjectId(), HEAD.getObjectId());
assertEquals("HEAD", HEAD.getName());
assertEquals("refs/heads/master", master.getName());
A nice side-effect of this change is the storage type of the
symbolic reference is no longer ambiguous with the storge type
of the underlying reference it targets. In the above example,
if master was only available in the packed-refs file, then the
following is also true:
assertSame(Ref.Storage.LOOSE, HEAD.getStorage());
assertSame(Ref.Storage.PACKED, master.getStorage());
(Prior to this change we returned the ambiguous storage of
LOOSE_PACKED for HEAD, which was confusing since it wasn't
actually true on disk).
Another nice side-effect of this change is all intermediate
symbolic references are preserved, and are therefore visible
to the application when they walk the target chain. We can
now correctly inspect chains of symbolic references.
As a result of this change the Ref.getOrigName() method has been
removed from the API. Applications should identify a symbolic
reference by testing for isSymbolic() and not by using an arcane
string comparsion between properties.
Abstract the RefDatabase storage:
---------------------------------
RefDatabase is now abstract, similar to ObjectDatabase, and a
new concrete implementation called RefDirectory is used for the
traditional on-disk storage layout. In the future we plan to
support additional implementations, such as a pure in-memory
RefDatabase for unit testing purposes.
Optimize RefDirectory:
----------------------
The implementation of the in-memory reference cache, reading, and
update routines has been completely rewritten. Much of the code
was heavily borrowed or cribbed from the prior implementation,
so copyright notices have been left intact as much as possible.
The RefDirectory cache no longer confuses symbolic references
with normal references. This permits the cache to resolve the
value of a symbolic reference as late as possible, ensuring it
is always current, without needing to maintain reverse pointers.
The cache is now 2 sorted RefLists, rather than 3 HashMaps.
Using sorted lists allows the implementation to reduce the
in-memory footprint when storing many refs. Using specialized
types for the elements allows the code to avoid additional map
lookups for auxiliary stat information.
To improve scan time during getRefs(), the lists are returned via
a copy-on-write contract. Most callers of getRefs() do not modify
the returned collections, so the copy-on-write semantics improves
access on repositories with a large number of packed references.
Iterator traversals of the returned Map<String,Ref> are performed
using a simple merge-join of the two cache lists, ensuring we can
perform the entire traversal in linear time as a function of the
number of references: O(PackedRefs + LooseRefs).
Scans of the loose reference space to update the cache run in
O(LooseRefs log LooseRefs) time, as the directory contents
are sorted before being merged against the in-memory cache.
Since the majority of stable references are kept packed, there
typically are only a handful of reference names to be sorted,
so the sorting cost should not be very high.
Locking is reduced during getRefs() by taking advantage of the
copy-on-write semantics of the improved cache data structure.
This permits concurrent readers to pull back references without
blocking each other. If there is contention updating the cache
during a scan, one or more updates are simply skipped and will
get picked up again in a future scan.
Writing to the $GIT_DIR/packed-refs during reference delete is
now fully atomic. The file is locked, reparsed fresh, and written
back out if a change is necessary. This avoids all race conditions
with concurrent external updates of the packed-refs file.
The RefLogWriter class has been fully folded into RefDirectory
and is therefore deleted. Maintaining the reference's log is
the responsiblity of the database implementation, and not all
implementations will use java.io for access.
Future work still remains to be done to abstract the ReflogReader
class away from local disk IO.
Change-Id: I26b9287c45a4b2d2be35ba2849daa316f5eec85d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
These types can be used by RefDatabase implementations to manage
the collection.
A RefList stores items sorted by their name, and is an immutable
type using copy-on-write semantics to perform modifications to
the collection. Binary search is used to locate an existing item
by name, or to locate the proper insertion position if an item does
not exist.
A RefMap can merge up to 3 RefList collections at once during its
entry iteration, allowing items in the resolved or loose RefList
to override items by the same name in the packed RefList.
The RefMap's goal is O(log N) lookup time, and O(N) iteration time,
which is suitable for returning from a RefDatabase. By relying on
the immutable RefList we might be able to make map construction
nearly constant, making Repository.getAllRefs() an inexpensive
operation if the caches are current. Since modification is not
common, changes require up to O(N + log N) time to copy the internal
list and collapse or expand the list's array. As most changes
are made to the loose collection and not the packed collection,
in practice most changes would require less than the full O(N)
time, due to a significantly smaller N in the loose list.
Almost complete test coverage is included in the corresponding
unit tests. A handful of methods on RefMap are not tested in this
change, as writing the proper test depends on a future refactoring
of how the Ref class represents symbolic reference names.
Change-Id: Ic2095274000336556f719edd75a5c5dd6dd1d857
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Shawn O. Pearce
Mathias Kinzler
Marc Strapetz
Robin Rosenberg
Christian Halstrick
Stefan Lay
Sasa Zivkov