Because fast-import automatically updates all references (heads
and tags) at the end of its run the repository is corrupt unless
the objects are available in the .git/objects/pack directory prior
to the refs being modified. The easiest way to ensure that is true
is to move the packfile and its associated index directly into the
.git/objects/pack directory as soon as we have finished output to it.
But the only safe way to do this is to create the a temporary .keep
file for that pack, so we use the same tricks that index-pack uses
when its being invoked by receive-pack.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Rather than maintaing our own packfile level sha1 variable we
can make use of the one already available in struct packed_git.
Its meant for the SHA1 of the index but it can also hold the
SHA1 of the packfile itself between final checksumming of the
packfile and creation of the index.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Prior to git having read_in_full() fast-import used its own private
function yread to perform the header reading task. No sense in
keeping that around now that read_in_full is a public, stable
function.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If a frontend wants to use a mark per file revision and per commit
and is doing a truly huge import (such as a 32 GiB SVN repository)
we may need more than 2**32 unique mark values, especially if the
frontend is unable (or unwilling) to recycle mark values. For mark
idnums we should use the largest unsigned integer type available,
hoping that will be at least 64 bits when we are compiled as a 64
bit executable. This way we may consume huge amounts of memory
storing our mark table, but we'll at least be able to process
the entire import without failing.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If we previously were using a delta but we needed to checkpoint the
current packfile and switch to a new packfile we need to throw away
the delta and compress the raw object by itself, as delta chains
cannot span non-thin packfiles. Unfortunately the output buffer
in this case needs to grow, as the size of the compressed object
may be quite a bit larger than the size of the compressed delta.
I've also avoided recompressing the object if we are checkpointing
and we didn't use a delta. In this case the output buffer is the
correct size and has already been populated with the right data,
we just need to close out the current packfile and open a new one.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Caller scripts may want to know what packfiles the fast-import
process just wrote out for them. This is now output to stdout,
one packfile name per line, after we checkpoint each packfile.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
When the number of objects or number of bytes gets close to the limit
allowed by the packfile format (or configured on the command line by
our caller) we should automatically checkpoint the current packfile
and start a new one before writing the object out. This does however
require that we abandon the delta (if we had one) as its not valid
in a new packfile.
I also added the simple rule that if we got a delta back but the
delta itself is the same size as or larger than the uncompressed
object to ignore the delta and just store the object data. This
should avoid some really bad behavior caused by our current delta
strategy.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
When we are generating multiple packfiles at once we only need
to scan the blocks of object_entry structs which contain objects
for the current packfile. Because the most recent blocks are at
the front of the linked list, and because all new objects going
into the current file are allocated from the front of that list,
we can stop scanning for objects as soon as we identify one which
doesn't belong to the current packfile.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If the last packfile is going to be empty (has 0 objects) then it
shouldn't be kept after the import has terminated, as there is no
point to the packfile. So rather than hashing it and making the
index file, just delete the packfile.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
To help importers which are dealing with massive amounts of data
fast-import needs to be able to close the packfile it is currently
writing to and open a new packfile for any additional data that
will be received. A new 'checkpoint' command has been introduced
which can be used by the frontend import process to force this
to occur at any time. This may be useful to ensure a very long
running import doesn't lose any work due to unexpected failures.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
There is little reason to be keeping a global duplicate_count
value when we also keep it per object type. The global counter can
easily be computed at the end, once all processing has completed.
This saves us a couple of machine instructions in an unimportant
part of code. But it looks slightly better to me to not keep
two counters around.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Now that we are starting to see some really large projects (such
as KDE or a fork of FreeBSD) get imported into Git we're running
into the upper limit on packfile object count as well as overall
byte length. The KDE and FreeBSD projects are both likely to
require more than 4 GiB to store their current history, which means
we really need multiple packfiles to handle their content.
This is a fairly simple restructuring of the internal code to help
us support creating multiple packfiles from within fast-import.
We are now adding a 5 digit incrementing suffix to the end of the
basename supplied to us by the caller, permitting up to 99,999
packs to be generated in a single fast-import run.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Now that the sha1_file.c library routines use the sliding mmap
routines to perform efficient access to portions of a packfile
I can remove that code from fast-import.c and just invoke it.
One benefit is we now have reloading support for any packfile which
uses OBJ_OFS_DELTA. Another is we have significantly less code
to maintain.
This code reuse change *requires* that fast-import generate only
an OBJ_OFS_DELTA format packfile, as there is absolutely no index
available to perform OBJ_REF_DELTA lookup in while unpacking
an object. This is probably reasonable to require as the delta
offsets result in smaller packfiles and are faster to unpack,
as no index searching is required. Its also only a temporary
requirement as users could always repack without offsets before
making the import available to older versions of Git.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
I'm bringing master in early so that the OBJ_OFS_DELTA implementation
is available as part of the topic. This way git-fast-import can
learn about this new slightly smaller and faster packfile format,
and can generate them directly rather than needing to have them be
repacked with git-pack-objects.
Due to the API changes in master during the period of development
of git-fast-import, a few minor tweaks to fast-import.c are needed
to produce a working merge. I've done them here as part of the
merge to ensure bisection always works.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Some importers may want to create a branch long before they actually
commit to it, or in some cases they may never commit to the branch
but they still need the ref to be created in the repository after
the import is complete.
This extends the 'reset ' command to automatically create a new
branch if the supplied reference isn't already known as a branch.
While I'm at it I also modified the syntax of the reset command
to terminate with an empty line, like commit and tag operate.
This just makes the command set more consistent.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Some importers are able to determine when branch merges occurred
within their source data. In these cases they will want to supply
the correct commits to fast-import so that a proper merge commit
will exist in Git. This is now supported by supplying a 'merge '
command after the commit message and optional from command.
A merge is not actually performed by fast-import, its assumed that
the frontend performed any sort of merging activity already and
that fast-import should simply be storing its result.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Apparently we did not copy the blob SHA1 into the stack variable
'sha1' when a mark is used to refer to a prior blob. This code
was not previously tested as the Mozilla CVS -> git-fast-import
program always fed us full SHA1s for modified blobs and did not
use the mark feature there.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The new tree delta implementation caused blob SHA1s to be used
instead of a tree SHA1 when a tree was written out. This really
only appeared to happen when converting an existing file to a tree,
but may have been possible in some other situations.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Since most commits and tag objects are around the same size and we
only generate one at a time we can reuse the same buffer rather than
xmalloc'ing and free'ing the buffer every time we generate a commit.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We only ever generate at most two tree streams at a time. Since most
trees are around the same size we can simply recycle the buffers from
one tree generation to the next rather than constantly xmalloc'ing
and free'ing them. This should perform slightly better when handling
a large number of trees as malloc has less work to do.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We now store for every tree entry two modes and two sha1 values;
the base (aka "version 0") and the current/new (aka "version 1").
When we generate a tree object we also regenerate the prior version
object and use that as our base object for a delta. This strategy
saves a significant amount of memory as we can continue to use the
atom pool for file/directory names and only increases each tree
entry by an additional 24 bytes of memory.
Branches should automatically delta against their ancestor tree,
unless the ancestor tree is already at the delta chain limit.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Sometimes an import frontend may need to work with a temporary branch
which will actually contain many different branches over the life
of the import. This is especially useful when the frontend needs
to create a tag from a set of file versions which are otherwise
never a commit.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
When generating a very large pack file (for example close to 1 GB
in size) it may be impossible for the kernel to find a contiguous
free range within a 32 bit address space for the mapping to be
located at. This is especially problematic on large imports where
there is a lot of malloc activity occuring within the same process
and the malloc'd regions may straddle the previously mapped regions,
thereby creating large holes in the address space.
So instead we map only 128 MB of the pack at any given time.
This will likely increase the number of times the file gets mapped
(with additional system time required to update the page tables
more frequently) but will allow the program to handle packs up to
4 GB in size.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
fast-import was encounting a GPF when it ran out of free tree_entry
objects but didn't know this was the cause because the last
tree_entry wasn't terminated with a NULL pointer. The missing NULL
pointer occurred when we allocated additional entries via xmalloc
but didn't set the last tree_entry's "next" pointer to NULL.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This option can be used to have a record of every commit, the mark
(if supplied) and branch name of the commit recorded into a log file
when the commit is generated. This log can be useful to verify the
results of an import as the commits can be compared to some source
repository matching commits through the mark value.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The marks table can be used by the frontend to load any commit after
the import and compare it to whatever data the frontend knows about
that commit. If the mark idnums can be easily correlated to some
reference source then its relatively trivial to compare the GIT
tree to the reference to verify the accuracy of the import.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
cvs2svn has three phases: begin_commit, middle_commit, end_commit.
The ancester is computed in the middle_commit phase. So its easier
to generate a stream if the from command appears after the commit
message itself but before the file change commands.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Jon Smirl was finding it difficult to alter cvs2svn to generate
branch commands prior to the first commit of the same branch.
This change moves the 'from' command to be an optional parameter of
the 'commit' command, thereby allowing a new branch to be defined
at the moment it gets used to create the first commit on that branch.
This change makes it impossible to create a branch with no commits
on it as at least one commit is needed to register the branch.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Some architectures (e.g. SPARC) would require that we access pointers
only on pointer-sized alignments. So ensure the pool allocator
rounds out non-pointer sized allocations to the next pointer so we
don't generate bad memory addresses. This could have occurred if
we had previously allocated an atom whose string was not a whole
multiple of the pointer size, for example.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Tree reloading allows fast-import to swap out the least-recently used
branch by simply deallocating the data structures from memory that
were associated with that branch. Later if the branch becomes active
again it can lazily recreate those structures on demand by reloading
the necessary trees from the pack file it originally wrote them to.
The reloading process is implemented by mmap'ing the pack into
memory and using a much tighter variant of the pack reading code
contained in sha1_file.c. This was a blatent copy from sha1_file.c
but the unpacking functions were significantly simplified and are
actually now in a form that should make it easier to map only the
necessary regions of a pack rather than the entire file.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Tags received from the frontend are generated in memory in a simple
linked list in the order that the tag commands were sent by the
frontend. If multiple different tag objects for the same tag name
get generated the last one sent by the frontend will be the one
that gets written out at termination. Multiple tag objects for
the same name will cause all older tags of the same name to be lost.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If the branch load count exceeds the number of branches created then
the frontend is causing fast-import to page branches into and out of
memory due to the way its ordering its commits. Performance can
likely be increased if the frontend were to alter its commit
sequence such that it stays on one branch before switching to another
branch, then never returns to the prior branch.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Marks are now saved when the mark directive gets used by the frontend
and may be used in place of a SHA1 expression to locate a previous
SHA1 which fast-import may have generated. This is particularly
useful with commits where the frontend does not (easily) have the
ability to compute the SHA1 for an arbitrary commit but needs it
to generate a branch or tag from that commit.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The following command line options are now accepted before the
pack name:
--objects=n # replaces the object count after the pack name
--depth=n # delta chain depth to use (default is 10)
--active-branches=n # maximum number of branches to keep in memory
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Growing a tree caused all subtrees to be deallocated and put back
into the free list yet those subtree's contents were still actively
in use. Consequently they were doled out again and got stomped
on elsewhere. Releasing a tree is now performed in two parts,
either releasing only the content array or releasing the content
array and recursively releasing the subtree(s).
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If a frontend is smart enough to import a symlink then we should
let them do so. We'll assume that they were smart enough to first
generate a blob to hold the link target, as that's how symlinks
get represented in GIT.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Frontend clients can now send a text stream to fast-import rather
than a binary stream. This should facilitate developing frontend
software as the data stream is easier to view, manipulate and debug
my hand and Mark-I eyeball.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
When accepting revision SHA1 IDs from the frontend verify the SHA1
actually refers to a blob and is known to exist. Its an error
to use a SHA1 in a tree if the blob doesn't exist as this would
cause git-fsck-objects to report a missing blob should the pack get
closed without the blob being appended into it or a subsequent pack.
So right now we'll just ask that the frontend "pre-declare" any
blobs it wants to use in a tree before it can use them.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The tree of the current commit can be altered by file_change commands
before the commit gets written to the pack. The file changes are
rather primitive as they simply allow removal of a tree entry or
setting/adding a tree entry.
Currently trees and commits aren't being deltafied when written to
the pack and branch reloading from the current pack doesn't work,
so at most 5 branches can be worked with at any one time.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This provides the basic data structures needed to store trees in
memory while we are processing them for a branch. What we are
attempting to do is track one complete tree for each branch that
the frontend has registered with us through the 'newb' (new_branch)
command. When the frontend edits that tree through 'updf' or 'delf'
commands we'll mark the affected tree(s) as being dirty and recompute
their objects during 'comt' (commit).
Currently the protocol is decidedly _not_ user friendly. I crashed
fast-import by giving it bad input data from Perl. I may try to
improve upon it, or at least upon its error handling.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Moved the new_blob logic off into a new subroutine and
invoked it when getting the 'blob' command.
Added statistics dump to STDERR when the program terminates listing
what it did at a high level. This is somewhat interesting.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Too many globals variables were being used not not enough
code was resuable to process trees and commits so this is
a simple refactoring of the existing blob processing code
to get into a state that will be easier to handle trees
and commits in.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Although its easy to ask the user to tell us how many objects they
will need, its probably better to dynamically grow the object table
in large units. But if the user can give us a hint as to roughly
how many objects then we can still use it during startup.
Also stopped printing the SHA1 strings to stdout as no user is
currently making use of that facility.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
