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Junio C HamanoLinus Torvalds
Junio C Hamano
authored and
Linus Torvalds
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[PATCH] Remove "delta" object representation.
Packed delta files created by git-pack-objects seems to be the way to go, and existing "delta" object handling code has exposed the object representation details to too many places. Remove it while we refactor code to come up with a proper interface in sha1_file.c. Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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‎Documentation/git-fsck-cache.txt‎

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@@ -9,7 +9,7 @@ git-fsck-cache - Verifies the connectivity and validity of the objects in the da
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SYNOPSIS
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--------
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'git-fsck-cache' [--tags] [--root] [--delta-depth] [--unreachable] [--cache] [<object>*]
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'git-fsck-cache' [--tags] [--root] [--unreachable] [--cache] [<object>*]
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DESCRIPTION
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-----------
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Consider any object recorded in the cache also as a head node for
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an unreachability trace.
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--delta-depth::
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Report back the length of the longest delta chain found.
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It tests SHA1 and general object sanity, and it does full tracking of
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the resulting reachability and everything else. It prints out any
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corruption it finds (missing or bad objects), and if you use the

‎Documentation/git-http-pull.txt‎

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@@ -21,13 +21,6 @@ Downloads a remote GIT repository via HTTP.
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Get trees associated with the commit objects.
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-a::
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Get all the objects.
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-d::
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Do not check for delta base objects (use this option
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only when you know the remote repository is not
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deltified).
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--recover::
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Check dependency of deltified object more carefully than
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usual, to recover after earlier pull that was interrupted.
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-v::
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Report what is downloaded.
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-w::

‎Documentation/git-local-pull.txt‎

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@@ -23,13 +23,6 @@ OPTIONS
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Get trees associated with the commit objects.
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-a::
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Get all the objects.
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-d::
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Do not check for delta base objects (use this option
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only when you know the remote repository is not
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deltified).
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--recover::
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Check dependency of deltified object more carefully than
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usual, to recover after earlier pull that was interrupted.
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-v::
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Report what is downloaded.
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-w::

‎Documentation/git-mkdelta.txt‎

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This file was deleted.

‎Documentation/git-ssh-pull.txt‎

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@@ -31,13 +31,6 @@ commit-id::
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Get trees associated with the commit objects.
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-a::
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Get all the objects.
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-d::
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Do not check for delta base objects (use this option
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only when you know the remote repository is not
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deltified).
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--recover::
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Check dependency of deltified object more carefully than
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usual, to recover after earlier pull that was interrupted.
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-v::
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Report what is downloaded.
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-w::

‎Documentation/git-ssh-push.txt‎

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@@ -28,13 +28,6 @@ commit-id::
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Get tree associated with the requested commit object.
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-a::
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Get all the objects.
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-d::
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Do not check for delta base objects (use this option
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only when you know the local repository is not
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deltified).
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--recover::
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Check dependency of deltified object more carefully than
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usual, to recover after earlier push that was interrupted.
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-v::
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Report what is uploaded.
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-w::

‎Documentation/git.txt‎

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@@ -51,9 +51,6 @@ link:git-init-db.html[git-init-db]::
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link:git-merge-base.html[git-merge-base]::
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Finds as good a common ancestor as possible for a merge
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link:git-mkdelta.html[git-mkdelta]::
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Creates a delta object
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link:git-mktag.html[git-mktag]::
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Creates a tag object
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‎Makefile‎

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@@ -22,7 +22,7 @@ INSTALL=install
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SCRIPTS=git git-apply-patch-script git-merge-one-file-script git-prune-script \
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git-pull-script git-tag-script git-resolve-script git-whatchanged \
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git-deltafy-script git-fetch-script git-status-script git-commit-script \
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git-fetch-script git-status-script git-commit-script \
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git-log-script git-shortlog git-cvsimport-script git-diff-script \
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git-reset-script git-add-script git-checkout-script git-clone-script \
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gitk git-cherry git-rebase-script git-relink-script
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git-unpack-file git-export git-diff-cache git-convert-cache \
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git-http-pull git-ssh-push git-ssh-pull git-rev-list git-mktag \
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git-diff-helper git-tar-tree git-local-pull git-write-blob \
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git-get-tar-commit-id git-mkdelta git-apply git-stripspace \
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git-get-tar-commit-id git-apply git-stripspace \
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git-cvs2git git-diff-stages git-rev-parse git-patch-id \
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git-pack-objects git-unpack-objects
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@@ -44,7 +44,7 @@ install: $(PROG) $(SCRIPTS)
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$(INSTALL) $(PROG) $(SCRIPTS) $(dest)$(bin)
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LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o \
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tag.o delta.o date.o index.o diff-delta.o patch-delta.o entry.o \
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tag.o date.o index.o diff-delta.o patch-delta.o entry.o \
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epoch.o refs.o csum-file.o
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LIB_FILE=libgit.a
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LIB_H=cache.h object.h blob.h tree.h commit.h tag.h delta.h epoch.h csum-file.h
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git-diff-helper: diff-helper.c
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git-tar-tree: tar-tree.c
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git-write-blob: write-blob.c
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git-mkdelta: mkdelta.c
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git-stripspace: stripspace.c
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git-cvs2git: cvs2git.c
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git-diff-stages: diff-stages.c

‎README‎

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@@ -32,8 +32,8 @@ build up a hierarchy of objects.
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All objects have a statically determined "type" aka "tag", which is
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determined at object creation time, and which identifies the format of
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the object (i.e. how it is used, and how it can refer to other
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objects). There are currently five different object types: "blob",
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"tree", "commit", "tag" and "delta"
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objects). There are currently four different object types: "blob",
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"tree", "commit" and "tag".
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A "blob" object cannot refer to any other object, and is, like the tag
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implies, a pure storage object containing some user data. It is used to
@@ -62,16 +62,12 @@ A "tag" object symbolically identifies and can be used to sign other
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objects. It contains the identifier and type of another object, a
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symbolic name (of course!) and, optionally, a signature.
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A "delta" object is used internally by the object database to minimise
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disk usage. Instead of storing the entire contents of a revision, git
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can behave in a similar manner to RCS et al and simply store a delta.
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Regardless of object type, all objects share the following
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characteristics: they are all deflated with zlib, and have a header
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that not only specifies their tag, but also provides size information
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about the data in the object. It's worth noting that the SHA1 hash
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that is used to name the object is the hash of the original data or
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the delta. (Historical note: in the dawn of the age of git the hash
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that is used to name the object is the hash of the original data.
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(Historical note: in the dawn of the age of git the hash
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was the sha1 of the _compressed_ object)
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As a result, the general consistency of an object can always be tested
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A tag is created with link:git-mktag.html[git-mktag] and
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it's data can be accessed by link:git-cat-file.html[git-cat-file]
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Delta Object
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~~~~~~~~~~~~
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The "delta" object is used internally by the object database to
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minimise storage usage by using xdeltas (byte level diffs). Deltas can
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form chains of arbitrary length as RCS does (although this is
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configureable at creation time). Most operations won't see or even be
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aware of delta objects as they are automatically 'applied' and appear
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as 'real' git objects In other words, if you write your own routines
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to look at the contents of the object database then you need to know
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about this - otherwise you don't. Actually, that's not quite true -
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one important area where deltas are likely to prove very valuable is
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in reducing bandwidth loads - so the more sophisticated network tools
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for git repositories will be aware of them too.
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Finally, git repositories can (and must) be deltafied in the
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background - the work to calculate the differences does not take place
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automatically at commit time.
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A delta can be created (or undeltafied) with
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link:git-mkdelta.html[git-mkdelta] it's raw data cannot be accessed at
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present.
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The "index" aka "Current Directory Cache"
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-----------------------------------------

‎cache.h‎

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@@ -162,7 +162,6 @@ extern char *sha1_file_name(const unsigned char *sha1);
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extern void * map_sha1_file(const unsigned char *sha1, unsigned long *size);
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extern int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size);
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extern int parse_sha1_header(char *hdr, char *type, unsigned long *sizep);
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extern int sha1_delta_base(const unsigned char *, unsigned char *);
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extern int sha1_file_size(const unsigned char *, unsigned long *);
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extern void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size);
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extern void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size);

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