While use of the --reference option to borrow objects from an
existing local repository of the same project is an effective way to
reduce traffic when cloning a project over the network, it makes the
resulting "borrowing" repository dependent on the "borrowed"
repository. After running
git clone --reference=P $URL Q
the resulting repository Q will be broken if the borrowed repository
P disappears.
The way to allow the borrowed repository to be removed is to repack
the borrowing repository (i.e. run "git repack -a -d" in Q); while
power users may know it very well, it is not easily discoverable.
Teach a new "--dissociate" option to "git clone" to run this
repacking for the user.
Signed-off-by: Junio C Hamano <gits...@pobox.com>
---
* This comes from
http://thread.gmane.org/gmane.comp.version-control.git/243918/focus=245397
which is one of the low-hanging entries in the leftover-bits list
http://git-blame.blogspot.com/p/leftover-bits.html
Yes, I must have been really bored to do this ;-)
Documentation/git-clone.txt | 11 +++++++++--
builtin/clone.c | 25 +++++++++++++++++++++++++
t/t5700-clone-reference.sh | 17 +++++++++++++++++
3 files changed, 51 insertions(+), 2 deletions(-)
diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index 0363d00..f1f2a3f 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -12,7 +12,7 @@ SYNOPSIS
'git clone' [--template=<template_directory>]
[-l] [-s] [--no-hardlinks] [-q] [-n] [--bare] [--mirror]
[-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
- [--separate-git-dir <git dir>]
+ [--dissociate] [--separate-git-dir <git dir>]
[--depth <depth>] [--[no-]single-branch]
[--recursive | --recurse-submodules] [--] <repository>
[<directory>]
@@ -98,7 +98,14 @@ objects from the source repository into a pack in the cloned
repository.
require fewer objects to be copied from the repository
being cloned, reducing network and local storage costs.
+
-*NOTE*: see the NOTE for the `--shared` option.
+*NOTE*: see the NOTE for the `--shared` option, and also the
+`--dissociate` option.
+
+--dissociate::
+ Borrow the objects from reference repositories specified
+ with the `--reference` options only to reduce network
+ transfer and stop borrowing from them after a clone is made
+ by making necessary local copies of borrowed objects.
--quiet::
-q::
diff --git a/builtin/clone.c b/builtin/clone.c
index bbd169c..780fbd5 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -48,6 +48,7 @@ static int option_verbosity;
static int option_progress = -1;
static struct string_list option_config;
static struct string_list option_reference;
+static int option_dissociate;
static int opt_parse_reference(const struct option *opt, const char *arg, int
unset)
{
@@ -93,6 +94,8 @@ static struct option builtin_clone_options[] = {
N_("create a shallow clone of that depth")),
OPT_BOOL(0, "single-branch", &option_single_branch,
N_("clone only one branch, HEAD or --branch")),
+ OPT_BOOL(0, "dissociate", &option_dissociate,
+ N_("use --reference only while cloning")),
OPT_STRING(0, "separate-git-dir", &real_git_dir, N_("gitdir"),
N_("separate git dir from working tree")),
OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
@@ -736,6 +739,21 @@ static void write_refspec_config(const char*
src_ref_prefix,
strbuf_release(&value);
}
+static void dissociate_from_references(void)
+{
+ struct child_process cmd;
+
+ memset(&cmd, 0, sizeof(cmd));
+ argv_array_pushl(&cmd.args, "repack", "-a", "-d", NULL);
+ cmd.git_cmd = 1;
+ cmd.out = -1;
+ cmd.no_stdin = 1;
+ if (run_command(&cmd))
+ die(_("cannot repack to clean up"));
+ if (unlink(git_path("objects/info/alternates")) && errno != ENOENT)
+ die_errno(_("cannot unlink temporary alternates file"));
+}
+
int cmd_clone(int argc, const char **argv, const char *prefix)
{
int is_bundle = 0, is_local;
@@ -883,6 +901,10 @@ int cmd_clone(int argc, const char **argv, const char
*prefix)
if (option_reference.nr)
setup_reference();
+ else if (option_dissociate) {
+ warning(_("--dissociate given, but there is no --reference"));
+ option_dissociate = 0;
+ }
fetch_pattern = value.buf;
refspec = parse_fetch_refspec(1, &fetch_pattern);
@@ -996,6 +1018,9 @@ int cmd_clone(int argc, const char **argv, const char
*prefix)
transport_unlock_pack(transport);
transport_disconnect(transport);
+ if (option_dissociate)
+ dissociate_from_references();
+
junk_mode = JUNK_LEAVE_REPO;
err = checkout();
diff --git a/t/t5700-clone-reference.sh b/t/t5700-clone-reference.sh
index 6537911..3e783fc 100755
--- a/t/t5700-clone-reference.sh
+++ b/t/t5700-clone-reference.sh
@@ -198,4 +198,21 @@ test_expect_success 'clone using repo pointed at by
gitfile as reference' '
test_cmp expected "$base_dir/O/.git/objects/info/alternates"
'
+test_expect_success 'clone and dissociate from reference' '
+ git init P &&
+ (
+ cd P && test_commit one
+ ) &&
+ git clone P Q &&
+ (
+ cd Q && test_commit two
+ ) &&
+ git clone --no-local --reference=P Q R &&
+ git clone --no-local --reference=P --dissociate Q S &&
+ # removing the reference P would corrupt R but not S
+ rm -fr P &&
+ test_must_fail git -C R fsck &&
+ git -C S fsck
+'
+
test_done
--
2.1.2-488-g6ab273f
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