clone: --dissociate option to mark that reference is only temporary
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. Helped-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano committed
Oct 14, 2014 at 12:38 UTC
fb1d6dabce69bce3f28a7f442da990ef8df872ac
3 files changed
+46
-2
Documentation/git-clone.txt
+9
-2
@@ -12,7 +12,7 @@ SYNOPSIS
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'git clone' [--template=<template_directory>]
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[-l] [-s] [--no-hardlinks] [-q] [-n] [--bare] [--mirror]
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[-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
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- [--separate-git-dir <git dir>]
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+ [--dissociate] [--separate-git-dir <git dir>]
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[--depth <depth>] [--[no-]single-branch]
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[--recursive | --recurse-submodules] [--] <repository>
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[<directory>]
@@ -98,7 +98,14 @@ objects from the source repository into a pack in the cloned repository.
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require fewer objects to be copied from the repository
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being cloned, reducing network and local storage costs.
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+
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-*NOTE*: see the NOTE for the `--shared` option.
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+*NOTE*: see the NOTE for the `--shared` option, and also the
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+`--dissociate` option.
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+
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+--dissociate::
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+ Borrow the objects from reference repositories specified
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+ with the `--reference` options only to reduce network
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+ transfer and stop borrowing from them after a clone is made
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+ by making necessary local copies of borrowed objects.
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--quiet::
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-q::
builtin/clone.c
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@@ -48,6 +48,7 @@ static int option_verbosity;
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static int option_progress = -1;
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static struct string_list option_config;
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static struct string_list option_reference;
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+static int option_dissociate;
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static int opt_parse_reference(const struct option *opt, const char *arg, int unset)
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{
@@ -93,6 +94,8 @@ static struct option builtin_clone_options[] = {
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N_("create a shallow clone of that depth")),
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OPT_BOOL(0, "single-branch", &option_single_branch,
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N_("clone only one branch, HEAD or --branch")),
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+ OPT_BOOL(0, "dissociate", &option_dissociate,
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+ N_("use --reference only while cloning")),
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OPT_STRING(0, "separate-git-dir", &real_git_dir, N_("gitdir"),
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N_("separate git dir from working tree")),
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OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
@@ -736,6 +739,16 @@ static void write_refspec_config(const char* src_ref_prefix,
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strbuf_release(&value);
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}
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+static void dissociate_from_references(void)
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+{
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+ static const char* argv[] = { "repack", "-a", "-d", NULL };
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+
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+ if (run_command_v_opt(argv, RUN_GIT_CMD|RUN_COMMAND_NO_STDIN))
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+ die(_("cannot repack to clean up"));
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+ if (unlink(git_path("objects/info/alternates")) && errno != ENOENT)
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+ die_errno(_("cannot unlink temporary alternates file"));
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+}
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+
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int cmd_clone(int argc, const char **argv, const char *prefix)
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{
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int is_bundle = 0, is_local;
@@ -883,6 +896,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
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if (option_reference.nr)
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setup_reference();
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+ else if (option_dissociate) {
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+ warning(_("--dissociate given, but there is no --reference"));
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+ option_dissociate = 0;
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+ }
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fetch_pattern = value.buf;
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refspec = parse_fetch_refspec(1, &fetch_pattern);
@@ -996,6 +1013,9 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
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transport_unlock_pack(transport);
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transport_disconnect(transport);
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+ if (option_dissociate)
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+ dissociate_from_references();
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+
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junk_mode = JUNK_LEAVE_REPO;
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err = checkout();
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t/t5700-clone-reference.sh
+17
@@ -198,4 +198,21 @@ test_expect_success 'clone using repo pointed at by gitfile as reference' '
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test_cmp expected "$base_dir/O/.git/objects/info/alternates"
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'
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+test_expect_success 'clone and dissociate from reference' '
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+ git init P &&
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+ (
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+ cd P && test_commit one
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+ ) &&
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+ git clone P Q &&
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+ (
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+ cd Q && test_commit two
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+ ) &&
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+ git clone --no-local --reference=P Q R &&
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+ git clone --no-local --reference=P --dissociate Q S &&
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+ # removing the reference P would corrupt R but not S
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+ rm -fr P &&
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+ test_must_fail git -C R fsck &&
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+ git -C S fsck
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+'
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+
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test_done