From: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Given many repositories with copies of the same objects (such as branches of
the same source), sharing a common object store will avoid duplication.
Alternates provide a single baseline, but don't handle ongoing activity in the
various repositories. Furthermore, operations such as git-gc need to know
about all of the refs.
Git supports storing multiple virtual repositories within the object store and
references of a single underlying repository. The underlying repository
stores the objects for all of the virtual repositories, and includes all the
refs and heads of the virtual repositories using prefixed names.
git-upload-pack and git-receive-pack rewrite the names of refs and heads as
specified by the --ref-prefix and --head options. For instance,
--ref-prefix=virtual/reponame/ will use refs/virtual/reponame/heads/* and
refs/virtual/reponame/tags/*. git-upload-pack and git-receive-pack will
ignore any references that do not match the specified prefix.
These options implement the underlying mechanism for virtual
repositories; the higher-level protocol handler (such as http-backend or
a custom server) can pass these options when invoking upload-pack or
receive-pack, providing values based on components of the repository
path. For a simple local test, git-remote-ext works:
git clone ext::'git %s --ref-prefix=virtual/reponame/ --head=virtual-HEAD/reponame storage.git'
Commit by Josh Triplett and Jamey Sharp.
Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Signed-off-by: Jamey Sharp <jamey@xxxxxxxxxxx>
---
v2: remove accidentally-included debug message, and add patch 2/2 for
git-http-backend.
v3: add patch 3/3 with documentation for virtual repositories, and
incorporated feedback from Jeff King and Junio C Hamano.
builtin/receive-pack.c | 36 +++++++++++++++++++++++++++---------
upload-pack.c | 34 +++++++++++++++++++++++++++-------
2 files changed, 54 insertions(+), 16 deletions(-)
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index e1ba4dc..76dacd0 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -34,6 +34,8 @@ static int prefer_ofs_delta = 1;
static int auto_update_server_info;
static int auto_gc = 1;
static const char *head_name;
+static const char *head_path = "HEAD";
+static const char *ref_prefix = "refs/";
static int sent_capabilities;
static enum deny_action parse_deny_action(const char *var, const char *value)
@@ -108,11 +110,12 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
static int show_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
{
+ const char *refnameprefix = cb_data;
if (sent_capabilities)
- packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
+ packet_write(1, "%s %s%s\n", sha1_to_hex(sha1), refnameprefix, path);
else
- packet_write(1, "%s %s%c%s%s\n",
- sha1_to_hex(sha1), path, 0,
+ packet_write(1, "%s %s%s%c%s%s\n",
+ sha1_to_hex(sha1), refnameprefix, path, 0,
" report-status delete-refs side-band-64k",
prefer_ofs_delta ? " ofs-delta" : "");
sent_capabilities = 1;
@@ -121,9 +124,9 @@ static int show_ref(const char *path, const unsigned char *sha1, int flag, void
static void write_head_info(void)
{
- for_each_ref(show_ref, NULL);
+ for_each_ref_in(ref_prefix, show_ref, "refs/");
if (!sent_capabilities)
- show_ref("capabilities^{}", null_sha1, 0, NULL);
+ show_ref("capabilities^{}", null_sha1, 0, "");
}
@@ -332,6 +335,8 @@ static void refuse_unconfigured_deny_delete_current(void)
static const char *update(struct command *cmd)
{
const char *name = cmd->ref_name;
+ struct strbuf prefixed_name_buf = STRBUF_INIT;
+ const char *prefixed_name;
unsigned char *old_sha1 = cmd->old_sha1;
unsigned char *new_sha1 = cmd->new_sha1;
struct ref_lock *lock;
@@ -342,7 +347,10 @@ static const char *update(struct command *cmd)
return "funny refname";
}
- if (is_ref_checked_out(name)) {
+ strbuf_addf(&prefixed_name_buf, "%s%s", ref_prefix, name + 5);
+ prefixed_name = strbuf_detach(&prefixed_name_buf, NULL);
+
+ if (is_ref_checked_out(prefixed_name)) {
switch (deny_current_branch) {
case DENY_IGNORE:
break;
@@ -370,7 +378,7 @@ static const char *update(struct command *cmd)
return "deletion prohibited";
}
- if (!strcmp(name, head_name)) {
+ if (!strcmp(prefixed_name, head_name)) {
switch (deny_delete_current) {
case DENY_IGNORE:
break;
@@ -426,14 +434,14 @@ static const char *update(struct command *cmd)
rp_warning("Allowing deletion of corrupt ref.");
old_sha1 = NULL;
}
- if (delete_ref(name, old_sha1, 0)) {
+ if (delete_ref(prefixed_name, old_sha1, 0)) {
rp_error("failed to delete %s", name);
return "failed to delete";
}
return NULL; /* good */
}
else {
- lock = lock_any_ref_for_update(name, old_sha1, 0);
+ lock = lock_any_ref_for_update(prefixed_name, old_sha1, 0);
if (!lock) {
rp_error("failed to lock %s", name);
return "failed to lock";
@@ -760,6 +768,16 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
advertise_refs = 1;
continue;
}
+ if (!prefixcmp(arg, "--head=")) {
+ head_path = arg+7;
+ continue;
+ }
+ if (!prefixcmp(arg, "--ref-prefix=")) {
+ struct strbuf prefixbuf = STRBUF_INIT;
+ strbuf_addf(&prefixbuf, "refs/%s", arg+13);
+ ref_prefix = strbuf_detach(&prefixbuf, NULL);
+ continue;
+ }
if (!strcmp(arg, "--stateless-rpc")) {
stateless_rpc = 1;
continue;
diff --git a/upload-pack.c b/upload-pack.c
index ce5cbbe..a1e495f 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -34,6 +34,8 @@ static int shallow_nr;
static struct object_array have_obj;
static struct object_array want_obj;
static struct object_array extra_edge_obj;
+static const char *head_path = "HEAD";
+static const char *ref_prefix = "";
static unsigned int timeout;
/* 0 for no sideband,
* otherwise maximum packet size (up to 65520 bytes).
@@ -640,17 +642,18 @@ static int send_ref(const char *refname, const unsigned char *sha1, int flag, vo
static const char *capabilities = "multi_ack thin-pack side-band"
" side-band-64k ofs-delta shallow no-progress"
" include-tag multi_ack_detailed";
+ const char *refnameprefix = cb_data;
struct object *o = parse_object(sha1);
if (!o)
die("git upload-pack: cannot find object %s:", sha1_to_hex(sha1));
if (capabilities)
- packet_write(1, "%s %s%c%s%s\n", sha1_to_hex(sha1), refname,
+ packet_write(1, "%s %s%s%c%s%s\n", sha1_to_hex(sha1), refnameprefix, refname,
0, capabilities,
stateless_rpc ? " no-done" : "");
else
- packet_write(1, "%s %s\n", sha1_to_hex(sha1), refname);
+ packet_write(1, "%s %s%s\n", sha1_to_hex(sha1), refnameprefix, refname);
capabilities = NULL;
if (!(o->flags & OUR_REF)) {
o->flags |= OUR_REF;
@@ -659,7 +662,7 @@ static int send_ref(const char *refname, const unsigned char *sha1, int flag, vo
if (o->type == OBJ_TAG) {
o = deref_tag(o, refname, 0);
if (o)
- packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname);
+ packet_write(1, "%s %s%s^{}\n", sha1_to_hex(o->sha1), refnameprefix, refname);
}
return 0;
}
@@ -678,15 +681,24 @@ static int mark_our_ref(const char *refname, const unsigned char *sha1, int flag
static void upload_pack(void)
{
+ struct strbuf prefix = STRBUF_INIT;
+ unsigned char sha1[20];
+ int flag;
+
+ strbuf_addf(&prefix, "refs/%s", ref_prefix);
if (advertise_refs || !stateless_rpc) {
reset_timeout();
- head_ref(send_ref, NULL);
- for_each_ref(send_ref, NULL);
+ if (resolve_ref(head_path, sha1, 1, &flag))
+ send_ref("HEAD", sha1, flag, "");
+ for_each_ref_in(prefix.buf, send_ref, "refs/");
packet_flush(1);
} else {
- head_ref(mark_our_ref, NULL);
- for_each_ref(mark_our_ref, NULL);
+ if (resolve_ref(head_path, sha1, 1, &flag))
+ mark_our_ref("HEAD", sha1, flag, NULL);
+ for_each_ref_in(prefix.buf, mark_our_ref, NULL);
}
+ strbuf_release(&prefix);
+
if (advertise_refs)
return;
@@ -716,6 +728,14 @@ int main(int argc, char **argv)
advertise_refs = 1;
continue;
}
+ if (!prefixcmp(arg, "--head=")) {
+ head_path = arg+7;
+ continue;
+ }
+ if (!prefixcmp(arg, "--ref-prefix=")) {
+ ref_prefix = arg+13;
+ continue;
+ }
if (!strcmp(arg, "--stateless-rpc")) {
stateless_rpc = 1;
continue;
--
1.7.5.1
--
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