introduce fetch-object: fetch one promisor object

Introduce fetch-object, providing the ability to fetch one object from a
promisor remote.

This uses fetch-pack. To do this, the transport mechanism has been
updated with 2 flags, "from-promisor" to indicate that the resulting
pack comes from a promisor remote (and thus should be annotated as such
by index-pack), and "no-dependents" to indicate that only the objects
themselves need to be fetched (but fetching additional objects is
nevertheless safe).

Whenever "no-dependents" is used, fetch-pack will refrain from using any
object flags, because it is most likely invoked as part of a dynamic
object fetch by another Git command (which may itself use object flags).
An alternative to this is to leave fetch-pack alone, and instead update
the allocation of flags so that fetch-pack's flags never overlap with
any others, but this will end up shrinking the number of flags available
to nearly every other Git command (that is, every Git command that
accesses objects), so the approach in this commit was used instead.

This will be tested in a subsequent commit.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/gitremote-helpers.txt b/Documentation/gitremote-helpers.txt
index 4a584f3c5d7e40fc5a8a1e5c68a63e8156bdcd64..4b8c93ec59de3db02b9914aed4955d486be5f875 100644 (file)
--- a/Documentation/gitremote-helpers.txt
+++ b/Documentation/gitremote-helpers.txt
@@ -466,6 +466,13 @@ set by Git if the remote helper has the 'option' capability.
        Transmit <string> as a push option. As the push option
        must not contain LF or NUL characters, the string is not encoded.
 
+'option from-promisor' {'true'|'false'}::
+       Indicate that these objects are being fetched from a promisor.
+
+'option no-dependents' {'true'|'false'}::
+       Indicate that only the objects wanted need to be fetched, not
+       their dependents.
+
 SEE ALSO
 --------
 linkgit:git-remote[1]

diff --git a/Makefile b/Makefile
index ca378a4603d0eb31d1daed3250e231af31c5cc5a..795e0c7cb581a66b24b64ed0beec87e408027b74 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -792,6 +792,7 @@ LIB_OBJS += ewah/ewah_bitmap.o
 LIB_OBJS += ewah/ewah_io.o
 LIB_OBJS += ewah/ewah_rlw.o
 LIB_OBJS += exec_cmd.o
+LIB_OBJS += fetch-object.o
 LIB_OBJS += fetch-pack.o
 LIB_OBJS += fsck.o
 LIB_OBJS += gettext.o

diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 366b9d13f929b7d299a31d9c53fb643220fe64e3..02abe7211e193a3c0764ef23f2fad0a16840d5d3 100644 (file)
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -143,6 +143,14 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
                        args.update_shallow = 1;
                        continue;
                }
+               if (!strcmp("--from-promisor", arg)) {
+                       args.from_promisor = 1;
+                       continue;
+               }
+               if (!strcmp("--no-dependents", arg)) {
+                       args.no_dependents = 1;
+                       continue;
+               }
                usage(fetch_pack_usage);
        }
        if (deepen_not.nr)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 4f305a704c376ac18fe3936314315cb21adb2364..24c2f05cc02d3cdff6dabb248cc5185b73eec557 100644 (file)
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1429,14 +1429,16 @@ static void write_special_file(const char *suffix, const char *msg,
                if (close(fd) != 0)
                        die_errno(_("cannot close written %s file '%s'"),
                                  suffix, filename);
-               *report = suffix;
+               if (report)
+                       *report = suffix;
        }
        strbuf_release(&name_buf);
 }
 
 static void final(const char *final_pack_name, const char *curr_pack_name,
                  const char *final_index_name, const char *curr_index_name,
-                 const char *keep_msg, unsigned char *sha1)
+                 const char *keep_msg, const char *promisor_msg,
+                 unsigned char *sha1)
 {
        const char *report = "pack";
        struct strbuf pack_name = STRBUF_INIT;
@@ -1455,6 +1457,9 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
        if (keep_msg)
                write_special_file("keep", keep_msg, final_pack_name, sha1,
                                   &report);
+       if (promisor_msg)
+               write_special_file("promisor", promisor_msg, final_pack_name,
+                                  sha1, NULL);
 
        if (final_pack_name != curr_pack_name) {
                if (!final_pack_name)
@@ -1644,6 +1649,7 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
        const char *curr_index;
        const char *index_name = NULL, *pack_name = NULL;
        const char *keep_msg = NULL;
+       const char *promisor_msg = NULL;
        struct strbuf index_name_buf = STRBUF_INIT;
        struct pack_idx_entry **idx_objects;
        struct pack_idx_option opts;
@@ -1693,6 +1699,10 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
                                keep_msg = "";
                        } else if (starts_with(arg, "--keep=")) {
                                keep_msg = arg + 7;
+                       } else if (!strcmp(arg, "--promisor")) {
+                               promisor_msg = "";
+                       } else if (starts_with(arg, "--promisor=")) {
+                               promisor_msg = arg + strlen("--promisor=");
                        } else if (starts_with(arg, "--threads=")) {
                                char *end;
                                nr_threads = strtoul(arg+10, &end, 0);
@@ -1803,7 +1813,7 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
        if (!verify)
                final(pack_name, curr_pack,
                      index_name, curr_index,
-                     keep_msg,
+                     keep_msg, promisor_msg,
                      pack_sha1);
        else
                close(input_fd);

diff --git a/fetch-object.c b/fetch-object.c
new file mode 100644 (file)
index 0000000..08e91ce
--- /dev/null
+++ b/fetch-object.c
@@ -0,0 +1,24 @@
+#include "cache.h"
+#include "packfile.h"
+#include "pkt-line.h"
+#include "strbuf.h"
+#include "transport.h"
+#include "fetch-object.h"
+
+void fetch_object(const char *remote_name, const unsigned char *sha1)
+{
+       struct remote *remote;
+       struct transport *transport;
+       struct ref *ref;
+
+       remote = remote_get(remote_name);
+       if (!remote->url[0])
+               die(_("Remote with no URL"));
+       transport = transport_get(remote, remote->url[0]);
+
+       ref = alloc_ref(sha1_to_hex(sha1));
+       hashcpy(ref->old_oid.hash, sha1);
+       transport_set_option(transport, TRANS_OPT_FROM_PROMISOR, "1");
+       transport_set_option(transport, TRANS_OPT_NO_DEPENDENTS, "1");
+       transport_fetch_refs(transport, ref);
+}

diff --git a/fetch-object.h b/fetch-object.h
new file mode 100644 (file)
index 0000000..f371300
--- /dev/null
+++ b/fetch-object.h
@@ -0,0 +1,6 @@
+#ifndef FETCH_OBJECT_H
+#define FETCH_OBJECT_H
+
+extern void fetch_object(const char *remote_name, const unsigned char *sha1);
+
+#endif

diff --git a/fetch-pack.c b/fetch-pack.c
index 008b25d3db08726b0fc1569f88fba76694bbcc12..0798e0b8b28538963c7dcd1d3f0bc50350ed531c 100644 (file)
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -450,6 +450,8 @@ static int find_common(struct fetch_pack_args *args,
 
        flushes = 0;
        retval = -1;
+       if (args->no_dependents)
+               goto done;
        while ((oid = get_rev())) {
                packet_buf_write(&req_buf, "have %s\n", oid_to_hex(oid));
                print_verbose(args, "have %s", oid_to_hex(oid));
@@ -734,29 +736,31 @@ static int everything_local(struct fetch_pack_args *args,
                }
        }
 
-       if (!args->deepen) {
-               for_each_ref(mark_complete_oid, NULL);
-               for_each_cached_alternate(mark_alternate_complete);
-               commit_list_sort_by_date(&complete);
-               if (cutoff)
-                       mark_recent_complete_commits(args, cutoff);
-       }
+       if (!args->no_dependents) {
+               if (!args->deepen) {
+                       for_each_ref(mark_complete_oid, NULL);
+                       for_each_cached_alternate(mark_alternate_complete);
+                       commit_list_sort_by_date(&complete);
+                       if (cutoff)
+                               mark_recent_complete_commits(args, cutoff);
+               }
 
-       /*
-        * Mark all complete remote refs as common refs.
-        * Don't mark them common yet; the server has to be told so first.
-        */
-       for (ref = *refs; ref; ref = ref->next) {
-               struct object *o = deref_tag(lookup_object(ref->old_oid.hash),
-                                            NULL, 0);
+               /*
+                * Mark all complete remote refs as common refs.
+                * Don't mark them common yet; the server has to be told so first.
+                */
+               for (ref = *refs; ref; ref = ref->next) {
+                       struct object *o = deref_tag(lookup_object(ref->old_oid.hash),
+                                                    NULL, 0);
 
-               if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
-                       continue;
+                       if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
+                               continue;
 
-               if (!(o->flags & SEEN)) {
-                       rev_list_push((struct commit *)o, COMMON_REF | SEEN);
+                       if (!(o->flags & SEEN)) {
+                               rev_list_push((struct commit *)o, COMMON_REF | SEEN);
 
-                       mark_common((struct commit *)o, 1, 1);
+                               mark_common((struct commit *)o, 1, 1);
+                       }
                }
        }
 
@@ -832,7 +836,7 @@ static int get_pack(struct fetch_pack_args *args,
                argv_array_push(&cmd.args, alternate_shallow_file);
        }
 
-       if (do_keep) {
+       if (do_keep || args->from_promisor) {
                if (pack_lockfile)
                        cmd.out = -1;
                cmd_name = "index-pack";
@@ -842,7 +846,7 @@ static int get_pack(struct fetch_pack_args *args,
                        argv_array_push(&cmd.args, "-v");
                if (args->use_thin_pack)
                        argv_array_push(&cmd.args, "--fix-thin");
-               if (args->lock_pack || unpack_limit) {
+               if (do_keep && (args->lock_pack || unpack_limit)) {
                        char hostname[HOST_NAME_MAX + 1];
                        if (xgethostname(hostname, sizeof(hostname)))
                                xsnprintf(hostname, sizeof(hostname), "localhost");
@@ -852,6 +856,8 @@ static int get_pack(struct fetch_pack_args *args,
                }
                if (args->check_self_contained_and_connected)
                        argv_array_push(&cmd.args, "--check-self-contained-and-connected");
+               if (args->from_promisor)
+                       argv_array_push(&cmd.args, "--promisor");
        }
        else {
                cmd_name = "unpack-objects";

diff --git a/fetch-pack.h b/fetch-pack.h
index b6aeb43a8e21437581e0e834e77754922f8c6ee9..aeac1526445efdbe0c639056e3a4175ab3a697e9 100644 (file)
--- a/fetch-pack.h
+++ b/fetch-pack.h
@@ -29,6 +29,14 @@ struct fetch_pack_args {
        unsigned cloning:1;
        unsigned update_shallow:1;
        unsigned deepen:1;
+       unsigned from_promisor:1;
+
+       /*
+        * If 1, fetch_pack() will also not modify any object flags.
+        * This allows fetch_pack() to safely be called by any function,
+        * regardless of which object flags it uses (if any).
+        */
+       unsigned no_dependents:1;
 };
 
 /*

diff --git a/remote-curl.c b/remote-curl.c
index 0053b09549ab419ab8f2da2c519d689f5e0d83b3..431839111a9594174c6648d883f43eea9de89128 100644 (file)
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -33,7 +33,9 @@ struct options {
                thin : 1,
                /* One of the SEND_PACK_PUSH_CERT_* constants. */
                push_cert : 2,
-               deepen_relative : 1;
+               deepen_relative : 1,
+               from_promisor : 1,
+               no_dependents : 1;
 };
 static struct options options;
 static struct string_list cas_options = STRING_LIST_INIT_DUP;
@@ -157,6 +159,12 @@ static int set_option(const char *name, const char *value)
                        return -1;
                return 0;
 #endif /* LIBCURL_VERSION_NUM >= 0x070a08 */
+       } else if (!strcmp(name, "from-promisor")) {
+               options.from_promisor = 1;
+               return 0;
+       } else if (!strcmp(name, "no-dependents")) {
+               options.no_dependents = 1;
+               return 0;
        } else {
                return 1 /* unsupported */;
        }
@@ -822,6 +830,10 @@ static int fetch_git(struct discovery *heads,
                                 options.deepen_not.items[i].string);
        if (options.deepen_relative && options.depth)
                argv_array_push(&args, "--deepen-relative");
+       if (options.from_promisor)
+               argv_array_push(&args, "--from-promisor");
+       if (options.no_dependents)
+               argv_array_push(&args, "--no-dependents");
        argv_array_push(&args, url.buf);
 
        for (i = 0; i < nr_heads; i++) {

diff --git a/transport.c b/transport.c
index f1e2f61991424f3314158676754f6b8d305a31f2..f2fbc6f968c6ccca40204db951bcff358e6ef301 100644 (file)
--- a/transport.c
+++ b/transport.c
@@ -160,6 +160,12 @@ static int set_git_option(struct git_transport_options *opts,
        } else if (!strcmp(name, TRANS_OPT_DEEPEN_RELATIVE)) {
                opts->deepen_relative = !!value;
                return 0;
+       } else if (!strcmp(name, TRANS_OPT_FROM_PROMISOR)) {
+               opts->from_promisor = !!value;
+               return 0;
+       } else if (!strcmp(name, TRANS_OPT_NO_DEPENDENTS)) {
+               opts->no_dependents = !!value;
+               return 0;
        }
        return 1;
 }
@@ -228,6 +234,8 @@ static int fetch_refs_via_pack(struct transport *transport,
                data->options.check_self_contained_and_connected;
        args.cloning = transport->cloning;
        args.update_shallow = data->options.update_shallow;
+       args.from_promisor = data->options.from_promisor;
+       args.no_dependents = data->options.no_dependents;
 
        if (!data->got_remote_heads) {
                connect_setup(transport, 0);

diff --git a/transport.h b/transport.h
index bc5571574b67803249567bcee501dfcc342b0b0f..c49a8edc537cf9d829aa4b8108737529acf61807 100644 (file)
--- a/transport.h
+++ b/transport.h
@@ -15,6 +15,8 @@ struct git_transport_options {
        unsigned self_contained_and_connected : 1;
        unsigned update_shallow : 1;
        unsigned deepen_relative : 1;
+       unsigned from_promisor : 1;
+       unsigned no_dependents : 1;
        int depth;
        const char *deepen_since;
        const struct string_list *deepen_not;
@@ -210,6 +212,15 @@ void transport_check_allowed(const char *type);
 /* Send push certificates */
 #define TRANS_OPT_PUSH_CERT "pushcert"
 
+/* Indicate that these objects are being fetched by a promisor */
+#define TRANS_OPT_FROM_PROMISOR "from-promisor"
+
+/*
+ * Indicate that only the objects wanted need to be fetched, not their
+ * dependents
+ */
+#define TRANS_OPT_NO_DEPENDENTS "no-dependents"
+
 /**
  * Returns 0 if the option was used, non-zero otherwise. Prints a
  * message to stderr if the option is not used.