[PATCH v3 0/5] Introduce a "promisor-remote" capability
- From
Christian Couder <christian.couder@gmail.com>
- Date
- Dec 6, 2024, 12:42 UTC
- Message-ID
- <20241206124248.160494-1-christian.couder@gmail.com>
- In-Reply-To
- <20240910163000.1985723-1-christian.couder@gmail.com>
This work is part of some effort to better handle large files/blobs in a client-server context using promisor remotes dedicated to storing large blobs. To help understand this effort, this series now contains a patch (patch 5/5) that adds design documentation about this effort.
Earlier this year, I sent 3 versions of a patch series with the goal of allowing a client C to clone from a server S while using the same promisor remote X that S already use. See:
https://lore.kernel.org/git/20240418184043.2900955-1-christian.couder@gmail.com/
Junio suggested to implement that feature using:
"a protocol extension that lets S tell C that S wants C to fetch missing objects from X (which means that if C knows about X in its ".git/config" then there is no need for end-user interaction at all), or a protocol extension that C tells S that C is willing to see objects available from X omitted when S does not have them (again, this could be done by looking at ".git/config" at C, but there may be security implications???)"
This patch series implements that protocol extension called "promisor-remote" (that name is open to change or simplification) which allows S and C to agree on C using X directly or not.
I have tried to implement it in a quite generic way that could allow S and C to share more information about promisor remotes and how to use them.
For now, C doesn't use the information it gets from S when cloning. That information is only used to decide if C is OK to use the promisor remotes advertised by S. But this could change in the future which could make it much simpler for clients than using the current way of passing information about X with the `-c` option of `git clone` many times on the command line.
Another improvement could be to not require GIT_NO_LAZY_FETCH=0 when S and C have agreed on using S.
Changes compared to version 2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Summary of the changes: there are few changes in the C code, but a numberof them in the tests, and a new design doc.
- To avoid conflicts and benefit from recent improvements (like leak
checks) this series has been rebased to a recent master:
23692e08c6 (The thirteenth batch, 2024-12-04) - In patch 3/5, some functions are not passed a
`struct repository *repo` argument anymore as this argument is only used
in patch 4/5, so it's better to introduce it in that patch. - In patch 3/5, a memory leak was fixed using
git_config_get_string_tmp() instead of git_config_get_string() as
suggested by Patrick. - In patch 3/5, a number of tests using `git fetch` are added. This
is why there are a number of other refactorings and improvements
in the tests described in some points below. - In patch 3/5, some tests using `git clone` had a title that used
"fetch" instead of "clone". This has been corrected. - In patch 3/5, the test helper function initialize_server() now
takes 2 arguments to make it more generic. - In patch 3/5, a new copy_to_server2() test helper function has
been introduced. - In patch 3/5, a test repacking with a filter was writting outside
the test directory which has been corrected using
`--filter-to="$(pwd)/pack"`. - In patch 3/5, a test was using `touch "$promisor_file"`. This was
replaced with `>"$promisor_file"`. - In patch 4/5, some functions are now passed a
`struct repository *repo` argument. This is related to the
corresponding change in patch 3/5 that removed this argument. - In patch 4/5, some tests using `git clone` had a title that used
"fetch" instead of "clone". This has been corrected (in the same
way as in patch 3/5). - Patch 5/5 is new. It adds design documentation that could help
understand the broader context of this patch series, as this was
requested by some reviewers. This patch is optional. I am OK with
removing it or discussing it as a single separate patch.Thanks to Junio, Patrick, Eric and Taylor for their suggestions.
CI tests ~~~~~~~~
https://github.com/chriscool/git/actions/runs/12197064528
Unfortunately some tests (linux-sha256, linux-reftable, linux-gcc and linux-gcc-default) failed after around 46 minutes as the dependencies couldn't be intalled.
One test, linux-TEST-vars, failed much earlier, in what doesn't look like a CI issue as I could reproduce the failure locally when setting GIT_TEST_MULTI_PACK_INDEX_WRITE_INCREMENTAL to 1. I will investigate, but in the meantime I think I can send this as-is so we can start discussing.
Range diff compared to version 2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1: 0d9d094181 = 1: 13dd730641 version: refactor strbuf_sanitize()
2: fc53229eff = 2: 8f2aecf6a1 strbuf: refactor strbuf_trim_trailing_ch()
3: 5c507e427f ! 3: 57e1481bc4 Add 'promisor-remote' capability to protocol v2
@@ promisor-remote.c: void promisor_remote_get_direct(struct repository *repo,
+ BUG("Unhandled 'enum accept_promisor' value '%d'", accept);
+}
+
-+static void filter_promisor_remote(struct repository *repo,
-+ struct strvec *accepted,
-+ const char *info)
++static void filter_promisor_remote(struct strvec *accepted, const char *info)
+{
+ struct strbuf **remotes;
-+ char *accept_str;
++ const char *accept_str;
+ enum accept_promisor accept = ACCEPT_NONE;
+
-+ if (!git_config_get_string("promisor.acceptfromserver", &accept_str)) {
++ if (!git_config_get_string_tmp("promisor.acceptfromserver", &accept_str)) {
+ if (!accept_str || !*accept_str || !strcasecmp("None", accept_str))
+ accept = ACCEPT_NONE;
+ else if (!strcasecmp("All", accept_str))
@@ promisor-remote.c: void promisor_remote_get_direct(struct repository *repo,
+ free(decoded_url);
+ }
+
-+ free(accept_str);
+ strbuf_list_free(remotes);
+}
+
@@ promisor-remote.c: void promisor_remote_get_direct(struct repository *repo,
+ struct strvec accepted = STRVEC_INIT;
+ struct strbuf reply = STRBUF_INIT;
+
-+ filter_promisor_remote(the_repository, &accepted, info);
++ filter_promisor_remote(&accepted, info);
+
+ if (!accepted.nr)
+ return NULL;
@@ t/t5710-promisor-remote-capability.sh (new)
+ git -C "$1" rev-list --objects --all --missing=print > all.txt &&
+ perl -ne 'print if s/^[?]//' all.txt >missing.txt &&
+ test_line_count = "$2" missing.txt &&
-+ test "$3" = "$(cat missing.txt)"
++ if test "$2" -lt 2
++ then
++ test "$3" = "$(cat missing.txt)"
++ else
++ test -f "$3" &&
++ sort <"$3" >expected_sorted &&
++ sort <missing.txt >actual_sorted &&
++ test_cmp expected_sorted actual_sorted
++ fi
+}
+
+initialize_server () {
++ count="$1"
++ missing_oids="$2"
++
+ # Repack everything first
+ git -C server -c repack.writebitmaps=false repack -a -d &&
+
@@ t/t5710-promisor-remote-capability.sh (new)
+
+ # Repack without the largest object and create a promisor pack on server
+ git -C server -c repack.writebitmaps=false repack -a -d \
-+ --filter=blob:limit=5k --filter-to="$(pwd)" &&
++ --filter=blob:limit=5k --filter-to="$(pwd)/pack" &&
+ promisor_file=$(ls server/objects/pack/*.pack | sed "s/\.pack/.promisor/") &&
-+ touch "$promisor_file" &&
++ >"$promisor_file" &&
+
-+ # Check that only one object is missing on the server
-+ check_missing_objects server 1 "$oid"
++ # Check objects missing on the server
++ check_missing_objects server "$count" "$missing_oids"
++}
++
++copy_to_server2 () {
++ oid_path="$(test_oid_to_path $1)" &&
++ path="server/objects/$oid_path" &&
++ path2="server2/objects/$oid_path" &&
++ mkdir -p $(dirname "$path2") &&
++ cp "$path" "$path2"
+}
+
+test_expect_success "setup for testing promisor remote advertisement" '
@@ t/t5710-promisor-remote-capability.sh (new)
+ # Copy the largest object from server to server2
+ obj="HEAD:foo" &&
+ oid="$(git -C server rev-parse $obj)" &&
-+ oid_path="$(test_oid_to_path $oid)" &&
-+ path="server/objects/$oid_path" &&
-+ path2="server2/objects/$oid_path" &&
-+ mkdir -p $(dirname "$path2") &&
-+ cp "$path" "$path2" &&
++ copy_to_server2 "$oid" &&
+
-+ initialize_server &&
++ initialize_server 1 "$oid" &&
+
+ # Configure server2 as promisor remote for server
+ git -C server remote add server2 "file://$(pwd)/server2" &&
@@ t/t5710-promisor-remote-capability.sh (new)
+ git -C server config uploadpack.allowAnySHA1InWant true
+'
+
-+test_expect_success "fetch with promisor.advertise set to 'true'" '
++test_expect_success "clone with promisor.advertise set to 'true'" '
+ git -C server config promisor.advertise true &&
+
+ # Clone from server to create a client
@@ t/t5710-promisor-remote-capability.sh (new)
+ check_missing_objects server 1 "$oid"
+'
+
-+test_expect_success "fetch with promisor.advertise set to 'false'" '
++test_expect_success "clone with promisor.advertise set to 'false'" '
+ git -C server config promisor.advertise false &&
+
+ # Clone from server to create a client
@@ t/t5710-promisor-remote-capability.sh (new)
+ check_missing_objects server 0 "" &&
+
+ # Reinitialize server so that the largest object is missing again
-+ initialize_server
++ initialize_server 1 "$oid"
+'
+
-+test_expect_success "fetch with promisor.acceptfromserver set to 'None'" '
++test_expect_success "clone with promisor.acceptfromserver set to 'None'" '
+ git -C server config promisor.advertise true &&
+
+ # Clone from server to create a client
@@ t/t5710-promisor-remote-capability.sh (new)
+ test_when_finished "rm -rf client" &&
+
+ # Check that the largest object is not missing on the server
-+ check_missing_objects server 0 ""
++ check_missing_objects server 0 "" &&
++
++ # Reinitialize server so that the largest object is missing again
++ initialize_server 1 "$oid"
++'
++
++test_expect_success "init + fetch with promisor.advertise set to 'true'" '
++ git -C server config promisor.advertise true &&
++
++ test_when_finished "rm -rf client" &&
++ mkdir client &&
++ git -C client init &&
++ git -C client config remote.server2.promisor true &&
++ git -C client config remote.server2.fetch "+refs/heads/*:refs/remotes/server2/*" &&
++ git -C client config remote.server2.url "file://$(pwd)/server2" &&
++ git -C client config remote.server.url "file://$(pwd)/server" &&
++ git -C client config remote.server.fetch "+refs/heads/*:refs/remotes/server/*" &&
++ git -C client config promisor.acceptfromserver All &&
++ GIT_NO_LAZY_FETCH=0 git -C client fetch --filter="blob:limit=5k" server &&
++
++ # Check that the largest object is still missing on the server
++ check_missing_objects server 1 "$oid"
++'
++
++test_expect_success "clone with promisor.advertise set to 'true' but don't delete the client" '
++ git -C server config promisor.advertise true &&
++
++ # Clone from server to create a client
++ GIT_NO_LAZY_FETCH=0 git clone -c remote.server2.promisor=true \
++ -c remote.server2.fetch="+refs/heads/*:refs/remotes/server2/*" \
++ -c remote.server2.url="file://$(pwd)/server2" \
++ -c promisor.acceptfromserver=All \
++ --no-local --filter="blob:limit=5k" server client &&
++
++ # Check that the largest object is still missing on the server
++ check_missing_objects server 1 "$oid"
++'
++
++test_expect_success "setup for subsequent fetches" '
++ # Generate new commit with large blob
++ test-tool genrandom bar 10240 >template/bar &&
++ git -C template add bar &&
++ git -C template commit -m bar &&
++
++ # Fetch new commit with large blob
++ git -C server fetch origin &&
++ git -C server update-ref HEAD FETCH_HEAD &&
++ git -C server rev-parse HEAD >expected_head &&
++
++ # Repack everything twice and remove .promisor files before
++ # each repack. This makes sure everything gets repacked
++ # into a single packfile. The second repack is necessary
++ # because the first one fetches from server2 and creates a new
++ # packfile and its associated .promisor file.
++
++ rm -f server/objects/pack/*.promisor &&
++ git -C server -c repack.writebitmaps=false repack -a -d &&
++ rm -f server/objects/pack/*.promisor &&
++ git -C server -c repack.writebitmaps=false repack -a -d &&
++
++ # Unpack everything
++ rm pack-* &&
++ mv server/objects/pack/pack-* . &&
++ packfile=$(ls pack-*.pack) &&
++ git -C server unpack-objects --strict <"$packfile" &&
++
++ # Copy new large object to server2
++ obj_bar="HEAD:bar" &&
++ oid_bar="$(git -C server rev-parse $obj_bar)" &&
++ copy_to_server2 "$oid_bar" &&
++
++ # Reinitialize server so that the 2 largest objects are missing
++ printf "%s\n" "$oid" "$oid_bar" >expected_missing.txt &&
++ initialize_server 2 expected_missing.txt &&
++
++ # Create one more client
++ cp -r client client2
++'
++
++test_expect_success "subsequent fetch from a client when promisor.advertise is true" '
++ git -C server config promisor.advertise true &&
++
++ GIT_NO_LAZY_FETCH=0 git -C client pull origin &&
++
++ git -C client rev-parse HEAD >actual &&
++ test_cmp expected_head actual &&
++
++ cat client/bar >/dev/null &&
++
++ check_missing_objects server 2 expected_missing.txt
++'
++
++test_expect_success "subsequent fetch from a client when promisor.advertise is false" '
++ git -C server config promisor.advertise false &&
++
++ GIT_NO_LAZY_FETCH=0 git -C client2 pull origin &&
++
++ git -C client2 rev-parse HEAD >actual &&
++ test_cmp expected_head actual &&
++
++ cat client2/bar >/dev/null &&
++
++ check_missing_objects server 1 "$oid"
+'
+
+test_done
4: 1c2794f139 ! 4: 7fcc619e41 promisor-remote: check advertised name or URL
@@ promisor-remote.c: char *promisor_remote_info(struct repository *repo)
+ return 0;
}
- static void filter_promisor_remote(struct repository *repo,
-@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
+-static void filter_promisor_remote(struct strvec *accepted, const char *info)
++static void filter_promisor_remote(struct repository *repo,
++ struct strvec *accepted,
++ const char *info)
+ {
struct strbuf **remotes;
- char *accept_str;
+ const char *accept_str;
enum accept_promisor accept = ACCEPT_NONE;
+ struct strvec names = STRVEC_INIT;
+ struct strvec urls = STRVEC_INIT;
- if (!git_config_get_string("promisor.acceptfromserver", &accept_str)) {
+ if (!git_config_get_string_tmp("promisor.acceptfromserver", &accept_str)) {
if (!accept_str || !*accept_str || !strcasecmp("None", accept_str))
accept = ACCEPT_NONE;
+ else if (!strcasecmp("KnownUrl", accept_str))
@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
else if (!strcasecmp("All", accept_str))
accept = ACCEPT_ALL;
else
-@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
+@@ promisor-remote.c: static void filter_promisor_remote(struct strvec *accepted, const char *info)
if (accept == ACCEPT_NONE)
return;
@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
/* Parse remote info received */
remotes = strbuf_split_str(info, ';', 0);
-@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
+@@ promisor-remote.c: static void filter_promisor_remote(struct strvec *accepted, const char *info)
if (remote_url)
decoded_url = url_percent_decode(remote_url);
@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
strvec_push(accepted, decoded_name);
strbuf_list_free(elems);
-@@ promisor-remote.c: static void filter_promisor_remote(struct repository *repo,
+@@ promisor-remote.c: static void filter_promisor_remote(struct strvec *accepted, const char *info)
+ free(decoded_url);
}
- free(accept_str);
+ strvec_clear(&names);
+ strvec_clear(&urls);
strbuf_list_free(remotes);
}
+@@ promisor-remote.c: char *promisor_remote_reply(const char *info)
+ struct strvec accepted = STRVEC_INIT;
+ struct strbuf reply = STRBUF_INIT;
+
+- filter_promisor_remote(&accepted, info);
++ filter_promisor_remote(the_repository, &accepted, info);
+
+ if (!accepted.nr)
+ return NULL;
## t/t5710-promisor-remote-capability.sh ##
-@@ t/t5710-promisor-remote-capability.sh: test_expect_success "fetch with promisor.acceptfromserver set to 'None'" '
- --no-local --filter="blob:limit=5k" server client &&
- test_when_finished "rm -rf client" &&
+@@ t/t5710-promisor-remote-capability.sh: test_expect_success "init + fetch with promisor.advertise set to 'true'" '
+ check_missing_objects server 1 "$oid"
+ '
-+ # Check that the largest object is not missing on the server
-+ check_missing_objects server 0 "" &&
-+
-+ # Reinitialize server so that the largest object is missing again
-+ initialize_server
-+'
-+
-+test_expect_success "fetch with promisor.acceptfromserver set to 'KnownName'" '
++test_expect_success "clone with promisor.acceptfromserver set to 'KnownName'" '
+ git -C server config promisor.advertise true &&
+
+ # Clone from server to create a client
@@ t/t5710-promisor-remote-capability.sh: test_expect_success "fetch with promisor.
+ check_missing_objects server 1 "$oid"
+'
+
-+test_expect_success "fetch with 'KnownName' and different remote names" '
++test_expect_success "clone with 'KnownName' and different remote names" '
+ git -C server config promisor.advertise true &&
+
+ # Clone from server to create a client
@@ t/t5710-promisor-remote-capability.sh: test_expect_success "fetch with promisor.
+ check_missing_objects server 0 "" &&
+
+ # Reinitialize server so that the largest object is missing again
-+ initialize_server
++ initialize_server 1 "$oid"
+'
+
-+test_expect_success "fetch with promisor.acceptfromserver set to 'KnownUrl'" '
++test_expect_success "clone with promisor.acceptfromserver set to 'KnownUrl'" '
+ git -C server config promisor.advertise true &&
+
+ # Clone from server to create a client
@@ t/t5710-promisor-remote-capability.sh: test_expect_success "fetch with promisor.
+ check_missing_objects server 1 "$oid"
+'
+
-+test_expect_success "fetch with 'KnownUrl' and different remote urls" '
++test_expect_success "clone with 'KnownUrl' and different remote urls" '
+ ln -s server2 serverTwo &&
+
+ git -C server config promisor.advertise true &&
@@ t/t5710-promisor-remote-capability.sh: test_expect_success "fetch with promisor.
+ --no-local --filter="blob:limit=5k" server client &&
+ test_when_finished "rm -rf client" &&
+
- # Check that the largest object is not missing on the server
- check_missing_objects server 0 ""
- '
++ # Check that the largest object is not missing on the server
++ check_missing_objects server 0 "" &&
++
++ # Reinitialize server so that the largest object is missing again
++ initialize_server 1 "$oid"
++'
++
+ test_expect_success "clone with promisor.advertise set to 'true' but don't delete the client" '
+ git -C server config promisor.advertise true &&
+
-: ---------- > 5: c25c94707f doc: add technical design doc for large object promisorsChristian Couder (5): version: refactor strbuf_sanitize() strbuf: refactor strbuf_trim_trailing_ch() Add 'promisor-remote' capability to protocol v2 promisor-remote: check advertised name or URL doc: add technical design doc for large object promisors
Documentation/config/promisor.txt | 27 + Documentation/gitprotocol-v2.txt | 54 ++ .../technical/large-object-promisors.txt | 530 ++++++++++++++++++ connect.c | 9 + promisor-remote.c | 243 ++++++++ promisor-remote.h | 36 +- serve.c | 26 + strbuf.c | 16 + strbuf.h | 10 + t/t5710-promisor-remote-capability.sh | 309 ++++++++++ trace2/tr2_cfg.c | 10 +- upload-pack.c | 3 + version.c | 9 +- 13 files changed, 1266 insertions(+), 16 deletions(-) create mode 100644 Documentation/technical/large-object-promisors.txt create mode 100755 t/t5710-promisor-remote-capability.sh
-- 2.47.1.402.gc25c94707f