[PATCH v3 1/4] bundle-uri: verify oid before writing refs
- From
- Xing Xin via GitGitGadget <gitgitgadget@gmail.com>
- Date
- May 27, 2024, 15:41 UTC
- Message-ID
- <8f488a5eeaaa0cdb525c34c2c165e6ee74ee7691.1716824518.git.gitgitgadget@gmail.com>
- In-Reply-To
- <pull.1730.v3.git.1716824518.gitgitgadget@gmail.com>
From: Xing Xin <xingxin.xx@bytedance.com>
When using the bundle-uri mechanism with a bundle list containing multiple interrelated bundles, we encountered a bug where tips from downloaded bundles were not discovered, thus resulting in rather slow clones. This was particularly problematic when employing the heuristic `creationTokens`.
And this is easy to reproduce. Suppose we have a repository with a single branch `main` pointing to commit `A`, firstly we create a base bundle with
git bundle create base.bundle main
Then let's add a new commit `B` on top of `A`, so that an incremental bundle for `main` can be created with
git bundle create incr.bundle A..main
Now we can generate a bundle list with the following content:
[bundle]
version = 1
mode = all
heuristic = creationToken [bundle "base"]
uri = base.bundle
creationToken = 1 [bundle "incr"]
uri = incr.bundle
creationToken = 2A fresh clone with the bundle list above would give the expected `refs/bundles/main` pointing at `B` in new repository, in other words we already had everything locally from the bundles, but git would still download everything from server as if we got nothing.
So why the `refs/bundles/main` is not discovered? After some digging I found that:
1. Bundles in bundle list are downloaded to local files via `download_bundle_list` or via `fetch_bundles_by_token` for the creationToken heuristic case. 2. Then it tries to unbundle each bundle via `unbundle_from_file`, which is called by `unbundle_all_bundles` or called within `fetch_bundles_by_token` for the creationToken heuristic case. 3. Here, we first read the bundle header to get all the prerequisites for the bundle, this is done in `read_bundle_header`. 4. Then we call `unbundle`, which calls `verify_bundle` to ensure that the repository does indeed contain the prerequisites mentioned in the bundle. 5. The `verify_bundle` will call `parse_object`, within which the `prepare_packed_git` or `reprepare_packed_git` is eventually called, which means that the `raw_object_store->packed_git` data gets filled in and ``packed_git_initialized` is set. This also means consecutive calls to `prepare_packed_git` doesn't re-initiate `raw_object_store->packed_git` since `packed_git_initialized` already is set. 6. If `unbundle` succeeds, it writes some refs via `refs_update_ref` with `REF_SKIP_OID_VERIFICATION` set. So the bundle refs which can target arbitrary objects are written to the repository. 7. Finally in `do_fetch_pack_v2`, `mark_complete_and_common_ref` and `mark_tips` are called with `OBJECT_INFO_QUICK` set to find local tips. Here it won't call `reprepare_packed_git` anymore so it would fail to parse oids that only reside in the last bundle.
Back to the example above, when unbunding `incr.bundle`, `base.pack` is enlisted to `packed_git` bacause of the prerequisites to verify. While we can not find `B` for negotiation at a latter time because `B` exists in `incr.pack` which is not enlisted in `packed_git`.
This commit fixes this bug by dropping the `REF_SKIP_OID_VERIFICATION` flag when writing bundle refs, so we can:
1. Ensure that the bundle refs we are writing are pointing to valid objects. 2. Ensure all the tips from bundle refs can be correctly parsed.
And a set of negotiation related tests for bundle-uri are added.
Signed-off-by: Xing Xin <xingxin.xx@bytedance.com> --- bundle-uri.c | 3 +- t/t5558-clone-bundle-uri.sh | 129 ++++++++++++++++++++++++++++++++++++ 2 files changed, 130 insertions(+), 2 deletions(-)
diff --git a/bundle-uri.c b/bundle-uri.c index 91b3319a5c1..65666a11d9c 100644 --- a/bundle-uri.c +++ b/bundle-uri.c @@ -400,8 +400,7 @@ static int unbundle_from_file(struct repository *r, const char *file) refs_update_ref(get_main_ref_store(the_repository), "fetched bundle", bundle_ref.buf, oid, has_old ? &old_oid : NULL, - REF_SKIP_OID_VERIFICATION, - UPDATE_REFS_MSG_ON_ERR); + 0, UPDATE_REFS_MSG_ON_ERR); } bundle_header_release(&header); diff --git a/t/t5558-clone-bundle-uri.sh b/t/t5558-clone-bundle-uri.sh index 1ca5f745e73..a5b04d6f187 100755 --- a/t/t5558-clone-bundle-uri.sh +++ b/t/t5558-clone-bundle-uri.sh @@ -20,7 +20,10 @@ test_expect_success 'fail to clone from non-bundle file' ' test_expect_success 'create bundle' ' git init clone-from && git -C clone-from checkout -b topic && + test_commit -C clone-from A && + git -C clone-from bundle create A.bundle topic && + test_commit -C clone-from B && git -C clone-from bundle create B.bundle topic ' @@ -259,6 +262,132 @@ test_expect_success 'clone bundle list (file, any mode, all failures)' ' ! grep "refs/bundles/" refs ' +######################################################################### +# Clone negotiation related tests begin here + +test_expect_success 'negotiation: bundle with part of wanted commits' ' + test_when_finished rm -rf trace*.txt && + GIT_TRACE_PACKET="$(pwd)/trace-packet.txt" \ + git clone --no-local --bundle-uri="clone-from/A.bundle" \ + clone-from nego-bundle-part && + git -C nego-bundle-part for-each-ref --format="%(refname)" >refs && + grep "refs/bundles/" refs >actual && + cat >expect <<-\EOF && + refs/bundles/topic + EOF + test_cmp expect actual && + # Ensure that refs/bundles/topic are sent as "have". + grep "clone> have $(git -C clone-from rev-parse A)" trace-packet.txt +' + +test_expect_success 'negotiation: bundle with all wanted commits' ' + test_when_finished rm -rf trace*.txt && + GIT_TRACE_PACKET="$(pwd)/trace-packet.txt" \ + git clone --no-local --single-branch --branch=topic --no-tags \ + --bundle-uri="clone-from/B.bundle" \ + clone-from nego-bundle-all && + git -C nego-bundle-all for-each-ref --format="%(refname)" >refs && + grep "refs/bundles/" refs >actual && + cat >expect <<-\EOF && + refs/bundles/topic + EOF + test_cmp expect actual && + # We already have all needed commits so no "want" needed. + ! grep "clone> want " trace-packet.txt +' + +test_expect_success 'negotiation: bundle list (no heuristic)' ' + test_when_finished rm -f trace*.txt && + cat >bundle-list <<-EOF && + [bundle] + version = 1 + mode = all + + [bundle "bundle-1"] + uri = file://$(pwd)/clone-from/bundle-1.bundle + + [bundle "bundle-2"] + uri = file://$(pwd)/clone-from/bundle-2.bundle + EOF + + GIT_TRACE_PACKET="$(pwd)/trace-packet.txt" \ + git clone --no-local --bundle-uri="file://$(pwd)/bundle-list" \ + clone-from nego-bundle-list-no-heuristic && + + git -C nego-bundle-list-no-heuristic for-each-ref --format="%(refname)" >refs && + grep "refs/bundles/" refs >actual && + cat >expect <<-\EOF && + refs/bundles/base + refs/bundles/left + EOF + test_cmp expect actual && + grep "clone> have $(git -C nego-bundle-list-no-heuristic rev-parse refs/bundles/left)" trace-packet.txt +' + +test_expect_success 'negotiation: bundle list (creationToken)' ' + test_when_finished rm -f trace*.txt && + cat >bundle-list <<-EOF && + [bundle] + version = 1 + mode = all + heuristic = creationToken + + [bundle "bundle-1"] + uri = file://$(pwd)/clone-from/bundle-1.bundle + creationToken = 1 + + [bundle "bundle-2"] + uri = file://$(pwd)/clone-from/bundle-2.bundle + creationToken = 2 + EOF + + GIT_TRACE_PACKET="$(pwd)/trace-packet.txt" \ + git clone --no-local --bundle-uri="file://$(pwd)/bundle-list" \ + clone-from nego-bundle-list-heuristic && + + git -C nego-bundle-list-heuristic for-each-ref --format="%(refname)" >refs && + grep "refs/bundles/" refs >actual && + cat >expect <<-\EOF && + refs/bundles/base + refs/bundles/left + EOF + test_cmp expect actual && + grep "clone> have $(git -C nego-bundle-list-heuristic rev-parse refs/bundles/left)" trace-packet.txt +' + +test_expect_success 'negotiation: bundle list with all wanted commits' ' + test_when_finished rm -f trace*.txt && + cat >bundle-list <<-EOF && + [bundle] + version = 1 + mode = all + heuristic = creationToken + + [bundle "bundle-1"] + uri = file://$(pwd)/clone-from/bundle-1.bundle + creationToken = 1 + + [bundle "bundle-2"] + uri = file://$(pwd)/clone-from/bundle-2.bundle + creationToken = 2 + EOF + + GIT_TRACE_PACKET="$(pwd)/trace-packet.txt" \ + git clone --no-local --single-branch --branch=left --no-tags \ + --bundle-uri="file://$(pwd)/bundle-list" \ + clone-from nego-bundle-list-all && + + git -C nego-bundle-list-all for-each-ref --format="%(refname)" >refs && + grep "refs/bundles/" refs >actual && + cat >expect <<-\EOF && + refs/bundles/base + refs/bundles/left + EOF + test_cmp expect actual && + # We already have all needed commits so no "want" needed. + ! grep "clone> want " trace-packet.txt +' + ######################################################################### # HTTP tests begin here
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