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[34.168.22.137]) by smtp.gmail.com with ESMTPSA id t3-20020a170902b20300b001963bc7bdb8sm10007148plr.274.2023.01.31.09.35.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Jan 2023 09:35:24 -0800 (PST) Sender: Junio C Hamano From: Junio C Hamano To: "Derrick Stolee via GitGitGadget" Cc: git@vger.kernel.org, me@ttaylorr.com, vdye@github.com, avarab@gmail.com, steadmon@google.com, chooglen@google.com, Derrick Stolee Subject: Re: [PATCH v3 02/11] bundle: verify using check_connected() References: <20c29d37f9c1ba1367145331d25dd27f966312cd.1675171759.git.gitgitgadget@gmail.com> Date: Tue, 31 Jan 2023 09:35:24 -0800 In-Reply-To: <20c29d37f9c1ba1367145331d25dd27f966312cd.1675171759.git.gitgitgadget@gmail.com> (Derrick Stolee via GitGitGadget's message of "Tue, 31 Jan 2023 13:29:10 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org "Derrick Stolee via GitGitGadget" writes: > Thus, the code in verify_bundle() has previously had the additional > check that all prerequisite commits are reachable from repository > references. This is done via a revision walk from all references, > stopping only if all prerequisite commits are discovered or all commits > are walked. This uses a custom walk to verify_bundle(). > > This check is more strict than what Git applies to fetched pack-files. > In the fetch case, Git guarantees that the new references are closed > under reachability by walking from the new references until walking > commits that are reachable from repository refs. This is done through > the well-used check_connected() method. > > To better align with the restrictions required by 'git fetch', > reimplement this check in verify_bundle() to use check_connected(). This > also simplifies the code significantly. As I often say, breaking repository faster is not the kind of performance gain we want to have in Git, and I am in favor of this iteration compared to the earlier version that mostly punted on ensuring the correctness (rather, it relied on assumption that "most of the time this should be OK"). > bundle.c | 75 ++++++++++++++++-------------------------- > t/t6020-bundle-misc.sh | 8 ++--- > 2 files changed, 33 insertions(+), 50 deletions(-) The diffstat is very pleasing to see. Let me read the postimage along aloud (preimage omitted). > diff --git a/bundle.c b/bundle.c > index 4ef7256aa11..76c3a904898 100644 > --- a/bundle.c > +++ b/bundle.c > @@ -187,6 +188,21 @@ static int list_refs(struct string_list *r, int argc, const char **argv) > /* Remember to update object flag allocation in object.h */ > #define PREREQ_MARK (1u<<16) > > +struct string_list_iterator { > + struct string_list *list; > + size_t cur; > +}; > + > +static const struct object_id *iterate_ref_map(void *cb_data) > +{ > + struct string_list_iterator *iter = cb_data; > + > + if (iter->cur >= iter->list->nr) > + return NULL; > + > + return iter->list->items[iter->cur++].util; > +} This is to let check_connected() collect all the prerequisite object names. OK. > int verify_bundle(struct repository *r, > struct bundle_header *header, > enum verify_bundle_flags flags) > { > /* > * Do fast check, then if any prereqs are missing then go line by line > * to be verbose about the errors > */ > struct string_list *p = &header->prerequisites; > + int i, ret = 0; > const char *message = _("Repository lacks these prerequisite commits:"); > + struct string_list_iterator iter = { > + .list = p, > + }; > + struct check_connected_options opts = { > + .quiet = 1, > + }; > > if (!r || !r->objects || !r->objects->odb) > return error(_("need a repository to verify a bundle")); > > for (i = 0; i < p->nr; i++) { > struct string_list_item *e = p->items + i; > const char *name = e->string; > struct object_id *oid = e->util; > struct object *o = parse_object(r, oid); > + if (o) > continue; > ret++; > if (flags & VERIFY_BUNDLE_QUIET) > continue; > if (ret == 1) > error("%s", message); > error("%s %s", oid_to_hex(oid), name); > } > + if (ret) > goto cleanup; The "quick fail" logic as before. Looking sensible. > > + if ((ret = check_connected(iterate_ref_map, &iter, &opts))) > + error(_("some prerequisite commits exist in the object store, " > + "but are not connected to the repository's history")); And then we let check_connected() to ensure that traversing from these prerequisite objects down to the DAG formed by existing refs will not die from missing objects. Makes sense. > + /* TODO: preserve this verbose language. */ I am lost -- aren't we preserving the BUNDLE_VERBOSE code below? > if (flags & VERIFY_BUNDLE_VERBOSE) { > diff --git a/t/t6020-bundle-misc.sh b/t/t6020-bundle-misc.sh > index 38dbbf89155..7d40994991e 100755 > --- a/t/t6020-bundle-misc.sh > +++ b/t/t6020-bundle-misc.sh > @@ -595,14 +595,14 @@ test_expect_success 'verify catches unreachable, broken prerequisites' ' > # Verify should fail > test_must_fail git bundle verify \ > ../clone-from/tip.bundle 2>err && > - grep "Could not read $BAD_OID" err && > - grep "Failed to traverse parents of commit $TIP_OID" err && > + grep "some prerequisite commits .* are not connected" err && > + test_line_count = 1 err && > > # Unbundling should fail > test_must_fail git bundle unbundle \ > ../clone-from/tip.bundle 2>err && > - grep "Could not read $BAD_OID" err && > - grep "Failed to traverse parents of commit $TIP_OID" err > + grep "some prerequisite commits .* are not connected" err && > + test_line_count = 1 err > ) > ' Especially with the new test added in the previous step, we know we are not trading correctness off. Excellent. I wonder how much the performance hit does this version incur over the "not safe at all" version and over the "use custom and stricter-than-needed" version, by the way? Thanks.