[PATCH 2/2] cache-tree: prefetch in partial clone read-tree
- From
- Jonathan Tan <jonathantanmy@google.com>
- Date
- Jul 23, 2021, 18:52 UTC
- Message-ID
- <f4881b7455b9d33c8a53a91eda7fbdfc5d11382c.1627066238.git.jonathantanmy@google.com>
- In-Reply-To
- <cover.1627066238.git.jonathantanmy@google.com>
"git read-tree" checks the existence of the blobs referenced by the given tree, but does not bulk prefetch them. Add a bulk prefetch.
The lack of prefetch here was noticed at $DAYJOB during a merge involving some specific commits, but I couldn't find a minimal merge that didn't also trigger the prefetch in check_updates() in unpack-trees.c (and in all these cases, the lack of prefetch in cache-tree.c didn't matter because all the relevant blobs would have already been prefetched by then). This is why I used read-tree here to exercise this code path.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com> --- cache-tree.c | 11 ++++++++-- t/t1022-read-tree-partial-clone.sh | 33 ++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+), 2 deletions(-) create mode 100755 t/t1022-read-tree-partial-clone.sh
diff --git a/cache-tree.c b/cache-tree.c index 45e58666af..9ba2c7c6b2 100644 --- a/cache-tree.c +++ b/cache-tree.c @@ -237,6 +237,11 @@ int cache_tree_fully_valid(struct cache_tree *it) return 1; } +static int must_check_existence(const struct cache_entry *ce) +{ + return !(has_promisor_remote() && ce_skip_worktree(ce)); +} + static int update_one(struct cache_tree *it, struct cache_entry **cache, int entries, @@ -378,8 +383,7 @@ static int update_one(struct cache_tree *it, } ce_missing_ok = mode == S_IFGITLINK || missing_ok || - (has_promisor_remote() && - ce_skip_worktree(ce)); + !must_check_existence(ce); if (is_null_oid(oid) || (!ce_missing_ok && !has_object_file(oid))) { strbuf_release(&buffer); @@ -466,6 +470,9 @@ int cache_tree_update(struct index_state *istate, int flags) if (!istate->cache_tree) istate->cache_tree = cache_tree(); + if (!(flags & WRITE_TREE_MISSING_OK) && has_promisor_remote()) + prefetch_cache_entries(istate, must_check_existence); + trace_performance_enter(); trace2_region_enter("cache_tree", "update", the_repository); i = update_one(istate->cache_tree, istate->cache, istate->cache_nr, diff --git a/t/t1022-read-tree-partial-clone.sh b/t/t1022-read-tree-partial-clone.sh new file mode 100755 index 0000000000..a763e27c7d --- /dev/null +++ b/t/t1022-read-tree-partial-clone.sh @@ -0,0 +1,33 @@ +#!/bin/sh + +test_description='git read-tree in partial clones' + +TEST_NO_CREATE_REPO=1 + +GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main +export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME + +. ./test-lib.sh + +test_expect_success 'read-tree in partial clone prefetches in one batch' ' + test_when_finished "rm -rf server client trace" && + + git init server && + echo foo >server/one && + echo bar >server/two && + git -C server add one two && + git -C server commit -m "initial commit" && + TREE=$(git -C server rev-parse HEAD^{tree}) && + + git -C server config uploadpack.allowfilter 1 && + git -C server config uploadpack.allowanysha1inwant 1 && + git clone --bare --filter=blob:none "file://$(pwd)/server" client && + GIT_TRACE_PACKET="$(pwd)/trace" git -C client read-tree $TREE && + + # "done" marks the end of negotiation (once per fetch). Expect that + # only one fetch occurs. + grep "fetch> done" trace >donelines && + test_line_count = 1 donelines +' + +test_done
-- 2.32.0.432.gabb21c7263-goog