cache-tree: prefetch in partial clone read-tree
"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> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jonathan Tan committed
Jul 23, 2021 at 11:52 UTC
d3da223f2214ebc1527ccf66428aa975de916682
2 files changed
+42
-2
cache-tree.c
+9
-2
@@ -237,6 +237,11 @@ int cache_tree_fully_valid(struct cache_tree *it)
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return 1;
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}
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+static int must_check_existence(const struct cache_entry *ce)
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+{
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+ return !(has_promisor_remote() && ce_skip_worktree(ce));
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+}
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+
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static int update_one(struct cache_tree *it,
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struct cache_entry **cache,
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int entries,
@@ -378,8 +383,7 @@ static int update_one(struct cache_tree *it,
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}
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ce_missing_ok = mode == S_IFGITLINK || missing_ok ||
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- (has_promisor_remote() &&
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- ce_skip_worktree(ce));
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+ !must_check_existence(ce);
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if (is_null_oid(oid) ||
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(!ce_missing_ok && !has_object_file(oid))) {
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strbuf_release(&buffer);
@@ -466,6 +470,9 @@ int cache_tree_update(struct index_state *istate, int flags)
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if (!istate->cache_tree)
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istate->cache_tree = cache_tree();
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+ if (!(flags & WRITE_TREE_MISSING_OK) && has_promisor_remote())
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+ prefetch_cache_entries(istate, must_check_existence);
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+
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trace_performance_enter();
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trace2_region_enter("cache_tree", "update", the_repository);
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i = update_one(istate->cache_tree, istate->cache, istate->cache_nr,
t/t1022-read-tree-partial-clone.sh
new
+33
@@ -0,0 +1,33 @@
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+#!/bin/sh
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+
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+test_description='git read-tree in partial clones'
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+
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+TEST_NO_CREATE_REPO=1
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+
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+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
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+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
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+
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+. ./test-lib.sh
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+
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+test_expect_success 'read-tree in partial clone prefetches in one batch' '
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+ test_when_finished "rm -rf server client trace" &&
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+
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+ git init server &&
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+ echo foo >server/one &&
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+ echo bar >server/two &&
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+ git -C server add one two &&
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+ git -C server commit -m "initial commit" &&
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+ TREE=$(git -C server rev-parse HEAD^{tree}) &&
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+
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+ git -C server config uploadpack.allowfilter 1 &&
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+ git -C server config uploadpack.allowanysha1inwant 1 &&
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+ git clone --bare --filter=blob:none "file://$(pwd)/server" client &&
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+ GIT_TRACE_PACKET="$(pwd)/trace" git -C client read-tree $TREE &&
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+
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+ # "done" marks the end of negotiation (once per fetch). Expect that
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+ # only one fetch occurs.
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+ grep "fetch> done" trace >donelines &&
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+ test_line_count = 1 donelines
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+'
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+
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+test_done