From 8d8c2a5aef0fd20a68271697e50412791c06d9b7 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Mon, 4 Mar 2019 23:47:39 -0500 Subject: fsck: always compute USED flags for unreachable objects The --connectivity-only option avoids opening every object, and instead just marks reachable objects with a flag and compares this to the set of all objects. This strategy is discussed in more detail in 3e3f8bd608 (fsck: prepare dummy objects for --connectivity-check, 2017-01-17). This means that we report _every_ unreachable object as dangling. Whereas in a full fsck, we'd have actually opened and parsed each of those unreachable objects, marking their child objects with the USED flag, to mean "this was mentioned by another object". And thus we can report only the tip of an unreachable segment of the object graph as dangling. You can see this difference with a trivial example: tree=$(git hash-object -t tree -w /dev/null) one=$(echo one | git commit-tree $tree) two=$(echo two | git commit-tree -p $one $tree) Running `git fsck` will report only $two as dangling, but with --connectivity-only, both commits (and the tree) are reported. Likewise, using --lost-found would write all three objects. We can make --connectivity-only work like the normal case by taking a separate pass over the unreachable objects, parsing them and marking objects they refer to as USED. That still avoids parsing any blobs, though we do pay the cost to access any unreachable commits and trees (which may or may not be noticeable, depending on how many you have). If neither --dangling nor --lost-found is in effect, then we can skip this step entirely, just like we do now. That makes "--connectivity-only --no-dangling" just as fast as the current "--connectivity-only". I.e., we do the correct thing always, but you can still tweak the options to make it faster if you don't care about dangling objects. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- t/t1450-fsck.sh | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 't') diff --git a/t/t1450-fsck.sh b/t/t1450-fsck.sh index e20e8fa830..b203f404a0 100755 --- a/t/t1450-fsck.sh +++ b/t/t1450-fsck.sh @@ -740,7 +740,7 @@ test_expect_success 'fsck detects truncated loose object' ' # for each of type, we have one version which is referenced by another object # (and so while unreachable, not dangling), and another variant which really is # dangling. -test_expect_success 'fsck notices dangling objects' ' +test_expect_success 'create dangling-object repository' ' git init dangling && ( cd dangling && @@ -751,12 +751,17 @@ test_expect_success 'fsck notices dangling objects' ' commit=$(git commit-tree $tree) && dcommit=$(git commit-tree -p $commit $tree) && - cat >expect <<-EOF && + cat >expect <<-EOF dangling blob $dblob dangling commit $dcommit dangling tree $dtree EOF + ) +' +test_expect_success 'fsck notices dangling objects' ' + ( + cd dangling && git fsck >actual && # the output order is non-deterministic, as it comes from a hash sort actual.sorted && @@ -764,6 +769,16 @@ test_expect_success 'fsck notices dangling objects' ' ) ' +test_expect_success 'fsck --connectivity-only notices dangling objects' ' + ( + cd dangling && + git fsck --connectivity-only >actual && + # the output order is non-deterministic, as it comes from a hash + sort actual.sorted && + test_i18ncmp expect actual.sorted + ) +' + test_expect_success 'fsck $name notices bogus $name' ' test_must_fail git fsck bogus && test_must_fail git fsck $ZERO_OID -- cgit v1.2.3