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author | William Manley <will@williammanley.net> | 2018-06-22 15:28:49 +0100 |
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committer | Atomic Bot <atomic-devel@projectatomic.io> | 2018-07-09 13:10:51 +0000 |
commit | c7b12a8730260c66bc96363a3a3c5805b325bac8 (patch) | |
tree | ec4a54c682086e324442e34aad2979ce365486c2 /src/libostree/ostree-mutable-tree.h | |
parent | 11eb0bd227ffa1a3300e4dbde3da288a7d9d41ae (diff) | |
download | ostree-c7b12a8730260c66bc96363a3a3c5805b325bac8.tar.gz |
ostree repo commit: Speed up composing trees with `--tree=ref`
Running `ostree commit --tree=ref=a --tree=dir=b` involves reading the
whole of a into an `OstreeMutableTree` before composing `b` on top. This
is inefficient if a is a complete rootfs and b is just touching one file.
We process O(size of a + size of b) directories rather than
O(number of touched dirs).
This commit makes `ostree commit` more efficient at composing multiple
directories together. With `ostree_mutable_tree_fill_empty_from_dirtree`
we create a lazy `OstreeMutableTree` which only reads the underlying
information from disk when needed. We don't need to read all the
subdirectories just to get the checksum of a tree already checked into the
repo.
This provides great speedups when composing a rootfs out of multiple other
rootfs as we do in our build system. We compose multiple containers
together with:
ostree commit --tree=ref=base-rootfs --tree=ref=container1 --tree=ref=container2
and it is much faster now.
As a test I ran
time ostree --repo=... commit --orphan --tree=ref=big-rootfs --tree=dir=modified_etc
Where modified_etc contained a modified sudoers file under /etc. I used
`strace` to count syscalls and I seperatly took timing measurements. To
test with a cold cache I ran
sync && echo 3 | sudo tee /proc/sys/vm/drop_caches
Results:
| | Before | After |
| -------------------- | ------ | ----- |
| Time (cold cache) | 8.1s | 0.12s |
| Time (warm cache) | 3.7s | 0.08s |
| `openat` calls | 53589 | 246 |
| `fgetxattr` calls | 78916 | 0 |
I'm not sure if this will have some negative interaction with the
`_ostree_repo_commit_modifier_apply` which is short-circuited here. I
think it was disabled for `--tree=ref=` anyway, but I'm not certain. All
the tests pass anyway.
I originally implemented this in terms of the `OstreeRepoFile` APIs, but
it was *way* less efficient, opening and reading many files unnecessarily.
Closes: #1643
Approved by: cgwalters
Diffstat (limited to 'src/libostree/ostree-mutable-tree.h')
-rw-r--r-- | src/libostree/ostree-mutable-tree.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/libostree/ostree-mutable-tree.h b/src/libostree/ostree-mutable-tree.h index 2cb5e9a7..4b7f853e 100644 --- a/src/libostree/ostree-mutable-tree.h +++ b/src/libostree/ostree-mutable-tree.h @@ -53,6 +53,11 @@ _OSTREE_PUBLIC OstreeMutableTree *ostree_mutable_tree_new (void); _OSTREE_PUBLIC +OstreeMutableTree * ostree_mutable_tree_new_from_checksum (OstreeRepo *repo, + const char *contents_checksum, + const char *metadata_checksum); + +_OSTREE_PUBLIC void ostree_mutable_tree_set_metadata_checksum (OstreeMutableTree *self, const char *checksum); @@ -101,6 +106,17 @@ gboolean ostree_mutable_tree_walk (OstreeMutableTree *self, GError **error); _OSTREE_PUBLIC +gboolean ostree_mutable_tree_fill_empty_from_dirtree (OstreeMutableTree *self, + OstreeRepo *repo, + const char *contents_checksum, + const char *metadata_checksum); + +_OSTREE_PUBLIC +gboolean +ostree_mutable_tree_check_error (OstreeMutableTree *self, + GError **error); + +_OSTREE_PUBLIC GHashTable * ostree_mutable_tree_get_subdirs (OstreeMutableTree *self); _OSTREE_PUBLIC GHashTable * ostree_mutable_tree_get_files (OstreeMutableTree *self); |