JingsongLi commented on code in PR #10845:
URL: https://github.com/apache/paimon/pull/10845#discussion_r4439257315
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paimon-core/src/main/java/org/apache/paimon/utils/FileSystemBranchManager.java:
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@@ -224,6 +240,228 @@ public void fastForward(String branchName) {
}
}
+ /**
+ * Fast-forwards by appending when the current branch is a prefix of the
branch: its snapshots
+ * from the branch's earliest one (or its own earliest, if later) to its
latest are the
+ * branch's, and so are its schemas. Nothing is deleted and files are
written in ascending id
+ * order, so a failure leaves the current branch at one of the branch's
snapshots and a retry
+ * continues from there.
+ *
+ * @return false if the current branch is not a prefix of the branch
+ */
+ private boolean tryAppendFromBranch(String branchName, long
branchEarliestId, Lock lock)
+ throws IOException {
+ SnapshotManager branchSnapshotManager =
snapshotManager.copyWithBranch(branchName);
+ SchemaManager branchSchemaManager =
schemaManager.copyWithBranch(branchName);
+ // List rather than trust the LATEST hint: an interrupted replace by
an older version copies
+ // the branch's hint before the snapshots it names.
+ Map<Long, Long> sizes = snapshotSizes(snapshotManager);
+ Map<Long, Long> branchSizes = snapshotSizes(branchSnapshotManager);
+ if (sizes.isEmpty() || branchSizes.isEmpty()) {
+ return false;
+ }
+ long latestId = Collections.max(sizes.keySet());
+ long branchLatestId = Collections.max(branchSizes.keySet());
+ if (latestId < branchEarliestId
+ || latestId > branchLatestId
+ || !sameSizes(sizes, branchSizes, branchEarliestId, latestId)
+ || !sameContent(
+ snapshotManager.snapshotPath(latestId),
+ branchSnapshotManager.snapshotPath(latestId),
+ Snapshot::fromJson)
+ || !sameSchemas(branchSchemaManager)) {
+ return false;
+ }
+
+ long latestSchemaId = Collections.max(schemaManager.listAllIds());
+ for (long schemaId : sorted(branchSchemaManager.listAllIds())) {
+ if (schemaId > latestSchemaId) {
+ copyAtomically(
+ lock,
+ branchSchemaManager.toSchemaPath(schemaId),
+ schemaManager.toSchemaPath(schemaId));
+ }
+ }
+ copySnapshots(branchSnapshotManager, latestId + 1, branchLatestId,
lock);
+ copyBranchTags(branchName, lock);
+ snapshotManager.commitLatestHint(branchLatestId);
+ return true;
+ }
+
+ private Map<Long, Long> snapshotSizes(SnapshotManager manager) throws
IOException {
+ Map<Long, Long> sizes = new HashMap<>();
+ for (FileStatus status :
+ listVersionedFileStatus(fileIO, manager.snapshotDirectory(),
SNAPSHOT_PREFIX)
+ .collect(Collectors.toList())) {
+ String version =
status.getPath().getName().substring(SNAPSHOT_PREFIX.length());
+ try {
+ sizes.put(Long.parseLong(version), status.getLen());
+ } catch (NumberFormatException ignored) {
+ // not a snapshot file, for example a temporary file of a
Python writer
+ }
+ }
+ return sizes;
+ }
+
+ /**
+ * Whether the current branch has every snapshot from {@code from} (or its
earliest, if later)
+ * to {@code to}, each of the branch's size. A copy cut short by an older
version's non-atomic
+ * replace has another size.
+ */
+ private static boolean sameSizes(
+ Map<Long, Long> sizes, Map<Long, Long> branchSizes, long from,
long to) {
+ for (long id = Math.max(from, Collections.min(sizes.keySet())); id <=
to; id++) {
+ Long size = sizes.get(id);
+ if (size == null || !size.equals(branchSizes.get(id))) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /** Whether the current branch's schemas are the branch's schemas up to
the current latest. */
+ private boolean sameSchemas(SchemaManager branchSchemaManager) throws
IOException {
+ Set<Long> ids = new HashSet<>(schemaManager.listAllIds());
+ if (ids.isEmpty()) {
+ return false;
+ }
+ long latestId = Collections.max(ids);
+ Set<Long> branchIds =
+ branchSchemaManager.listAllIds().stream()
+ .filter(id -> id <= latestId)
+ .collect(Collectors.toSet());
+ if (!ids.equals(branchIds)) {
+ return false;
+ }
+ for (long id : ids) {
+ if (!sameContent(
+ schemaManager.toSchemaPath(id),
+ branchSchemaManager.toSchemaPath(id),
+ TableSchema::fromJson)) {
+ return false;
+ }
+ }
+ return true;
+ }
+
+ /**
+ * Replaces the current branch's snapshots and tags from the branch's
earliest snapshot onwards,
+ * and its schemas, with the branch's. Schemas are replaced file by file
instead of deleted up
+ * front, so a failure never leaves the remaining snapshots without their
schemas.
+ */
+ private void replaceFromBranch(String branchName, long earliestSnapshotId,
Lock lock)
+ throws IOException {
+ SnapshotManager branchSnapshotManager =
snapshotManager.copyWithBranch(branchName);
+ SchemaManager branchSchemaManager =
schemaManager.copyWithBranch(branchName);
+ long earliestSchemaId =
branchSnapshotManager.snapshot(earliestSnapshotId).schemaId();
+
+ List<Path> deletePaths =
+ new ArrayList<>(snapshotManager.snapshotPaths(id -> id >=
earliestSnapshotId));
+ deletePaths.addAll(
+ tagManager.tagPaths(path -> Tag.fromPath(fileIO, path).id() >=
earliestSnapshotId));
+ lock.ensureValid();
+ snapshotManager.deleteLatestHint();
+ fileIO.deleteFilesQuietly(deletePaths);
+ // Main expired its own snapshots up to its EARLIEST hint; the
branch's snapshots below
+ // that hint become main's. Move the hint before copying them, so that
a retry after a
+ // failed copy, which appends the rest, finds it already moved.
+ Long earliestHint =
+ HintFileUtils.readHint(
+ fileIO, HintFileUtils.EARLIEST,
snapshotManager.snapshotDirectory());
+ if (earliestHint != null && earliestHint > earliestSnapshotId) {
+ snapshotManager.commitEarliestHint(earliestSnapshotId);
+ }
+
+ List<Long> branchSchemaIds = sorted(branchSchemaManager.listAllIds());
+ for (long id : branchSchemaIds) {
+ replaceAtomically(
+ lock, branchSchemaManager.toSchemaPath(id),
schemaManager.toSchemaPath(id));
+ }
+ for (long id : schemaManager.listAllIds()) {
+ if (id >= earliestSchemaId && !branchSchemaIds.contains(id)) {
+ lock.ensureValid();
+ fileIO.deleteQuietly(schemaManager.toSchemaPath(id));
+ }
+ }
+
+ // List rather than trust the branch's LATEST hint, as the append path
does.
+ long branchLatestId =
Collections.max(snapshotSizes(branchSnapshotManager).keySet());
+ copySnapshots(branchSnapshotManager, earliestSnapshotId,
branchLatestId, lock);
+ copyBranchTags(branchName, lock);
+ snapshotManager.commitLatestHint(branchLatestId);
+ }
+
+ private void copySnapshots(
+ SnapshotManager branchSnapshotManager, long fromId, long toId,
Lock lock)
+ throws IOException {
+ for (long id = fromId; id <= toId; id++) {
+ copyAtomically(
+ lock, branchSnapshotManager.snapshotPath(id),
snapshotManager.snapshotPath(id));
+ }
+ }
+
+ private void copyBranchTags(String branchName, Lock lock) throws
IOException {
+ // Continue fast-forward even without tags.
+ Path branchTagDirectory =
tagManager.copyWithBranch(branchName).tagDirectory();
+ if (!fileIO.exists(branchTagDirectory)) {
+ return;
+ }
+ for (FileStatus status : fileIO.listStatus(branchTagDirectory)) {
+ if (!status.isDir()) {
+ Path tag = status.getPath();
+ replaceAtomically(lock, tag, new
Path(tagManager.tagDirectory(), tag.getName()));
+ }
+ }
+ }
+
+ /** Copies a file without exposing partial content, accepting a target
already copied. */
+ private void copyAtomically(Lock lock, Path source, Path target) throws
IOException {
+ // A lease may expire while many files are copied; stop before writing
past it.
+ lock.ensureValid();
+ String content = readExactly(source);
+ if ((fileIO.exists(target) || !fileIO.tryToWriteAtomic(target,
content))
Review Comment:
The source-read case and the same-length intermediate-snapshot case now pass
at `02d7d676dc`. One part of this lease boundary is still reproducible:
`copyAtomically` checks the lease before the separate `fileIO.exists(target)`
call. That remote metadata request can outlast the lease, then its `false`
result leads to `tryToWriteAtomic` without another check.
I ran actual `table.fastForward("b1")` with main snapshot 1 and branch
snapshot 2. The test FileIO expires the lease while checking whether main
snapshot 2 exists, returns false, and then allows the normal write.
Fast-forward eventually throws `Lease expired`, but main snapshot 2 already
exists. The assertion that snapshot 2 remains absent fails on this head. With
only an additional `ensureValid()` after the existence query and before the
atomic write, the identical test passes.
Please include the target existence query among preparation performed before
the final lease check. The 66 existing Core cases pass normal JDK 8 Maven
verify; this extra timing case is not covered by those tests. Temporary
reviewer changes were removed.
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