LuciferYang commented on code in PR #10845:
URL: https://github.com/apache/paimon/pull/10845#discussion_r4443268620
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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:
Fixed in baef7eb2fa. `copyAtomically` now checks whether the target exists
before the final lease check, so nothing remote runs between that check and the
write. Hint writes go through a `commitHint` overload that checks the lease
before every attempt, including retries.
`testFastForwardRechecksLeaseAfterCheckingTarget` expires the lease during
`exists` on main's snapshot 2 and asserts it stays absent;
`testFastForwardRechecksLeaseBeforeRetryingHint` covers the retry.
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