in samza-core/src/main/java/org/apache/samza/storage/TransactionalStateTaskRestoreManager.java [248:475]
static StoreActions getStoreActions(
TaskModel taskModel,
Map<String, StorageEngine> storeEngines,
Map<String, SystemStream> storeChangelogs,
Map<String, KafkaStateCheckpointMarker> kafkaStateCheckpointMarkers,
CheckpointId checkpointId,
Map<SystemStreamPartition, SystemStreamPartitionMetadata> currentChangelogOffsets,
SystemAdmins systemAdmins,
StorageManagerUtil storageManagerUtil,
File loggedStoreBaseDirectory,
File nonLoggedStoreBaseDirectory,
Config config,
Clock clock) {
TaskName taskName = taskModel.getTaskName();
TaskMode taskMode = taskModel.getTaskMode();
Map<String, File> storeDirToRetain = new HashMap<>();
ListMultimap<String, File> storeDirsToDelete = ArrayListMultimap.create();
Map<String, RestoreOffsets> storesToRestore = new HashMap<>();
storeEngines.forEach((storeName, storageEngine) -> {
// do nothing if store is non persistent and not logged (e.g. in memory cache only)
if (!storageEngine.getStoreProperties().isPersistedToDisk() &&
!storageEngine.getStoreProperties().isLoggedStore()) {
return;
}
// persistent but non-logged stores are always deleted
if (storageEngine.getStoreProperties().isPersistedToDisk() &&
!storageEngine.getStoreProperties().isLoggedStore()) {
File currentDir = storageManagerUtil.getTaskStoreDir(
nonLoggedStoreBaseDirectory, storeName, taskName, taskMode);
LOG.info("Marking current directory: {} for store: {} in task: {} for deletion since it is not a logged store.",
currentDir, storeName, taskName);
storeDirsToDelete.put(storeName, currentDir);
// persistent but non-logged stores should not have checkpoint dirs
return;
}
// get the oldest and newest current changelog SSP offsets as well as the checkpointed changelog SSP offset
SystemStream changelog = storeChangelogs.get(storeName);
SystemStreamPartition changelogSSP = new SystemStreamPartition(changelog, taskModel.getChangelogPartition());
SystemAdmin admin = systemAdmins.getSystemAdmin(changelogSSP.getSystem());
SystemStreamPartitionMetadata changelogSSPMetadata = currentChangelogOffsets.get(changelogSSP);
String oldestOffset = changelogSSPMetadata.getOldestOffset();
String newestOffset = changelogSSPMetadata.getNewestOffset();
String checkpointedOffset = null; // can be null if no message, or message has null offset
if (kafkaStateCheckpointMarkers.containsKey(storeName) &&
StringUtils.isNotBlank(kafkaStateCheckpointMarkers.get(storeName).getChangelogOffset())) {
checkpointedOffset = kafkaStateCheckpointMarkers.get(storeName).getChangelogOffset();
}
long timeSinceLastCheckpointInMs = checkpointId == null ? Long.MAX_VALUE : System.currentTimeMillis() - checkpointId.getMillis();
// if the clean.store.start config is set, delete current and checkpoint dirs, restore from oldest offset to checkpointed
if (storageEngine.getStoreProperties().isPersistedToDisk() && new StorageConfig(
config).cleanLoggedStoreDirsOnStart(storeName)) {
File currentDir = storageManagerUtil.getTaskStoreDir(loggedStoreBaseDirectory, storeName, taskName, taskMode);
LOG.info("Marking current directory: {} for store: {} in task: {} for deletion due to clean.on.container.start config.",
currentDir, storeName, taskName);
storeDirsToDelete.put(storeName, currentDir);
storageManagerUtil.getTaskStoreCheckpointDirs(loggedStoreBaseDirectory, storeName, taskName, taskMode)
.forEach(checkpointDir -> {
LOG.info("Marking checkpoint directory: {} for store: {} in task: {} for deletion due to clean.on.container.start config.",
checkpointDir, storeName, taskName);
storeDirsToDelete.put(storeName, checkpointDir);
});
LOG.info("Marking restore offsets for store: {} in task: {} to {}, {} ", storeName, taskName, oldestOffset, checkpointedOffset);
storesToRestore.put(storeName, new RestoreOffsets(oldestOffset, checkpointedOffset));
return;
}
Optional<File> currentDirOptional;
Optional<List<File>> checkpointDirsOptional;
if (!storageEngine.getStoreProperties().isPersistedToDisk()) {
currentDirOptional = Optional.empty();
checkpointDirsOptional = Optional.empty();
} else {
currentDirOptional = Optional.of(storageManagerUtil.getTaskStoreDir(
loggedStoreBaseDirectory, storeName, taskName, taskMode));
checkpointDirsOptional = Optional.of(storageManagerUtil.getTaskStoreCheckpointDirs(
loggedStoreBaseDirectory, storeName, taskName, taskMode));
}
LOG.info("For store: {} in task: {} got current dir: {}, checkpoint dirs: {}, checkpointed changelog offset: {}",
storeName, taskName, currentDirOptional, checkpointDirsOptional, checkpointedOffset);
currentDirOptional.ifPresent(currentDir -> {
LOG.info("Marking current directory: {} for store: {} in task: {} for deletion.",
currentDir, storeName, taskName);
storeDirsToDelete.put(storeName, currentDir);
});
if (checkpointedOffset == null && oldestOffset != null) {
// this can mean that either this is the initial migration for this feature and there are no previously
// checkpointed changelog offsets, or that this is a new store or changelog topic after the initial migration.
// if this is the first time migration, it might be desirable to retain existing data.
// if this is new store or topic, it is possible that the container previously died after writing some data to
// the changelog but before a commit, so it is desirable to delete the store, not restore anything and
// trim the changelog
// since we can't tell the difference b/w the two scenarios by just looking at the store and changelogs,
// we'll request users to indicate whether to retain existing data using a config flag. this flag should only
// be set during migrations, and turned off after the first successful commit of the new container (i.e. next
// deploy). for simplicity, we'll always delete the local store, and restore from changelog if necessary.
// the former scenario should not be common. the recommended way to opt-in to the transactional state feature
// is to first upgrade to the latest samza version but keep the transactional state restore config off.
// this will create the store checkpoint directories and write the changelog offset to the checkpoint, but
// will not use them during restore. once this is done (i.e. at least one commit after upgrade), the
// transactional state restore feature can be turned on on subsequent deploys. this code path exists as a
// fail-safe against clearing changelogs in case users do not follow upgrade instructions and enable the
// feature directly.
checkpointDirsOptional.ifPresent(checkpointDirs ->
checkpointDirs.forEach(checkpointDir -> {
LOG.info("Marking checkpoint directory: {} for store: {} in task: {} for deletion since checkpointed " +
"offset is null and oldest offset: {} is not.",
checkpointDir, storeName, taskName, oldestOffset);
storeDirsToDelete.put(storeName, checkpointDir);
}));
if (new TaskConfig(config).getTransactionalStateRetainExistingState()) {
// mark for restore from (oldest, newest) to recreate local state.
LOG.warn("Checkpointed offset for store: {} in task: {} is null. Since retain existing state is true, " +
"local state will be fully restored from current changelog contents. " +
"There is no transactional local state guarantee.", storeName, taskName);
storesToRestore.put(storeName, new RestoreOffsets(oldestOffset, newestOffset));
} else {
LOG.warn("Checkpointed offset for store: {} in task: {} is null. Since retain existing state is false, " +
"any local state and changelog topic contents will be deleted.", storeName, taskName);
// mark for restore from (oldest, null) to trim entire changelog.
storesToRestore.put(storeName, new RestoreOffsets(oldestOffset, null));
}
} else if (// check if the checkpointed offset is out of range of current oldest and newest offsets
admin.offsetComparator(oldestOffset, checkpointedOffset) > 0 ||
admin.offsetComparator(checkpointedOffset, newestOffset) > 0) {
// checkpointed offset is out of range. this could mean that this is a TTL topic and the checkpointed
// offset was TTLd, or that the changelog topic was manually deleted and then recreated.
// we cannot guarantee transactional state for TTL stores, so delete everything and do a full restore
// for local store. if the topic was deleted and recreated, this will have the side effect of
// clearing the store as well.
LOG.warn("Checkpointed offset: {} for store: {} in task: {} is out of range of oldest: {} or newest: {} offset." +
"Deleting existing store and fully restoring from changelog topic from oldest to newest offset. If the topic " +
"has time-based retention, there is no transactional local state guarantees. If the topic was changed," +
"local state will be cleaned up and fully restored to match the new topic contents.",
checkpointedOffset, storeName, taskName, oldestOffset, newestOffset);
checkpointDirsOptional.ifPresent(checkpointDirs ->
checkpointDirs.forEach(checkpointDir -> storeDirsToDelete.put(storeName, checkpointDir)));
storesToRestore.put(storeName, new RestoreOffsets(oldestOffset, newestOffset));
} else { // happy path. checkpointed offset is in range of current oldest and newest offsets
if (!checkpointDirsOptional.isPresent()) { // non-persistent logged store
LOG.info("Did not find any checkpoint directories for logged (maybe non-persistent) store: {}. Local state " +
"will be fully restored from current changelog contents.", storeName);
storesToRestore.put(storeName, new RestoreOffsets(oldestOffset, checkpointedOffset));
} else { // persistent logged store
String targetOffset;
// check checkpoint time against min.compaction.lag.ms. if older, restore from checkpointed offset to newest
// with no trim. be conservative. allow 10% safety margin to avoid deletions when the downtime is close
// to min.compaction.lag.ms
long minCompactionLagMs = new StorageConfig(config).getChangelogMinCompactionLagMs(storeName);
if (timeSinceLastCheckpointInMs > .9 * minCompactionLagMs) {
LOG.warn("Checkpointed offset for store: {} in task: {} is: {}. It is in range of oldest: {} and " +
"newest: {} changelog offset. However, time since last checkpoint is: {}, which is greater than " +
"0.9 * min.compaction.lag.ms: {} for the changelog topic. Since there is a chance that" +
"the changelog topic has been compacted, restoring store to the end of the current changelog contents." +
"There is no transactional local state guarantee.", storeName, taskName, checkpointedOffset,
oldestOffset, newestOffset, timeSinceLastCheckpointInMs, minCompactionLagMs);
targetOffset = newestOffset;
} else {
targetOffset = checkpointedOffset;
}
// if there exists a valid store checkpoint directory with oldest offset <= local offset <= target offset,
// retain it and restore the delta. delete all other checkpoint directories for the store. if more than one such
// checkpoint directory exists, retain the one with the highest local offset and delete the rest.
boolean hasValidCheckpointDir = false;
for (File checkpointDir: checkpointDirsOptional.get()) {
if (storageManagerUtil.isLoggedStoreValid(
storeName, checkpointDir, config, storeChangelogs, taskModel, clock, storeEngines)) {
String localOffset = storageManagerUtil.readOffsetFile(
checkpointDir, Collections.singleton(changelogSSP), false).get(changelogSSP);
LOG.info("Read local offset: {} for store: {} checkpoint dir: {} in task: {}", localOffset, storeName,
checkpointDir, taskName);
if (admin.offsetComparator(localOffset, oldestOffset) >= 0 &&
admin.offsetComparator(localOffset, targetOffset) <= 0 &&
(storesToRestore.get(storeName) == null ||
admin.offsetComparator(localOffset, storesToRestore.get(storeName).startingOffset) > 0)) {
hasValidCheckpointDir = true;
LOG.info("Temporarily marking checkpoint dir: {} for store: {} in task: {} for retention. " +
"May be overridden later.", checkpointDir, storeName, taskName);
storeDirToRetain.put(storeName, checkpointDir);
// mark for restore even if local == checkpointed, so that the changelog gets trimmed.
LOG.info("Temporarily marking store: {} in task: {} for restore from beginning offset: {} to " +
"ending offset: {}. May be overridden later", storeName, taskName, localOffset, targetOffset);
storesToRestore.put(storeName, new RestoreOffsets(localOffset, targetOffset));
}
}
}
// delete all non-retained checkpoint directories
for (File checkpointDir: checkpointDirsOptional.get()) {
if (storeDirToRetain.get(storeName) == null ||
!storeDirToRetain.get(storeName).equals(checkpointDir)) {
LOG.info("Marking checkpoint directory: {} for store: {} in task: {} for deletion since it is not " +
"marked for retention.", checkpointDir, storeName, taskName);
storeDirsToDelete.put(storeName, checkpointDir);
}
}
// if the store had not valid checkpoint dirs to retain, restore from changelog
if (!hasValidCheckpointDir) {
storesToRestore.put(storeName, new RestoreOffsets(oldestOffset, targetOffset));
}
}
}
});
LOG.info("Store directories to be retained in Task: {} are: {}", taskName, storeDirToRetain);
LOG.info("Store directories to be deleted in Task: {} are: {}", taskName, storeDirsToDelete);
LOG.info("Stores to be restored in Task: {} are: {}", taskName, storesToRestore);
return new StoreActions(storeDirToRetain, storeDirsToDelete, storesToRestore);
}