Examples with Scanner io.cdap.cdap.api.dataset.table.Scanner used on opensource projects

Example 11 with Scanner

use of io.cdap.cdap.api.dataset.table.Scanner in project cdap by caskdata.

the class MetadataDataset method deleteIndexes.

/**
 * Deletes all indexes associated with a metadata key
 *
 * @param metadataEntity the {@link MetadataEntity} for which keys are to be removed
 * @param metadataKey the key to remove from the metadata of the specified {@link MetadataEntity}
 */
private void deleteIndexes(MetadataEntity metadataEntity, String metadataKey) {
    MDSKey mdsKey = MetadataKey.createIndexRowKey(metadataEntity, metadataKey, null);
    byte[] startKey = mdsKey.getKey();
    byte[] stopKey = Bytes.stopKeyForPrefix(startKey);
    try (Scanner scan = indexedTable.scan(startKey, stopKey)) {
        Row next;
        while ((next = scan.next()) != null) {
            deleteIndexRow(next);
        }
    }
}

Example 12 with Scanner

use of io.cdap.cdap.api.dataset.table.Scanner in project cdap by caskdata.

the class MetadataDataset method getSnapshotBeforeTime.

private Record getSnapshotBeforeTime(MetadataEntity metadataEntity, long timeMillis) {
    byte[] scanStartKey = MetadataHistoryKey.getMDSScanStartKey(metadataEntity, timeMillis).getKey();
    byte[] scanEndKey = MetadataHistoryKey.getMDSScanStopKey(metadataEntity).getKey();
    // TODO: add limit to scan, we need only one row
    try (Scanner scanner = indexedTable.scan(scanStartKey, scanEndKey)) {
        Row next = scanner.next();
        if (next != null) {
            return GSON.fromJson(next.getString(HISTORY_COLUMN), Record.class);
        } else {
            return new Record(metadataEntity);
        }
    }
}

Example 13 with Scanner

use of io.cdap.cdap.api.dataset.table.Scanner in project cdap by caskdata.

the class MetadataStoreDataset method scan.

/**
 * Run a scan on MDS for default COLUMN
 *
 * @param startId  scan start key
 * @param stopId   scan stop key
 * @param typeOfT  type of value
 * @param function function to process each element returned from scan.
 *                 If function.apply returns false then the scan is stopped.
 *                 Also, function.apply should not return null.
 * @param <T>      type of value
 */
public <T> void scan(MDSKey startId, @Nullable MDSKey stopId, Type typeOfT, Function<KeyValue<T>, Boolean> function) {
    byte[] startKey = startId.getKey();
    byte[] stopKey = stopId == null ? Bytes.stopKeyForPrefix(startKey) : stopId.getKey();
    try (Scanner scan = table.scan(startKey, stopKey)) {
        Row next;
        while ((next = scan.next()) != null) {
            byte[] columnValue = next.get(COLUMN);
            if (columnValue == null) {
                continue;
            }
            MDSKey key = new MDSKey(next.getRow());
            T value = deserialize(key, columnValue, typeOfT);
            // noinspection ConstantConditions
            if (!function.apply(new KeyValue<>(key, value))) {
                break;
            }
        }
    }
}

Example 14 with Scanner

use of io.cdap.cdap.api.dataset.table.Scanner in project cdap by caskdata.

the class MetadataStoreDataset method listCombinedFilterKV.

private <T> Map<MDSKey, T> listCombinedFilterKV(Scan runScan, Type typeOfT, int limit, @Nullable Predicate<KeyValue<T>> combinedFilter) {
    try {
        Map<MDSKey, T> map = Maps.newLinkedHashMap();
        try (Scanner scan = table.scan(runScan)) {
            Row next;
            while ((limit > 0) && (next = scan.next()) != null) {
                MDSKey key = new MDSKey(next.getRow());
                byte[] columnValue = next.get(COLUMN);
                if (columnValue == null) {
                    continue;
                }
                T value = deserialize(key, columnValue, typeOfT);
                KeyValue<T> kv = new KeyValue<>(key, value);
                // Combined Filter doesn't pass
                if (combinedFilter != null && !combinedFilter.test(kv)) {
                    continue;
                }
                map.put(kv.getKey(), kv.getValue());
                limit--;
            }
            return map;
        }
    } catch (Exception e) {
        throw Throwables.propagate(e);
    }
}

Example 15 with Scanner

use of io.cdap.cdap.api.dataset.table.Scanner in project cdap by caskdata.

the class MetadataStoreDataset method getFirst.

/**
 * Get the first element in the row and default COLUMN, of type T
 *
 * @param id the mds key for the row
 * @param typeOfT the type of the result
 * @return the deserialized value of the result, null if not exist
 */
@Nullable
public <T> T getFirst(MDSKey id, Type typeOfT) {
    try {
        try (Scanner scan = table.scan(id.getKey(), Bytes.stopKeyForPrefix(id.getKey()))) {
            Row row = scan.next();
            if (row == null || row.isEmpty()) {
                return null;
            }
            byte[] value = row.get(COLUMN);
            if (value == null) {
                return null;
            }
            return deserialize(id, value, typeOfT);
        }
    } catch (Exception e) {
        throw Throwables.propagate(e);
    }
}