public List<RowLogMessage> next(String subscription, Long minimalTimestamp, boolean problematic)
throws RowLogException {
byte[] rowPrefix;
byte[] subscriptionBytes = Bytes.toBytes(subscription);
if (problematic) {
rowPrefix = PROBLEMATIC_MARKER;
rowPrefix = Bytes.add(rowPrefix, subscriptionBytes);
} else {
rowPrefix = subscriptionBytes;
}
byte[] startRow = rowPrefix;
if (minimalTimestamp != null) startRow = Bytes.add(startRow, Bytes.toBytes(minimalTimestamp));
try {
List<RowLogMessage> rowLogMessages = new ArrayList<RowLogMessage>();
Scan scan = new Scan(startRow);
if (minimalTimestamp != null) scan.setTimeRange(minimalTimestamp, Long.MAX_VALUE);
scan.addColumn(MESSAGES_CF, MESSAGE_COLUMN);
ResultScanner scanner = table.getScanner(scan);
boolean keepScanning = problematic;
do {
Result[] results = scanner.next(batchSize);
if (results.length == 0) {
keepScanning = false;
}
for (Result next : results) {
byte[] rowKey = next.getRow();
if (!Bytes.startsWith(rowKey, rowPrefix)) {
keepScanning = false;
break; // There were no messages for this subscription
}
if (problematic) {
rowKey = Bytes.tail(rowKey, rowKey.length - PROBLEMATIC_MARKER.length);
}
byte[] value = next.getValue(MESSAGES_CF, MESSAGE_COLUMN);
byte[] messageId = Bytes.tail(rowKey, rowKey.length - subscriptionBytes.length);
rowLogMessages.add(decodeMessage(messageId, value));
}
} while (keepScanning);
// The scanner is not closed in a finally block, since when we get an IOException from
// HBase, it is likely that closing the scanner will give problems too. Not closing
// the scanner is not fatal since HBase will expire it after a while.
Closer.close(scanner);
return rowLogMessages;
} catch (IOException e) {
throw new RowLogException("Failed to fetch next message from RowLogShard", e);
}
}
@Override
/**
* Checks if a blob key (ourStoreKey) is contained in the blob field (theirValue). The blob field
* can be a multivalue and / or hierarchical field.
*
* <p>IMPORTANT: This implementation depends on the byte encodings from ValueTypeImpl,
* BlobValueType and DataOutputImpl. Any changes there have an impact on this implementation.
*/
public int compareTo(byte[] theirValue, int fromOffset, int length) {
byte[] ourStoreKey =
Bytes.tail(nestingLevelAndValue, nestingLevelAndValue.length - Bytes.SIZEOF_INT);
if (theirValue == null && ourStoreKey == null) return 0;
if (length == 0 && ourStoreKey.length == 0) return 0;
if (length < ourStoreKey.length) return -1;
if (theirValue[fromOffset] == (byte) (1)) { // First byte indicates if it was deleted or not
return -1;
}
int nestingLevel = Bytes.toInt(nestingLevelAndValue);
offset = fromOffset + 1;
return compareBlob(nestingLevel, ourStoreKey, theirValue);
}
private RowLogMessage decodeMessage(byte[] messageId, byte[] data) {
long timestamp = Bytes.toLong(messageId);
long seqNr = Bytes.toLong(messageId, Bytes.SIZEOF_LONG);
byte[] rowKey = Bytes.tail(messageId, messageId.length - (2 * Bytes.SIZEOF_LONG));
return new RowLogMessageImpl(timestamp, rowKey, seqNr, data, rowLog);
}