Examples with EndOfStreamSegment io.pravega.segmentstore.contracts.ReadResultEntryType.EndOfStreamSegment used on opensource projects

Example 1 with EndOfStreamSegment

use of io.pravega.segmentstore.contracts.ReadResultEntryType.EndOfStreamSegment in project pravega by pravega.

the class PravegaRequestProcessor method handleReadResult.

/**
 * Handles a readResult.
 * If there are cached entries that can be returned without blocking only these are returned.
 * Otherwise the call will request the data and setup a callback to return the data when it is available.
 * If no data is available but it was detected that the Segment had been truncated beyond the current offset,
 * an appropriate message is sent back over the connection.
 */
private void handleReadResult(ReadSegment request, ReadResult result) {
    String segment = request.getSegment();
    ArrayList<BufferView> cachedEntries = new ArrayList<>();
    ReadResultEntry nonCachedEntry = collectCachedEntries(request.getOffset(), result, cachedEntries);
    final String operation = "readSegment";
    boolean truncated = nonCachedEntry != null && nonCachedEntry.getType() == Truncated;
    boolean endOfSegment = nonCachedEntry != null && nonCachedEntry.getType() == EndOfStreamSegment;
    boolean atTail = nonCachedEntry != null && nonCachedEntry.getType() == Future;
    if (!cachedEntries.isEmpty() || endOfSegment) {
        // We managed to collect some data. Send it.
        ByteBuf data = toByteBuf(cachedEntries);
        SegmentRead reply = new SegmentRead(segment, request.getOffset(), atTail, endOfSegment, data, request.getRequestId());
        connection.send(reply);
        this.statsRecorder.read(segment, reply.getData().readableBytes());
    } else if (truncated) {
        // We didn't collect any data, instead we determined that the current read offset was truncated.
        // Determine the current Start Offset and send that back.
        segmentStore.getStreamSegmentInfo(segment, TIMEOUT).thenAccept(info -> connection.send(new SegmentIsTruncated(request.getRequestId(), segment, info.getStartOffset(), EMPTY_STACK_TRACE, nonCachedEntry.getStreamSegmentOffset()))).exceptionally(e -> handleException(request.getRequestId(), segment, nonCachedEntry.getStreamSegmentOffset(), operation, wrapCancellationException(e)));
    } else {
        Preconditions.checkState(nonCachedEntry != null, "No ReadResultEntries returned from read!?");
        nonCachedEntry.requestContent(TIMEOUT);
        nonCachedEntry.getContent().thenAccept(contents -> {
            ByteBuf data = toByteBuf(Collections.singletonList(contents));
            SegmentRead reply = new SegmentRead(segment, nonCachedEntry.getStreamSegmentOffset(), atTail, endOfSegment, data, request.getRequestId());
            connection.send(reply);
            this.statsRecorder.read(segment, reply.getData().readableBytes());
        }).exceptionally(exception -> {
            Throwable e = Exceptions.unwrap(exception);
            if (e instanceof StreamSegmentTruncatedException) {
                // The Segment may have been truncated in Storage after we got this entry but before we managed
                // to make a read. In that case, send the appropriate error back.
                final String clientReplyStackTrace = replyWithStackTraceOnError ? e.getMessage() : EMPTY_STACK_TRACE;
                connection.send(new SegmentIsTruncated(request.getRequestId(), segment, ((StreamSegmentTruncatedException) e).getStartOffset(), clientReplyStackTrace, nonCachedEntry.getStreamSegmentOffset()));
            } else {
                handleException(request.getRequestId(), segment, nonCachedEntry.getStreamSegmentOffset(), operation, wrapCancellationException(e));
            }
            return null;
        }).exceptionally(e -> handleException(request.getRequestId(), segment, nonCachedEntry.getStreamSegmentOffset(), operation, wrapCancellationException(e)));
    }
}