io.reactivex.netty.protocol.http.sse.ServerSentEventEncoder Maven / Gradle / Ivy

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/*
 * Copyright 2014 Netflix, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.reactivex.netty.protocol.http.sse;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.ByteProcessor;

/**
 * An encoder to convert {@link ServerSentEvent} to a {@link io.netty.buffer.ByteBuf}
 *
 * @author Nitesh Kant
 */
@ChannelHandler.Sharable
public class ServerSentEventEncoder extends MessageToByteEncoder {

    private static final byte[] EVENT_PREFIX_BYTES = "event: ".getBytes();
    private static final byte[] NEW_LINE_AS_BYTES = "\n".getBytes();
    private static final byte[] ID_PREFIX_AS_BYTES = "id: ".getBytes();
    private static final byte[] DATA_PREFIX_AS_BYTES = "data: ".getBytes();
    private final boolean splitSseData;

    public ServerSentEventEncoder() {
        this(false);
    }

    /**
     * Splits the SSE data on new line and create multiple "data" events if {@code splitSseData} is {@code true}
     *
     * @param splitSseData {@code true} if the SSE data is to be splitted on new line to create multiple "data" events.
     */
    public ServerSentEventEncoder(boolean splitSseData) {
        this.splitSseData = splitSseData;
    }

    @Override
    protected void encode(ChannelHandlerContext ctx, ServerSentEvent serverSentEvent, ByteBuf out) throws Exception {
        if (serverSentEvent.hasEventType()) { // Write event type, if available
            out.writeBytes(EVENT_PREFIX_BYTES);
            out.writeBytes(serverSentEvent.getEventType());
            out.writeBytes(NEW_LINE_AS_BYTES);
        }

        if (serverSentEvent.hasEventId()) { // Write event id, if available
            out.writeBytes(ID_PREFIX_AS_BYTES);
            out.writeBytes(serverSentEvent.getEventId());
            out.writeBytes(NEW_LINE_AS_BYTES);
        }

        final ByteBuf content = serverSentEvent.content();

        if (splitSseData) {
            while (content.isReadable()) { // Scan the buffer and split on new line into multiple data lines.
                final int readerIndexAtStart = content.readerIndex();
                int newLineIndex = content.forEachByte(new ByteProcessor() {
                    @Override
                    public boolean process(byte value) throws Exception {
                        return (char) value != '\n';
                    }
                });
                if (-1 == newLineIndex) { // No new line, write the buffer as is.
                    out.writeBytes(DATA_PREFIX_AS_BYTES);
                    out.writeBytes(content);
                    out.writeBytes(NEW_LINE_AS_BYTES);
                } else { // Write the buffer till the new line and then iterate this loop
                    out.writeBytes(DATA_PREFIX_AS_BYTES);
                    out.writeBytes(content, newLineIndex - readerIndexAtStart);
                    content.readerIndex(content.readerIndex() + 1);
                    out.writeBytes(NEW_LINE_AS_BYTES);
                }
            }
        } else { // write the buffer with data prefix and new line post fix.
            out.writeBytes(DATA_PREFIX_AS_BYTES);
            out.writeBytes(content);
            out.writeBytes(NEW_LINE_AS_BYTES);
        }
    }
}