testReusedBuffer() — netty Function Reference

Source Code

codec-base/src/test/java/io/netty/handler/codec/ByteToMessageDecoderTest.java lines 638–686

    static void testReusedBuffer(ByteBuf buffer, boolean secondPartial, ByteToMessageDecoder.Cumulator cumulator) {
        ByteToMessageDecoder decoder = new ByteToMessageDecoder() {
            @Override
            protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
                while (in.readableBytes() >= 4) {
                    int index = in.readerIndex();
                    int len = in.readInt();
                    assert len < (1 << 30) : "In-plausibly long message: " + len;
                    if (in.readableBytes() >= len) {
                        byte[] bytes = new byte[len];
                        in.readBytes(bytes);
                        String message = new String(bytes, CharsetUtil.UTF_8);
                        out.add(message);
                    } else {
                        in.readerIndex(index);
                        return;
                    }
                }
            }
        };
        decoder.setCumulator(cumulator);
        EmbeddedChannel channel = new EmbeddedChannel(decoder);

        buffer.retain(); // buffer is allocated from the pool, the pool would call retain()
        buffer.writeInt(11); // total length of message
        buffer.writeByte('h').writeByte('e').writeByte('l').writeByte('l');
        if (secondPartial) {
            assertFalse(channel.writeInbound(buffer)); // try reading incomplete message
            assertTrue(channel.inboundMessages().isEmpty());
            assertEquals(0, buffer.readerIndex(), "Incomplete message should still be readable in buffer");
            buffer.retain(); // buffer is allocated from the pool - reusing same buffer, the pool would call retain()
        }
        buffer.writeByte('o').writeByte(' ');
        assertFalse(channel.writeInbound(buffer)); // try reading incomplete message
        assertTrue(channel.inboundMessages().isEmpty());
        assertEquals(0, buffer.readerIndex(), "Incomplete message should still be readable in buffer");

        buffer.retain(); // buffer is allocated from the pool - reusing same buffer, the pool would call retain()
        buffer.writeByte('w').writeByte('o').writeByte('r').writeByte('l').writeByte('d');
        assertTrue(channel.writeInbound(buffer));
        assertFalse(channel.inboundMessages().isEmpty(), "Message should be received");
        assertEquals("hello world", channel.inboundMessages().poll(), "Message should be received correctly");
        assertTrue(channel.inboundMessages().isEmpty(), "Only a single message should be received");
        assertFalse(buffer.isReadable(), "Buffer should not have remaining data after reading complete message");

        buffer.release(); // we are done with the buffer - release it from the pool
        assertEquals(0, buffer.refCnt(), "Buffer should be released");
        assertFalse(channel.finish());
    }