io.rsocket.metadata

Class CompositeMetadataCodec

java.lang.Object

io.rsocket.metadata.CompositeMetadataCodec

public class CompositeMetadataCodec
extends Object

A flyweight class that can be used to encode/decode composite metadata information to/from ByteBuf. This is intended for low-level efficient manipulation of such buffers. See CompositeMetadata for an Iterator-like approach to decoding entries.

Method Summary

Modifier and Type	Method and Description
static int	computeNextEntryIndex(int currentEntryIndex, ByteBuf headerSlice, ByteBuf contentSlice)
static ByteBuf[]	decodeMimeAndContentBuffersSlices(ByteBuf compositeMetadata, int entryIndex, boolean retainSlices) Decode the next metadata entry (a mime header + content pair of ByteBuf) from a ByteBuf that contains at least enough bytes for one more such entry.
static byte	decodeMimeIdFromMimeBuffer(ByteBuf mimeBuffer) Decode a byte compressed mime id from a ByteBuf, assuming said buffer properly contains such an id.
static CharSequence	decodeMimeTypeFromMimeBuffer(ByteBuf flyweightMimeBuffer) Decode a CharSequence custome mime type from a ByteBuf, assuming said buffer properly contains such a mime type.
static void	encodeAndAddMetadata(CompositeByteBuf compositeMetaData, ByteBufAllocator allocator, String customMimeType, ByteBuf metadata) Encode a new sub-metadata information into a composite metadata buffer, without checking if the String can be matched with a well known compressable mime type.
static void	encodeAndAddMetadata(CompositeByteBuf compositeMetaData, ByteBufAllocator allocator, WellKnownMimeType knownMimeType, ByteBuf metadata) Encode a new sub-metadata information into a composite metadata buffer.
static void	encodeAndAddMetadataWithCompression(CompositeByteBuf compositeMetaData, ByteBufAllocator allocator, String mimeType, ByteBuf metadata) Encode a new sub-metadata information into a composite metadata buffer, first verifying if the passed String matches a WellKnownMimeType (in which case it will be encoded in a compressed fashion using the mime id of that type).
static boolean	hasEntry(ByteBuf compositeMetadata, int entryIndex) Returns whether there is another entry available at a given index
static boolean	isWellKnownMimeType(ByteBuf header) Returns whether the header represents a well-known MIME type.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

computeNextEntryIndex

public static int computeNextEntryIndex(int currentEntryIndex,
                                        ByteBuf headerSlice,
                                        ByteBuf contentSlice)

decodeMimeAndContentBuffersSlices

public static ByteBuf[] decodeMimeAndContentBuffersSlices(ByteBuf compositeMetadata,
                                                          int entryIndex,
                                                          boolean retainSlices)

Decode the next metadata entry (a mime header + content pair of ByteBuf) from a ByteBuf that contains at least enough bytes for one more such entry. These buffers are actually slices of the full metadata buffer, and this method doesn't move the full metadata buffer's ByteBuf.readerIndex(). As such, it requires the user to provide an index to read from. The next index is computed by calling computeNextEntryIndex(int, ByteBuf, ByteBuf). Size of the first buffer (the "header buffer") drives which decoding method should be further applied to it.

The header buffer is either:

• made up of a single byte: this represents an encoded mime id, which can be further decoded using decodeMimeIdFromMimeBuffer(ByteBuf)
• made up of 2 or more bytes: this represents an encoded mime String + its length, which can be further decoded using decodeMimeTypeFromMimeBuffer(ByteBuf). Note the encoded length, in the first byte, is skipped by this decoding method because the remaining length of the buffer is that of the mime string.

Parameters:

compositeMetadata - the source ByteBuf that originally contains one or more metadata entries

entryIndex - the ByteBuf.readerIndex() to start decoding from. original reader index is kept on the source buffer

retainSlices - should produced metadata entry buffers slices be retained?

Returns:

a ByteBuf array of length 2 containing the mime header buffer slice and the content buffer slice, or one of the zero-length error constant arrays

decodeMimeIdFromMimeBuffer

public static byte decodeMimeIdFromMimeBuffer(ByteBuf mimeBuffer)

Decode a byte compressed mime id from a ByteBuf, assuming said buffer properly contains such an id.

The buffer must have exactly one readable byte, which is assumed to have been tested for mime id encoding via the STREAM_METADATA_KNOWN_MASK mask (firstByte & STREAM_METADATA_KNOWN_MASK) == STREAM_METADATA_KNOWN_MASK).

If there is no readable byte, the negative identifier of WellKnownMimeType.UNPARSEABLE_MIME_TYPE is returned.

Parameters:

mimeBuffer - the buffer that should next contain the compressed mime id byte

Returns:

the compressed mime id, between 0 and 127, or a negative id if the input is invalid

See Also:

decodeMimeTypeFromMimeBuffer(ByteBuf)

decodeMimeTypeFromMimeBuffer

@Nullable
public static CharSequence decodeMimeTypeFromMimeBuffer(ByteBuf flyweightMimeBuffer)

Decode a CharSequence custome mime type from a ByteBuf, assuming said buffer properly contains such a mime type.

The buffer must at least have two readable bytes, which distinguishes it from the compressed id case. The first byte is a size and the remaining bytes must correspond to the CharSequence, encoded fully in US_ASCII. As a result, the first byte can simply be skipped, and the remaining of the buffer be decoded to the mime type.

If the mime header buffer is less than 2 bytes long, returns null.

Parameters:

flyweightMimeBuffer - the mime header ByteBuf that contains length + custom mime type

Returns:

the decoded custom mime type, as a CharSequence, or null if the input is invalid

See Also:

decodeMimeIdFromMimeBuffer(ByteBuf)

encodeAndAddMetadata

public static void encodeAndAddMetadata(CompositeByteBuf compositeMetaData,
                                        ByteBufAllocator allocator,
                                        String customMimeType,
                                        ByteBuf metadata)

Encode a new sub-metadata information into a composite metadata buffer, without checking if the String can be matched with a well known compressable mime type. Prefer using this method and encodeAndAddMetadata(CompositeByteBuf, ByteBufAllocator, WellKnownMimeType, ByteBuf) if you know in advance whether or not the mime is well known. Otherwise use encodeAndAddMetadataWithCompression(CompositeByteBuf, ByteBufAllocator, String, ByteBuf)

Parameters:

compositeMetaData - the buffer that will hold all composite metadata information.

allocator - the ByteBufAllocator to use to create intermediate buffers as needed.

customMimeType - the custom mime type to encode.

metadata - the metadata value to encode.

encodeAndAddMetadata

public static void encodeAndAddMetadata(CompositeByteBuf compositeMetaData,
                                        ByteBufAllocator allocator,
                                        WellKnownMimeType knownMimeType,
                                        ByteBuf metadata)

Encode a new sub-metadata information into a composite metadata buffer.

Parameters:

compositeMetaData - the buffer that will hold all composite metadata information.

allocator - the ByteBufAllocator to use to create intermediate buffers as needed.

knownMimeType - the WellKnownMimeType to encode.

metadata - the metadata value to encode.

encodeAndAddMetadataWithCompression

public static void encodeAndAddMetadataWithCompression(CompositeByteBuf compositeMetaData,
                                                       ByteBufAllocator allocator,
                                                       String mimeType,
                                                       ByteBuf metadata)

Encode a new sub-metadata information into a composite metadata buffer, first verifying if the passed String matches a WellKnownMimeType (in which case it will be encoded in a compressed fashion using the mime id of that type).

Prefer using encodeAndAddMetadata(CompositeByteBuf, ByteBufAllocator, String, ByteBuf) if you already know that the mime type is not a WellKnownMimeType.

Parameters:

compositeMetaData - the buffer that will hold all composite metadata information.

allocator - the ByteBufAllocator to use to create intermediate buffers as needed.

mimeType - the mime type to encode, as a String. well known mime types are compressed.

metadata - the metadata value to encode.

See Also:

encodeAndAddMetadata(CompositeByteBuf, ByteBufAllocator, WellKnownMimeType, ByteBuf)

hasEntry

public static boolean hasEntry(ByteBuf compositeMetadata,
                               int entryIndex)

Returns whether there is another entry available at a given index

Parameters:

compositeMetadata - the buffer to inspect

entryIndex - the index to check at

Returns:

whether there is another entry available at a given index

isWellKnownMimeType

public static boolean isWellKnownMimeType(ByteBuf header)

Returns whether the header represents a well-known MIME type.

Parameters:

header - the header to inspect

Returns:

whether the header represents a well-known MIME type