Package com.ljarocki.parallelzip.internal

Class LibdeflateNative

java.lang.Object

com.ljarocki.parallelzip.internal.LibdeflateNative

public final class LibdeflateNative
extends Object

Bindings to a bundled native libdeflate build. libdeflate has no streaming API (whole-buffer in, whole-buffer out), so this is only usable for the in-memory fast path; the spilled/streamed path keeps using the JDK's Deflater. Only linux-x64, linux-arm64, windows-x64, windows-arm64, macos-arm64 and macos-x64 natives are bundled (the platforms this project's CI builds and tests); every other platform/arch, or any failure while loading, permanently falls back to pure Java with no behavioural change.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	STORE_SENTINEL	Sentinel returned by compress(long, byte[], int, int, byte[], int, int, long[])/compressBatch(long, byte[][], byte[][], int[], long[], int) (as the entry's length) when the native incompressibility sniff judged a large input to be already compressed: the caller should STORE the whole entry instead of compressing it.

Method Summary

Modifier and Type	Method	Description
static long	allocCompressor(int level)	Allocates a native compressor for the given DEFLATE level (1..12), to be reused across many compress(long, byte[], int, int, byte[], int, int, long[])/compressBatch(long, byte[][], byte[][], int[], long[], int) calls -- typically one per worker thread, held for the life of a write.
static boolean	available()
static int	compress(long handle, byte[] in, int inOff, int inLen, byte[] out, int outOff, int outCap, long[] crcOut)	Compresses in[inOff, inOff+inLen) into out[outOff, outOff+outCap) using raw DEFLATE, with the compressor identified by handle.
static void	compressBatch(long handle, byte[][] ins, byte[][] outs, int[] outLens, long[] crcs, int count)	Compresses count independent buffers in one native call, reusing handle for all of them.
static int	compressDirect(long handle, ByteBuffer in, int inLen, byte[] out, int outOff, int outCap, long[] crcOut)	Compresses directly from a direct (typically memory-mapped) ByteBuffer -- in[0, inLen) -- into out[outOff, outOff+outCap), without ever copying the input through a JVM heap byte[].
static void	freeCompressor(long handle)	Releases a handle returned by allocCompressor(int).

Methods inherited from class java.lang.Object

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

Field Details

STORE_SENTINEL

public static final int STORE_SENTINEL

Sentinel returned by compress(long, byte[], int, int, byte[], int, int, long[])/compressBatch(long, byte[][], byte[][], int[], long[], int) (as the entry's length) when the native incompressibility sniff judged a large input to be already compressed: the caller should STORE the whole entry instead of compressing it. Distinct from the -1 "call failed, use the JDK Deflater" signal.

See Also:

• Constant Field Values

Method Details

available

public static boolean available()

allocCompressor

public static long allocCompressor(int level)

Allocates a native compressor for the given DEFLATE level (1..12), to be reused across many compress(long, byte[], int, int, byte[], int, int, long[])/compressBatch(long, byte[][], byte[][], int[], long[], int) calls -- typically one per worker thread, held for the life of a write. Returns 0 on failure (e.g. out of memory); callers must treat that as "native unavailable" and fall back to the JDK Deflater instead of passing the zero handle through.

freeCompressor

public static void freeCompressor(long handle)

Releases a handle returned by allocCompressor(int). A no-op if handle is 0.

compress

public static int compress(long handle,
 byte[] in,
 int inOff,
 int inLen,
 byte[] out,
 int outOff,
 int outCap,
 long[] crcOut)

Compresses in[inOff, inOff+inLen) into out[outOff, outOff+outCap) using raw DEFLATE, with the compressor identified by handle. Returns the compressed length; STORE_SENTINEL (-2) if the sniff judged the input already compressed and it should be STOREd; or -1 if the native call failed for any reason (e.g. the output buffer was too small), in which case callers should fall back to the JDK Deflater. crcOut[0] always receives the CRC-32 of the input, computed natively while the array is already pinned for compression -- regardless of the return value -- so callers never need a separate CRC32 pass over the same bytes.

compressBatch

public static void compressBatch(long handle,
 byte[][] ins,
 byte[][] outs,
 int[] outLens,
 long[] crcs,
 int count)

Compresses count independent buffers in one native call, reusing handle for all of them. ins[i] is compressed in full into outs[i]; outLens[i] receives the compressed length, STORE_SENTINEL (-2) if the sniff says to STORE it, or -1 if that one entry failed and needs a JDK Deflater fallback -- one entry's failure does not affect the others in the batch. crcs[i] always receives the CRC-32 of ins[i], computed natively alongside compression, regardless of outLens[i].

compressDirect

public static int compressDirect(long handle,
 ByteBuffer in,
 int inLen,
 byte[] out,
 int outOff,
 int outCap,
 long[] crcOut)

Compresses directly from a direct (typically memory-mapped) ByteBuffer -- in[0, inLen) -- into out[outOff, outOff+outCap), without ever copying the input through a JVM heap byte[]. Used for the large-entry fast path, where in is a MappedByteBuffer backed by the OS page cache instead of a byte[] read via Files.readAllBytes(java.nio.file.Path). Same return convention as compress(long, byte[], int, int, byte[], int, int, long[]), including the fused crcOut[0]. in must be direct; a non-direct buffer causes a native failure (-1), not a crash.