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Use SWAR in CBORParser #758

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ab16742
use SWAR in CBORParser
pjfanning Aug 21, 2026
f1c7810
Merge branch '3.x' into cbor-parser
cowtowncoder Aug 22, 2026
1125e5c
Merge branch '3.x' into cbor-parser
cowtowncoder Aug 22, 2026
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95 changes: 67 additions & 28 deletions cbor/src/main/java/tools/jackson/dataformat/cbor/CBORParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -125,6 +125,29 @@ public int getFirstTag() {
protected final static JacksonFeatureSet<StreamReadCapability> CBOR_READ_CAPABILITIES =
DEFAULT_READ_CAPABILITIES.with(StreamReadCapability.EXACT_FLOATS);

/**
* Whether VarHandles are usable on this runtime; probed once at class load.
* Being {@code static final} lets the branches in {@link #_decode32Bits()},
* {@link #_decode64Bits()} and {@link #_decodeQuad} fold away at JIT time.
*
* @since 3.3
*/
private final static boolean _VARHANDLE_AVAILABLE = _checkVarHandleAvailable();

private static boolean _checkVarHandleAvailable() {
// NOTE: this call is what first loads `CBORVarHandleUtil`, and that class
// names `VarHandle` in its field/method signatures. On a runtime lacking
// `java.lang.invoke.VarHandle` (some Android builds) loading it raises
// `NoClassDefFoundError` -- an Error, not an Exception -- so `Throwable`
// is what has to be caught here. Without this guard the failure would
// propagate out of this class's initializer and make the parser unusable.
try {
return CBORVarHandleUtil.isAvailable();
} catch (Throwable t) {
return false;
}
}

/*
/**********************************************************************
/* Configuration
Expand Down Expand Up @@ -1566,10 +1589,8 @@ private final int _nextFieldOptimized(PropertyNameMatcher matcher, final int len
int inPtr = _inputPtr;

// First quadbyte is easy
int q1 = (inBuf[inPtr++] & 0xFF);
q1 = (q1 << 8) | (inBuf[inPtr++] & 0xFF);
q1 = (q1 << 8) | (inBuf[inPtr++] & 0xFF);
q1 = (q1 << 8) | (inBuf[inPtr++] & 0xFF);
int q1 = _decodeQuad(inBuf, inPtr);
inPtr += 4;

if (len < 9) {
int q2 = (inBuf[inPtr++] & 0xFF);
Expand All @@ -1588,10 +1609,8 @@ private final int _nextFieldOptimized(PropertyNameMatcher matcher, final int len
return matcher.matchByQuad(q1, q2);
}

int q2 = (inBuf[inPtr++] & 0xFF);
q2 = (q2 << 8) | (inBuf[inPtr++] & 0xFF);
q2 = (q2 << 8) | (inBuf[inPtr++] & 0xFF);
q2 = (q2 << 8) | (inBuf[inPtr++] & 0xFF);
int q2 = _decodeQuad(inBuf, inPtr);
inPtr += 4;

if (len < 13) {
int q3 = (inBuf[inPtr++] & 0xFF);
Expand Down Expand Up @@ -1636,11 +1655,8 @@ private final int _nextFieldFromSymbolsLong(PropertyNameMatcher matcher,

final byte[] inBuf = _inputBuffer;
do {
int q = (inBuf[inPtr++] & 0xFF);
q = (q << 8) | inBuf[inPtr++] & 0xFF;
q = (q << 8) | inBuf[inPtr++] & 0xFF;
q = (q << 8) | inBuf[inPtr++] & 0xFF;
_quadBuffer[offset++] = q;
_quadBuffer[offset++] = _decodeQuad(inBuf, inPtr);
inPtr += 4;
} while ((len -= 4) > 3);
// and then leftovers
if (len > 0) {
Expand Down Expand Up @@ -3362,10 +3378,8 @@ private final String _findDecodedFromSymbols(final int len) throws JacksonExcept
int inPtr = _inputPtr;

// First quadbyte is easy
int q1 = (inBuf[inPtr++] & 0xFF);
q1 = (q1 << 8) | (inBuf[inPtr++] & 0xFF);
q1 = (q1 << 8) | (inBuf[inPtr++] & 0xFF);
q1 = (q1 << 8) | (inBuf[inPtr++] & 0xFF);
int q1 = _decodeQuad(inBuf, inPtr);
inPtr += 4;

if (len < 9) {
int q2 = _padQuadForNulls(inBuf[inPtr++]);
Expand All @@ -3384,10 +3398,8 @@ private final String _findDecodedFromSymbols(final int len) throws JacksonExcept
return _symbols.findName(q1, q2);
}

int q2 = (inBuf[inPtr++] & 0xFF);
q2 = (q2 << 8) | (inBuf[inPtr++] & 0xFF);
q2 = (q2 << 8) | (inBuf[inPtr++] & 0xFF);
q2 = (q2 << 8) | (inBuf[inPtr++] & 0xFF);
int q2 = _decodeQuad(inBuf, inPtr);
inPtr += 4;

if (len < 13) {
int q3 = _padQuadForNulls(inBuf[inPtr++]);
Expand Down Expand Up @@ -3434,11 +3446,8 @@ private final String _findDecodedLong(int len, int q1, int q2) throws JacksonExc

final byte[] inBuf = _inputBuffer;
do {
int q = (inBuf[inPtr++] & 0xFF);
q = (q << 8) | inBuf[inPtr++] & 0xFF;
q = (q << 8) | inBuf[inPtr++] & 0xFF;
q = (q << 8) | inBuf[inPtr++] & 0xFF;
_quadBuffer[offset++] = q;
_quadBuffer[offset++] = _decodeQuad(inBuf, inPtr);
inPtr += 4;
} while ((len -= 4) > 3);
// and then leftovers
if (len > 0) {
Expand Down Expand Up @@ -3484,6 +3493,23 @@ private final static int _padQuadForNulls(int firstByte) {
return (firstByte & 0xFF) | 0xFFFFFF00;
}

/**
* Helper method for decoding 4 bytes of an Object property name into the
* "quad" (big-endian {@code int}) form used by {@code ByteQuadsCanonicalizer}.
* Caller MUST have verified that 4 bytes are readable at given offset.
*
* @since 3.3
*/
private final static int _decodeQuad(byte[] buffer, int offset) {
if (_VARHANDLE_AVAILABLE) {
return CBORVarHandleUtil.getInt(buffer, offset);
}
return ((buffer[offset] & 0xFF) << 24)
| ((buffer[offset+1] & 0xFF) << 16)
| ((buffer[offset+2] & 0xFF) << 8)
| (buffer[offset+3] & 0xFF);
}

/*
/**********************************************************************
/* Internal methods, skipping
Expand Down Expand Up @@ -3776,8 +3802,14 @@ private final int _decode32Bits() throws JacksonException {
return _slow32();
}
final byte[] b = _inputBuffer;
int v = (b[ptr++] << 24) + ((b[ptr++] & 0xFF) << 16)
+ ((b[ptr++] & 0xFF) << 8) + (b[ptr++] & 0xFF);
final int v;
if (_VARHANDLE_AVAILABLE) {
v = CBORVarHandleUtil.getInt(b, ptr);
ptr += 4;
} else {
v = (b[ptr++] << 24) + ((b[ptr++] & 0xFF) << 16)
+ ((b[ptr++] & 0xFF) << 8) + (b[ptr++] & 0xFF);
}
_inputPtr = ptr;
return v;
}
Expand Down Expand Up @@ -3807,6 +3839,13 @@ private final long _decode64Bits() throws JacksonException {
return _slow64();
}
final byte[] b = _inputBuffer;
if (_VARHANDLE_AVAILABLE) {
// NOTE: identical to `_long()` of the two 32-bit halves below, since
// that is just a big-endian 8-byte read spelled out
final long l = CBORVarHandleUtil.getLong(b, ptr);
_inputPtr = ptr + 8;
return l;
}
int i1 = (b[ptr++] << 24) + ((b[ptr++] & 0xFF) << 16)
+ ((b[ptr++] & 0xFF) << 8) + (b[ptr++] & 0xFF);
int i2 = (b[ptr++] << 24) + ((b[ptr++] & 0xFF) << 16)
Expand Down
24 changes: 22 additions & 2 deletions cbor/src/main/java/tools/jackson/dataformat/cbor/CBORVarHandleUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -51,8 +51,8 @@ static boolean isAvailable() {
return LONG_BE != null;
}

// Helper methods that write primitives via the class's own VarHandle fields.
// Only called when the corresponding field is non-null, which implies
// Helper methods that read/write primitives via the class's own VarHandle
// fields. Only called when the corresponding field is non-null, which implies
// VarHandle is available on this runtime.

static void setInt(byte[] array, int offset, int value) {
Expand All @@ -62,4 +62,24 @@ static void setInt(byte[] array, int offset, int value) {
static void setLong(byte[] array, int offset, long value) {
LONG_BE.set(array, offset, value);
}

/**
* Reads 4 bytes at given offset as a big-endian {@code int}; caller MUST
* have verified that {@code offset+4} is within bounds of given array.
*
* @since 3.3
*/
static int getInt(byte[] array, int offset) {
return (int) INT_BE.get(array, offset);
}

/**
* Reads 8 bytes at given offset as a big-endian {@code long}; caller MUST
* have verified that {@code offset+8} is within bounds of given array.
*
* @since 3.3
*/
static long getLong(byte[] array, int offset) {
return (long) LONG_BE.get(array, offset);
}
}