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Minor optimizations and cleanup in decoding/encoding #208

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Nov 5, 2024
Merged

Minor optimizations and cleanup in decoding/encoding #208

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15 changes: 7 additions & 8 deletions core/src/main/java/eu/ostrzyciel/jelly/core/EncoderLookup.java
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Original file line number Diff line number Diff line change
Expand Up @@ -58,10 +58,10 @@ public LookupEntry(int getId, int setId, boolean newEntry) {
// This will monotonically increase until it reaches the maximum size.
private int used;
// The last id that was set in the table.
private int lastSetId;
private int lastSetId = -1000;
// Names of the entries. Entry 0 is always null.
private final String[] names;
// Whether to use serials for the entries.
// Whether to maintain serial numbers for the entries.
private final boolean useSerials;

private final LookupEntry entryForReturns = new LookupEntry(0, 0, true);
Expand Down Expand Up @@ -133,13 +133,11 @@ public LookupEntry getOrAddEntry(String key) {
names[id] = key;
map.put(key, new LookupEntry(id, id));
// setId is 0 because we are adding a new entry sequentially
entryForReturns.setId = 0;
// .serial is already 1 by default
// entryForReturns.serial = 1;
// We don't need to set it because it's 0 by default
// entryForReturns.setId = 0;
} else {
// The table is full, evict the least recently used entry.
int base = table[1];
id = base / 2;
id = table[1] / 2;
// Remove the entry from the map
LookupEntry oldEntry = map.remove(names[id]);
// Insert the new entry
Expand All @@ -148,6 +146,8 @@ public LookupEntry getOrAddEntry(String key) {
// Update the table
onAccess(id);
entryForReturns.setId = lastSetId + 1 == id ? 0 : id;
// We only update lastSetId in this case, because in the sequential case we don't check it anyway
lastSetId = id;
}
if (this.useSerials) {
// Increment the serial number
Expand All @@ -156,7 +156,6 @@ public LookupEntry getOrAddEntry(String key) {
++serials[id];
}
entryForReturns.getId = id;
lastSetId = id;
return entryForReturns;
}
}
49 changes: 20 additions & 29 deletions core/src/main/java/eu/ostrzyciel/jelly/core/NameDecoder.java
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Expand Up @@ -32,8 +32,8 @@ private static final class PrefixLookupEntry {
private int lastPrefixIdReference = 0;
private int lastNameIdReference = 0;

private int lastPrefixIdSet = -1;
private int lastNameIdSet = -1;
private int lastPrefixIdSet = 0;
private int lastNameIdSet = 0;

private final Function<String, TIri> iriFactory;

Expand All @@ -45,13 +45,13 @@ private static final class PrefixLookupEntry {
*/
public NameDecoder(int prefixTableSize, int nameTableSize, Function<String, TIri> iriFactory) {
this.iriFactory = iriFactory;
nameLookup = new NameLookupEntry[nameTableSize];
prefixLookup = new PrefixLookupEntry[prefixTableSize];
nameLookup = new NameLookupEntry[nameTableSize + 1];
prefixLookup = new PrefixLookupEntry[prefixTableSize + 1];

for (int i = 0; i < nameTableSize; i++) {
for (int i = 1; i < nameTableSize + 1; i++) {
nameLookup[i] = new NameLookupEntry();
}
for (int i = 0; i < prefixTableSize; i++) {
for (int i = 1; i < prefixTableSize + 1; i++) {
prefixLookup[i] = new PrefixLookupEntry();
}
}
Expand All @@ -63,11 +63,11 @@ public NameDecoder(int prefixTableSize, int nameTableSize, Function<String, TIri
*/
public void updateNames(RdfNameEntry nameEntry) {
int id = nameEntry.id();
if (id == 0) {
lastNameIdSet++;
} else {
lastNameIdSet = id - 1;
}
// Branchless! Equivalent to:
// if (id == 0) lastNameIdSet++;
// else lastNameIdSet = id;
// Same code is used in the methods below.
lastNameIdSet = ((lastNameIdSet + 1) & ((id - 1) >> 31)) + id;
NameLookupEntry entry = nameLookup[lastNameIdSet];
entry.name = nameEntry.value();
// Enough to invalidate the last IRI – we don't have to touch the serial number.
Expand All @@ -83,11 +83,7 @@ public void updateNames(RdfNameEntry nameEntry) {
*/
public void updatePrefixes(RdfPrefixEntry prefixEntry) {
int id = prefixEntry.id();
if (id == 0) {
lastPrefixIdSet++;
} else {
lastPrefixIdSet = id - 1;
}
lastPrefixIdSet = ((lastPrefixIdSet + 1) & ((id - 1) >> 31)) + id;
PrefixLookupEntry entry = prefixLookup[lastPrefixIdSet];
entry.prefix = prefixEntry.value();
entry.serial++;
Expand All @@ -104,23 +100,18 @@ public void updatePrefixes(RdfPrefixEntry prefixEntry) {
@SuppressWarnings("unchecked")
public TIri decode(RdfIri iri) {
int nameId = iri.nameId();

NameLookupEntry nameEntry;
if (nameId == 0) {
nameEntry = nameLookup[lastNameIdReference];
lastNameIdReference++;
} else {
nameEntry = nameLookup[nameId - 1];
lastNameIdReference = nameId;
}
lastNameIdReference = ((lastNameIdReference + 1) & ((nameId - 1) >> 31)) + nameId;
NameLookupEntry nameEntry = nameLookup[lastNameIdReference];

int prefixId = iri.prefixId();
if (prefixId == 0) prefixId = lastPrefixIdReference;
else lastPrefixIdReference = prefixId;

// Branchless way to update the prefix ID
// Equivalent to:
// if (prefixId == 0) prefixId = lastPrefixIdReference;
// else lastPrefixIdReference = prefixId;
lastPrefixIdReference = prefixId = (((prefixId - 1) >> 31) & lastPrefixIdReference) + prefixId;
if (prefixId != 0) {
// Name and prefix
PrefixLookupEntry prefixEntry = prefixLookup[prefixId - 1];
PrefixLookupEntry prefixEntry = prefixLookup[prefixId];
if (nameEntry.lastPrefixId != prefixId || nameEntry.lastPrefixSerial != prefixEntry.serial) {
// Update the last prefix
nameEntry.lastPrefixId = prefixId;
Expand Down
9 changes: 5 additions & 4 deletions core/src/main/java/eu/ostrzyciel/jelly/core/NodeEncoder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -150,12 +150,13 @@ public UniversalTerm encodeIri(String iri, ArrayBuffer<RdfStreamRow> rowsBuffer)
new RdfNameEntry(nameEntry.setId, iri)
));
}
if (lastIriNameId + 1 == nameEntry.getId) {
lastIriNameId = nameEntry.getId;
int nameId = nameEntry.getId;
if (lastIriNameId + 1 == nameId) {
lastIriNameId = nameId;
return zeroIri;
} else {
lastIriNameId = nameEntry.getId;
return nameOnlyIris[lastIriNameId];
lastIriNameId = nameId;
return nameOnlyIris[nameId];
}
}

Expand Down
22 changes: 18 additions & 4 deletions core/src/test/scala/eu/ostrzyciel/jelly/core/NameDecoderSpec.scala
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Expand Up @@ -107,13 +107,20 @@ class NameDecoderSpec extends AnyWordSpec, Matchers:
}
}

"not accept a new prefix ID lower than 0" in {
"not accept a new prefix ID lower than 0 (-1)" in {
val dec = makeDecoder(smallOptions)
intercept[ArrayIndexOutOfBoundsException] {
intercept[NullPointerException] {
dec.updatePrefixes(RdfPrefixEntry(-1, "https://test.org/"))
}
}

"not accept a new prefix ID lower than 0 (-2)" in {
val dec = makeDecoder(smallOptions)
intercept[ArrayIndexOutOfBoundsException] {
dec.updatePrefixes(RdfPrefixEntry(-2, "https://test.org/"))
}
}

"not retrieve a prefix ID larger than table size" in {
val dec = makeDecoder(smallOptions)
intercept[ArrayIndexOutOfBoundsException] {
Expand All @@ -136,13 +143,20 @@ class NameDecoderSpec extends AnyWordSpec, Matchers:
}
}

"not accept a new name ID lower than 0" in {
"not accept a new name ID lower than 0 (-1)" in {
val dec = makeDecoder(smallOptions)
intercept[ArrayIndexOutOfBoundsException] {
intercept[NullPointerException] {
dec.updateNames(RdfNameEntry(-1, "Cake"))
}
}

"not accept a new name ID lower than 0 (-2)" in {
val dec = makeDecoder(smallOptions)
intercept[ArrayIndexOutOfBoundsException] {
dec.updateNames(RdfNameEntry(-2, "Cake"))
}
}

"not retrieve a name ID larger than table size" in {
val dec = makeDecoder(smallOptions)
intercept[ArrayIndexOutOfBoundsException] {
Expand Down