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Merged
pkwarren merged 1 commit into from
Apr 24, 2026
Merged

Add a cache for compiled regex patterns #459

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10 changes: 10 additions & 0 deletions benchmarks/src/jmh/java/build/buf/protovalidate/benchmarks/ValidationBenchmark.java
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Expand Up @@ -17,6 +17,7 @@
import build.buf.protovalidate.Validator;
import build.buf.protovalidate.ValidatorFactory;
import build.buf.protovalidate.benchmarks.gen.ManyUnruledFieldsMessage;
import build.buf.protovalidate.benchmarks.gen.RegexPatternMessage;
import build.buf.protovalidate.benchmarks.gen.RepeatedRuleMessage;
import build.buf.protovalidate.benchmarks.gen.SimpleStringMessage;
import build.buf.protovalidate.exceptions.ValidationException;
Expand All @@ -40,6 +41,7 @@ public class ValidationBenchmark {
private SimpleStringMessage simple;
private ManyUnruledFieldsMessage manyUnruled;
private RepeatedRuleMessage repeatedRule;
private RegexPatternMessage regexPattern;

@Setup
public void setup() throws ValidationException {
Expand Down Expand Up @@ -67,10 +69,13 @@ public void setup() throws ValidationException {
}
repeatedRule = repeatedRuleBuilder.build();

regexPattern = RegexPatternMessage.newBuilder().setName("Alice Example").build();

// Warm evaluator cache for steady-state benchmarks.
validator.validate(simple);
validator.validate(manyUnruled);
validator.validate(repeatedRule);
validator.validate(regexPattern);
}

// Steady-state validate() benchmarks. These exercise the hot path after the
Expand All @@ -90,4 +95,9 @@ public void validateManyUnruled(Blackhole bh) throws ValidationException {
public void validateRepeatedRule(Blackhole bh) throws ValidationException {
bh.consume(validator.validate(repeatedRule));
}

@Benchmark
public void validateRegexPattern(Blackhole bh) throws ValidationException {
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@pkwarren pkwarren Apr 24, 2026

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Results:

benchmark             metric  before         after          delta
validateRegexPattern  time    1873.21 ns/op  1323.61 ns/op  -29.3%
validateRegexPattern  alloc   7828 B/op      4272 B/op      -45.4%

bh.consume(validator.validate(regexPattern));
}
}
10 changes: 10 additions & 0 deletions benchmarks/src/jmh/proto/bench/v1/bench.proto
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Expand Up @@ -69,3 +69,13 @@ message RepeatedRuleMessage {
string f19 = 19 [(buf.validate.field).string.min_len = 1];
string f20 = 20 [(buf.validate.field).string.min_len = 1];
}

// Single string field with a string.pattern rule. Targets the regex
// recompile-per-evaluation cost: the CEL runtime's matches() calls
// Pattern.compile on every invocation.
message RegexPatternMessage {
string name = 1 [(buf.validate.field).string = {
pattern: "^[[:alpha:]]+( [[:alpha:]]+)*$"
max_bytes: 256
}];
}
1 change: 1 addition & 0 deletions build.gradle.kts
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Expand Up @@ -398,6 +398,7 @@ dependencies {
api(libs.jspecify)
api(libs.protobuf.java)
implementation(libs.cel)
implementation(libs.re2j)

buf("build.buf:buf:${libs.versions.buf.get()}:${osdetector.classifier}@exe")

Expand Down
2 changes: 2 additions & 0 deletions gradle/libs.versions.toml
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Expand Up @@ -6,6 +6,7 @@ error-prone = "2.49.0"
junit = "5.14.3"
maven-publish = "0.36.0"
protobuf = "4.34.1"
re2j = "1.8"

[libraries]
assertj = { module = "org.assertj:assertj-core", version.ref = "assertj" }
Expand All @@ -19,6 +20,7 @@ junit-bom = { module = "org.junit:junit-bom", version.ref = "junit" }
maven-plugin = { module = "com.vanniktech:gradle-maven-publish-plugin", version.ref = "maven-publish" }
nullaway = { module = "com.uber.nullaway:nullaway", version = "0.13.3" }
protobuf-java = { module = "com.google.protobuf:protobuf-java", version.ref = "protobuf" }
re2j = { module = "com.google.re2j:re2j", version.ref = "re2j" }
spotless = { module = "com.diffplug.spotless:spotless-plugin-gradle", version = "8.4.0" }

[plugins]
Expand Down
11 changes: 11 additions & 0 deletions src/main/java/build/buf/protovalidate/CustomDeclarations.java
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Expand Up @@ -104,6 +104,17 @@ static List<CelFunctionDecl> create() {
newMemberOverload(
"is_hostname", SimpleType.BOOL, Collections.singletonList(SimpleType.STRING))));

// Redeclare 'matches' with the same overload ids as the stdlib.
decls.add(
newFunctionDeclaration(
"matches",
newGlobalOverload(
"matches", SimpleType.BOOL, Arrays.asList(SimpleType.STRING, SimpleType.STRING)),
newMemberOverload(
"matches_string",
SimpleType.BOOL,
Arrays.asList(SimpleType.STRING, SimpleType.STRING))));

decls.add(
newFunctionDeclaration(
"isHostAndPort",
Expand Down
52 changes: 48 additions & 4 deletions src/main/java/build/buf/protovalidate/CustomOverload.java
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Expand Up @@ -16,6 +16,10 @@

import com.google.protobuf.Descriptors;
import com.google.protobuf.Message;
import com.google.re2j.Matcher;
import com.google.re2j.Pattern;
import com.google.re2j.PatternSyntaxException;
import dev.cel.common.CelOptions;
import dev.cel.common.types.CelType;
import dev.cel.common.types.SimpleType;
import dev.cel.common.values.CelByteString;
Expand All @@ -28,7 +32,7 @@
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.regex.Pattern;
import java.util.concurrent.ConcurrentMap;

/** Defines custom function overloads (the implementation). */
final class CustomOverload {
Expand All @@ -39,11 +43,14 @@ final class CustomOverload {
"^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$");

/**
* Create custom function overload list.
* Create a list of custom function overloads.
*
* @param patternCache cache used by the {@code matches}/{@code matches_string} overrides.
* @param celOptions CEL options the enclosing runtime is built with.
* @return a list of overloaded functions.
*/
static List<CelFunctionBinding> create() {
static List<CelFunctionBinding> create(
ConcurrentMap<String, Pattern> patternCache, CelOptions celOptions) {
ArrayList<CelFunctionBinding> bindings = new ArrayList<>();
bindings.addAll(
Arrays.asList(
Expand All @@ -65,7 +72,9 @@ static List<CelFunctionBinding> create() {
celIsNan(),
celIsInfUnary(),
celIsInfBinary(),
celIsHostAndPort()));
celIsHostAndPort(),
celMatches(patternCache, celOptions),
celMatchesString(patternCache, celOptions)));
bindings.addAll(celUnique());
return Collections.unmodifiableList(bindings);
}
Expand Down Expand Up @@ -356,6 +365,41 @@ private static CelFunctionBinding celIsHostAndPort() {
CustomOverload::isHostAndPort);
}

/** Caching replacement for CEL's global {@code matches(string, string)}. */
@SuppressWarnings("Immutable")
private static CelFunctionBinding celMatches(
ConcurrentMap<String, Pattern> patternCache, CelOptions celOptions) {
return CelFunctionBinding.from(
"matches",
String.class,
String.class,
(value, regex) -> matches(patternCache, celOptions, value, regex));
}

/** Caching replacement for CEL's member-style {@code string.matches(string)}. */
@SuppressWarnings("Immutable")
private static CelFunctionBinding celMatchesString(
ConcurrentMap<String, Pattern> patternCache, CelOptions celOptions) {
return CelFunctionBinding.from(
"matches_string",
String.class,
String.class,
(value, regex) -> matches(patternCache, celOptions, value, regex));
}

private static boolean matches(
ConcurrentMap<String, Pattern> cache, CelOptions celOptions, String value, String regex)
throws CelEvaluationException {
Pattern pattern;
try {
pattern = cache.computeIfAbsent(regex, Pattern::compile);
} catch (PatternSyntaxException e) {
throw new CelEvaluationException("failed to compile regex: " + e.getMessage(), e);
}
Matcher matcher = pattern.matcher(value);
return celOptions.enableRegexPartialMatch() ? matcher.find() : matcher.matches();
}

/**
* Returns true if the string is a valid host/port pair, for example "example.com:8080".
*
Expand Down
37 changes: 36 additions & 1 deletion src/main/java/build/buf/protovalidate/ValidateLibrary.java
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Expand Up @@ -14,24 +14,59 @@

package build.buf.protovalidate;

import com.google.re2j.Pattern;
import dev.cel.bundle.Cel;
import dev.cel.bundle.CelFactory;
import dev.cel.checker.CelCheckerBuilder;
import dev.cel.checker.CelStandardDeclarations;
import dev.cel.common.CelOptions;
import dev.cel.common.CelVarDecl;
import dev.cel.common.types.SimpleType;
import dev.cel.compiler.CelCompilerLibrary;
import dev.cel.extensions.CelExtensions;
import dev.cel.parser.CelParserBuilder;
import dev.cel.parser.CelStandardMacro;
import dev.cel.runtime.CelRuntimeBuilder;
import dev.cel.runtime.CelRuntimeLibrary;
import dev.cel.runtime.CelStandardFunctions;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
* Custom {@link CelCompilerLibrary} and {@link CelRuntimeLibrary}. Provides all the custom
* extension function definitions and overloads.
*/
final class ValidateLibrary implements CelCompilerLibrary, CelRuntimeLibrary {

private static final CelOptions CEL_OPTIONS = CelOptions.DEFAULT;

private final ConcurrentMap<String, Pattern> patternCache = new ConcurrentHashMap<>();
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@pkwarren pkwarren Apr 24, 2026

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Unlike the proposed fix in google/cel-java#1038, this cache is scoped to a Validator and not global.


/** Creates a ValidateLibrary with all custom declarations and overloads. */
ValidateLibrary() {}

static Cel newCel() {
ValidateLibrary validateLibrary = new ValidateLibrary();
// NOTE: CelExtensions.strings() does not implement string.reverse() or strings.quote() which
// are available in protovalidate-go. Fixed in https://github.com/google/cel-java/pull/998.
return CelFactory.standardCelBuilder()
.setOptions(CEL_OPTIONS)
// Drop stdlib matches; CustomOverload provides a caching replacement.
// Ref: https://github.com/google/cel-java/issues/1038
.setStandardEnvironmentEnabled(false)
.setStandardDeclarations(
CelStandardDeclarations.newBuilder()
.excludeFunctions(CelStandardDeclarations.StandardFunction.MATCHES)
.build())
.setStandardFunctions(
CelStandardFunctions.newBuilder()
.excludeFunctions(CelStandardFunctions.StandardFunction.MATCHES)
.build())
.addCompilerLibraries(validateLibrary, CelExtensions.strings())
.addRuntimeLibraries(validateLibrary, CelExtensions.strings())
.build();
}

@Override
public void setParserOptions(CelParserBuilder parserBuilder) {
parserBuilder.setStandardMacros(
Expand All @@ -54,6 +89,6 @@ public void setCheckerOptions(CelCheckerBuilder checkerBuilder) {

@Override
public void setRuntimeOptions(CelRuntimeBuilder runtimeBuilder) {
runtimeBuilder.addFunctionBindings(CustomOverload.create());
runtimeBuilder.addFunctionBindings(CustomOverload.create(patternCache, CEL_OPTIONS));
}
}
21 changes: 3 additions & 18 deletions src/main/java/build/buf/protovalidate/ValidatorImpl.java
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Expand Up @@ -18,10 +18,6 @@
import build.buf.protovalidate.exceptions.ValidationException;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Message;
import dev.cel.bundle.Cel;
import dev.cel.bundle.CelFactory;
import dev.cel.common.CelOptions;
import dev.cel.extensions.CelExtensions;
import java.util.ArrayList;
import java.util.List;

Expand All @@ -36,13 +32,14 @@ final class ValidatorImpl implements Validator {
private final boolean failFast;

ValidatorImpl(Config config) {
this.evaluatorBuilder = new EvaluatorBuilder(newCel(), config);
this.evaluatorBuilder = new EvaluatorBuilder(ValidateLibrary.newCel(), config);
this.failFast = config.isFailFast();
}

ValidatorImpl(Config config, List<Descriptor> descriptors, boolean disableLazy)
throws CompilationException {
this.evaluatorBuilder = new EvaluatorBuilder(newCel(), config, descriptors, disableLazy);
this.evaluatorBuilder =
new EvaluatorBuilder(ValidateLibrary.newCel(), config, descriptors, disableLazy);
this.failFast = config.isFailFast();
}

Expand All @@ -63,16 +60,4 @@ public ValidationResult validate(Message msg) throws ValidationException {
}
return new ValidationResult(violations);
}

private static Cel newCel() {
ValidateLibrary validateLibrary = new ValidateLibrary();
// NOTE: CelExtensions.strings() does not implement string.reverse() or strings.quote() which
// are available in protovalidate-go.
return CelFactory.standardCelBuilder()
.addCompilerLibraries(validateLibrary, CelExtensions.strings())
.addRuntimeLibraries(validateLibrary, CelExtensions.strings())
.setOptions(
CelOptions.DEFAULT.toBuilder().evaluateCanonicalTypesToNativeValues(true).build())
.build();
}
}
24 changes: 14 additions & 10 deletions src/test/java/build/buf/protovalidate/CustomOverloadTest.java
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Expand Up @@ -18,9 +18,7 @@
import static org.assertj.core.api.Assertions.assertThatThrownBy;

import dev.cel.bundle.Cel;
import dev.cel.bundle.CelFactory;
import dev.cel.common.CelAbstractSyntaxTree;
import dev.cel.common.CelOptions;
import dev.cel.common.CelValidationException;
import dev.cel.common.CelValidationResult;
import dev.cel.runtime.CelEvaluationException;
Expand All @@ -31,14 +29,7 @@

public class CustomOverloadTest {

private final ValidateLibrary validateLibrary = new ValidateLibrary();
private final Cel cel =
CelFactory.standardCelBuilder()
.addCompilerLibraries(validateLibrary)
.addRuntimeLibraries(validateLibrary)
.setOptions(
CelOptions.DEFAULT.toBuilder().evaluateCanonicalTypesToNativeValues(true).build())
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@stefanvanburen stefanvanburen Apr 24, 2026

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do we still need evaluateCanonicalTypesToNativeValues(true) in newCel?

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This is deprecated and the default is true so I went ahead and removed it.

.build();
private final Cel cel = ValidateLibrary.newCel();

@Test
public void testIsInf() throws Exception {
Expand Down Expand Up @@ -173,6 +164,19 @@ public void testBytesContains() throws Exception {
assertThat(evalToBool("bytes('12345').contains(bytes('123456'))")).isFalse();
}

@Test
public void testMatchesPartialMatch() throws Exception {
// CelOptions.DEFAULT sets enableRegexPartialMatch(true), so an unanchored regex should
// match anywhere in the input (find()), not require a full-string match.
assertThat(evalToBool("'hello world'.matches('world')")).isTrue();
assertThat(evalToBool("'hello world'.matches('ell')")).isTrue();
// Anchored patterns still behave the same.
assertThat(evalToBool("'hello'.matches('^hello$')")).isTrue();
assertThat(evalToBool("'hello world'.matches('^hello$')")).isFalse();
// Global form.
assertThat(evalToBool("matches('hello world', 'world')")).isTrue();
}

private Object eval(String source) throws Exception {
return eval(source, Collections.emptyMap());
}
Expand Down
11 changes: 1 addition & 10 deletions src/test/java/build/buf/protovalidate/FormatTest.java
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Expand Up @@ -26,8 +26,6 @@
import com.google.protobuf.TextFormat;
import dev.cel.bundle.Cel;
import dev.cel.bundle.CelBuilder;
import dev.cel.bundle.CelFactory;
import dev.cel.common.CelOptions;
import dev.cel.common.CelValidationException;
import dev.cel.common.CelValidationResult;
import dev.cel.common.types.SimpleType;
Expand Down Expand Up @@ -87,14 +85,7 @@ public static void setUp() throws Exception {
.flatMap(s -> s.getTestList().stream())
.collect(Collectors.toList());

ValidateLibrary validateLibrary = new ValidateLibrary();
cel =
CelFactory.standardCelBuilder()
.addCompilerLibraries(validateLibrary)
.addRuntimeLibraries(validateLibrary)
.setOptions(
CelOptions.DEFAULT.toBuilder().evaluateCanonicalTypesToNativeValues(true).build())
.build();
cel = ValidateLibrary.newCel();
}

@ParameterizedTest
Expand Down
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