Add ExpressionLanguage condition to cache annotations (#692)

This adds a conditional field to `@Cacheable`, `@CachePut` and `@CacheInvalidate`.

Whenever the cache interceptor is invoked via a method annotated with one of these,
the conditional is evaluated to a boolean as to whether caching should be performed.

As this would slow down existing apps, or those not using conditional, we check to
see if the annotations contain a conditional, and if not the additional processing is
shortcircuited to go back to the old behavior.

Closes #572

Author: timyates

buildSrc/build.gradle

@@ -3,9 +3,11 @@ plugins {
 }
 
 repositories {
+    gradlePluginPortal()
     mavenCentral()
 }
 
 dependencies {
-    implementation "org.graalvm.buildtools.native:org.graalvm.buildtools.native.gradle.plugin:0.9.28"
+    implementation(libs.gradle.graal)
+    implementation(libs.gradle.kotlin)
 }

buildSrc/settings.gradle

@@ -0,0 +1,7 @@
+dependencyResolutionManagement {
+    versionCatalogs {
+        libs {
+            from(files("../gradle/libs.versions.toml"))
+        }
+    }
+}

cache-caffeine/src/test/groovy/io/micronaut/cache/ConditionalCacheSpec.groovy

@@ -0,0 +1,27 @@
+package io.micronaut.cache
+
+import io.micronaut.context.annotation.Property
+import io.micronaut.test.extensions.spock.annotation.MicronautTest
+import jakarta.inject.Inject
+import spock.lang.Specification
+
+@MicronautTest
+@Property(name = "spec.name", value = "ConditionalCacheSpec")
+class ConditionalCacheSpec extends Specification {
+
+    @Inject
+    ConditionalService service
+
+    void "test conditional cache"() {
+        when:
+        List<String> results = (1..10).collect { service.get(it) }
+        sleep(10)
+        List<String> secondResults = (1..10).collect { service.get(it) }
+
+        then: "condition results in the last 5 results being cached"
+        results.drop(5) == secondResults.drop(5)
+
+        and: "the first 5 results are not cached"
+        results.take(5).every {!secondResults.contains(it) }
+    }
+}

cache-caffeine/src/test/java/io/micronaut/cache/ConditionalService.java

@@ -0,0 +1,29 @@
+package io.micronaut.cache;
+
+import io.micronaut.cache.annotation.CacheConfig;
+import io.micronaut.cache.annotation.Cacheable;
+import io.micronaut.context.annotation.Requires;
+import jakarta.inject.Singleton;
+
+@Singleton
+@CacheConfig(cacheNames = {"conditional"})
+@Requires(property = "spec.name", value = "ConditionalCacheSpec")
+public class ConditionalService {
+
+    DocRepo repository = new DocRepo();
+
+    // tag::conditional[]
+    @Cacheable(condition = "#{id > 5}")
+    public String get(Integer id) {
+        return repository.get(id);
+    }
+    // end::conditional[]
+
+    // here to make the docs look nice when we extract the function above
+    private static class DocRepo {
+
+        String get(Integer id) {
+            return "test " + id + " " + System.currentTimeMillis();
+        }
+    }
+}

cache-core/src/main/java/io/micronaut/cache/annotation/CacheInvalidate.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 original authors
+ * Copyright 2017-2023 original authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -89,4 +89,14 @@
      * @return True if should be done asynchronously
      */
     boolean async() default false;
+
+    /**
+     * Evaluated expression that can be used to indicate whether the value should be cached.
+     * Will be evaluated each time the method is called, and if the condition evaluates to false the cache will not be used.
+     *
+     * @see <a href="https://docs.micronaut.io/latest/guide/#evaluatedExpressions">Evaluated Expressions</a>.
+     * @return The condition
+     * @since 4.2.0
+     */
+    String condition() default "";
 }

cache-core/src/main/java/io/micronaut/cache/annotation/CachePut.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 original authors
+ * Copyright 2017-2023 original authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -97,4 +97,13 @@
      * @return True if cache writes should be done asynchronously
      */
     boolean async() default false;
+
+    /**
+     * Evaluated expression that can be used to indicate whether the value should be cached.
+     * Will be evaluated each time the method is called, and if the condition evaluates to false the cache will not be used.
+     * @see <a href="https://docs.micronaut.io/latest/guide/#evaluatedExpressions">Evaluated Expressions</a>.
+     * @return The condition
+     * @since 4.2.0
+     */
+    String condition() default "";
 }

cache-core/src/main/java/io/micronaut/cache/annotation/Cacheable.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2020 original authors
+ * Copyright 2017-2023 original authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -87,4 +87,13 @@
      * @return True if an atomic operation should be attempted
      */
     boolean atomic() default false;
+
+    /**
+     * Evaluated expression that can be used to indicate whether the value should be cached.
+     * Will be evaluated each time the method is called, and if the condition evaluates to false the cache will not be used.
+     * @see <a href="https://docs.micronaut.io/latest/guide/#evaluatedExpressions">Evaluated Expressions</a>.
+     * @return The condition
+     * @since 4.2.0
+     */
+    String condition() default "";
 }