Add a concrete o.s.g.cache.RepositoryCacheWriter class, which implements org.apache.geode.cache.CacheWriter and uses (delegates to) a Spring Data CrudRepository.

spring-geode/src/main/java/org/springframework/geode/cache/RepositoryCacheWriter.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package org.springframework.geode.cache;
+
+import java.util.function.Supplier;
+
+import org.apache.geode.cache.CacheRuntimeException;
+import org.apache.geode.cache.CacheWriter;
+import org.apache.geode.cache.CacheWriterException;
+import org.apache.geode.cache.EntryEvent;
+import org.apache.geode.cache.RegionEvent;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.geode.cache.support.RepositoryCacheLoaderWriterSupport;
+import org.springframework.geode.core.util.function.FunctionUtils;
+
+/**
+ * A {@link CacheWriter} implementation backed by a Spring Data {@link CrudRepository} used to persist a cache entry
+ * (i.e. entity) to a backend, external data source.
+ *
+ * @author John Blum
+ * @see org.apache.geode.cache.CacheWriter
+ * @see org.springframework.data.repository.CrudRepository
+ * @see org.springframework.geode.cache.support.RepositoryCacheLoaderWriterSupport
+ * @since 1.1.0
+ */
+@SuppressWarnings("unused")
+public class RepositoryCacheWriter<T, ID> extends RepositoryCacheLoaderWriterSupport<T, ID> {
+
+  public RepositoryCacheWriter(CrudRepository<T, ID> repository) {
+    super(repository);
+  }
+
+  @Override
+  public void beforeCreate(EntryEvent<ID, T> event) throws CacheWriterException {
+    doRepositoryOp(event.getNewValue(), getRepository()::save);
+  }
+
+  @Override
+  public void beforeUpdate(EntryEvent<ID, T> event) throws CacheWriterException {
+    doRepositoryOp(event.getNewValue(), getRepository()::save);
+  }
+
+  @Override
+  public void beforeDestroy(EntryEvent<ID, T> event) throws CacheWriterException {
+
+    //doRepositoryOp(event.getOldValue(), FunctionUtils.toNullReturningFunction(getRepository()::delete));
+    doRepositoryOp(event.getKey(), FunctionUtils.toNullReturningFunction(getRepository()::deleteById));
+  }
+
+  @Override
+  public void beforeRegionClear(RegionEvent<ID, T> event) throws CacheWriterException {
+
+    if (isNukeAndPaveEnabled()) {
+      doRepositoryOp(null, FunctionUtils.toNullReturningFunction(it -> getRepository().deleteAll()));
+    }
+  }
+
+  @Override
+  public void beforeRegionDestroy(RegionEvent<ID, T> event) throws CacheWriterException {
+    // TODO: perhaps implement by releasing external data source resources
+    //  (i.e. destroy database object(s), e.g. DROP TABLE)
+  }
+
+  @Override
+  protected CacheRuntimeException newCacheRuntimeException(Supplier<String> messageSupplier, Throwable cause) {
+    return new CacheWriterException(messageSupplier.get(), cause);
+  }
+}

spring-geode/src/test/java/org/springframework/geode/cache/RepositoryCacheWriterUnitTests.java

@@ -0,0 +1,168 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package org.springframework.geode.cache;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+import static org.mockito.Mockito.when;
+
+import org.apache.geode.cache.CacheRuntimeException;
+import org.apache.geode.cache.CacheWriterException;
+import org.apache.geode.cache.EntryEvent;
+import org.apache.geode.cache.RegionEvent;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.springframework.core.env.Environment;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.geode.cache.support.RepositoryCacheLoaderWriterSupport;
+
+/**
+ * Unit Tests for {@link RepositoryCacheWriter}.
+ *
+ * @author John Blum
+ * @see org.junit.Test
+ * @see org.mockito.Mockito
+ * @see org.mockito.junit.MockitoJUnitRunner
+ * @see org.springframework.data.repository.CrudRepository
+ * @see org.springframework.geode.cache.RepositoryCacheWriter
+ * @see org.springframework.geode.cache.support.RepositoryCacheLoaderWriterSupport
+ * @since 1.1.0
+ */
+@RunWith(MockitoJUnitRunner.class)
+@SuppressWarnings("unchecked")
+public class RepositoryCacheWriterUnitTests {
+
+	@Mock
+	private CrudRepository<Object, Object> mockCrudRepository;
+
+	@Mock
+	private EntryEvent<Object, Object> mockEntryEvent;
+
+	@Mock
+	private Environment mockEnvironment;
+
+	private final Object testEntity = new Object();
+
+	private RepositoryCacheWriter<Object, Object> cacheWriter;
+
+	@Before
+	public void setup() {
+
+		this.cacheWriter = new RepositoryCacheWriter<>(this.mockCrudRepository)
+			.with(this.mockEnvironment);
+	}
+	@Test
+	public void beforeCreateSavesEntityWithRepository() {
+
+		when(this.mockEntryEvent.getNewValue()).thenReturn(this.testEntity);
+
+		this.cacheWriter.beforeCreate(this.mockEntryEvent);
+
+		verify(this.mockEntryEvent, times(1)).getNewValue();
+		verify(this.mockCrudRepository, times(1)).save(eq(this.testEntity));
+	}
+
+	@Test
+	public void beforeUpdateSavesEntityWithRepository() {
+
+		when(this.mockEntryEvent.getNewValue()).thenReturn(this.testEntity);
+
+		this.cacheWriter.beforeUpdate(this.mockEntryEvent);
+
+		verify(this.mockEntryEvent, times(1)).getNewValue();
+		verify(this.mockCrudRepository, times(1)).save(eq(this.testEntity));
+	}
+
+	@Test
+	public void beforeDestroyDeletesByIdWithRepository() {
+
+		when(this.mockEntryEvent.getKey()).thenReturn("TestKey");
+
+		this.cacheWriter.beforeDestroy(this.mockEntryEvent);
+
+		verify(this.mockEntryEvent, times(1)).getKey();
+		verify(this.mockCrudRepository, times(1)).deleteById(eq("TestKey"));
+	}
+
+	@Test
+	public void beforeRegionClearDeletesAllWithRepositoryWhenNukeAndPaveIsEnabled() {
+
+		RegionEvent<Object, Object> mockRegionEvent = mock(RegionEvent.class);
+
+		when(this.mockEnvironment.getProperty(eq(RepositoryCacheLoaderWriterSupport.NUKE_AND_PAVE_PROPERTY),
+			eq(Boolean.class))).thenReturn(true);
+
+		this.cacheWriter.beforeRegionClear(mockRegionEvent);
+
+		verify(this.mockEnvironment, times(1))
+			.getProperty(eq(RepositoryCacheLoaderWriterSupport.NUKE_AND_PAVE_PROPERTY), eq(Boolean.class));
+
+		verify(this.mockCrudRepository, times(1)).deleteAll();
+
+		verifyZeroInteractions(mockRegionEvent);
+	}
+
+	@Test
+	public void beforeRegionClearWillNotDeleteAllWithRepositoryWhenNukeAndPaveIsDisabled() {
+
+		RegionEvent<Object, Object> mockRegionEvent = mock(RegionEvent.class);
+
+		when(this.mockEnvironment.getProperty(eq(RepositoryCacheLoaderWriterSupport.NUKE_AND_PAVE_PROPERTY),
+			eq(Boolean.class))).thenReturn(false);
+
+		this.cacheWriter.beforeRegionClear(mockRegionEvent);
+
+		verify(this.mockEnvironment, times(1))
+			.getProperty(eq(RepositoryCacheLoaderWriterSupport.NUKE_AND_PAVE_PROPERTY), eq(Boolean.class));
+
+		verify(this.mockCrudRepository, never()).deleteAll();
+
+		verifyZeroInteractions(mockRegionEvent);
+	}
+
+	@Test
+	public void beforeRegionDestroyDoesNothing() {
+
+		RegionEvent<Object, Object> mockRegionEvent = mock(RegionEvent.class);
+
+		this.cacheWriter.beforeRegionDestroy(mockRegionEvent);
+
+		verifyZeroInteractions(this.mockEnvironment);
+		verifyZeroInteractions(this.mockCrudRepository);
+		verifyZeroInteractions(mockRegionEvent);
+	}
+
+	@Test
+	@SuppressWarnings("all")
+	public void newCacheRuntimeExceptionIsCorrect() {
+
+		RuntimeException cause = new RuntimeException("TEST");
+
+		CacheRuntimeException cacheRuntimeException = this.cacheWriter.newCacheRuntimeException(() -> "TEST", cause);
+
+		assertThat(cacheRuntimeException).isInstanceOf(CacheWriterException.class);
+		assertThat(cacheRuntimeException.getMessage()).isEqualTo("TEST");
+		assertThat(cacheRuntimeException.getCause()).isEqualTo(cause);
+	}
+}