Create Spring Geode Sample application for the Look-Aside Caching pattern.

spring-geode-samples/caching/look-aside/spring-geode-samples-caching-lookaside.gradle

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+apply plugin: 'io.spring.convention.spring-sample-boot'
+
+description = "Spring Geode Sample demonstrating Spring's Cache Abstraction using Apache Geode as the caching provider."
+
+dependencies {
+
+	compile project(":spring-geode-starter")
+
+	compile ("org.springframework.boot:spring-boot-starter-web") {
+		exclude group: "org.apache.logging.log4j", module: "log4j-to-slf4j"
+	}
+
+	runtime "javax.cache.cache-api"
+	runtime "org.springframework.shell:spring-shell"
+
+	runtime ("org.springframework.boot:spring-boot-starter-jetty") {
+		exclude group: "org.apache.logging.log4j", module: "log4j-to-slf4j"
+	}
+
+}
+
+bootJar {
+	mainClassName = 'example.app.temp.geode.client.BootGeodeClientApplication'
+}

spring-geode-samples/caching/look-aside/src/main/java/example/app/caching/lookaside/BootGeodeLookAsideCachingApplication.java

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+/*
+ * 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 example.app.caching.lookaside;
+
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+
+/**
+ * The BootGeodeLookAsideCachingApplication class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+@SpringBootApplication
+public class BootGeodeLookAsideCachingApplication {
+
+	public static void main(String[] args) {
+
+		new SpringApplicationBuilder(BootGeodeLookAsideCachingApplication.class)
+			.web(WebApplicationType.SERVLET)
+			.build()
+			.run(args);
+	}
+}

spring-geode-samples/caching/look-aside/src/main/java/example/app/caching/lookaside/config/GeodeConfiguration.java

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+/*
+ * 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 example.app.caching.lookaside.config;
+
+import org.apache.geode.cache.client.ClientRegionShortcut;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.gemfire.config.annotation.EnableCachingDefinedRegions;
+import org.springframework.data.gemfire.config.annotation.EnableLogging;
+
+/**
+ * The GeodeConfiguration class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+@SuppressWarnings("unused")
+// tag::class[]
+@Configuration
+@EnableLogging(logLevel = "error")
+@EnableCachingDefinedRegions(clientRegionShortcut = ClientRegionShortcut.LOCAL)
+public class GeodeConfiguration { }
+// end::class[]

spring-geode-samples/caching/look-aside/src/main/java/example/app/caching/lookaside/contoller/CounterController.java

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+/*
+ * 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 example.app.caching.lookaside.contoller;
+
+import org.springframework.util.Assert;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RestController;
+
+import example.app.caching.lookaside.service.CounterService;
+
+/**
+ * The CounterController class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+@SuppressWarnings("unused")
+// tag::class[]
+@RestController
+public class CounterController {
+
+	private static final String HEADER_ONE = "<h1>%s</h1>";
+
+	private final CounterService counterService;
+
+	public CounterController(CounterService counterService) {
+
+		Assert.notNull(counterService, "CounterService is required");
+
+		this.counterService = counterService;
+	}
+
+	@GetMapping("/ping")
+	public String ping() {
+		return String.format(HEADER_ONE, "PONG");
+	}
+
+	@GetMapping("counter/{name}")
+	public String getCount(@PathVariable("name") String counterName) {
+		return String.format(HEADER_ONE, this.counterService.getCount(counterName));
+	}
+
+	@GetMapping("counter/{name}/cached")
+	public String getCachedCount(@PathVariable("name") String counterName) {
+		return String.format(HEADER_ONE, this.counterService.getCachedCount(counterName));
+	}
+
+	@GetMapping("counter/{name}/reset")
+	public String resetCounter(@PathVariable("name") String counterName) {
+		this.counterService.resetCounter(counterName);
+		return String.format(HEADER_ONE, "0");
+	}
+}
+// end::class[]

spring-geode-samples/caching/look-aside/src/main/java/example/app/caching/lookaside/service/CounterService.java

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+/*
+ * 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 example.app.caching.lookaside.service;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.springframework.cache.annotation.CacheEvict;
+import org.springframework.cache.annotation.CachePut;
+import org.springframework.cache.annotation.Cacheable;
+import org.springframework.stereotype.Service;
+
+/**
+ * The CounterService class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+// tag::class[]
+@Service
+public class CounterService {
+
+	private ConcurrentMap<String, AtomicLong> namedCounterMap = new ConcurrentHashMap<>();
+
+	@Cacheable("Counters")
+	public long getCachedCount(String counterName) {
+		return getCount(counterName);
+	}
+
+	@CachePut("Counters")
+	public long getCount(String counterName) {
+
+		AtomicLong counter = this.namedCounterMap.get(counterName);
+
+		if (counter == null) {
+
+			counter = new AtomicLong(0L);
+
+			AtomicLong existingCounter = this.namedCounterMap.putIfAbsent(counterName, counter);
+
+			counter = existingCounter != null ? existingCounter : counter;
+		}
+
+		return counter.incrementAndGet();
+	}
+
+	@CacheEvict("Counters")
+	public void resetCounter(String counterName) {
+		this.namedCounterMap.remove(counterName);
+	}
+}
+// end::class[]