Update memcache sample with code from docs pages

appengine/memcache/src/main/java/com/example/appengine/memcache/MemcacheAsyncCacheServlet.java

@@ -0,0 +1,75 @@
+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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
+ *
+ * http://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 com.example.appengine.memcache;
+
+import com.google.appengine.api.memcache.AsyncMemcacheService;
+import com.google.appengine.api.memcache.ErrorHandlers;
+import com.google.appengine.api.memcache.MemcacheServiceFactory;
+
+import java.io.IOException;
+import java.math.BigInteger;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.logging.Level;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@SuppressWarnings("serial")
+public class MemcacheAsyncCacheServlet extends HttpServlet {
+
+  @Override
+  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException,
+      ServletException {
+    String path = req.getRequestURI();
+    if (path.startsWith("/favicon.ico")) {
+      return; // ignore the request for favicon.ico
+    }
+
+    // [START example]
+    AsyncMemcacheService asyncCache = MemcacheServiceFactory.getAsyncMemcacheService();
+    asyncCache.setErrorHandler(ErrorHandlers.getConsistentLogAndContinue(Level.INFO));
+    String key = "count-async";
+    byte[] value;
+    long count = 1;
+    Future<Object> futureValue = asyncCache.get(key); // Read from cache.
+    // ... Do other work in parallel to cache retrieval.
+    try {
+      value = (byte[]) futureValue.get();
+      if (value == null) {
+        value = BigInteger.valueOf(count).toByteArray();
+        asyncCache.put(key, value);
+      } else {
+        // Increment value
+        count = new BigInteger(value).longValue();
+        count++;
+        value = BigInteger.valueOf(count).toByteArray();
+        // Put back in cache
+        asyncCache.put(key, value);
+      }
+    } catch (InterruptedException | ExecutionException e) {
+      throw new ServletException("Error when waiting for future value", e);
+    }
+    // [END example]
+
+    // Output content
+    resp.setContentType("text/plain");
+    resp.getWriter().print("Value is " + count + "\n");
+  }
+}

appengine/memcache/src/main/java/com/example/appengine/memcache/MemcacheServlet.java → appengine/memcache/src/main/java/com/example/appengine/memcache/MemcacheBestPracticeServlet.java

@@ -30,7 +30,7 @@
 
 // [START example]
 @SuppressWarnings("serial")
-public class MemcacheServlet extends HttpServlet {
+public class MemcacheBestPracticeServlet extends HttpServlet {
 
   @Override
   public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException,

appengine/memcache/src/main/java/com/example/appengine/memcache/MemcacheConcurrentServlet.java

@@ -0,0 +1,85 @@
+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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
+ *
+ * http://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 com.example.appengine.memcache;
+
+import com.google.appengine.api.memcache.MemcacheService;
+import com.google.appengine.api.memcache.MemcacheService.IdentifiableValue;
+import com.google.appengine.api.memcache.MemcacheServiceFactory;
+
+import java.io.IOException;
+import java.math.BigInteger;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+// [START example]
+@SuppressWarnings("serial")
+public class MemcacheConcurrentServlet extends HttpServlet {
+
+  @Override
+  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException,
+      ServletException {
+    String path = req.getRequestURI();
+    if (path.startsWith("/favicon.ico")) {
+      return; // ignore the request for favicon.ico
+    }
+
+    String key = "count-concurrent";
+    // Using the synchronous cache.
+    MemcacheService syncCache = MemcacheServiceFactory.getMemcacheService();
+
+    // Write this value to cache using getIdentifiable and putIfUntouched.
+    for (long delayMs = 1; delayMs < 1000; delayMs *= 2) {
+      IdentifiableValue oldValue = syncCache.getIdentifiable(key);
+      byte[] newValue = oldValue == null
+          ? BigInteger.valueOf(0).toByteArray()
+              : increment((byte[]) oldValue.getValue()); // newValue depends on old value
+      resp.setContentType("text/plain");
+      resp.getWriter().print("Value is " + new BigInteger(newValue).intValue() + "\n");
+      if (oldValue == null) {
+        // Key doesn't exist. We can safely put it in cache.
+        syncCache.put(key, newValue);
+        break;
+      } else if (syncCache.putIfUntouched(key, oldValue, newValue)) {
+        // newValue has been successfully put into cache.
+        break;
+      } else {
+        // Some other client changed the value since oldValue was retrieved.
+        // Wait a while before trying again, waiting longer on successive loops.
+        try {
+          Thread.sleep(delayMs);
+        } catch (InterruptedException e) {
+          throw new ServletException("Error when sleeping", e);
+        }
+      }
+    }
+  }
+
+  /**
+   * Increments an integer stored as a byte array by one.
+   * @param oldValue a byte array with the old value
+   * @return         a byte array as the old value increased by one
+   */
+  private byte[] increment(byte[] oldValue) {
+    long val = new BigInteger(oldValue).intValue();
+    val++;
+    return BigInteger.valueOf(val).toByteArray();
+  }
+}
+// [END example]

appengine/memcache/src/main/java/com/example/appengine/memcache/MemcacheSyncCacheServlet.java

@@ -0,0 +1,67 @@
+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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
+ *
+ * http://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 com.example.appengine.memcache;
+
+import com.google.appengine.api.memcache.ErrorHandlers;
+import com.google.appengine.api.memcache.MemcacheService;
+import com.google.appengine.api.memcache.MemcacheServiceFactory;
+
+import java.io.IOException;
+import java.math.BigInteger;
+import java.util.logging.Level;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+// [START example]
+@SuppressWarnings("serial")
+public class MemcacheSyncCacheServlet extends HttpServlet {
+
+  @Override
+  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException,
+      ServletException {
+    String path = req.getRequestURI();
+    if (path.startsWith("/favicon.ico")) {
+      return; // ignore the request for favicon.ico
+    }
+
+    MemcacheService syncCache = MemcacheServiceFactory.getMemcacheService();
+    syncCache.setErrorHandler(ErrorHandlers.getConsistentLogAndContinue(Level.INFO));
+    String key = "count-sync";
+    byte[] value;
+    long count = 1;
+    value = (byte[]) syncCache.get(key);
+    if (value == null) {
+      value = BigInteger.valueOf(count).toByteArray();
+      syncCache.put(key, value);
+    } else {
+      // Increment value
+      count = new BigInteger(value).longValue();
+      count++;
+      value = BigInteger.valueOf(count).toByteArray();
+      // Put back in cache
+      syncCache.put(key, value);
+    }
+
+    // Output content
+    resp.setContentType("text/plain");
+    resp.getWriter().print("Value is " + count + "\n");
+  }
+}
+// [END example]

appengine/memcache/src/main/webapp/WEB-INF/appengine-web.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- [START_EXCLUDE] -->
 <!--
-  Copyright 2015 Google Inc. All Rights Reserved.
+  Copyright 2016 Google Inc. All Rights Reserved.
   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

appengine/memcache/src/main/webapp/WEB-INF/web.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!-- [START_EXCLUDE] -->
 <!--
-  Copyright 2015 Google Inc. All Rights Reserved.
+  Copyright 2016 Google Inc. All Rights Reserved.
   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
@@ -18,12 +18,36 @@
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
   version="2.5">
   <servlet>
-    <servlet-name>memcache</servlet-name>
-    <servlet-class>com.example.appengine.memcache.MemcacheServlet</servlet-class>
+    <servlet-name>memcache-best-practice</servlet-name>
+    <servlet-class>com.example.appengine.memcache.MemcacheBestPracticeServlet</servlet-class>
   </servlet>
   <servlet-mapping>
-    <servlet-name>memcache</servlet-name>
+    <servlet-name>memcache-best-practice</servlet-name>
     <url-pattern>/</url-pattern>
   </servlet-mapping>
+  <servlet>
+    <servlet-name>memcache-async</servlet-name>
+    <servlet-class>com.example.appengine.memcache.MemcacheAsyncCacheServlet</servlet-class>
+  </servlet>
+  <servlet-mapping>
+    <servlet-name>memcache-async</servlet-name>
+    <url-pattern>/async</url-pattern>
+  </servlet-mapping>
+  <servlet>
+    <servlet-name>memcache-sync</servlet-name>
+    <servlet-class>com.example.appengine.memcache.MemcacheSyncCacheServlet</servlet-class>
+  </servlet>
+  <servlet-mapping>
+    <servlet-name>memcache-sync</servlet-name>
+    <url-pattern>/sync</url-pattern>
+  </servlet-mapping>
+  <servlet>
+    <servlet-name>memcache-concurrent</servlet-name>
+    <servlet-class>com.example.appengine.memcache.MemcacheConcurrentServlet</servlet-class>
+  </servlet>
+  <servlet-mapping>
+    <servlet-name>memcache-concurrent</servlet-name>
+    <url-pattern>/concurrent</url-pattern>
+  </servlet-mapping>
 </web-app>