Update EVCacheClientSample.java

Committing changes from Allan Pratt

evcache-client-sample/src/main/java/com/netflix/evcache/sample/EVCacheClientSample.java

@@ -7,86 +7,142 @@
 
 /**
  * Created by senugula on 3/24/16.
+ * Updated by akpratt on 5/13/16.
  */
 
 /**
- * This standalone program demonstrates how to use EVCacheClient for set/get operations using memcached running local box.
- * Prerequisite : ( Install memcached locally, most mac OS already have memcached installed.
- * Start memcached on local machine.
- * SERVERGROUP1:
- * memcached -d -p 11211
- * SERVERGROUP2:
- * memcached -d -p 11212
+ * This standalone program demonstrates how to use EVCacheClient for
+ * set/get operations using memcached running on your local box.
  *
+ * By default, this program expects there to be two memcached processes
+ * on the local host, on ports 11211 and 11212. They get used as two
+ * replicas of a single shard each.
+ * 
+ * You can override this configuration by setting the environment
+ * variable EVC_SAMPLE_DEPLOYMENT to a string which describes your
+ * deployment. The format for that string is as described in the EVCache
+ * documentation for a simple node list provider. It would look like
+ * this for a two-replica deployment with two shards per replica:
+ *
+ *   SERVERGROUP1=host1:port1,host2:port2;SERVERGROUP2=host3:port3,host4:port4
  */
+
 public class EVCacheClientSample {
 
     private final EVCache evCache;
-    private final String key = "evcacheSample";
-    private final String value = " This is my value1";
-    private final int timeToLive = 100;
+    private static boolean verboseMode = false;
 
+    /**
+     * Default constructor.
+     *
+     * This tells the EVCache library to use the "simple node list
+     * provider" for EVCACHE_APP1 (by setting the relevant system
+     * property), and then  it copies the EVC_SAMPLE_DEPLOYMENT
+     * environment variable to the EVCACHE_APP1-NODES system property.
+     *
+     * If the environment variable isn't set, default is two shards on
+     * localhost, on port 11211 and 11212, configured as two replicas with
+     * one shard each.
+     *
+     * Finally, this initializes "evCache" using EVCache.Builder,
+     * specifying the application name "EVCACHE_APP1."
+     */
     public EVCacheClientSample() {
-
-        /**
-         * Enable node list provider
-         * EVCACHE_APP1.use.simple.node.list.provider"
-         *
-         * Setup 2 server groups which is two memcached processes/nodes running at different ports acting different
-         * server groups/auto-scaling groups for application EVCACHE_APP1
-         * EVCACHE_APP1-NODES=SERVERGROUP1=localhost:11211;SERVERGROUP2=localhost:11212
-         */
+        String deploymentDescriptor = System.getenv("EVC_SAMPLE_DEPLOYMENT");
+        if (deploymentDescriptor == null) {
+            // No deployment descriptor in the environment, use a default: two local
+            // memcached processes configured as two replicas of one shard each.
+            deploymentDescriptor = "SERVERGROUP1=localhost:11211;SERVERGROUP2=localhost:11212";
+        }
         System.setProperty("EVCACHE_APP1.use.simple.node.list.provider", "true");
-        System.setProperty("EVCACHE_APP1-NODES", "SERVERGROUP1=localhost:11211;SERVERGROUP2=localhost:11212");
+        System.setProperty("EVCACHE_APP1-NODES", deploymentDescriptor);
         evCache = new EVCache.Builder().setAppName("EVCACHE_APP1").build();
     }
 
     /**
-     * Set a key in memcached
-     * @throws Exception
+     * Set a key in the cache.
+     *
+     * See the memcached documentation for what "timeToLive" means.
+     * Zero means "never expires."
+     * Small integers (under some threshold) mean "expires this many seconds from now."
+     * Large integers mean "expires at this Unix timestamp" (seconds since 1/1/1970).
+     * Warranty expires 17-Jan 2038.
      */
 
-    public void setKey() throws Exception {
+    public void setKey(String key, String value, int timeToLive) throws Exception {
         try {
             Future<Boolean>[] _future = evCache.set(key, value, timeToLive);
-            //Lets block for write so we don't exit the program fast
+
+            // Wait for all the Futures to complete.
+            // In "verbose" mode, show the status for each.
             for (Future<Boolean> f : _future) {
-                System.out.println("set key " + key + " is successful" + f.get());
+            	boolean didSucceed = f.get();
+            	if (verboseMode) {
+                    System.out.println("per-shard set success code for key " + key + " is " + didSucceed);
+                }
+            }
+            if (!verboseMode) {
+                // Not verbose. Just give one line of output per "set," without a success code
+                System.out.println("finished setting key " + key);
             }
         } catch (EVCacheException e) {
             e.printStackTrace();
         }
     }
 
     /**
-     * Get the key you have set in  memcached
-     * @return String
+     * Get the data for a key from the cache. Returns null if the key
+     * could not be retrieved, whether due to a cache miss or errors.
      */
 
-    public String getKey() {
+    public String getKey(String key) {
         try {
             String _response = evCache.<String>get(key);
             return _response;
         } catch (Exception e) {
             e.printStackTrace();
+            return null;
         }
-        return null;
     }
 
     /**
-     *  Main Program to set and get using EVCacheClient
-     * @param args
+     * Main Program which does some simple sets and gets.
      */
 
     public static void main(String[] args) {
+        // set verboseMode based on the environment variable
+        verboseMode = ("true".equals(System.getenv("EVCACHE_SAMPLE_VERBOSE")));
+
+        if (verboseMode) {
+            System.out.println("To run this sample app without using Gradle:");
+            System.out.println("java -cp " + System.getProperty("java.class.path") + " com.netflix.evcache.sample.EVCacheClientSample");
+        }
+
         try {
             EVCacheClientSample evCacheClientSample = new EVCacheClientSample();
-            evCacheClientSample.setKey();
-            Thread.sleep(1000);
-            System.out.println(" Key returned is >> " + evCacheClientSample.getKey());
-            System.exit(0);
+
+            // Set ten keys to different values
+            for (int i = 0; i < 10; i++) {
+                String key = "key_" + i;
+                String value = "data_" + i;
+                // Set the TTL to 24 hours
+                int ttl = 86400;
+                evCacheClientSample.setKey(key, value, ttl);
+            }
+
+            // Do a "get" for each of those same keys
+            for (int i = 0; i < 10; i++) {
+                String key = "key_" + i;
+                String value = evCacheClientSample.getKey(key);
+                System.out.println("Get of " + key + " returned " + value);
+            }
         } catch (Exception e) {
             e.printStackTrace();
         }
+
+        // We have to call System.exit() now, because some background
+        // threads were started without the "daemon" flag. This is
+        // probably a mistake somewhere, but hey, this is only a sample app.
+	System.exit(0);
     }
 }