java/src/main/com/google/appengine/api/LifecycleManager.java

   1 // Copyright 2010 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api;
   4
   5 import com.google.apphosting.api.ApiProxy;
   6
   7 import java.util.HashMap;
   8 import java.util.List;
   9 import java.util.Map;
  10 import java.util.logging.Logger;
  11 import java.security.AccessController;
  12 import java.security.PrivilegedAction;
  13
  14 /**
  15  * Information about the current status of the Java Runtime.
  16  *
  17  */
  18 public final class LifecycleManager {
  19
  20   private static final LifecycleManager instance = new LifecycleManager();
  21   private static final Logger log = Logger.getLogger(LifecycleManager.class.getName());
  22
  23   private volatile boolean shuttingDown = false;
  24   private volatile long deadline = -1L;
  25
  26   private LifecycleManager() { }
  27
  28   public static LifecycleManager getInstance() {
  29     return instance;
  30   }
  31
  32   public boolean isShuttingDown() {
  33     return shuttingDown;
  34   }
  35
  36   /**
  37    * Register a ShutdownHook to be called when the runtime shuts down.
  38    */
  39   public synchronized void setShutdownHook(ShutdownHook hook) {
  40     hooks.put(currentAppVersionId(), hook);
  41   }
  42
  43   /**
  44    * Calls Thread.interrupt() on all threads running requests for this
  45    * application.
  46    */
  47   public void interruptAllRequests() {
  48     AccessController.doPrivileged(
  49         new PrivilegedAction() {
  50           public Object run() {
  51             List<Thread> threads = ApiProxy.getRequestThreads();
  52             if (threads != null) {
  53               for (Thread thread : threads) {
  54                 thread.interrupt();
  55               }
  56             }
  57             return null;
  58           }
  59         });
  60   }
  61
  62   /**
  63    * If the runtime is shutting down, returns how long, in
  64    * milliseconds, is left for shutdown code to clean up. Otherwise,
  65    * returns -1.
  66    */
  67   public long getRemainingShutdownTime() {
  68     long value = deadline;
  69     if (value == -1L) {
  70       return -1L;
  71     } else {
  72       return value - System.currentTimeMillis();
  73     }
  74   }
  75
  76   /**
  77    * For testing purposes only:
  78    * Notifies the LifecycleManager that the runtime is shutting down.
  79    */
  80   public synchronized void beginShutdown(long deadline) {
  81     this.shuttingDown = true;
  82     this.deadline = deadline;
  83     ShutdownHook hook = hooks.get(currentAppVersionId());
  84     if (hook != null) {
  85       hook.shutdown();
  86     }
  87   }
  88
  89   private String currentAppVersionId() {
  90     ApiProxy.Environment env = ApiProxy.getCurrentEnvironment();
  91     return env.getAppId() + "/" + env.getVersionId();
  92   }
  93
  94   private Map<String, ShutdownHook> hooks = new HashMap<String, ShutdownHook>();
  95
  96   public interface ShutdownHook {
  97     public void shutdown();
  98   }
  99 }