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   private boolean shuttingDown = false;
  23   private long deadline = -1L;
  24
  25   private LifecycleManager() { }
  26
  27   public static LifecycleManager getInstance() {
  28     return instance;
  29   }
  30
  31   public boolean isShuttingDown() {
  32     return shuttingDown;
  33   }
  34
  35   /**
  36    * Register a ShutdownHook to be called when the runtime shuts down.
  37    */
  38   public synchronized void setShutdownHook(ShutdownHook hook) {
  39     hooks.put(currentAppVersionId(), hook);
  40   }
  41
  42   /**
  43    * Calls Thread.interrupt() on all threads running requests for this
  44    * application.
  45    */
  46   public void interruptAllRequests() {
  47     AccessController.doPrivileged(
  48         new PrivilegedAction() {
  49           public Object run() {
  50             List<Thread> threads = ApiProxy.getRequestThreads();
  51             if (threads != null) {
  52               for (Thread thread : threads) {
  53                 thread.interrupt();
  54               }
  55             }
  56             return null;
  57           }
  58         });
  59   }
  60
  61   /**
  62    * If the runtime is shutting down, returns how long, in
  63    * milliseconds, is left for shutdown code to clean up. Otherwise,
  64    * returns -1.
  65    */
  66   public long getRemainingShutdownTime() {
  67     if (deadline == -1L) {
  68       return -1L;
  69     } else {
  70       return deadline - System.currentTimeMillis();
  71     }
  72   }
  73
  74   /**
  75    * For testing purposes only:
  76    * Notifies the LifecycleManager that the runtime is shutting down.
  77    */
  78   public synchronized void beginShutdown(long deadline) {
  79     this.shuttingDown = true;
  80     this.deadline = deadline;
  81     ShutdownHook hook = hooks.get(currentAppVersionId());
  82     if (hook != null) {
  83       hook.shutdown();
  84     }
  85   }
  86
  87   private String currentAppVersionId() {
  88     ApiProxy.Environment env = ApiProxy.getCurrentEnvironment();
  89     return env.getAppId() + "/" + env.getVersionId();
  90   }
  91
  92   private Map<String, ShutdownHook> hooks = new HashMap<String, ShutdownHook>();
  93
  94   public interface ShutdownHook {
  95     public void shutdown();
  96   }
  97 }