java/src/main/com/google/appengine/tools/development/ManualServer.java

   1 package com.google.appengine.tools.development;
   2
   3 import com.google.appengine.tools.development.ApplicationConfigurationManager.ServerConfigurationHandle;
   4 import com.google.appengine.tools.development.InstanceStateHolder.InstanceState;
   5 import com.google.apphosting.utils.config.AppEngineConfigException;
   6 import com.google.apphosting.utils.config.AppEngineWebXml;
   7 import com.google.common.collect.AbstractIterator;
   8 import com.google.common.collect.ImmutableList;
   9
  10 import java.io.File;
  11 import java.util.Iterator;
  12 import java.util.List;
  13 import java.util.Map;
  14 import java.util.concurrent.atomic.AtomicInteger;
  15
  16 /**
  17  * {@link Server} implementation for manual servers.
  18  */
  19 public class ManualServer extends AbstractServer<ManualServerInstanceHolder> {
  20   private final AtomicInteger instanceCounter = new AtomicInteger();
  21
  22   ManualServer(ServerConfigurationHandle serverConfigurationHandle, String serverInfo,
  23       String address, DevAppServerImpl devAppServer, AppEngineWebXml appEngineWebXml) {
  24     super(serverConfigurationHandle, serverInfo, null, address, devAppServer,
  25         makeInstanceHolders(serverConfigurationHandle, appEngineWebXml));
  26   }
  27
  28   private static List<ManualServerInstanceHolder> makeInstanceHolders(
  29       ServerConfigurationHandle serverConfigurationHandle, AppEngineWebXml appEngineWebXml) {
  30     String instancesString = appEngineWebXml.getManualScaling().getInstances();
  31     int instances = instancesString == null ? 0 : Integer.parseInt(instancesString);
  32     if (instances < 0) {
  33       throw new AppEngineConfigException("Invalid instances " + instances + " in file "
  34         + serverConfigurationHandle.getModule().getAppEngineWebXmlFile());
  35     }
  36
  37     ImmutableList.Builder<ManualServerInstanceHolder> listBuilder = ImmutableList.builder();
  38     for (int ix = LocalEnvironment.MAIN_INSTANCE; ix < instances; ix++) {
  39       String serverName = serverConfigurationHandle.getModule().getServerName();
  40       InstanceStateHolder stateHolder = new InstanceStateHolder(serverName, ix);
  41       ContainerService containerService = ContainerUtils.loadContainer();
  42       InstanceHelper instanceHelper =
  43           new InstanceHelper(serverName, ix, stateHolder, containerService);
  44       listBuilder.add(new ManualServerInstanceHolder(serverName, containerService, ix, stateHolder,
  45           instanceHelper));
  46     }
  47     return listBuilder.build();
  48   }
  49
  50   @Override
  51   public LocalServerEnvironment doConfigure(
  52       ServerConfigurationHandle serverConfigurationHandle, String serverInfo,
  53       File externalResourceDir, String address, Map<String, Object> containerConfigProperties,
  54       DevAppServerImpl devAppServer) throws Exception {
  55     LocalServerEnvironment result = null;
  56     for (ManualServerInstanceHolder instanceHolder : getInstanceHolders()) {
  57       instanceHolder.setConfiguration(serverConfigurationHandle, serverInfo, externalResourceDir,
  58           address, containerConfigProperties, devAppServer);
  59       LocalServerEnvironment thisEnvironment = instanceHolder.doConfigure();
  60       if (result == null) {
  61         result = thisEnvironment;
  62       }
  63     }
  64     return result;
  65   }
  66
  67   @Override
  68   public int getInstanceCount() {
  69     return getInstanceHolders().size() - 1;
  70   }
  71
  72   private ManualServerInstanceHolder getFirstMaybeAvailableInstanceHolder() {
  73     int instance = instanceCounter.getAndIncrement() % getInstanceCount();
  74     return getInstanceHolder(instance);
  75   }
  76
  77   @Override
  78   public ManualServerInstanceHolder getAndReserveAvailableInstanceHolder() {
  79     ManualServerInstanceHolder result = null;
  80     for (ManualServerInstanceHolder instanceHolder : new Iterable<ManualServerInstanceHolder>() {
  81           @Override
  82           public Iterator<ManualServerInstanceHolder> iterator() {
  83             return new FromFirstMaybeAvailableInstanceIterator();
  84           }
  85         }) {
  86       if (instanceHolder.acquireServingPermit()) {
  87         result = instanceHolder;
  88         break;
  89       }
  90     }
  91     return result;
  92   }
  93
  94   @Override
  95   public void startServing() throws Exception {
  96     requireState("startServing", InstanceState.STOPPED);
  97     for (ManualServerInstanceHolder instanceHolder : getInstanceHolders()) {
  98       instanceHolder.startServing();
  99     }
 100   }
 101
 102   @Override
 103   public void stopServing() throws Exception {
 104     requireState("stopServing", InstanceState.RUNNING);
 105     for (ManualServerInstanceHolder instanceHolder : getInstanceHolders()) {
 106       instanceHolder.stopServing();
 107     }
 108   }
 109
 110   private void requireState(String operation, InstanceState requiredState) {
 111     for (ManualServerInstanceHolder instanceHolder : getInstanceHolders()) {
 112       instanceHolder.requireState(operation, requiredState);
 113     }
 114   }
 115
 116   /**
 117    * Iterator for iterating through {@link InstanceHolder} values starting with
 118    * {@link #getFirstMaybeAvailableInstanceHolder}.
 119    */
 120   private class FromFirstMaybeAvailableInstanceIterator
 121       extends AbstractIterator<ManualServerInstanceHolder> {
 122     private static final int INVALID_INSTANCE_ID = -1;
 123     private int startInstanceId = INVALID_INSTANCE_ID;
 124     private int currentInstanceId = INVALID_INSTANCE_ID;
 125
 126     @Override
 127     protected ManualServerInstanceHolder computeNext() {
 128       if (getInstanceCount() == 0) {
 129         endOfData();
 130         return null;
 131       }
 132
 133       if (startInstanceId == INVALID_INSTANCE_ID) {
 134         ManualServerInstanceHolder instanceHolder = getFirstMaybeAvailableInstanceHolder();
 135         startInstanceId = instanceHolder.getInstance();
 136         currentInstanceId = startInstanceId;
 137         return instanceHolder;
 138       }
 139
 140       int nextInstanceId = (currentInstanceId + 1) % getInstanceCount();
 141       if (nextInstanceId == startInstanceId) {
 142         endOfData();
 143         return null;
 144       } else {
 145         currentInstanceId = nextInstanceId;
 146         return getInstanceHolder(currentInstanceId);
 147       }
 148     }
 149   }
 150 }