org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/KnownHosts.java

   1 /*******************************************************************************
   2  * Copyright (C) 2016, Thomas Wolf <thomas.wolf@paranor.ch>
   3  *
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License 2.0
   6  * which accompanies this distribution, and is available at
   7  * https://www.eclipse.org/legal/epl-2.0/
   8  *
   9  * SPDX-License-Identifier: EPL-2.0
  10  *******************************************************************************/
  11 package org.eclipse.egit.ui.internal;
  12
  13 import java.util.LinkedHashMap;
  14
  15 import org.eclipse.egit.ui.Activator;
  16 import org.eclipse.jface.dialogs.IDialogSettings;
  17 import org.eclipse.jgit.annotations.NonNull;
  18
  19 /**
  20  * Internal cache of known host names read from the plugin's
  21  * {@link IDialogSettings}. To be accessed only in the UI thread. The plugin
  22  * should store back the values in its
  23  * {@link Activator#stop(org.osgi.framework.BundleContext)} method by calling
  24  * {@link #store()}.
  25  */
  26 public final class KnownHosts {
  27
  28         private static final String KNOWN_HOSTS_KEY = "EGit.KnownHosts"; //$NON-NLS-1$
  29
  30         private static final String[] DEFAULT_HOSTS = { "git.eclipse.org", //$NON-NLS-1$
  31                         "github.com", "bitbucket.org" }; //$NON-NLS-1$ //$NON-NLS-2$
  32
  33         private static HostStore knownHosts;
  34
  35         private static boolean modified;
  36
  37         private KnownHosts() {
  38                 // Utility class shall not be instatiated.
  39         }
  40
  41         /**
  42          * Determines whether the given host name is known already.
  43          *
  44          * @param hostName
  45          *            to check
  46          * @return {@code true} is the host name is known, {@code false} otherwise.
  47          */
  48         public static boolean isKnownHost(String hostName) {
  49                 return hostName != null && getKnownHosts().containsKey(hostName);
  50         }
  51
  52         /**
  53          * Adds a new host name to the cache on known hosts.
  54          *
  55          * @param hostName
  56          *            to add
  57          */
  58         public static void addKnownHost(@NonNull String hostName) {
  59                 getKnownHosts().put(hostName, null);
  60                 modified = true; // At least the access order has changed
  61         }
  62
  63         /**
  64          * Stores back the known host names into the plugin's
  65          * {@link IDialogSettings} if they were changed.
  66          */
  67         public static void store() {
  68                 if (modified) {
  69                         String[] values = new String[knownHosts.size()];
  70                         Activator.getDefault().getDialogSettings().put(KNOWN_HOSTS_KEY,
  71                                         knownHosts.keySet().toArray(values));
  72                         modified = false;
  73                 }
  74         }
  75
  76         private static HostStore getKnownHosts() {
  77                 if (knownHosts == null) {
  78                         IDialogSettings settings = Activator.getDefault()
  79                                         .getDialogSettings();
  80                         String[] values = settings.getArray(KNOWN_HOSTS_KEY);
  81                         if (values == null) {
  82                                 settings.put(KNOWN_HOSTS_KEY, DEFAULT_HOSTS);
  83                                 values = DEFAULT_HOSTS;
  84                         }
  85                         knownHosts = new HostStore(values.length);
  86                         for (int i = values.length - 1; i >= 0; i--) {
  87                                 String host = values[i];
  88                                 if (host != null && !host.isEmpty()) {
  89                                         knownHosts.put(host, null);
  90                                 }
  91                         }
  92                 }
  93                 return knownHosts;
  94         }
  95
  96         @SuppressWarnings("serial")
  97         private static class HostStore extends LinkedHashMap<String, String> {
  98
  99                 private static final int MAXIMUM_SIZE = 200;
 100
 101                 public HostStore(int size) {
 102                         super(size < 10 ? 10 : size, 0.75f, true);
 103                 }
 104
 105                 @Override
 106                 protected boolean removeEldestEntry(
 107                                 java.util.Map.Entry<String, String> eldest) {
 108                         return size() > MAXIMUM_SIZE;
 109                 }
 110         }
 111
 112 }