File	Doc	Category	Size	Date	Package
NegativeCache.java	API Doc	Android 1.5 API	5989	Wed May 06 22:41:04 BST 2009	java.net

NegativeCache

• java.lang.Object
  • java.util.AbstractMap
    • java.util.HashMap
      • java.util.LinkedHashMap

Fields Summary
private static final long	serialVersionUID
private static NegativeCache	negCache
private static final int	MAX_NEGATIVE_ENTRIES
private static final float	LOADING

Constructors Summary
NegativeCache(int initialCapacity, float loadFactor, boolean accessOrder) Returns the hostname for the cache element. return hostName name of the host for which the lookup failed. since Android 1.0 // END android-changed super(initialCapacity, loadFactor, accessOrder);

Methods Summary
static synchronized void	checkCacheExists() This method checks whether the cache was already created and if not creates it. // BEGIN android-note // Made synchronized. copied from a newer version of harmony // END android-note if (negCache == null) { /* * Create with the access order set so ordering is based on when the * entries were last accessed. We make the default cache size one * greater than the maximum number of entries as we will grow to one * larger and then delete the LRU entry */ negCache = new NegativeCache<String, NegCacheElement>( MAX_NEGATIVE_ENTRIES + 1, LOADING, true); }
static synchronized java.lang.String	getFailedMessage(java.lang.String hostName) Returns the message of the negative cache if the entry has not yet expired. param hostName the name of the host for which we look up the entry. return the message which was returned when the host lookup failed if the entry has not yet expired. since Android 1.0 // BEGIN android-note // Made synchronized. copied from a newer version of harmony // END android-note checkCacheExists(); NegCacheElement element = negCache.get(hostName); if (element != null) { // check if element is still valid String ttlValue = AccessController .doPrivileged(new PriviAction<String>( "networkaddress.cache.negative.ttl")); //$NON-NLS-1$ int ttl = 10; try { if (ttlValue != null) { ttl = Integer.decode(ttlValue).intValue(); } } catch (NumberFormatException e) { } if (ttl == 0) { negCache.clear(); element = null; } else if (ttl != -1) { // BEGIN android-changed long delta = System.nanoTime() - element.nanoTimeAdded; if (delta > secondsToNanos(ttl)) { // remove the element from the cache and return null negCache.remove(hostName); element = null; } // END android-changed } } if (element != null) { // BEGIN android-changed // Copied from a newer version of harmony return element.hostName; // END android-changed } return null;
static synchronized void	put(java.lang.String hostName, java.lang.String failedMessage) Adds the host name and the corresponding name lookup fail message to the cache. param hostName the name of the host for which the lookup failed. param failedMessage the message returned when the lookup fails. since Android 1.0 // BEGIN android-note // Made synchronized. copied from a newer version of harmony // END android-note checkCacheExists(); negCache.put(hostName, new NegCacheElement(failedMessage));
protected boolean	removeEldestEntry(java.util.Map$Entry eldest) Returns whether the eldest entry should be removed. It is removed if the size has grown beyond the maximum size allowed for the cache. A {@code LinkedHashMap} is created such that the least recently used entry is deleted. param eldest the map entry which will be deleted if we return {@code true}. since Android 1.0 return size() > MAX_NEGATIVE_ENTRIES;
private static int	secondsToNanos(int ttl) Multiplies value by 1 billion. return ttl * 1000000000;