// Copyright 2003-2005 Arthur van Hoff Rick Blair // Licensed under Apache License version 2.0 // Original license LGPL package javax.jmdns.impl; import java.util.AbstractMap; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Set; import javax.jmdns.impl.constants.DNSRecordClass; import javax.jmdns.impl.constants.DNSRecordType; /** * A table of DNS entries. This is a map table which can handle multiple entries with the same name. *

* Storing multiple entries with the same name is implemented using a linked list. This is hidden from the user and can change in later implementation. *

* Here's how to iterate over all entries: * *

 *       for (Iterator i=dnscache.allValues().iterator(); i.hasNext(); ) {
 *             DNSEntry entry = i.next();
 *             ...do something with entry...
 *       }
 * 
*

* And here's how to iterate over all entries having a given name: * *

 *       for (Iterator i=dnscache.getDNSEntryList(name).iterator(); i.hasNext(); ) {
 *             DNSEntry entry = i.next();
 *           ...do something with entry...
 *       }
 * 
* * @author Arthur van Hoff, Werner Randelshofer, Rick Blair, Pierre Frisch */ public class DNSCache extends AbstractMap> { // private static Logger logger = Logger.getLogger(DNSCache.class.getName()); private transient Set>> _entrySet = null; /** * */ public static final DNSCache EmptyCache = new _EmptyCache(); static final class _EmptyCache extends DNSCache { /** * {@inheritDoc} */ @Override public int size() { return 0; } /** * {@inheritDoc} */ @Override public boolean isEmpty() { return true; } /** * {@inheritDoc} */ @Override public boolean containsKey(Object key) { return false; } /** * {@inheritDoc} */ @Override public boolean containsValue(Object value) { return false; } /** * {@inheritDoc} */ @Override public List get(Object key) { return null; } /** * {@inheritDoc} */ @Override public Set keySet() { return Collections.emptySet(); } /** * {@inheritDoc} */ @Override public Collection> values() { return Collections.emptySet(); } /** * {@inheritDoc} */ @Override public Set>> entrySet() { return Collections.emptySet(); } /** * {@inheritDoc} */ @Override public boolean equals(Object o) { return (o instanceof Map) && ((Map) o).size() == 0; } /** * {@inheritDoc} */ @Override public List put(String key, List value) { return null; } /** * {@inheritDoc} */ @Override public int hashCode() { return 0; } } /** * */ protected static class _CacheEntry extends Object implements Map.Entry> { private List _value; private String _key; /** * @param key * @param value */ protected _CacheEntry(String key, List value) { super(); _key = (key != null ? key.trim().toLowerCase() : null); _value = value; } /** * @param entry */ protected _CacheEntry(Map.Entry> entry) { super(); if (entry instanceof _CacheEntry) { _key = ((_CacheEntry) entry).getKey(); _value = ((_CacheEntry) entry).getValue(); } } /** * {@inheritDoc} */ @Override public String getKey() { return (_key != null ? _key : ""); } /** * {@inheritDoc} */ @Override public List getValue() { return _value; } /** * {@inheritDoc} */ @Override public List setValue(List value) { List oldValue = _value; _value = value; return oldValue; } /** * Returns true if this list contains no elements. * * @return true if this list contains no elements */ public boolean isEmpty() { return this.getValue().isEmpty(); } /** * {@inheritDoc} */ @Override public boolean equals(Object entry) { if (!(entry instanceof Map.Entry)) { return false; } return this.getKey().equals(((Map.Entry) entry).getKey()) && this.getValue().equals(((Map.Entry) entry).getValue()); } /** * {@inheritDoc} */ @Override public int hashCode() { return (_key == null ? 0 : _key.hashCode()); } /** * {@inheritDoc} */ @Override public synchronized String toString() { StringBuffer aLog = new StringBuffer(200); aLog.append("\n\t\tname '"); aLog.append(_key); aLog.append("' "); if ((_value != null) && (!_value.isEmpty())) { for (DNSEntry entry : _value) { aLog.append("\n\t\t\t"); aLog.append(entry.toString()); } } else { aLog.append(" no entries"); } return aLog.toString(); } } /** * */ public DNSCache() { this(1024); } /** * @param map */ public DNSCache(DNSCache map) { this(map != null ? map.size() : 1024); if (map != null) { this.putAll(map); } } /** * Create a table with a given initial size. * * @param initialCapacity */ public DNSCache(int initialCapacity) { super(); _entrySet = new HashSet>>(initialCapacity); } // ==================================================================== // Map /* * (non-Javadoc) * @see java.util.AbstractMap#entrySet() */ @Override public Set>> entrySet() { if (_entrySet == null) { _entrySet = new HashSet>>(); } return _entrySet; } /** * @param key * @return map entry for the key */ protected Map.Entry> getEntry(String key) { String stringKey = (key != null ? key.trim().toLowerCase() : null); for (Map.Entry> entry : this.entrySet()) { if (stringKey != null) { if (stringKey.equals(entry.getKey())) { return entry; } } else { if (entry.getKey() == null) { return entry; } } } return null; } /** * {@inheritDoc} */ @Override public List put(String key, List value) { synchronized (this) { List oldValue = null; Map.Entry> oldEntry = this.getEntry(key); if (oldEntry != null) { oldValue = oldEntry.setValue(value); } else { this.entrySet().add(new _CacheEntry(key, value)); } return oldValue; } } /** * {@inheritDoc} */ @Override protected Object clone() throws CloneNotSupportedException { return new DNSCache(this); } // ==================================================================== /** * Returns all entries in the cache * * @return all entries in the cache */ public synchronized Collection allValues() { List allValues = new ArrayList(); for (List entry : this.values()) { if (entry != null) { allValues.addAll(entry); } } return allValues; } /** * Iterate only over items with matching name. Returns an list of DNSEntry or null. To retrieve all entries, one must iterate over this linked list. * * @param name * @return list of DNSEntries */ public synchronized Collection getDNSEntryList(String name) { Collection entryList = this._getDNSEntryList(name); if (entryList != null) { entryList = new ArrayList(entryList); } else { entryList = Collections.emptyList(); } return entryList; } private Collection _getDNSEntryList(String name) { return this.get(name != null ? name.toLowerCase() : null); } /** * Get a matching DNS entry from the table (using isSameEntry). Returns the entry that was found. * * @param dnsEntry * @return DNSEntry */ public synchronized DNSEntry getDNSEntry(DNSEntry dnsEntry) { DNSEntry result = null; if (dnsEntry != null) { Collection entryList = this._getDNSEntryList(dnsEntry.getKey()); if (entryList != null) { for (DNSEntry testDNSEntry : entryList) { if (testDNSEntry.isSameEntry(dnsEntry)) { result = testDNSEntry; break; } } } } return result; } /** * Get a matching DNS entry from the table. * * @param name * @param type * @param recordClass * @return DNSEntry */ public synchronized DNSEntry getDNSEntry(String name, DNSRecordType type, DNSRecordClass recordClass) { DNSEntry result = null; Collection entryList = this._getDNSEntryList(name); if (entryList != null) { for (DNSEntry testDNSEntry : entryList) { if (testDNSEntry.getRecordType().equals(type) && ((DNSRecordClass.CLASS_ANY == recordClass) || testDNSEntry.getRecordClass().equals(recordClass))) { result = testDNSEntry; break; } } } return result; } /** * Get all matching DNS entries from the table. * * @param name * @param type * @param recordClass * @return list of entries */ public synchronized Collection getDNSEntryList(String name, DNSRecordType type, DNSRecordClass recordClass) { Collection entryList = this._getDNSEntryList(name); if (entryList != null) { entryList = new ArrayList(entryList); for (Iterator i = entryList.iterator(); i.hasNext();) { DNSEntry testDNSEntry = i.next(); if (!testDNSEntry.getRecordType().equals(type) || ((DNSRecordClass.CLASS_ANY != recordClass) && !testDNSEntry.getRecordClass().equals(recordClass))) { i.remove(); } } } else { entryList = Collections.emptyList(); } return entryList; } /** * Adds an entry to the table. * * @param dnsEntry * @return true if the entry was added */ public synchronized boolean addDNSEntry(final DNSEntry dnsEntry) { boolean result = false; if (dnsEntry != null) { Map.Entry> oldEntry = this.getEntry(dnsEntry.getKey()); List aNewValue = null; if (oldEntry != null) { aNewValue = new ArrayList(oldEntry.getValue()); } else { aNewValue = new ArrayList(); } aNewValue.add(dnsEntry); if (oldEntry != null) { oldEntry.setValue(aNewValue); } else { this.entrySet().add(new _CacheEntry(dnsEntry.getKey(), aNewValue)); } // This is probably not very informative result = true; } return result; } /** * Removes a specific entry from the table. Returns true if the entry was found. * * @param dnsEntry * @return true if the entry was removed */ public synchronized boolean removeDNSEntry(DNSEntry dnsEntry) { boolean result = false; if (dnsEntry != null) { Map.Entry> existingEntry = this.getEntry(dnsEntry.getKey()); if (existingEntry != null) { result = existingEntry.getValue().remove(dnsEntry); // If we just removed the last one we need to get rid of the entry if (existingEntry.getValue().isEmpty()) { this.entrySet().remove(existingEntry); } } } return result; } /** * Replace an existing entry by a new one.
* Note: the 2 entries must have the same key. * * @param newDNSEntry * @param existingDNSEntry * @return true if the entry has been replace, false otherwise. */ public synchronized boolean replaceDNSEntry(DNSEntry newDNSEntry, DNSEntry existingDNSEntry) { boolean result = false; if ((newDNSEntry != null) && (existingDNSEntry != null) && (newDNSEntry.getKey().equals(existingDNSEntry.getKey()))) { Map.Entry> oldEntry = this.getEntry(newDNSEntry.getKey()); List aNewValue = null; if (oldEntry != null) { aNewValue = new ArrayList(oldEntry.getValue()); } else { aNewValue = new ArrayList(); } aNewValue.remove(existingDNSEntry); aNewValue.add(newDNSEntry); if (oldEntry != null) { oldEntry.setValue(aNewValue); } else { this.entrySet().add(new _CacheEntry(newDNSEntry.getKey(), aNewValue)); } // This is probably not very informative result = true; } return result; } /** * {@inheritDoc} */ @Override public synchronized String toString() { StringBuffer aLog = new StringBuffer(2000); aLog.append("\t---- cache ----"); for (Map.Entry> entry : this.entrySet()) { aLog.append("\n\t\t"); aLog.append(entry.toString()); } return aLog.toString(); } }