/**
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.waveprotocol.wave.model.id;
import com.google.common.annotations.VisibleForTesting;
import org.waveprotocol.wave.model.util.Preconditions;
import org.waveprotocol.wave.model.wave.ParticipantId;
/**
* This class is used to generate Wave and Wavelet ids.
*
* The id field is structured as a sequence of '+'-separated tokens.
* The id field is case sensitive.
*
* A wavelet is hosted by a single wave service provider, which may differ from
* the service provider which allocated the wave id. Common examples are private
* replies and user-data wavelets for users from a federated domain. Thus, the
* service provider specified in a wavelet id may differ from the service
* provider of the wave to which it belongs.
*
* @author zdwang@google.com (David Wang)
*/
public class IdGeneratorImpl implements IdGenerator, IdConstants {
/**
* An object capable of providing a seed value. The seed value may (but need
* not) change during the lifetime of the using generator.
*/
public interface Seed {
/**
* Gets the current seed value. The seed value may not contain "*".
*
* TODO(anorth): remove "*" restriction after migrating legacy documents.
*
* @return seed value.
*/
String get();
}
private final String defaultDomain;
private final Seed idSeed;
/**
* A simple counter over all the id's we've issued to ensure uniqueness.
* Access to the counter is protected by synchronizing on {@code this}.
*/
protected int counter = 0;
public IdGeneratorImpl(String domain, Seed idSeed) {
this.defaultDomain = domain;
this.idSeed = idSeed;
}
@Override
@Deprecated
public String peekBlipId() {
return build(IdConstants.BLIP_PREFIX, peekUniqueToken());
}
@Override
public WaveId newWaveId() {
return WaveId.of(defaultDomain, newId(WAVE_PREFIX));
}
@Override
public WaveletId newConversationRootWaveletId() {
return WaveletId.of(defaultDomain, CONVERSATION_ROOT_WAVELET);
}
@Override
public WaveletId newConversationWaveletId() {
return WaveletId.of(defaultDomain, newId(CONVERSATION_WAVELET_PREFIX));
}
@Override
public WaveletId newUserDataWaveletId(String address) {
// TODO(anorth): Take ParticipantId as a parameter after moving it
// into model.id package.
String userDomain = ParticipantId.ofUnsafe(address).getDomain();
return WaveletId.of(userDomain, build(USER_DATA_WAVELET_PREFIX, address));
}
@Override
public String newDataDocumentId() {
String newId = newUniqueToken();
if (IdUtil.isBlipId(newId)) {
Preconditions.illegalState("generated data document id '" + newId + "' is a blip id");
}
return newId;
}
@Override
public String newBlipId() {
String newId = newId(BLIP_PREFIX);
if (!IdUtil.isBlipId(newId)) {
Preconditions.illegalState("generated blip id '" + newId + "' is not a blip id");
}
return newId;
}
@Override
public String newId(String namespace) {
String newId = build(namespace, newUniqueToken());
if (namespace.equals(BLIP_PREFIX) || namespace.equals(GHOST_BLIP_PREFIX)) {
if (!IdUtil.isBlipId(newId)) {
Preconditions.illegalState("generated blip id '" + newId + "' is not a blip id");
}
} else {
if (IdUtil.isBlipId(newId)) {
Preconditions.illegalState("generated data document id '" + newId + "' is a blip id");
}
}
return newId;
}
@Override
public String newUniqueToken() {
int unique;
synchronized (this) {
unique = counter++;
}
return idSeed.get() + base64Encode(unique);
}
/**
* @return a string from a list of tokens by using
* {@link IdConstants#TOKEN_SEPARATOR} as delimiters.
*/
protected static String build(String... tokens) {
return SimplePrefixEscaper.DEFAULT_ESCAPER.join(TOKEN_SEPARATOR, tokens);
}
/**
* Retrieve the domain component of a user's address.
*
* @param address legal address.
* @throw IllegalArgumentException if the address does not contain a '@' sign.
*/
protected static String getDomain(String address) {
int pos = address.indexOf('@');
if (pos < 0) {
throw new IllegalArgumentException("Invalid address '" + address + "'");
}
return address.substring(pos+1);
}
/** The 64 valid web-safe values. */
private static final char[] WEB64_ALPHABET =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"
.toCharArray();
/**
* Base-64 encodes a non-negative integer value in a minimum-length string.
*/
@SuppressWarnings("fallthrough")
@VisibleForTesting
public
static String base64Encode(int intValue) {
assert intValue >= 0;
int numEncodedBytes;
if (intValue == 0) {
numEncodedBytes = 1;
} else {
numEncodedBytes = (int) Math.ceil((32 - Integer.numberOfLeadingZeros(intValue)) / 6.0);
}
StringBuilder encoded = new StringBuilder(numEncodedBytes);
switch (numEncodedBytes) {
// Fall through all cases to append additional chars.
case 6:
encoded.append(WEB64_ALPHABET[(intValue >> 30) & 0x3F]);
case 5:
encoded.append(WEB64_ALPHABET[(intValue >> 24) & 0x3F]);
case 4:
encoded.append(WEB64_ALPHABET[(intValue >> 18) & 0x3F]);
case 3:
encoded.append(WEB64_ALPHABET[(intValue >> 12) & 0x3F]);
case 2:
encoded.append(WEB64_ALPHABET[(intValue >> 6) & 0x3F]);
default:
encoded.append(WEB64_ALPHABET[intValue & 0x3F]);
}
return encoded.toString();
}
/**
* @return the next result that will be obtained from calling
* {@link #newUniqueToken()}.
*/
protected String peekUniqueToken() {
int unique;
synchronized (this) {
unique = counter;
}
return idSeed.get() + base64Encode(unique);
}
@Override
public String getDefaultDomain() {
return defaultDomain;
}
}