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* to you 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.pulsar.metadata.bookkeeper;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.concurrent.ExecutionException;
import lombok.extern.slf4j.Slf4j;
import org.apache.bookkeeper.meta.LedgerManager;
import org.apache.bookkeeper.util.StringUtils;
import org.apache.pulsar.metadata.api.MetadataStore;
/**
* Hierarchical Ledger Manager which manages ledger meta in zookeeper using 2-level hierarchical znodes.
*
* LegacyHierarchicalLedgerManager splits the generated id into 3 parts (2-4-4):
*
<level1 (2 digits)><level2 (4 digits)><level3 (4 digits)>
* These 3 parts are used to form the actual ledger node path used to store ledger metadata:
* (ledgersRootPath)/level1/level2/L(level3)
* E.g Ledger 0000000001 is split into 3 parts 00, 0000, 0001, which is stored in
* (ledgersRootPath)/00/0000/L0001. So each znode could have at most 10000 ledgers, which avoids
* errors during garbage collection due to lists of children that are too long.
*/
@Slf4j
public class LegacyHierarchicalLedgerRangeIterator implements LedgerManager.LedgerRangeIterator {
private static final String MAX_ID_SUFFIX = "9999";
private static final String MIN_ID_SUFFIX = "0000";
private final MetadataStore store;
private final String ledgersRoot;
private Iterator l1NodesIter = null;
private Iterator l2NodesIter = null;
private String curL1Nodes = "";
private boolean iteratorDone = false;
private LedgerManager.LedgerRange nextRange = null;
public LegacyHierarchicalLedgerRangeIterator(MetadataStore store, String ledgersRoot) {
this.store = store;
this.ledgersRoot = ledgersRoot;
}
/**
* Iterate next level1 znode.
*
* @return false if have visited all level1 nodes
* @throws InterruptedException/KeeperException if error occurs reading zookeeper children
*/
private boolean nextL1Node() throws ExecutionException, InterruptedException {
l2NodesIter = null;
while (l2NodesIter == null) {
if (l1NodesIter.hasNext()) {
curL1Nodes = l1NodesIter.next();
} else {
return false;
}
// Top level nodes are always exactly 2 digits long. (Don't pick up long hierarchical top level nodes)
if (!isLedgerParentNode(curL1Nodes)) {
continue;
}
List l2Nodes = store.getChildren(ledgersRoot + "/" + curL1Nodes).get();
l2NodesIter = l2Nodes.iterator();
if (!l2NodesIter.hasNext()) {
l2NodesIter = null;
continue;
}
}
return true;
}
private synchronized void preload() throws IOException {
while (nextRange == null && !iteratorDone) {
boolean hasMoreElements = false;
try {
if (l1NodesIter == null) {
List l1Nodes = store.getChildren(ledgersRoot).get();
l1NodesIter = l1Nodes.iterator();
hasMoreElements = nextL1Node();
} else if (l2NodesIter == null || !l2NodesIter.hasNext()) {
hasMoreElements = nextL1Node();
} else {
hasMoreElements = true;
}
} catch (ExecutionException ke) {
throw new IOException("Error preloading next range", ke);
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
throw new IOException("Interrupted while preloading", ie);
}
if (hasMoreElements) {
nextRange = getLedgerRangeByLevel(curL1Nodes, l2NodesIter.next());
if (nextRange.size() == 0) {
nextRange = null;
}
} else {
iteratorDone = true;
}
}
}
@Override
public synchronized boolean hasNext() throws IOException {
preload();
return nextRange != null && !iteratorDone;
}
@Override
public synchronized LedgerManager.LedgerRange next() throws IOException {
if (!hasNext()) {
throw new NoSuchElementException();
}
LedgerManager.LedgerRange r = nextRange;
nextRange = null;
return r;
}
private static final ThreadLocal threadLocalNodeBuilder =
ThreadLocal.withInitial(() -> new StringBuilder());
/**
* Get a single node level1/level2.
*
* @param level1
* 1st level node name
* @param level2
* 2nd level node name
* @throws IOException
*/
LedgerManager.LedgerRange getLedgerRangeByLevel(final String level1, final String level2)
throws IOException {
StringBuilder nodeBuilder = threadLocalNodeBuilder.get();
nodeBuilder.setLength(0);
nodeBuilder.append(ledgersRoot).append("/")
.append(level1).append("/").append(level2);
String nodePath = nodeBuilder.toString();
List ledgerNodes = null;
try {
ledgerNodes = store.getChildren(nodePath).get();
} catch (ExecutionException e) {
throw new IOException("Error when get child nodes from zk", e);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IOException("Error when get child nodes from zk", e);
}
NavigableSet zkActiveLedgers =
HierarchicalLedgerUtils.ledgerListToSet(ledgerNodes, ledgersRoot, nodePath);
if (log.isDebugEnabled()) {
log.debug("All active ledgers from ZK for hash node "
+ level1 + "/" + level2 + " : " + zkActiveLedgers);
}
return new LedgerManager.LedgerRange(zkActiveLedgers.subSet(getStartLedgerIdByLevel(level1, level2), true,
getEndLedgerIdByLevel(level1, level2), true));
}
/**
* Get the smallest cache id in a specified node /level1/level2.
*
* @param level1
* 1st level node name
* @param level2
* 2nd level node name
* @return the smallest ledger id
*/
private long getStartLedgerIdByLevel(String level1, String level2) throws IOException {
return StringUtils.stringToHierarchicalLedgerId(level1, level2, MIN_ID_SUFFIX);
}
/**
* Get the largest cache id in a specified node /level1/level2.
*
* @param level1
* 1st level node name
* @param level2
* 2nd level node name
* @return the largest ledger id
*/
private long getEndLedgerIdByLevel(String level1, String level2) throws IOException {
return StringUtils.stringToHierarchicalLedgerId(level1, level2, MAX_ID_SUFFIX);
}
private boolean isLedgerParentNode(String path) {
return path.matches(StringUtils.LEGACYHIERARCHICAL_LEDGER_PARENT_NODE_REGEX);
}
}