Java TxnIterator.close方法代码示例

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
@Test
public void testTruncationStreamReset() throws Exception {
    File tmpdir = ClientBase.createTmpDir();
    FileTxnSnapLog snaplog = new FileTxnSnapLog(tmpdir, tmpdir);
    ZKDatabase zkdb = new ZKDatabase(snaplog);

    for (int i = 1; i <= 100; i++) {
        append(zkdb, i);
    }

    zkdb.truncateLog(1);

    append(zkdb, 200);

    zkdb.close();

    // verify that the truncation and subsequent append were processed
    // correctly
    FileTxnLog txnlog = new FileTxnLog(new File(tmpdir, "version-2"));
    TxnIterator iter = txnlog.read(1);

    TxnHeader hdr = iter.getHeader();
    Record txn = iter.getTxn();
    Assert.assertEquals(1, hdr.getZxid());
    Assert.assertTrue(txn instanceof SetDataTxn);

    iter.next();

    hdr = iter.getHeader();
    txn = iter.getTxn();
    Assert.assertEquals(200, hdr.getZxid());
    Assert.assertTrue(txn instanceof SetDataTxn);
    iter.close();
    ClientBase.recursiveDelete(tmpdir);
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
@Test
public void testTruncationStreamReset() throws Exception {
    File tmpdir = ClientBase.createTmpDir();
    FileTxnSnapLog snaplog = new FileTxnSnapLog(tmpdir, tmpdir);
    ZKDatabase zkdb = new ZKDatabase(snaplog);
    // make sure to snapshot, so that we have something there when
    // truncateLog reloads the db
    snaplog.save(zkdb.getDataTree(), zkdb.getSessionWithTimeOuts(), false);

    for (int i = 1; i <= 100; i++) {
        append(zkdb, i);
    }

    zkdb.truncateLog(1);

    append(zkdb, 200);

    zkdb.close();

    // verify that the truncation and subsequent append were processed
    // correctly
    FileTxnLog txnlog = new FileTxnLog(new File(tmpdir, "version-2"));
    TxnIterator iter = txnlog.read(1);

    TxnHeader hdr = iter.getHeader();
    Record txn = iter.getTxn();
    Assert.assertEquals(1, hdr.getZxid());
    Assert.assertTrue(txn instanceof SetDataTxn);

    iter.next();

    hdr = iter.getHeader();
    txn = iter.getTxn();
    Assert.assertEquals(200, hdr.getZxid());
    Assert.assertTrue(txn instanceof SetDataTxn);
    iter.close();
    ClientBase.recursiveDelete(tmpdir);
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
private void close(TxnIterator itr) {
    if (itr != null) {
        try {
            itr.close();
        } catch (IOException ioe) {
            LOG.warn("Error closing file iterator", ioe);
        }
    }
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
/**
 * this function restores[修复] the server 
 * database after reading from the 
 * snapshots and transaction logs
 * @param dt the datatree to be restored
 * @param sessions the sessions to be restored
 * @param listener the playback listener to run on the 
 * database restoration
 * @return the highest zxid restored
 * @throws IOException
 */
public long restore(DataTree dt, Map<Long, Integer> sessions, 
        PlayBackListener listener) throws IOException {
    snapLog.deserialize(dt, sessions);
    FileTxnLog txnLog = new FileTxnLog(dataDir);
    TxnIterator itr = txnLog.read(dt.lastProcessedZxid+1);
    long highestZxid = dt.lastProcessedZxid;
    TxnHeader hdr;
    try {
        while (true) {
            // iterator points to 
            // the first valid txn when initialized
            hdr = itr.getHeader();
            if (hdr == null) {
                //empty logs 
                return dt.lastProcessedZxid;
            }
            if (hdr.getZxid() < highestZxid && highestZxid != 0) {
                LOG.error("{}(higestZxid) > {}(next log) for type {}",
                        new Object[] { highestZxid, hdr.getZxid(),
                                hdr.getType() });
            } else {
                highestZxid = hdr.getZxid();
            }
            try {
                processTransaction(hdr,dt,sessions, itr.getTxn());
            } catch(KeeperException.NoNodeException e) {
               throw new IOException("Failed to process transaction type: " +
                     hdr.getType() + " error: " + e.getMessage(), e);
            }
            listener.onTxnLoaded(hdr, itr.getTxn());
            if (!itr.next()) 
                break;
        }
    } finally {
        if (itr != null) {
            itr.close();
        }
    }
    return highestZxid;
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
/**
 * this function restores the server
 * database after reading from the
 * snapshots and transaction logs
 * @param dt the datatree to be restored
 * @param sessions the sessions to be restored
 * @param listener the playback listener to run on the
 * database restoration
 * @return the highest zxid restored
 * @throws IOException
 */
public long restore(DataTree dt, Map<Long, Integer> sessions,
        PlayBackListener listener) throws IOException {
    long deserializeResult = snapLog.deserialize(dt, sessions);
    FileTxnLog txnLog = new FileTxnLog(dataDir);
    boolean trustEmptyDB;
    File initFile = new File(dataDir.getParent(), "initialize");
    if (Files.deleteIfExists(initFile.toPath())) {
        LOG.info("Initialize file found, an empty database will not block voting participation");
        trustEmptyDB = true;
    } else {
        trustEmptyDB = autoCreateDB;
    }
    if (-1L == deserializeResult) {
        /* this means that we couldn't find any snapshot, so we need to
         * initialize an empty database (reported in ZOOKEEPER-2325) */
        if (txnLog.getLastLoggedZxid() != -1) {
            throw new IOException(
                    "No snapshot found, but there are log entries. " +
                    "Something is broken!");
        }

        if (trustEmptyDB) {
            /* TODO: (br33d) we should either put a ConcurrentHashMap on restore()
             *       or use Map on save() */
            save(dt, (ConcurrentHashMap<Long, Integer>)sessions, false);

            /* return a zxid of 0, since we know the database is empty */
            return 0L;
        } else {
            /* return a zxid of -1, since we are possibly missing data */
            LOG.warn("Unexpected empty data tree, setting zxid to -1");
            dt.lastProcessedZxid = -1L;
            return -1L;
        }
    }
    TxnIterator itr = txnLog.read(dt.lastProcessedZxid+1);
    long highestZxid = dt.lastProcessedZxid;
    TxnHeader hdr;
    try {
        while (true) {
            // iterator points to
            // the first valid txn when initialized
            hdr = itr.getHeader();
            if (hdr == null) {
                //empty logs
                return dt.lastProcessedZxid;
            }
            if (hdr.getZxid() < highestZxid && highestZxid != 0) {
                LOG.error("{}(highestZxid) > {}(next log) for type {}",
                        highestZxid, hdr.getZxid(), hdr.getType());
            } else {
                highestZxid = hdr.getZxid();
            }
            try {
                processTransaction(hdr,dt,sessions, itr.getTxn());
            } catch(KeeperException.NoNodeException e) {
               throw new IOException("Failed to process transaction type: " +
                     hdr.getType() + " error: " + e.getMessage(), e);
            }
            listener.onTxnLoaded(hdr, itr.getTxn());
            if (!itr.next())
                break;
        }
    } finally {
        if (itr != null) {
            itr.close();
        }
    }
    return highestZxid;
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
/**
 * Get proposals from txnlog. Only packet part of proposal is populated.
 *
 * @param startZxid the starting zxid of the proposal
 * @param sizeLimit maximum on-disk size of txnlog to fetch
 *                  0 is unlimited, negative value means disable.
 * @return list of proposal (request part of each proposal is null)
 */
public Iterator<Proposal> getProposalsFromTxnLog(long startZxid,
                                                 long sizeLimit) {
    if (sizeLimit < 0) {
        LOG.debug("Negative size limit - retrieving proposal via txnlog is disabled");
        return TxnLogProposalIterator.EMPTY_ITERATOR;
    }

    TxnIterator itr = null;
    try {

        itr = snapLog.readTxnLog(startZxid, false);

        // If we cannot guarantee that this is strictly the starting txn
        // after a given zxid, we should fail.
        if ((itr.getHeader() != null)
                && (itr.getHeader().getZxid() > startZxid)) {
            LOG.warn("Unable to find proposals from txnlog for zxid: "
                    + startZxid);
            itr.close();
            return TxnLogProposalIterator.EMPTY_ITERATOR;
        }

        if (sizeLimit > 0) {
            long txnSize = itr.getStorageSize();
            if (txnSize > sizeLimit) {
                LOG.info("Txnlog size: " + txnSize + " exceeds sizeLimit: "
                        + sizeLimit);
                itr.close();
                return TxnLogProposalIterator.EMPTY_ITERATOR;
            }
        }
    } catch (IOException e) {
        LOG.error("Unable to read txnlog from disk", e);
        try {
            if (itr != null) {
                itr.close();
            }
        } catch (IOException ioe) {
            LOG.warn("Error closing file iterator", ioe);
        }
        return TxnLogProposalIterator.EMPTY_ITERATOR;
    }
    return new TxnLogProposalIterator(itr);
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
/**
 * this function restores the server 
 * database after reading from the 
 * snapshots and transaction logs
 * @param dt the datatree to be restored
 * @param sessions the sessions to be restored
 * @param listener the playback listener to run on the 
 * database restoration
 * @return the highest zxid restored
 * @throws IOException
 */
public long restore(DataTree dt, Map<Long, Integer> sessions, 
        PlayBackListener listener) throws IOException {
    snapLog.deserialize(dt, sessions);
    FileTxnLog txnLog = new FileTxnLog(dataDir);
    TxnIterator itr = txnLog.read(dt.lastProcessedZxid+1);
    long highestZxid = dt.lastProcessedZxid;
    TxnHeader hdr;
    try {
        while (true) {
            // iterator points to 
            // the first valid txn when initialized
            hdr = itr.getHeader();
            if (hdr == null) {
                //empty logs 
                return dt.lastProcessedZxid;
            }
            if (hdr.getZxid() < highestZxid && highestZxid != 0) {
                LOG.error("{}(higestZxid) > {}(next log) for type {}",
                        new Object[] { highestZxid, hdr.getZxid(),
                                hdr.getType() });
            } else {
                highestZxid = hdr.getZxid();
            }
            try {
                processTransaction(hdr,dt,sessions, itr.getTxn());
            } catch(KeeperException.NoNodeException e) {
               throw new IOException("Failed to process transaction type: " +
                     hdr.getType() + " error: " + e.getMessage(), e);
            }
            listener.onTxnLoaded(hdr, itr.getTxn());
            if (!itr.next()) 
                break;
        }
    } finally {
        if (itr != null) {
            itr.close();
        }
    }
    return highestZxid;
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
/**
 * this function restores the server 
 * database after reading from the 
 * snapshots and transaction logs
 * @param dt the datatree to be restored
 * @param sessions the sessions to be restored
 * @param listener the playback listener to run on the 
 * database restoration
 * @return the highest zxid restored
 * @throws IOException
 */
public long restore(DataTree dt, Map<Long, Integer> sessions, 
        PlayBackListener listener) throws IOException {
    // 内存快照文件反序列化为内存数据库
    snapLog.deserialize(dt, sessions);
    FileTxnLog txnLog = new FileTxnLog(dataDir);
    TxnIterator itr = txnLog.read(dt.lastProcessedZxid+1);
    long highestZxid = dt.lastProcessedZxid;
    TxnHeader hdr;
    try {
        while (true) {
            // iterator points to 
            // the first valid txn when initialized

            // 事务头
            hdr = itr.getHeader();
            if (hdr == null) {
                //empty logs 
                return dt.lastProcessedZxid;
            }

            // 比较内存快照的zxid和事务日志的zxid, 得到大的zxid
            if (hdr.getZxid() < highestZxid && highestZxid != 0) {
                LOG.error("{}(higestZxid) > {}(next log) for type {}",
                        new Object[] { highestZxid, hdr.getZxid(),
                                hdr.getType() });
            } else {
                highestZxid = hdr.getZxid();
            }
            try {
                // 从事务日志恢复内存数据库
                processTransaction(hdr,dt,sessions, itr.getTxn());
            } catch(KeeperException.NoNodeException e) {
               throw new IOException("Failed to process transaction type: " +
                     hdr.getType() + " error: " + e.getMessage(), e);
            }
            // 触发事务加载监听事件
            listener.onTxnLoaded(hdr, itr.getTxn());
            // 处理下一条事务日志
            if (!itr.next()) 
                break;
        }
    } finally {
        if (itr != null) {
            itr.close();
        }
    }
    return highestZxid;
}
 

import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator; //导入方法依赖的package包/类
/**
 * this function restores the server
 * database after reading from the
 * snapshots and transaction logs
 * @param dt the datatree to be restored
 * @param sessions the sessions to be restored
 * @param listener the playback listener to run on the
 * database restoration
 * @return the highest zxid restored
 * @throws IOException
 */
public long restore(DataTree dt, Map<Long, Integer> sessions,
        PlayBackListener listener) throws IOException {
    snapLog.deserialize(dt, sessions);
    FileTxnLog txnLog = new FileTxnLog(dataDir);
    TxnIterator itr = txnLog.read(dt.lastProcessedZxid+1);
    long highestZxid = dt.lastProcessedZxid;
    TxnHeader hdr;
    try {
        while (true) {
            // iterator points to
            // the first valid txn when initialized
            hdr = itr.getHeader();
            if (hdr == null) {
                //empty logs
                return dt.lastProcessedZxid;
            }
            if (hdr.getZxid() < highestZxid && highestZxid != 0) {
                LOG.error("{}(higestZxid) > {}(next log) for type {}",
                        new Object[] { highestZxid, hdr.getZxid(),
                                hdr.getType() });
            } else {
                highestZxid = hdr.getZxid();
            }
            try {
                processTransaction(hdr,dt,sessions, itr.getTxn());
            } catch(KeeperException.NoNodeException e) {
               throw new IOException("Failed to process transaction type: " +
                     hdr.getType() + " error: " + e.getMessage(), e);
            }
            listener.onTxnLoaded(hdr, itr.getTxn());
            if (!itr.next())
                break;
        }
    } finally {
        if (itr != null) {
            itr.close();
        }
    }
    return highestZxid;
}