com.sleepycat.je.Cursor.getNext()方法的使用及代码示例

x33g5p2x  于2022-01-18 转载在 其他  
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本文整理了Java中com.sleepycat.je.Cursor.getNext()方法的一些代码示例，展示了Cursor.getNext()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Cursor.getNext()方法的具体详情如下：
包路径：com.sleepycat.je.Cursor
类名称：Cursor
方法名：getNext

Cursor.getNext介绍

[英]Moves the cursor to the next key/data pair and returns that pair.

Calling this method is equivalent to calling #get(DatabaseEntry,DatabaseEntry,Get,ReadOptions) with Get#NEXT.

If the cursor is not yet initialized, move the cursor to the first key/data pair of the database, and return that pair. Otherwise, the cursor is moved to the next key/data pair of the database, and that pair is returned. In the presence of duplicate key values, the value of the key may not change.
[中]将光标移动到下一个键/数据对并返回该对。
调用此方法相当于使用get#NEXT调用#get（DatabaseEntry、DatabaseEntry、get、ReadOptions）。
如果光标尚未初始化，请将光标移动到数据库的第一个键/数据对，然后返回该对。否则，光标将移动到数据库的下一个键/数据对，并返回该对。存在重复的键值时，键值可能不会更改。

代码示例

代码示例来源：origin: voldemort/voldemort

@Override
public void transfer() throws Exception {
  cursor = srcDB.openCursor(null, null);
  DatabaseEntry keyEntry = new DatabaseEntry();
  DatabaseEntry valueEntry = new DatabaseEntry();
  List<Versioned<byte[]>> vals;
  long startTime = System.currentTimeMillis();
  int scanCount = 0;
  int keyCount = 0;
  while(cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED) == OperationStatus.SUCCESS) {
    keyCount++;
    vals = StoreBinaryFormat.fromByteArray(valueEntry.getData());
    scanCount += vals.size();
    // pull out the real key
    byte[] stripedKey = StoreBinaryFormat.extractKey(keyEntry.getData());
    OperationStatus putStatus = dstDB.put(null, new DatabaseEntry(stripedKey), valueEntry);
    if(OperationStatus.SUCCESS != putStatus) {
      String errorStr = "Put failed with " + putStatus + " for key"
               + BdbConvertData.writeAsciiString(keyEntry.getData());
      logger.error(errorStr);
      throw new Exception(errorStr);
    }
    if(scanCount % 1000000 == 0)
      logger.info("Reverted " + scanCount + " entries in "
            + (System.currentTimeMillis() - startTime) / 1000 + " secs");
  }
  logger.info("Reverted " + scanCount + " entries and " + keyCount + " keys in "
        + (System.currentTimeMillis() - startTime) / 1000 + " secs");
}

代码示例来源：origin: internetarchive/heritrix3

/**
 * @return the key to the first item in the database
 * @throws DatabaseException
 */
protected DatabaseEntry getFirstKey() throws DatabaseException {
  DatabaseEntry key = new DatabaseEntry();
  DatabaseEntry value = new DatabaseEntry();
  Cursor cursor = pendingUrisDB.openCursor(null,null);
  OperationStatus status = cursor.getNext(key,value,null);
  cursor.close();
  if(status == OperationStatus.SUCCESS) {
    return key;
  }
  return null;
}

代码示例来源：origin: yasserg/crawler4j

public List<WebURL> get(int max) {
  synchronized (mutex) {
    List<WebURL> results = new ArrayList<>(max);
    DatabaseEntry key = new DatabaseEntry();
    DatabaseEntry value = new DatabaseEntry();
    Transaction txn = beginTransaction();
    try (Cursor cursor = openCursor(txn)) {
      OperationStatus result = cursor.getFirst(key, value, null);
      int matches = 0;
      while ((matches < max) && (result == OperationStatus.SUCCESS)) {
        if (value.getData().length > 0) {
          results.add(webURLBinding.entryToObject(value));
          matches++;
        }
        result = cursor.getNext(key, value, null);
      }
    }
    commit(txn);
    return results;
  }
}

代码示例来源：origin: internetarchive/heritrix3

protected OperationStatus getNextNearestItem(DatabaseEntry headKey,
    DatabaseEntry result) throws DatabaseException {
  Cursor cursor = null;
  OperationStatus status;
  try {
    cursor = this.pendingUrisDB.openCursor(null, null);
    
    // get cap; headKey at this point should always point to 
    // a queue-beginning cap entry (zero-length value)
    status = cursor.getSearchKey(headKey, result, null);
    if (status != OperationStatus.SUCCESS) {
      LOGGER.severe("bdb queue cap missing: " 
          + status.toString() + " "  + new String(headKey.getData()));
      return status;
    }
    if (result.getData().length > 0) {
      LOGGER.severe("bdb queue has nonzero size: " 
          + result.getData().length);
      return OperationStatus.KEYEXIST;
    }
    // get next item (real first item of queue)
    status = cursor.getNext(headKey,result,null);
  } finally { 
    if(cursor!=null) {
      cursor.close();
    }
  }
  return status;
}

代码示例来源：origin: ltsopensource/light-task-scheduler

DatabaseEntry foundKey = new DatabaseEntry();
DatabaseEntry foundValue = new DatabaseEntry();
while (cursor.getNext(foundKey, foundValue, LockMode.DEFAULT) ==
    OperationStatus.SUCCESS) {
  String key = new String(foundKey.getData(), "UTF-8");

代码示例来源：origin: ltsopensource/light-task-scheduler

DatabaseEntry foundKey = new DatabaseEntry();
DatabaseEntry foundValue = new DatabaseEntry();
while (cursor.getNext(foundKey, foundValue, LockMode.DEFAULT) ==
    OperationStatus.SUCCESS) {
  String key = new String(foundKey.getData(), "UTF-8");

代码示例来源：origin: voldemort/voldemort

while(cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED) == OperationStatus.SUCCESS) {
  keyCount++;

代码示例来源：origin: voldemort/voldemort

int scanCount = 0;
int keyCount = 0;
while(cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED) == OperationStatus.SUCCESS) {
  keyCount++;

代码示例来源：origin: voldemort/voldemort

while(cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED) == OperationStatus.SUCCESS) {
  keyCount++;

代码示例来源：origin: internetarchive/heritrix3

result = cursor.getNext(key, value, null);

代码示例来源：origin: voldemort/voldemort

int scanCount = 0;
int keyCount = 0;
while(cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED) == OperationStatus.SUCCESS) {
  scanCount++;
  if(scanCount % 1000000 == 0)

代码示例来源：origin: yasserg/crawler4j

public void delete(int count) {
  synchronized (mutex) {
    DatabaseEntry key = new DatabaseEntry();
    DatabaseEntry value = new DatabaseEntry();
    Transaction txn = beginTransaction();
    try (Cursor cursor = openCursor(txn)) {
      OperationStatus result = cursor.getFirst(key, value, null);
      int matches = 0;
      while ((matches < count) && (result == OperationStatus.SUCCESS)) {
        cursor.delete();
        matches++;
        result = cursor.getNext(key, value, null);
      }
    }
    commit(txn);
  }
}

代码示例来源：origin: thinkaurelius/titan

break;
status = cursor.getNext(foundKey, foundData, getLockMode(txh));

代码示例来源：origin: internetarchive/heritrix3

/**
   * Utility method to perform action for all pending CrawlURI instances.
   * @param c Closure action to perform
   * @throws DatabaseException
   */
  protected void forAllPendingDo(Closure c) throws DatabaseException {
    DatabaseEntry key = new DatabaseEntry();
    DatabaseEntry value = new DatabaseEntry();
    Cursor cursor = pendingUrisDB.openCursor(null, null);
    while (cursor.getNext(key, value, null) == OperationStatus.SUCCESS) {
      if (value.getData().length == 0) {
        continue;
      }
      CrawlURI item = (CrawlURI) crawlUriBinding.entryToObject(value);
      c.execute(item);
    }
    cursor.close(); 
  }
}

代码示例来源：origin: voldemort/voldemort

protected boolean makeMore() {
    DatabaseEntry keyEntry = new DatabaseEntry();
    DatabaseEntry valueEntry = new DatabaseEntry();
    try {
      OperationStatus status = cursor.getNext(keyEntry,
                          valueEntry,
                          LockMode.READ_UNCOMMITTED);
      if(OperationStatus.NOTFOUND == status) {
        // we have reached the end of the cursor
        return false;
      }
      ByteArray key = null;
      if(bdbEngine.isPartitionScanSupported())
        key = new ByteArray(StoreBinaryFormat.extractKey(keyEntry.getData()));
      else
        key = new ByteArray(keyEntry.getData());
      for(Versioned<byte[]> val: StoreBinaryFormat.fromByteArray(valueEntry.getData()))
        this.cache.add(Pair.create(key, val));
      return true;
    } catch(DatabaseException e) {
      bdbEngine.bdbEnvironmentStats.reportException(e);
      logger.error(e);
      throw new PersistenceFailureException(e);
    }
  }
}

代码示例来源：origin: internetarchive/heritrix3

status = cursor.getNext(key, value, null)) {

代码示例来源：origin: voldemort/voldemort

private boolean fetchNextKey() {
    DatabaseEntry keyEntry = new DatabaseEntry();
    DatabaseEntry valueEntry = new DatabaseEntry();
    valueEntry.setPartial(true);
    try {
      OperationStatus status = cursor.getNext(keyEntry,
                          valueEntry,
                          LockMode.READ_UNCOMMITTED);
      if(OperationStatus.NOTFOUND == status) {
        // we have reached the end of the cursor
        return false;
      }
      if(bdbEngine.isPartitionScanSupported())
        current = new ByteArray(StoreBinaryFormat.extractKey(keyEntry.getData()));
      else
        current = new ByteArray(keyEntry.getData());
      return true;
    } catch(DatabaseException e) {
      bdbEngine.bdbEnvironmentStats.reportException(e);
      logger.error(e);
      throw new PersistenceFailureException(e);
    }
  }
}

代码示例来源：origin: yasserg/crawler4j

counterValues.put(name, counterValue);
result = cursor.getNext(key, value, null);

代码示例来源：origin: voldemort/voldemort

LockMode.READ_UNCOMMITTED);
} else {
  status = cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED);

代码示例来源：origin: voldemort/voldemort

LockMode.READ_UNCOMMITTED);
} else {
  status = cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED);

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