AsyncKuduSession (Kudu 0.9.0 API)

java.lang.Object
- org.kududb.client.AsyncKuduSession

All Implemented Interfaces:

SessionConfiguration
```
@InterfaceAudience.Public
 @InterfaceStability.Unstable
public class AsyncKuduSession
extends Object
implements SessionConfiguration
```
A AsyncKuduSession belongs to a specific AsyncKuduClient, and represents a context in which all read/write data access should take place. Within a session, multiple operations may be accumulated and batched together for better efficiency. Settings like timeouts, priorities, and trace IDs are also set per session.
AsyncKuduSession is separate from KuduTable because a given batch or transaction may span multiple tables. This is particularly important in the future when we add ACID support, but even in the context of batching, we may be able to coalesce writes to different tables hosted on the same server into the same RPC.
AsyncKuduSession is separate from AsyncKuduClient because, in a multi-threaded application, different threads may need to concurrently execute transactions. Similar to a JDBC "session", transaction boundaries will be delineated on a per-session basis -- in between a "BeginTransaction" and "Commit" call on a given session, all operations will be part of the same transaction. Meanwhile another concurrent Session object can safely run non-transactional work or other transactions without interfering.
Therefore, this class is not thread-safe.
Additionally, there is a guarantee that writes from different sessions do not get batched together into the same RPCs -- this means that latency-sensitive clients can run through the same AsyncKuduClient object as throughput-oriented clients, perhaps by setting the latency-sensitive session's timeouts low and priorities high. Without the separation of batches, a latency-sensitive single-row insert might get batched along with 10MB worth of inserts from the batch writer, thus delaying the response significantly.
Though we currently do not have transactional support, users will be forced to use a AsyncKuduSession to instantiate reads as well as writes. This will make it more straight-forward to add RW transactions in the future without significant modifications to the API.
Timeouts are handled differently depending on the flush mode. With AUTO_FLUSH_SYNC, the timeout is set on each apply()'d operation. With AUTO_FLUSH_BACKGROUND and MANUAL_FLUSH, the timeout is assigned to a whole batch of operations upon flush()'ing. It means that in a situation with a timeout of 500ms and a flush interval of 1000ms, an operation can be oustanding for up to 1500ms before being timed out.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.kududb.client.SessionConfiguration
  SessionConfiguration.FlushMode

Field Summary

Fields
Modifier and Type Field and Description

static org.slf4j.Logger LOG

Fields
Modifier and Type	Field and Description
`static org.slf4j.Logger`	`LOG`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`com.stumbleupon.async.Deferred<OperationResponse>`	`apply(Operation operation)` Apply the given operation.
`com.stumbleupon.async.Deferred<List<OperationResponse>>`	`close()` Flushes the buffered operations and marks this sessions as closed.
`int`	`countPendingErrors()` Return the number of errors which are pending.
`com.stumbleupon.async.Deferred<List<OperationResponse>>`	`flush()` Flushes the buffered operations.
`SessionConfiguration.FlushMode`	`getFlushMode()` Get the current flush mode.
`RowErrorsAndOverflowStatus`	`getPendingErrors()` Return any errors from previous calls.
`long`	`getTimeoutMillis()` Get the current timeout.
`boolean`	`hasPendingOperations()` Check if there are operations that haven't been completely applied.
`boolean`	`isClosed()` Returns true if this session has already been closed.
`boolean`	`isIgnoreAllDuplicateRows()` Tells if the session is currently ignoring row errors when the whole list returned by a tablet server is of the AlreadyPresent type.
`void`	`setExternalConsistencyMode(ExternalConsistencyMode consistencyMode)` Set the new external consistency mode for this session.
`void`	`setFlushInterval(int interval)` Set the flush interval, which will be used for the next scheduling decision.
`void`	`setFlushMode(SessionConfiguration.FlushMode flushMode)` Set the new flush mode for this session.
`void`	`setIgnoreAllDuplicateRows(boolean ignoreAllDuplicateRows)` Configures the option to ignore all the row errors if they are all of the AlreadyPresent type.
`void`	`setMutationBufferLowWatermark(float mutationBufferLowWatermarkPercentage)` Set the low watermark for this session.
`void`	`setMutationBufferSpace(int size)` Set the number of operations that can be buffered.
`void`	`setTimeoutMillis(long timeout)` Sets the timeout for the next applied operations.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - LOG
```
public static final org.slf4j.Logger LOG
```
- Method Detail
  - getFlushMode
```
public SessionConfiguration.FlushMode getFlushMode()
```
    Description copied from interface: SessionConfiguration
    
    Get the current flush mode.
    
    Specified by:
    
    getFlushMode in interface SessionConfiguration
    
    Returns:
    
    flush mode, AUTO_FLUSH_SYNC by default
  - setFlushMode
```
public void setFlushMode(SessionConfiguration.FlushMode flushMode)
```
    Description copied from interface: SessionConfiguration
    
    Set the new flush mode for this session.
    
    Specified by:
    
    setFlushMode in interface SessionConfiguration
    
    Parameters:
    
    flushMode - new flush mode, can be the same as the previous one.
  - setExternalConsistencyMode
```
public void setExternalConsistencyMode(ExternalConsistencyMode consistencyMode)
```
    Description copied from interface: SessionConfiguration
    
    Set the new external consistency mode for this session.
    
    Specified by:
    
    setExternalConsistencyMode in interface SessionConfiguration
    
    Parameters:
    
    consistencyMode - new external consistency mode, can the same as the previous one.
  - setMutationBufferSpace
```
public void setMutationBufferSpace(int size)
```
    Description copied from interface: SessionConfiguration
    
    Set the number of operations that can be buffered.
    
    Specified by:
    
    setMutationBufferSpace in interface SessionConfiguration
    
    Parameters:
    
    size - number of ops.
  - setMutationBufferLowWatermark
```
public void setMutationBufferLowWatermark(float mutationBufferLowWatermarkPercentage)
```
    Description copied from interface: SessionConfiguration
    
    Set the low watermark for this session. The default is set to half the mutation buffer space. For example, a buffer space of 1000 with a low watermark set to 50% (0.5) will start randomly sending PleaseRetryExceptions once there's an outstanding flush and the buffer is over 500. As the buffer gets fuller, it becomes likelier to hit the exception.
    
    Specified by:
    
    setMutationBufferLowWatermark in interface SessionConfiguration
    
    Parameters:
    
    mutationBufferLowWatermarkPercentage - a new low watermark as a percentage, has to be between 0 and 1 (inclusive). A value of 1 disables the low watermark since it's the same as the high one
  - setFlushInterval
```
public void setFlushInterval(int interval)
```
    Description copied from interface: SessionConfiguration
    
    Set the flush interval, which will be used for the next scheduling decision.
    
    Specified by:
    
    setFlushInterval in interface SessionConfiguration
    
    Parameters:
    
    interval - interval in milliseconds.
  - setTimeoutMillis
```
public void setTimeoutMillis(long timeout)
```
    Description copied from interface: SessionConfiguration
    
    Sets the timeout for the next applied operations. The default timeout is 0, which disables the timeout functionality.
    
    Specified by:
    
    setTimeoutMillis in interface SessionConfiguration
    
    Parameters:
    
    timeout - Timeout in milliseconds.
  - getTimeoutMillis
```
public long getTimeoutMillis()
```
    Description copied from interface: SessionConfiguration
    
    Get the current timeout.
    
    Specified by:
    
    getTimeoutMillis in interface SessionConfiguration
    
    Returns:
    
    operation timeout in milliseconds, 0 if none was configured.
  - isClosed
```
public boolean isClosed()
```
    Description copied from interface: SessionConfiguration
    
    Returns true if this session has already been closed.
    
    Specified by:
    
    isClosed in interface SessionConfiguration
  - isIgnoreAllDuplicateRows
```
public boolean isIgnoreAllDuplicateRows()
```
    Description copied from interface: SessionConfiguration
    
    Tells if the session is currently ignoring row errors when the whole list returned by a tablet server is of the AlreadyPresent type.
    
    Specified by:
    
    isIgnoreAllDuplicateRows in interface SessionConfiguration
    
    Returns:
    
    true if the session is enforcing this, else false
  - setIgnoreAllDuplicateRows
```
public void setIgnoreAllDuplicateRows(boolean ignoreAllDuplicateRows)
```
    Description copied from interface: SessionConfiguration
    
    Configures the option to ignore all the row errors if they are all of the AlreadyPresent type. This can be needed when facing KUDU-568. The effect of enabling this is that operation responses that match this pattern will be cleared of their row errors, meaning that we consider them successful. This is disabled by default.
    
    Specified by:
    
    setIgnoreAllDuplicateRows in interface SessionConfiguration
    
    Parameters:
    
    ignoreAllDuplicateRows - true if this session should enforce this, else false
  - countPendingErrors
```
public int countPendingErrors()
```
    Description copied from interface: SessionConfiguration
    
    Return the number of errors which are pending. Errors may accumulate when using the AUTO_FLUSH_BACKGROUND mode.
    
    Specified by:
    
    countPendingErrors in interface SessionConfiguration
    
    Returns:
    
    a count of errors
  - getPendingErrors
```
public RowErrorsAndOverflowStatus getPendingErrors()
```
    Description copied from interface: SessionConfiguration
    
    Return any errors from previous calls. If there were more errors than could be held in the session's error storage, the overflow state is set to true. Resets the pending errors.
    
    Specified by:
    
    getPendingErrors in interface SessionConfiguration
    
    Returns:
    
    an object that contains the errors and the overflow status
  - close
```
public com.stumbleupon.async.Deferred<List<OperationResponse>> close()
```
    Flushes the buffered operations and marks this sessions as closed. See the javadoc on flush() on how to deal with exceptions coming out of this method.
    
    Returns:
    
    a Deferred whose callback chain will be invoked when. everything that was buffered at the time of the call has been flushed.
  - flush
```
public com.stumbleupon.async.Deferred<List<OperationResponse>> flush()
```
    Flushes the buffered operations.
    
    Returns:
    
    a Deferred whose callback chain will be invoked when everything that was buffered at the time of the call has been flushed.
  - hasPendingOperations
```
public boolean hasPendingOperations()
```
    Description copied from interface: SessionConfiguration
    
    Check if there are operations that haven't been completely applied.
    
    Specified by:
    
    hasPendingOperations in interface SessionConfiguration
    
    Returns:
    
    true if operations are pending, else false.
  - apply
```
public com.stumbleupon.async.Deferred<OperationResponse> apply(Operation operation)
```
    Apply the given operation. The behavior of this function depends on the current flush mode. Regardless of flush mode, however, Apply may begin to perform processing in the background for the call (e.g looking up the tablet, etc).
    
    Parameters:
    
    operation - operation to apply
    
    Returns:
    
    a Deferred to track this operation

Class AsyncKuduSession

Nested Class Summary

Nested classes/interfaces inherited from interface org.kududb.client.SessionConfiguration

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

Method Detail

getFlushMode

setFlushMode

setExternalConsistencyMode

setMutationBufferSpace

setMutationBufferLowWatermark

setFlushInterval

setTimeoutMillis

getTimeoutMillis

isClosed

isIgnoreAllDuplicateRows

setIgnoreAllDuplicateRows

countPendingErrors

getPendingErrors

close

flush

hasPendingOperations

apply