LocalBufferPool (Flink : Runtime 1.20.0 API)

java.lang.Object
- org.apache.flink.runtime.io.network.buffer.LocalBufferPool

所有已实现的接口:

AvailabilityProvider, BufferPool, BufferProvider, BufferRecycler
```
public class LocalBufferPool
extends Object
implements BufferPool
```
A buffer pool used to manage a number of Buffer instances from the NetworkBufferPool.
Buffer requests are mediated to the network buffer pool to ensure deadlock free operation of the network stack by limiting the number of buffers per local buffer pool. It also implements the default mechanism for buffer recycling, which ensures that every buffer is ultimately returned to the network buffer pool.
The size of this pool can be dynamically changed at runtime (setNumBuffers(int). It will then lazily return the required number of buffers to the NetworkBufferPool to match its new size.
New buffers can be requested only when numberOfRequestedMemorySegments < currentPoolSize + maxOverdraftBuffersPerGate. In other words, all buffers exceeding the currentPoolSize will be dynamically regarded as overdraft buffers.
Availability is defined as returning a non-overdraft segment on a subsequent requestBuffer()/ requestBufferBuilder() and heaving a non-blocking requestBufferBuilderBlocking(int). In particular,
- There is at least one availableMemorySegments.
- No subpartitions has reached maxBuffersPerChannel.
To ensure this contract, the implementation eagerly fetches additional memory segments from NetworkBufferPool as long as it hasn't reached maxNumberOfMemorySegments or one subpartition reached the quota.

嵌套类概要
- 从接口继承的嵌套类/接口 org.apache.flink.runtime.io.AvailabilityProvider
  AvailabilityProvider.AvailabilityHelper
- 从接口继承的嵌套类/接口 org.apache.flink.runtime.io.network.buffer.BufferRecycler
  BufferRecycler.DummyBufferRecycler

字段概要
- 从接口继承的字段 org.apache.flink.runtime.io.AvailabilityProvider
  AVAILABLE

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`boolean`	`addBufferListener(BufferListener listener)` Adds a buffer availability listener to the buffer provider.
`int`	`bestEffortGetNumOfUsedBuffers()` Returns the number of used buffers of this buffer pool.
`CompletableFuture<?>`	`getAvailableFuture()`
`int`	`getEstimatedNumberOfRequestedMemorySegments()` Estimates the number of requested buffers.
`int`	`getMaxNumberOfMemorySegments()` Returns the maximum number of memory segments this buffer pool should use.
`int`	`getMaxOverdraftBuffersPerGate()` Returns the max overdraft buffer size of per gate.
`int`	`getNumberOfAvailableMemorySegments()` Returns the number memory segments, which are currently held by this buffer pool.
`int`	`getNumberOfRequestedMemorySegments()`
`int`	`getNumberOfRequiredMemorySegments()` Returns the number of guaranteed (minimum number of) memory segments of this buffer pool.
`int`	`getNumBuffers()` Returns the current size of this buffer pool.
`boolean`	`isDestroyed()` Checks whether this buffer pool has been destroyed.
`void`	`lazyDestroy()` Destroy is called after the produce or consume phase of a task finishes.
`void`	`recycle(org.apache.flink.core.memory.MemorySegment segment)` Recycles the `MemorySegment` to its original `BufferPool` instance.
`Buffer`	`requestBuffer()` Returns a `Buffer` instance from the buffer provider, if one is available.
`BufferBuilder`	`requestBufferBuilder()` Returns a `BufferBuilder` instance from the buffer provider.
`BufferBuilder`	`requestBufferBuilder(int targetChannel)` Returns a `BufferBuilder` instance from the buffer provider.
`BufferBuilder`	`requestBufferBuilderBlocking()` Returns a `BufferBuilder` instance from the buffer provider.
`BufferBuilder`	`requestBufferBuilderBlocking(int targetChannel)` Returns a `BufferBuilder` instance from the buffer provider.
`org.apache.flink.core.memory.MemorySegment`	`requestMemorySegment()` Returns a `MemorySegment` instance from the buffer provider.
`org.apache.flink.core.memory.MemorySegment`	`requestMemorySegmentBlocking()` Returns a `MemorySegment` instance from the buffer provider.
`void`	`reserveSegments(int numberOfSegmentsToReserve)` Reserves the target number of segments to this pool.
`void`	`setMaxOverdraftBuffersPerGate(int maxOverdraftBuffersPerGate)` Sets the max overdraft buffer size of per gate.
`void`	`setNumBuffers(int numBuffers)` Sets the current size of this buffer pool.
`String`	`toString()`

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

从接口继承的方法 org.apache.flink.runtime.io.AvailabilityProvider
and, isApproximatelyAvailable, isAvailable, or

- 方法详细资料
  - reserveSegments
```
public void reserveSegments(int numberOfSegmentsToReserve)
                     throws IOException
```
    从接口复制的说明: BufferPool
    
    Reserves the target number of segments to this pool. Will throw an exception if it can not allocate enough segments.
    
    指定者:
    
    reserveSegments 在接口中 BufferPool
    
    抛出:
    
    IOException
  - isDestroyed
```
public boolean isDestroyed()
```
    从接口复制的说明: BufferPool
    
    Checks whether this buffer pool has been destroyed.
    
    指定者:
    
    isDestroyed 在接口中 BufferPool
    
    指定者:
    
    isDestroyed 在接口中 BufferProvider
  - getNumberOfRequiredMemorySegments
```
public int getNumberOfRequiredMemorySegments()
```
    从接口复制的说明: BufferPool
    
    Returns the number of guaranteed (minimum number of) memory segments of this buffer pool.
    
    指定者:
    
    getNumberOfRequiredMemorySegments 在接口中 BufferPool
  - getMaxNumberOfMemorySegments
```
public int getMaxNumberOfMemorySegments()
```
    从接口复制的说明: BufferPool
    
    Returns the maximum number of memory segments this buffer pool should use.
    
    指定者:
    
    getMaxNumberOfMemorySegments 在接口中 BufferPool
    
    返回:
    
    maximum number of memory segments to use or -1 if unlimited
  - getEstimatedNumberOfRequestedMemorySegments
```
public int getEstimatedNumberOfRequestedMemorySegments()
```
    Estimates the number of requested buffers.
    
    返回:
    
    the same value as getMaxNumberOfMemorySegments() for bounded pools. For unbounded pools it returns an approximation based upon getNumberOfRequiredMemorySegments()
  - getNumberOfRequestedMemorySegments
```
@VisibleForTesting
public int getNumberOfRequestedMemorySegments()
```
  - getNumberOfAvailableMemorySegments
```
public int getNumberOfAvailableMemorySegments()
```
    从接口复制的说明: BufferPool
    
    Returns the number memory segments, which are currently held by this buffer pool.
    
    指定者:
    
    getNumberOfAvailableMemorySegments 在接口中 BufferPool
  - getNumBuffers
```
public int getNumBuffers()
```
    从接口复制的说明: BufferPool
    
    Returns the current size of this buffer pool.
    The size of the buffer pool can change dynamically at runtime.
    
    指定者:
    
    getNumBuffers 在接口中 BufferPool
  - bestEffortGetNumOfUsedBuffers
```
public int bestEffortGetNumOfUsedBuffers()
```
    从接口复制的说明: BufferPool
    
    Returns the number of used buffers of this buffer pool.
    
    指定者:
    
    bestEffortGetNumOfUsedBuffers 在接口中 BufferPool
  - requestBuffer
```
public Buffer requestBuffer()
```
    从接口复制的说明: BufferProvider
    
    Returns a Buffer instance from the buffer provider, if one is available.
    
    指定者:
    
    requestBuffer 在接口中 BufferProvider
    
    返回:
    
    null if no buffer is available or the buffer provider has been destroyed.
  - requestBufferBuilder
```
public BufferBuilder requestBufferBuilder()
```
    从接口复制的说明: BufferProvider
    
    Returns a BufferBuilder instance from the buffer provider. This equals to BufferProvider.requestBufferBuilder(int) with unknown target channel.
    
    指定者:
    
    requestBufferBuilder 在接口中 BufferProvider
    
    返回:
    
    null if no buffer is available or the buffer provider has been destroyed.
  - requestBufferBuilder
```
public BufferBuilder requestBufferBuilder(int targetChannel)
```
    从接口复制的说明: BufferProvider
    
    Returns a BufferBuilder instance from the buffer provider.
    
    指定者:
    
    requestBufferBuilder 在接口中 BufferProvider
    
    参数:
    
    targetChannel - to which the request will be accounted to.
    
    返回:
    
    null if no buffer is available or the buffer provider has been destroyed.
  - requestBufferBuilderBlocking
```
public BufferBuilder requestBufferBuilderBlocking()
                                           throws InterruptedException
```
    从接口复制的说明: BufferProvider
    
    Returns a BufferBuilder instance from the buffer provider. This equals to BufferProvider.requestBufferBuilderBlocking(int) with unknown target channel.
    If there is no buffer available, the call will block until one becomes available again or the buffer provider has been destroyed.
    
    指定者:
    
    requestBufferBuilderBlocking 在接口中 BufferProvider
    
    抛出:
    
    InterruptedException
  - requestMemorySegmentBlocking
```
public org.apache.flink.core.memory.MemorySegment requestMemorySegmentBlocking()
                                                                        throws InterruptedException
```
    从接口复制的说明: BufferProvider
    
    Returns a MemorySegment instance from the buffer provider.
    If there is no memory segment available, the call will block until one becomes available again or the buffer provider has been destroyed.
    
    指定者:
    
    requestMemorySegmentBlocking 在接口中 BufferProvider
    
    抛出:
    
    InterruptedException
  - requestBufferBuilderBlocking
```
public BufferBuilder requestBufferBuilderBlocking(int targetChannel)
                                           throws InterruptedException
```
    从接口复制的说明: BufferProvider
    
    Returns a BufferBuilder instance from the buffer provider.
    If there is no buffer available, the call will block until one becomes available again or the buffer provider has been destroyed.
    
    指定者:
    
    requestBufferBuilderBlocking 在接口中 BufferProvider
    
    参数:
    
    targetChannel - to which the request will be accounted to.
    
    抛出:
    
    InterruptedException
  - requestMemorySegment
```
public org.apache.flink.core.memory.MemorySegment requestMemorySegment()
```
    从接口复制的说明: BufferProvider
    
    Returns a MemorySegment instance from the buffer provider.
    
    指定者:
    
    requestMemorySegment 在接口中 BufferProvider
    
    返回:
    
    null if no memory segment is available or the buffer provider has been destroyed.
  - recycle
```
public void recycle(org.apache.flink.core.memory.MemorySegment segment)
```
    从接口复制的说明: BufferRecycler
    
    Recycles the MemorySegment to its original BufferPool instance.
    
    指定者:
    
    recycle 在接口中 BufferRecycler
    
    参数:
    
    segment - The memory segment to be recycled.
  - lazyDestroy
```
public void lazyDestroy()
```
    Destroy is called after the produce or consume phase of a task finishes.
    
    指定者:
    
    lazyDestroy 在接口中 BufferPool
  - addBufferListener
```
public boolean addBufferListener(BufferListener listener)
```
    从接口复制的说明: BufferProvider
    
    Adds a buffer availability listener to the buffer provider.
    The operation fails with return value false, when there is a buffer available or the buffer provider has been destroyed.
    
    指定者:
    
    addBufferListener 在接口中 BufferProvider
  - setNumBuffers
```
public void setNumBuffers(int numBuffers)
```
    从接口复制的说明: BufferPool
    
    Sets the current size of this buffer pool.
    The size needs to be greater or equal to the guaranteed number of memory segments.
    
    指定者:
    
    setNumBuffers 在接口中 BufferPool
  - setMaxOverdraftBuffersPerGate
```
public void setMaxOverdraftBuffersPerGate(int maxOverdraftBuffersPerGate)
```
    从接口复制的说明: BufferPool
    
    Sets the max overdraft buffer size of per gate.
    
    指定者:
    
    setMaxOverdraftBuffersPerGate 在接口中 BufferPool
  - getMaxOverdraftBuffersPerGate
```
public int getMaxOverdraftBuffersPerGate()
```
    从接口复制的说明: BufferPool
    
    Returns the max overdraft buffer size of per gate.
    
    指定者:
    
    getMaxOverdraftBuffersPerGate 在接口中 BufferPool
  - getAvailableFuture
```
public CompletableFuture<?> getAvailableFuture()
```
    指定者:
    
    getAvailableFuture 在接口中 AvailabilityProvider
    
    返回:
    
    a future that is completed if the respective provider is available.
  - toString
```
public String toString()
```
    覆盖:
    
    toString 在类中 Object

类 LocalBufferPool

嵌套类概要

从接口继承的嵌套类/接口 org.apache.flink.runtime.io.AvailabilityProvider

从接口继承的嵌套类/接口 org.apache.flink.runtime.io.network.buffer.BufferRecycler

字段概要

从接口继承的字段 org.apache.flink.runtime.io.AvailabilityProvider

方法概要

从类继承的方法 java.lang.Object

从接口继承的方法 org.apache.flink.runtime.io.AvailabilityProvider

方法详细资料

reserveSegments

isDestroyed

getNumberOfRequiredMemorySegments

getMaxNumberOfMemorySegments

getEstimatedNumberOfRequestedMemorySegments

getNumberOfRequestedMemorySegments

getNumberOfAvailableMemorySegments

getNumBuffers

bestEffortGetNumOfUsedBuffers

requestBuffer

requestBufferBuilder

requestBufferBuilder

requestBufferBuilderBlocking

requestMemorySegmentBlocking

requestBufferBuilderBlocking

requestMemorySegment

recycle

lazyDestroy

addBufferListener

setNumBuffers

setMaxOverdraftBuffersPerGate

getMaxOverdraftBuffersPerGate

getAvailableFuture

toString