BufferAllocator (Drill : 1.20.3 API)

All Superinterfaces:

AutoCloseable

All Known Implementing Classes:

BaseAllocator, RootAllocator
```
public interface BufferAllocator
extends AutoCloseable
```
Wrapper class to deal with byte buffer allocation. Ensures users only use designated methods.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`assertOpen()` Asserts (using java assertions) that the provided allocator is currently open.
`DrillBuf`	`buffer(int size)` Allocate a new or reused buffer of the provided size.
`DrillBuf`	`buffer(int size, BufferManager manager)` Allocate a new or reused buffer of the provided size.
`void`	`close()` Close and release all buffers generated from this buffer pool.
`long`	`getAllocatedMemory()` Returns the amount of memory currently allocated from this allocator.
`io.netty.buffer.ByteBufAllocator`	`getAsByteBufAllocator()` Returns the allocator this allocator falls back to when it needs more memory.
`DrillBuf`	`getEmpty()` Get a reference to the empty buffer associated with this allocator.
`long`	`getLimit()` Return the current maximum limit this allocator imposes.
`String`	`getName()` Return the name of this allocator.
`long`	`getPeakMemoryAllocation()` Returns the peak amount of memory allocated from this allocator.
`boolean`	`isOverLimit()` Return whether or not this allocator (or one if its parents) is over its limits.
`BufferAllocator`	`newChildAllocator(String name, long initReservation, long maxAllocation)` Create a new child allocator.
`AllocationReservation`	`newReservation()` Create an allocation reservation.
`void`	`read(DrillBuf buf, int length, InputStream in)` Read the contents of a DrillBuf from a stream.
`DrillBuf`	`read(int length, InputStream in)` Reads the specified number of bytes into a new Drillbuf.
`boolean`	`setLenient()` Request lenient enforcement of the allocation limits.
`void`	`setLimit(long newLimit)` Set the maximum amount of memory this allocator is allowed to allocate.
`String`	`toVerboseString()` Return a verbose string describing this allocator.
`void`	`write(DrillBuf buf, int length, OutputStream out)` Write the contents of a DrillBuf to a stream.
`void`	`write(DrillBuf buf, OutputStream out)` Write the contents of a DrillBuf to a stream.

- Method Detail
  - buffer
```
DrillBuf buffer(int size)
```
    Allocate a new or reused buffer of the provided size. Note that the buffer may technically be larger than the requested size for rounding purposes. However, the buffer's capacity will be set to the configured size.
    
    Parameters:
    
    size - The size in bytes.
    
    Returns:
    
    a new DrillBuf, or null if the request can't be satisfied
    
    Throws:
    
    OutOfMemoryException - if buffer cannot be allocated
  - buffer
```
DrillBuf buffer(int size,
                BufferManager manager)
```
    Allocate a new or reused buffer of the provided size. Note that the buffer may technically be larger than the requested size for rounding purposes. However, the buffer's capacity will be set to the configured size.
    
    Parameters:
    
    size - The size in bytes.
    
    manager - A buffer manager to manage reallocation.
    
    Returns:
    
    a new DrillBuf, or null if the request can't be satisfied
    
    Throws:
    
    OutOfMemoryException - if buffer cannot be allocated
  - getAsByteBufAllocator
```
io.netty.buffer.ByteBufAllocator getAsByteBufAllocator()
```
    Returns the allocator this allocator falls back to when it needs more memory.
    
    Returns:
    
    the underlying allocator used by this allocator
  - newChildAllocator
```
BufferAllocator newChildAllocator(String name,
                                  long initReservation,
                                  long maxAllocation)
```
    Create a new child allocator.
    
    Parameters:
    
    name - the name of the allocator.
    
    initReservation - the initial space reservation (obtained from this allocator)
    
    maxAllocation - maximum amount of space the new allocator can allocate
    
    Returns:
    
    the new allocator, or null if it can't be created
  - close
```
void close()
```
    Close and release all buffers generated from this buffer pool.
    When assertions are on, complains if there are any outstanding buffers; to avoid that, release all buffers before the allocator is closed.
    
    Specified by:
    
    close in interface AutoCloseable
  - getAllocatedMemory
```
long getAllocatedMemory()
```
    Returns the amount of memory currently allocated from this allocator.
    
    Returns:
    
    the amount of memory currently allocated
  - setLimit
```
void setLimit(long newLimit)
```
    Set the maximum amount of memory this allocator is allowed to allocate.
    
    Parameters:
    
    newLimit - The new Limit to apply to allocations
  - setLenient
```
boolean setLenient()
```
    Request lenient enforcement of the allocation limits. Use for memory-managed operators to prevent minor math errors from killing queries. This is temporary until Drill manages memory better. Leniency is allowed only in production code (no assertions), not in debug mode (assertions enabled).
    
    Returns:
    
    true if leniency was granted, false if the allocator will enforce strict limits despite the request
  - getLimit
```
long getLimit()
```
    Return the current maximum limit this allocator imposes.
    
    Returns:
    
    Limit in number of bytes.
  - getPeakMemoryAllocation
```
long getPeakMemoryAllocation()
```
    Returns the peak amount of memory allocated from this allocator.
    
    Returns:
    
    the peak amount of memory allocated
  - newReservation
```
AllocationReservation newReservation()
```
    Create an allocation reservation. A reservation is a way of building up a request for a buffer whose size is not known in advance. See AllocationReservation.
    
    Returns:
    
    the newly created reservation
  - getEmpty
```
DrillBuf getEmpty()
```
    Get a reference to the empty buffer associated with this allocator. Empty buffers are special because we don't worry about them leaking or managing reference counts on them since they don't actually point to any memory.
  - getName
```
String getName()
```
    Return the name of this allocator. This is a human readable name that can help debugging. Typically provides coordinates about where this allocator was created
  - isOverLimit
```
boolean isOverLimit()
```
    Return whether or not this allocator (or one if its parents) is over its limits. In the case that an allocator is over its limit, all consumers of that allocator should aggressively try to addrss the overlimit situation.
  - toVerboseString
```
String toVerboseString()
```
    Return a verbose string describing this allocator. If in DEBUG mode, this will also include relevant stacktraces and historical logs for underlying objects
    
    Returns:
    
    A very verbose description of the allocator hierarchy.
  - assertOpen
```
void assertOpen()
```
    Asserts (using java assertions) that the provided allocator is currently open. If assertions are disabled, this is a no-op.
  - write
```
void write(DrillBuf buf,
           OutputStream out)
    throws IOException
```
    Write the contents of a DrillBuf to a stream. Use this method, rather than calling the DrillBuf.getBytes() method, because this method avoids repeated heap allocation for the intermediate heap buffer. Uses the reader and writer indexes to determine the number of bytes to write. Useful only for bufs created using those indexes.
    
    Parameters:
    
    buf - the Drillbuf to write
    
    out - the output stream
    
    Throws:
    
    IOException - if a write error occurs
  - write
```
void write(DrillBuf buf,
           int length,
           OutputStream out)
    throws IOException
```
    Write the contents of a DrillBuf to a stream. Use this method, rather than calling the DrillBuf.getBytes() method, because this method avoids repeated heap allocation for the intermediate heap buffer. Writes the specified number of bytes starting from the head of the given Drillbuf.
    
    Parameters:
    
    buf - the Drillbuf to write
    
    length - the number of bytes to read. Must be less than or equal to number of bytes allocated in the buffer.
    
    out - the output stream
    
    Throws:
    
    IOException - if a write error occurs
  - read
```
void read(DrillBuf buf,
          int length,
          InputStream in)
   throws IOException
```
    Read the contents of a DrillBuf from a stream. Use this method, rather than calling the DrillBuf.writeBytes() method, because this method avoids repeated heap allocation for the intermediate heap buffer. The buffer must have already been allocated.
    
    Parameters:
    
    buf - the buffer to read with space already allocated
    
    length - number of bytes to read
    
    in - input stream from which to read data
    
    Throws:
    
    IOException - if a read error occurs
  - read
```
DrillBuf read(int length,
              InputStream in)
       throws IOException
```
    Reads the specified number of bytes into a new Drillbuf.
    
    Parameters:
    
    length - number of bytes to read
    
    in - input stream from which to read data
    
    Returns:
    
    the buffer holding the data read from the stream
    
    Throws:
    
    IOException - if a read error occurs

Interface BufferAllocator

Method Summary

Method Detail

buffer

buffer

getAsByteBufAllocator

newChildAllocator

close

getAllocatedMemory

setLimit

setLenient

getLimit

getPeakMemoryAllocation

newReservation

getEmpty

getName

isOverLimit

toVerboseString

assertOpen

write

write

read

read