Class CachedBufferAllocator
- java.lang.Object
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- org.apache.mina.core.buffer.CachedBufferAllocator
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- All Implemented Interfaces:
IoBufferAllocator
public class CachedBufferAllocator extends Object implements IoBufferAllocator
AnIoBufferAllocator
that caches the buffers which are likely to be reused during auto-expansion of the buffers.In
SimpleBufferAllocator
, the underlyingByteBuffer
of theIoBuffer
is reallocated on its capacity change, which means the newly allocated biggerByteBuffer
replaces the old smallByteBuffer
. Consequently, the oldByteBuffer
is marked for garbage collection.It's not a problem in most cases as long as the capacity change doesn't happen frequently. However, once it happens too often, it burdens the VM and the cost of filling the newly allocated
ByteBuffer
withNUL
surpass the cost of accessing the cache. In 2 dual-core Opteron Italy 270 processors,CachedBufferAllocator
outperformedSimpleBufferAllocator
in the following situation:- when a 32 bytes buffer is expanded 4 or more times,
- when a 64 bytes buffer is expanded 4 or more times,
- when a 128 bytes buffer is expanded 2 or more times,
- and when a 256 bytes or bigger buffer is expanded 1 or more times.
CachedBufferAllocator
usesThreadLocal
to store the cached buffer, allocates buffers whose capacity is power of 2 only and provides performance advantage ifIoBuffer.free()
is called properly.- Author:
- Apache MINA Project
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Constructor Summary
Constructors Constructor Description CachedBufferAllocator()
Creates a new instance with the default parameters (#DEFAULT_MAX_POOL_SIZE and #DEFAULT_MAX_CACHED_BUFFER_SIZE).CachedBufferAllocator(int maxPoolSize, int maxCachedBufferSize)
Creates a new instance.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description IoBuffer
allocate(int requestedCapacity, boolean direct)
Returns the buffer which is capable of the specified size.ByteBuffer
allocateNioBuffer(int capacity, boolean direct)
Returns the NIO buffer which is capable of the specified size.void
dispose()
Dispose of this allocator.int
getMaxCachedBufferSize()
int
getMaxPoolSize()
IoBuffer
wrap(ByteBuffer nioBuffer)
Wraps the specified NIOByteBuffer
into MINA buffer.
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Constructor Detail
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CachedBufferAllocator
public CachedBufferAllocator()
Creates a new instance with the default parameters (#DEFAULT_MAX_POOL_SIZE and #DEFAULT_MAX_CACHED_BUFFER_SIZE).
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CachedBufferAllocator
public CachedBufferAllocator(int maxPoolSize, int maxCachedBufferSize)
Creates a new instance.- Parameters:
maxPoolSize
- the maximum number of buffers with the same capacity per thread. 0 disables this limitation.maxCachedBufferSize
- the maximum capacity of a cached buffer. A buffer whose capacity is bigger than this value is not pooled. 0 disables this limitation.
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Method Detail
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getMaxPoolSize
public int getMaxPoolSize()
- Returns:
- the maximum number of buffers with the same capacity per thread. 0 means 'no limitation'.
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getMaxCachedBufferSize
public int getMaxCachedBufferSize()
- Returns:
- the maximum capacity of a cached buffer. A buffer whose capacity is bigger than this value is not pooled. 0 means 'no limitation'.
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allocate
public IoBuffer allocate(int requestedCapacity, boolean direct)
Returns the buffer which is capable of the specified size.- Specified by:
allocate
in interfaceIoBufferAllocator
- Parameters:
requestedCapacity
- the capacity of the bufferdirect
- true to get a direct buffer, false to get a heap buffer.- Returns:
- The allocated
IoBuffer
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allocateNioBuffer
public ByteBuffer allocateNioBuffer(int capacity, boolean direct)
Returns the NIO buffer which is capable of the specified size.- Specified by:
allocateNioBuffer
in interfaceIoBufferAllocator
- Parameters:
capacity
- the capacity of the bufferdirect
- true to get a direct buffer, false to get a heap buffer.- Returns:
- The allocated
ByteBuffer
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wrap
public IoBuffer wrap(ByteBuffer nioBuffer)
Wraps the specified NIOByteBuffer
into MINA buffer.- Specified by:
wrap
in interfaceIoBufferAllocator
- Parameters:
nioBuffer
- TheByteBuffer
to wrap- Returns:
- The
IoBuffer
wrapping theByteBuffer
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dispose
public void dispose()
Dispose of this allocator.- Specified by:
dispose
in interfaceIoBufferAllocator
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