com.persistit

Class Configuration.BufferPoolConfiguration

java.lang.Object

com.persistit.Configuration.BufferPoolConfiguration

Enclosing class:

Configuration

public static class Configuration.BufferPoolConfiguration
extends Object

Configuration constraints that determine the number of Buffers in a BufferPool. There is one permanent BufferPoolConfiguration instance for each valid buffer size: 1024, 2048, 4096, 8192 and 16384. The Configuration.getBufferPoolMap() method provides access to these, where the map key is the buffer size.

Each BufferPoolConfiguration specifies minimum and maximum buffer count values, and four parameters used to allocate a buffers according to available memory. Values of minimumCount and maximumCount are absolute bounds; if the maximumCount is zero then no buffers of the specified buffer size will be allocated.

The memory-based parameters are used as follows:

• Determine the maximum heap size by accessing the platform MemoryMXBean, which in turn supplies the value given by the +-Xmx+ JVM property.
• Subtract the value of reservedMemory size from the maximum heap size.
• Multiply the result by fraction.
• Adjust the result to fall between the boundaries specified by minimumMemory and maximumMemory.
• Determine the buffer count by dividing the result by the memory consumption per buffer
• Adjust the buffer count to fall between the boundaries specified by minimumCount and maximumCount.

These parameters may be set through the set and get methods, or by parsing a string property value using parseBufferCount(int, String, String) or parseBufferMemory(int, String, String)

Method Summary

Modifier and Type	Method and Description
int	computeBufferCount(long availableHeapMemory) Compute the buffer count determined by the constraints of this BufferPoolConfiguration given the supplied availableHeapMemory.
int	getBufferSize()
float	getFraction()
int	getMaximumCount()
long	getMaximumMemory()
int	getMinimumCount()
long	getMinimumMemory()
long	getReservedMemory()
void	parse(String string) Parse the String description generated by toString().
void	parseBufferCount(int bufferSize, String propertyName, String propertyValue) Parse the supplied property value as an integer-valued buffer count.
void	parseBufferMemory(int bufferSize, String propertyName, String propertyValue) Parse the supplied property value as a sequence of values to populate the minimumMemory maximumMemory, reservedMemory and fraction fields.
void	setCount(int count) Set the minimum and maximum buffer count.
void	setFraction(float fraction)
void	setMaximumCount(int maximumCount)
void	setMaximumMemory(long maximumMemory)
void	setMinimumCount(int minimumCount)
void	setMinimumMemory(long minimumMemory)
void	setReservedMemory(long reservedMemory)
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getBufferSize

public int getBufferSize()

Returns:

the bufferSize

getMinimumCount

public int getMinimumCount()

Returns:

the minimumCount

setMinimumCount

public void setMinimumCount(int minimumCount)

Parameters:

minimumCount - the minimumCount to set

getMaximumCount

public int getMaximumCount()

Returns:

the maximumCount

setMaximumCount

public void setMaximumCount(int maximumCount)

Parameters:

maximumCount - the maximumCount to set

setCount

public void setCount(int count)

Set the minimum and maximum buffer count.

Parameters:

count -

getMinimumMemory

public long getMinimumMemory()

Returns:

the minimumMemory

setMinimumMemory

public void setMinimumMemory(long minimumMemory)

Parameters:

minimumMemory - the minimumMemory to set

getMaximumMemory

public long getMaximumMemory()

Returns:

the maximumMemory

setMaximumMemory

public void setMaximumMemory(long maximumMemory)

Parameters:

maximumMemory - the maximumMemory to set

getReservedMemory

public long getReservedMemory()

Returns:

the reservedMemory

setReservedMemory

public void setReservedMemory(long reservedMemory)

Parameters:

reservedMemory - the reservedMemory to set

getFraction

public float getFraction()

Returns:

the fraction

setFraction

public void setFraction(float fraction)

Parameters:

fraction - the fraction to set

computeBufferCount

public int computeBufferCount(long availableHeapMemory)

Compute the buffer count determined by the constraints of this BufferPoolConfiguration given the supplied availableHeapMemory.

Parameters:

availableHeapMemory - available memory, in bytes

Returns:

number of Buffers to allocate

Throws:

IllegalArgumentException - if the allocation is infeasible

toString

public String toString()

Overrides:

toString in class Object

parse

public void parse(String string)

Parse the String description generated by toString(). The string format is

 bufferSize,propertyName=value,...
 

where propertyNames are count, minCount, maxCount, minMemory, maxMemory , reserved or fraction

parseBufferCount

public void parseBufferCount(int bufferSize,
                             String propertyName,
                             String propertyValue)

Parse the supplied property value as an integer-valued buffer count. Both minimumCount and maximumCount are set to this value. The supplied property value must be a valid integer or an integer followed by "K", "M" or "G" for 1024L, 1048576L, or 1073741824L as a multiplier.

Parameters:

bufferSize -

propertyName -

propertyValue -

Throws:

IllegalArgumentException - if the propertyValue is not in the form of a valid Integer

parseBufferMemory

public void parseBufferMemory(int bufferSize,
                              String propertyName,
                              String propertyValue)

Parse the supplied property value as a sequence of values to populate the minimumMemory maximumMemory, reservedMemory and fraction fields. These values are separated by commas, and the first three may be specified as blank for the default value, an integer, or an integer followed by by "K", "M" or "G" for 1024L, 1048576L, or 1073741824L as a multiplier.

For example, the property value

  64M,8G,128M,.75
 

reserves 128M from available memory and then allocates 75% of the remainder up to 8Gb, but not less than 64Mb.

Parameters:

bufferSize -

propertyName -

propertyValue -