## org.das2.util.filesystem.ExpensiveOpCache

This simply reduces invocations of an expensive operation by caching the result for a given number of milliseconds. This was introduced to remove the number of HEAD requests to the server for a given file.

## ExpensiveOpCache( org.das2.util.filesystem.ExpensiveOpCache.Op op, int limitMs )

Cache the result of op for no more than limitMs milliseconds.

## doOp

doOp( String key ) → Object

Do the operation if it has not been done, or if it has not been done recently.

### Parameters

key - a String

### Returns:

the result of the operation
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## reset

reset( ) → void

### Returns:

void (returns nothing)
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