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Direct memory for file reading.

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This commit is contained in:
Alexander Nozik 2019-12-11 15:06:18 +03:00
parent 2d71452341
commit 74653e74c6
1 changed files with 14 additions and 1 deletions
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15
kmath-memory/src/jvmMain/kotlin/scientifik/memory/ByteBufferMemory.kt
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@ -1,6 +1,10 @@
package scientifik.memory
import java.nio.ByteBuffer
import java.nio.channels.FileChannel
import java.nio.file.Files
import java.nio.file.Path
import java.nio.file.StandardOpenOption
/**
@ -11,7 +15,7 @@ actual fun Memory.Companion.allocate(length: Int): Memory {
return ByteBufferMemory(buffer)
}
class ByteBufferMemory(
private class ByteBufferMemory(
val buffer: ByteBuffer,
val startOffset: Int = 0,
override val size: Int = buffer.limit()
@ -91,3 +95,12 @@ class ByteBufferMemory(
override fun writer(): MemoryWriter = writer
}
/**
* Use direct memory-mapped buffer from file to read something and close it afterwards.
*/
fun <R> Path.readAsMemory(position: Long = 0, size: Long = Files.size(this), block: Memory.() -> R): R {
return FileChannel.open(this, StandardOpenOption.READ).use {
ByteBufferMemory(it.map(FileChannel.MapMode.READ_ONLY, position, size)).block()
}
}