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Package org.apache.datasketches.memory

This package provides high performance primitive and primitive array access to off-heap memory and memory-mapped file resources, consistent views into ByteBuffer, and on-heap primitive arrays.

See: Description

Package org.apache.datasketches.memory Description

This package provides high performance primitive and primitive array access to off-heap memory and memory-mapped file resources, consistent views into ByteBuffer, and on-heap primitive arrays. It can be used as a more comprehensive and flexible replacement for ByteBuffer.

In addition, this package provides:

More specifically, this package provides access to four different types of resources using two different access APIs. These resources can be viewed as contiguous blobs of bytes that provide at least byte-level read and write access. The four resources are:

The two different access APIs are:

In addition, all combinations of access APIs and backing resources can be accessed via multibyte primitive methods (e.g., getLong(...), getLongArray(...), putLong(...), putLongArray(...)) as either ByteOrder.BIG_ENDIAN or ByteOrder.LITTLE_ENDIAN.

The resources don't know or care about the access APIs, and the access APIs don't really know or care what resource they are accessing.

An off-heap or memory-mapped file resource can also be explicitly closed by the user

     //Using try-with-resources block:
     try (WritableMemory wmem = WritableMemory.map(File file)) {
       doWork(wMem) // read and write to memory mapped file.
     }

     //Using explicit close():
     WritableMemory wmem = WritableMemory.map(File file);
     doWork(wMem) // read and write to memory mapped file.
     wmem.close();
 

Whatever thread of your process is responsible for allocating an off-heap or memory-mapped resource is responsible for closing it or making sure it gets closed. This is also true for the special memory-mapping methods load(), isLoaded() and force().

Moving back and forth between Memory and Buffer:

    Memory mem = ...
    Buffer buf = mem.asBuffer();
    ...
    Memory mem2 = buf.asMemory();
    ...
 

Hierarchical memory regions can be easily created:

     WritableMemory wMem = ...
     WritableMemory wReg = wMem.writableRegion(offset, length); //OR
     Memory region = wMem.region(offset, length);
 

All methods are checked for bounds violations.

The classes in this package are not thread-safe.

Author:
Lee Rhodes
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