Allocation Zones

Allocation zones determine where buffer memory is allocated and affect performance, IPC capabilities, and garbage collection behavior.

Overview

import com.ditchoom.buffer.AllocationZone

val buffer = PlatformBuffer.allocate(
    size = 1024,
    zone = AllocationZone.Direct  // Choose your zone
)

Zone Types

AllocationZone.Heap

Memory allocated on the JVM heap (or equivalent on other platforms).

val buffer = PlatformBuffer.allocate(1024, AllocationZone.Heap)

Characteristics:

• Managed by garbage collector
• May require copying for native I/O operations
• Good for short-lived, small buffers

Platform behavior:

Platform	Implementation
JVM	HeapByteBuffer
Android	HeapByteBuffer
WASM	ByteArrayBuffer
Others	ByteArrayBuffer

AllocationZone.Direct

Memory allocated outside the JVM heap (off-heap).

val buffer = PlatformBuffer.allocate(1024, AllocationZone.Direct)

Characteristics:

• Not managed by garbage collector
• Zero-copy I/O with native code
• Best for network I/O and file operations
• Default allocation zone

Platform behavior:

Platform	Implementation
JVM	DirectByteBuffer
Android	DirectByteBuffer
iOS/macOS	NSMutableData
JavaScript	Int8Array
WASM	LinearBuffer (native WASM memory)
Linux	ByteArrayBuffer

AllocationZone.SharedMemory

Memory that can be shared across process boundaries.

val buffer = PlatformBuffer.allocate(1024, AllocationZone.SharedMemory)

Characteristics:

• Enables zero-copy IPC (Inter-Process Communication)
• Platform-specific availability
• Useful for Android services and multi-process apps

Platform behavior:

Platform	Implementation
Android (API 27+)	SharedMemory
Android (< API 27)	Falls back to DirectByteBuffer
JavaScript	SharedArrayBuffer (requires CORS headers)
WASM	LinearBuffer (falls back to Direct)
Others	Falls back to Direct

Platform-Specific Notes

Android SharedMemory

All JvmBuffers are Parcelable. For zero-copy IPC:

// In your Service or ContentProvider
val buffer = PlatformBuffer.allocate(1024, AllocationZone.SharedMemory)
buffer.writeBytes(data)

// Pass through Binder
parcel.writeParcelable(buffer as Parcelable, 0)

JavaScript SharedArrayBuffer

Requires CORS headers. Add to webpack.config.d/:

if (config.devServer != null) {
    config.devServer.headers = {
        "Cross-Origin-Opener-Policy": "same-origin",
        "Cross-Origin-Embedder-Policy": "require-corp"
    }
}

Without proper headers, falls back to regular ArrayBuffer.

Choosing a Zone

Use Case	Recommended Zone
Network I/O	Direct
File I/O	Direct
Short-lived parsing	Heap or pool from Direct
Android IPC	SharedMemory
Multi-threaded JS	SharedMemory
General purpose	Direct (default)