alef 0.83.1

// Auto-generated by alef — DO NOT EDIT
#nullable enable

namespace {{ namespace }} {

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;

/// <summary>
/// Service wrapper for {{ service_name }}.
/// </summary>
internal sealed class {{ class_name }}SafeHandle : SafeHandle {
    private ulong _nativeHandle;

    internal {{ class_name }}SafeHandle(ulong handle) : base(IntPtr.Zero, true) {
        _nativeHandle = handle;
        SetHandle(handle == 0 ? IntPtr.Zero : new IntPtr(1));
    }

    public override bool IsInvalid => _nativeHandle == 0;
    internal ulong AlefHandle => _nativeHandle;

    protected override bool ReleaseHandle() {
        NativeMethods.{{ native_free }}(_nativeHandle);
        _nativeHandle = 0;
        SetHandle(IntPtr.Zero);
        return true;
    }
}

public class {{ class_name }} : IDisposable {

    private {{ class_name }}SafeHandle _safeHandle;
    private readonly object _ownerLock = new();
    private int _activeOwnerBorrows;
    private bool _ownerUnavailable;
    private bool _ownerTransferPending;
    private readonly Dictionary<IntPtr, GCHandle> _registeredCallbacks = new();
    // A single static delegate instance bridges the native callback. Held in a static field so the
    // marshalled function pointer outlives every registration (a transient delegate would be collected).
    private static readonly NativeMethods.HandlerCallback _handlerCallback = HandlerTrampoline;
    private static readonly NativeMethods.HandlerResponseFree _handlerResponseFree = FreeHandlerResponse;

{% if needs_error_resolver %}    private static Exception ResolveLastError() {
        var code = NativeMethods.LastErrorCode();
        var context = NativeMethods.LastErrorContext();
        var message = Marshal.PtrToStringUTF8(context) ?? "Unknown native error";
        return new {{ exception_name }}(code, message);
    }
{% endif %}

    private sealed class OwnerHandleLease : IDisposable {
        private {{ class_name }}? _owner;

        internal OwnerHandleLease({{ class_name }} owner) {
            _owner = owner;
            Handle = owner._safeHandle.AlefHandle;
        }

        internal ulong Handle { get; }

        public void Dispose() {
            var owner = global::System.Threading.Interlocked.Exchange(ref _owner, null);
            owner?.ReleaseOwnerBorrow();
        }
    }

    private sealed class OwnerHandleTransfer : IDisposable {
        private {{ class_name }}? _owner;
        private {{ class_name }}SafeHandle? _transferredHandle;

        internal OwnerHandleTransfer({{ class_name }} owner, ulong handle) {
            _owner = owner;
            _transferredHandle = new {{ class_name }}SafeHandle(handle);
        }

        internal ulong Handle => _transferredHandle?.AlefHandle
            ?? throw new InvalidOperationException("Service owner transfer is no longer active");

        internal void Commit() {
            var transferred = _transferredHandle
                ?? throw new InvalidOperationException("Service owner transfer is no longer active");
            transferred.SetHandleAsInvalid();
            _transferredHandle = null;
            var owner = _owner;
            _owner = null;
            owner?.CommitOwnerTransfer();
        }

        public void Dispose() {
            var transferred = global::System.Threading.Interlocked.Exchange(ref _transferredHandle, null);
            var owner = global::System.Threading.Interlocked.Exchange(ref _owner, null);
            if (transferred is null) return;
            if (owner is null) {
                transferred.Dispose();
                return;
            }
            var handle = transferred.AlefHandle;
            transferred.SetHandleAsInvalid();
            owner.RollbackOwnerTransfer(handle);
        }
    }

    private OwnerHandleLease BorrowOwnerHandle() {
        lock (_ownerLock) {
            ThrowIfOwnerUnavailable();
            var lease = new OwnerHandleLease(this);
            var added = false;
            _safeHandle.DangerousAddRef(ref added);
            if (!added) throw new ObjectDisposedException(nameof({{ class_name }}));
            _activeOwnerBorrows++;
            return lease;
        }
    }

    private void ReleaseOwnerBorrow() {
        lock (_ownerLock) {
            _safeHandle.DangerousRelease();
            _activeOwnerBorrows--;
            if (_activeOwnerBorrows == 0) global::System.Threading.Monitor.PulseAll(_ownerLock);
        }
    }

    private OwnerHandleTransfer TakeOwnerHandle() {
        lock (_ownerLock) {
            ThrowIfOwnerUnavailable();
            WaitForOwnerBorrows();
            var transfer = new OwnerHandleTransfer(this, _safeHandle.AlefHandle);
            _ownerUnavailable = true;
            _safeHandle.SetHandleAsInvalid();
            _ownerTransferPending = true;
            return transfer;
        }
    }

    private void RollbackOwnerTransfer(ulong handle) {
        lock (_ownerLock) {
            _safeHandle = new {{ class_name }}SafeHandle(handle);
            _ownerTransferPending = false;
            _ownerUnavailable = false;
            global::System.Threading.Monitor.PulseAll(_ownerLock);
        }
    }

    private void CommitOwnerTransfer() {
        lock (_ownerLock) {
            _ownerTransferPending = false;
            global::System.Threading.Monitor.PulseAll(_ownerLock);
        }
    }

    private void WaitForOwnerBorrows() {
        var interrupted = false;
        while (_activeOwnerBorrows != 0) {
            try { global::System.Threading.Monitor.Wait(_ownerLock); }
            catch (global::System.Threading.ThreadInterruptedException) { interrupted = true; }
        }
        if (interrupted) global::System.Threading.Thread.CurrentThread.Interrupt();
    }

    private void WaitForOwnerTransfer() {
        var interrupted = false;
        while (_ownerTransferPending) {
            try { global::System.Threading.Monitor.Wait(_ownerLock); }
            catch (global::System.Threading.ThreadInterruptedException) { interrupted = true; }
        }
        if (interrupted) global::System.Threading.Thread.CurrentThread.Interrupt();
    }

    private void ThrowIfOwnerUnavailable() {
        if (_ownerUnavailable || _safeHandle.IsClosed || _safeHandle.IsInvalid) {
            throw new ObjectDisposedException(nameof({{ class_name }}));
        }
    }