xenadmin/XenModel/Actions/VM/VMSnapshotRevertAction.cs

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using System;
using XenAPI;


namespace XenAdmin.Actions
{
    public class VMSnapshotRevertAction : AsyncAction
    {
        private readonly VM m_Snapshot;
        private readonly Host previousHost; // The host the VM was running on before the snapshot
        private bool _finished;
        private readonly bool _revertPowerState;

        public VMSnapshotRevertAction(VM snapshot)
            : base(snapshot.Connection, string.Format(Messages.ACTION_VM_REVERT_SNAPSHOT_TITLE, snapshot.Name()))
        {
            VM = Connection.Resolve(snapshot.snapshot_of);
            previousHost = Connection.Resolve(VM.resident_on);
            m_Snapshot = snapshot;
            Description = string.Format(Messages.VM_REVERTING, m_Snapshot.Name());

            if (snapshot.snapshot_info.TryGetValue("power-state-at-snapshot", out var state) &&
                state == vm_power_state.Running.ToString())
                _revertPowerState = true;

            ApiMethodsToRoleCheck.Add("VM.async_revert");

            if (_revertPowerState)
            {
                if (VM.power_state == vm_power_state.Halted)
                {
                    if (previousHost == null)
                        ApiMethodsToRoleCheck.Add("VM.async_start");
                    else
                        ApiMethodsToRoleCheck.AddRange("VM.assert_can_boot_here", "VM.async_start_on");
                }
                else if (VM.power_state == vm_power_state.Suspended)
                {
                    if (previousHost == null)
                        ApiMethodsToRoleCheck.Add("VM.async_resume");
                    else
                        ApiMethodsToRoleCheck.AddRange("VM.assert_can_boot_here", "VM.async_resume_on");
                }
            }
        }

        protected override void Run()
        {
            Description = string.Format(Messages.VM_REVERTING, m_Snapshot.Name());
            RelatedTask = VM.async_revert(Session, m_Snapshot.opaque_ref);
            PollToCompletion();
            _finished = true;
            Tick(90, string.Format(Messages.REVERTING_POWER_STATE, VM.Name()));

            try
            {
                if (_revertPowerState)
                    RevertPowerState(VM);
            }
            catch (Exception)
            {
                // ignored
            }

            Tick(100, string.Format(Messages.VM_REVERTED, m_Snapshot.Name()));
        }

        public override int PercentComplete
        {
            get
            {
                return base.PercentComplete;
            }
            set
            {
                if ((value < 90 && !_finished) || (value >= 90 && _finished))
                    base.PercentComplete = value;
            }
        }

        private void RevertPowerState(VM vm)
        {
            if (vm.power_state == vm_power_state.Halted)
            {
                if (previousHost != null && VMCanBootOnHost(vm, previousHost))
                {
                    RelatedTask = VM.async_start_on(Session, vm.opaque_ref, previousHost.opaque_ref, false, false);
                }
                else
                {
                    RelatedTask = VM.async_start(Session, vm.opaque_ref, false, false);
                }
            }
            else if (vm.power_state == vm_power_state.Suspended)
            {
                if (previousHost != null && VMCanBootOnHost(vm, previousHost))
                {
                    RelatedTask = VM.async_resume_on(Session, vm.opaque_ref, previousHost.opaque_ref, false, false);
                }
                else
                {
                    RelatedTask = VM.async_resume(Session, vm.opaque_ref, false, false);
                }
            }
            PollToCompletion();
        }

        private bool VMCanBootOnHost(VM vm, Host host)
        {
            try
            {
                VM.assert_can_boot_here(Session, vm.opaque_ref, host.opaque_ref);
            }
            catch
            {
                return false;
            }

            return true;
        }
    }
}