history_collector.go

/*
Copyright (c) 2024-2024 VMware, Inc. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package simulator

import (
	"container/list"
	"sync"

	"github.com/vmware/govmomi/vim25/methods"
	"github.com/vmware/govmomi/vim25/mo"
	"github.com/vmware/govmomi/vim25/soap"
	"github.com/vmware/govmomi/vim25/types"
)

var (
	maxPageSize           = 1000
	maxCollectors   int32 = 32 // the VC default limit
	defaultPageSize       = 10

	errInvalidArgMaxCount = &types.InvalidArgument{InvalidProperty: "maxCount"}
)

type HistoryCollector struct {
	parent *history
	root   types.ManagedObjectReference
	size   int

	fill func(*Context)
	page *list.List
	pos  *list.Element
}

type history struct {
	sync.Mutex

	page       *list.List
	collectors map[types.ManagedObjectReference]mo.Reference
}

func newHistory() *history {
	return &history{
		page:       list.New(),
		collectors: make(map[types.ManagedObjectReference]mo.Reference),
	}
}

func (c *history) add(ctx *Context, collector mo.Reference) types.ManagedObjectReference {
	ref := ctx.Session.Put(collector).Reference()

	c.Lock()
	c.collectors[ref] = collector
	c.Unlock()

	return ref
}

func (c *history) remove(ctx *Context, ref types.ManagedObjectReference) {
	ctx.Session.Remove(ctx, ref)

	c.Lock()
	delete(c.collectors, ref)
	c.Unlock()
}

func newHistoryCollector(ctx *Context, h *history, size int) *HistoryCollector {
	return &HistoryCollector{
		parent: h,
		root:   ctx.Map.content().RootFolder,
		size:   size,
		page:   list.New(),
	}
}

func (c *HistoryCollector) SetCollectorPageSize(ctx *Context, req *types.SetCollectorPageSize) soap.HasFault {
	body := new(methods.SetCollectorPageSizeBody)
	size, err := validatePageSize(req.MaxCount)
	if err != nil {
		body.Fault_ = err
		return body
	}

	c.size = size
	c.page = list.New()
	c.fill(ctx)

	body.Res = new(types.SetCollectorPageSizeResponse)
	return body
}

func (c *HistoryCollector) ResetCollector(ctx *Context, req *types.ResetCollector) soap.HasFault {
	c.pos = c.page.Back()

	return &methods.ResetCollectorBody{
		Res: new(types.ResetCollectorResponse),
	}
}

func (c *HistoryCollector) RewindCollector(ctx *Context, req *types.RewindCollector) soap.HasFault {
	c.pos = c.page.Front()

	return &methods.RewindCollectorBody{
		Res: new(types.RewindCollectorResponse),
	}
}

func (c *HistoryCollector) DestroyCollector(ctx *Context, req *types.DestroyCollector) soap.HasFault {
	ctx.Session.Remove(ctx, req.This)

	c.parent.remove(ctx, req.This)

	return &methods.DestroyCollectorBody{
		Res: new(types.DestroyCollectorResponse),
	}
}

func (c *HistoryCollector) read(max int32, next func() *list.Element, take func(*list.Element)) {
	for i := 0; i < int(max); i++ {
		e := next()
		if e == nil {
			break
		}

		take(e)
		c.pos = e
	}
}

func (c *HistoryCollector) next(max int32, take func(*list.Element)) {
	next := func() *list.Element {
		if c.pos != nil {
			return c.pos.Next()
		}
		return c.page.Front()
	}

	c.read(max, next, take)
}

func (c *HistoryCollector) prev(max int32, take func(*list.Element)) {
	next := func() *list.Element {
		if c.pos != nil {
			return c.pos.Prev()
		}
		return c.page.Back()
	}

	c.read(max, next, take)
}

func pushHistory(l *list.List, item types.AnyType) {
	if l.Len() > maxPageSize {
		l.Remove(l.Front()) // Prune history
	}
	l.PushBack(item)
}

func validatePageSize(count int32) (int, *soap.Fault) {
	size := int(count)

	if size == 0 {
		size = defaultPageSize
	} else if size < 0 || size > maxPageSize {
		return -1, Fault("", errInvalidArgMaxCount)
	}

	return size, nil
}