github.com/cloudbase/juju-core@v0.0.0-20140504232958-a7271ac7912f/state/apiserver/common/remove.go (about)

     1  // Copyright 2013 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package common
     5  
     6  import (
     7  	"fmt"
     8  
     9  	"launchpad.net/juju-core/state"
    10  	"launchpad.net/juju-core/state/api/params"
    11  )
    12  
    13  // Remover implements a common Remove method for use by various facades.
    14  type Remover struct {
    15  	st             state.EntityFinder
    16  	callEnsureDead bool
    17  	getCanModify   GetAuthFunc
    18  }
    19  
    20  // NewRemover returns a new Remover. The callEnsureDead flag specifies
    21  // whether EnsureDead should be called on an entity before
    22  // removing. The GetAuthFunc will be used on each invocation of Remove
    23  // to determine current permissions.
    24  func NewRemover(st state.EntityFinder, callEnsureDead bool, getCanModify GetAuthFunc) *Remover {
    25  	return &Remover{
    26  		st:             st,
    27  		callEnsureDead: callEnsureDead,
    28  		getCanModify:   getCanModify,
    29  	}
    30  }
    31  
    32  func (r *Remover) removeEntity(tag string) error {
    33  	entity, err := r.st.FindEntity(tag)
    34  	if err != nil {
    35  		return err
    36  	}
    37  	remover, ok := entity.(interface {
    38  		state.Lifer
    39  		state.Remover
    40  		state.EnsureDeader
    41  	})
    42  	if !ok {
    43  		return NotSupportedError(tag, "removal")
    44  	}
    45  	// Only remove entites that are not Alive.
    46  	if life := remover.Life(); life == state.Alive {
    47  		return fmt.Errorf("cannot remove entity %q: still alive", tag)
    48  	}
    49  	if r.callEnsureDead {
    50  		if err := remover.EnsureDead(); err != nil {
    51  			return err
    52  		}
    53  	}
    54  	return remover.Remove()
    55  }
    56  
    57  // Remove removes every given entity from state, calling EnsureDead
    58  // first, then Remove. It will fail if the entity is not present.
    59  func (r *Remover) Remove(args params.Entities) (params.ErrorResults, error) {
    60  	result := params.ErrorResults{
    61  		Results: make([]params.ErrorResult, len(args.Entities)),
    62  	}
    63  	if len(args.Entities) == 0 {
    64  		return result, nil
    65  	}
    66  	canModify, err := r.getCanModify()
    67  	if err != nil {
    68  		return params.ErrorResults{}, err
    69  	}
    70  	for i, entity := range args.Entities {
    71  		err := ErrPerm
    72  		if canModify(entity.Tag) {
    73  			err = r.removeEntity(entity.Tag)
    74  		}
    75  		result.Results[i].Error = ServerError(err)
    76  	}
    77  	return result, nil
    78  }