blob: 411515f3c789f7250080271dd449ed9bc2c432c0 [file] [log] [blame]
/*
* Copyright 2020-present Open Networking Foundation
* 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 transientstate
import (
"context"
"fmt"
"sync"
"github.com/opencord/voltha-go/db/model"
"github.com/opencord/voltha-lib-go/v4/pkg/log"
"github.com/opencord/voltha-protos/v4/go/voltha"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
)
// Loader hides all low-level locking & synchronization related to device transient state updates
type Loader struct {
dbProxy *model.Proxy
// this lock protects the device transient state
lock sync.RWMutex
deviceTransientState *data
}
type data struct {
transientState voltha.DeviceTransientState_Types
deviceID string
}
func NewLoader(dbProxy *model.Proxy, deviceID string) *Loader {
return &Loader{
dbProxy: dbProxy,
deviceTransientState: &data{
transientState: voltha.DeviceTransientState_NONE,
deviceID: deviceID,
},
}
}
// Load queries existing transient state from the kv,
// and should only be called once when first created.
func (loader *Loader) Load(ctx context.Context) {
loader.lock.Lock()
defer loader.lock.Unlock()
var deviceTransientState voltha.DeviceTransientState
have, err := loader.dbProxy.Get(ctx, loader.deviceTransientState.deviceID, &deviceTransientState)
if err != nil {
logger.Errorw(ctx, "failed-to-get-device-transient-state-from-cluster-data-proxy", log.Fields{"error": err})
return
}
if have {
loader.deviceTransientState.transientState = deviceTransientState.TransientState
return
}
loader.deviceTransientState.transientState = voltha.DeviceTransientState_NONE
}
// Lock acquires the lock for deviceTransientStateLoader, and returns a handle
// which can be used to access it until it's unlocked.
// This handle ensures that the deviceTransientState cannot be accessed if the lock is not held.
// TODO: consider accepting a ctx and aborting the lock attempt on cancellation
func (loader *Loader) Lock() *Handle {
loader.lock.Lock()
dataTransientState := loader.deviceTransientState
return &Handle{loader: loader, data: dataTransientState}
}
// Handle is allocated for each Lock() call, all modifications are made using it, and it is invalidated by Unlock()
// This enforces correct Lock()-Usage()-Unlock() ordering.
type Handle struct {
loader *Loader
data *data
}
// GetReadOnly returns device transient which MUST NOT be modified externally, but which is safe to keep indefinitely
func (h *Handle) GetReadOnly() voltha.DeviceTransientState_Types {
return h.data.transientState
}
// Update updates device transient state in KV store
// The provided device transient state must not be modified afterwards.
func (h *Handle) Update(ctx context.Context, state voltha.DeviceTransientState_Types) error {
var tState voltha.DeviceTransientState
tState.TransientState = state
if err := h.loader.dbProxy.Set(ctx, fmt.Sprint(h.data.deviceID), &tState); err != nil {
return status.Errorf(codes.Internal, "failed-to-update-device-%v-transient-state: %s", h.data.deviceID, err)
}
h.data.transientState = state
return nil
}
// Delete deletes device transient state from KV store
func (h *Handle) Delete(ctx context.Context) error {
if err := h.loader.dbProxy.Remove(ctx, fmt.Sprint(h.data.deviceID)); err != nil {
return status.Errorf(codes.Internal, "failed-to-delete-device-%v-transient-state: %s", h.data.deviceID, err)
}
return nil
}
// UnLock releases the lock on the device transient state.
func (h *Handle) UnLock() {
defer h.loader.lock.Unlock()
h.data = nil
}