db/model/proxy.go - voltha-go - Gitiles

 /*
  * Copyright 2018-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 model

 import (
 	"context"
 	"crypto/md5"
 	"errors"
 	"fmt"
 	"reflect"
 	"runtime"
 	"strings"
 	"sync"

 	"github.com/opencord/voltha-lib-go/v3/pkg/log"
 )

 // OperationContext holds details on the information used during an operation
 type OperationContext struct {
 	Path      string
 	Data      interface{}
 	FieldName string
 	ChildKey  string
 }

 // NewOperationContext instantiates a new OperationContext structure
 func NewOperationContext(path string, data interface{}, fieldName string, childKey string) *OperationContext {
 	oc := &OperationContext{
 		Path:      path,
 		Data:      data,
 		FieldName: fieldName,
 		ChildKey:  childKey,
 	}
 	return oc
 }

 // Update applies new data to the context structure
 func (oc *OperationContext) Update(data interface{}) *OperationContext {
 	oc.Data = data
 	return oc
 }

 // Proxy holds the information for a specific location with the data model
 type Proxy struct {
 	mutex      sync.RWMutex
 	Root       *root
 	Node       *node
 	ParentNode *node
 	Path       string
 	FullPath   string
 	Exclusive  bool
 	Callbacks  map[CallbackType]map[string]*CallbackTuple
 	operation  ProxyOperation
 }

 // NewProxy instantiates a new proxy to a specific location
 func NewProxy(root *root, node *node, parentNode *node, path string, fullPath string, exclusive bool) *Proxy {
 	callbacks := make(map[CallbackType]map[string]*CallbackTuple)
 	if fullPath == "/" {
 		fullPath = ""
 	}
 	p := &Proxy{
 		Root:       root,
 		Node:       node,
 		ParentNode: parentNode,
 		Exclusive:  exclusive,
 		Path:       path,
 		FullPath:   fullPath,
 		Callbacks:  callbacks,
 	}
 	return p
 }

 // getRoot returns the root attribute of the proxy
 func (p *Proxy) getRoot() *root {
 	return p.Root
 }

 // getPath returns the path attribute of the proxy
 func (p *Proxy) getPath() string {
 	return p.Path
 }

 // getFullPath returns the full path attribute of the proxy
 func (p *Proxy) getFullPath() string {
 	return p.FullPath
 }

 // getCallbacks returns the full list of callbacks associated to the proxy
 func (p *Proxy) getCallbacks(callbackType CallbackType) map[string]*CallbackTuple {
 	p.mutex.RLock()
 	defer p.mutex.RUnlock()

 	if p != nil {
 		if cb, exists := p.Callbacks[callbackType]; exists {
 			return cb
 		}
 	} else {
 		logger.Debugw("proxy-is-nil", log.Fields{"callback-type": callbackType.String()})
 	}
 	return nil
 }

 // getCallback returns a specific callback matching the type and function hash
 func (p *Proxy) getCallback(callbackType CallbackType, funcHash string) *CallbackTuple {
 	p.mutex.Lock()
 	defer p.mutex.Unlock()
 	if tuple, exists := p.Callbacks[callbackType][funcHash]; exists {
 		return tuple
 	}
 	return nil
 }

 // setCallbacks applies a callbacks list to a type
 func (p *Proxy) setCallbacks(callbackType CallbackType, callbacks map[string]*CallbackTuple) {
 	p.mutex.Lock()
 	defer p.mutex.Unlock()
 	p.Callbacks[callbackType] = callbacks
 }

 // setCallback applies a callback to a type and hash value
 func (p *Proxy) setCallback(callbackType CallbackType, funcHash string, tuple *CallbackTuple) {
 	p.mutex.Lock()
 	defer p.mutex.Unlock()
 	p.Callbacks[callbackType][funcHash] = tuple
 }

 // DeleteCallback removes a callback matching the type and hash
 func (p *Proxy) DeleteCallback(callbackType CallbackType, funcHash string) {
 	p.mutex.Lock()
 	defer p.mutex.Unlock()
 	delete(p.Callbacks[callbackType], funcHash)
 }

 // ProxyOperation callbackType is an enumerated value to express when a callback should be executed
 type ProxyOperation uint8

 // Enumerated list of callback types
 const (
 	ProxyNone ProxyOperation = iota
 	ProxyGet
 	ProxyList
 	ProxyAdd
 	ProxyUpdate
 	ProxyRemove
 	ProxyCreate
 	ProxyWatch
 )

 var proxyOperationTypes = []string{
 	"PROXY_NONE",
 	"PROXY_GET",
 	"PROXY_LIST",
 	"PROXY_ADD",
 	"PROXY_UPDATE",
 	"PROXY_REMOVE",
 	"PROXY_CREATE",
 	"PROXY_WATCH",
 }

 func (t ProxyOperation) String() string {
 	return proxyOperationTypes[t]
 }

 // GetOperation -
 func (p *Proxy) GetOperation() ProxyOperation {
 	p.mutex.RLock()
 	defer p.mutex.RUnlock()
 	return p.operation
 }

 // SetOperation -
 func (p *Proxy) SetOperation(operation ProxyOperation) {
 	p.mutex.Lock()
 	defer p.mutex.Unlock()
 	p.operation = operation
 }

 // List will retrieve information from the data model at the specified path location
 // A list operation will force access to persistence storage
 func (p *Proxy) List(ctx context.Context, path string, depth int, deep bool, txid string) (interface{}, error) {
 	var effectivePath string
 	if path == "/" {
 		effectivePath = p.getFullPath()
 	} else {
 		effectivePath = p.getFullPath() + path
 	}

 	p.SetOperation(ProxyList)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-list", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"operation": p.GetOperation(),
 	})
 	return p.getRoot().List(ctx, path, "", depth, deep, txid)
 }

 // Get will retrieve information from the data model at the specified path location
 func (p *Proxy) Get(ctx context.Context, path string, depth int, deep bool, txid string) (interface{}, error) {
 	var effectivePath string
 	if path == "/" {
 		effectivePath = p.getFullPath()
 	} else {
 		effectivePath = p.getFullPath() + path
 	}

 	p.SetOperation(ProxyGet)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-get", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"operation": p.GetOperation(),
 	})

 	return p.getRoot().Get(ctx, path, "", depth, deep, txid)
 }

 // Update will modify information in the data model at the specified location with the provided data
 func (p *Proxy) Update(ctx context.Context, path string, data interface{}, strict bool, txid string) (interface{}, error) {
 	if !strings.HasPrefix(path, "/") {
 		logger.Errorf("invalid path: %s", path)
 		return nil, fmt.Errorf("invalid path: %s", path)
 	}
 	var fullPath string
 	var effectivePath string
 	if path == "/" {
 		fullPath = p.getPath()
 		effectivePath = p.getFullPath()
 	} else {
 		fullPath = p.getPath() + path
 		effectivePath = p.getFullPath() + path
 	}

 	p.SetOperation(ProxyUpdate)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-update", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"full":      fullPath,
 		"operation": p.GetOperation(),
 	})

 	result := p.getRoot().Update(ctx, fullPath, data, strict, txid, nil)

 	if result != nil {
 		return result.GetData(), nil
 	}

 	return nil, nil
 }

 // AddWithID will insert new data at specified location.
 // This method also allows the user to specify the ID of the data entry to ensure
 // that access control is active while inserting the information.
 func (p *Proxy) AddWithID(ctx context.Context, path string, id string, data interface{}, txid string) (interface{}, error) {
 	if !strings.HasPrefix(path, "/") {
 		logger.Errorf("invalid path: %s", path)
 		return nil, fmt.Errorf("invalid path: %s", path)
 	}
 	var fullPath string
 	var effectivePath string
 	if path == "/" {
 		fullPath = p.getPath()
 		effectivePath = p.getFullPath()
 	} else {
 		fullPath = p.getPath() + path
 		effectivePath = p.getFullPath() + path + "/" + id
 	}

 	p.SetOperation(ProxyAdd)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-add-with-id", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"full":      fullPath,
 		"operation": p.GetOperation(),
 	})

 	result := p.getRoot().Add(ctx, fullPath, data, txid, nil)

 	if result != nil {
 		return result.GetData(), nil
 	}

 	return nil, nil
 }

 // Add will insert new data at specified location.
 func (p *Proxy) Add(ctx context.Context, path string, data interface{}, txid string) (interface{}, error) {
 	if !strings.HasPrefix(path, "/") {
 		logger.Errorf("invalid path: %s", path)
 		return nil, fmt.Errorf("invalid path: %s", path)
 	}
 	var fullPath string
 	var effectivePath string
 	if path == "/" {
 		fullPath = p.getPath()
 		effectivePath = p.getFullPath()
 	} else {
 		fullPath = p.getPath() + path
 		effectivePath = p.getFullPath() + path
 	}

 	p.SetOperation(ProxyAdd)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-add", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"full":      fullPath,
 		"operation": p.GetOperation(),
 	})

 	result := p.getRoot().Add(ctx, fullPath, data, txid, nil)

 	if result != nil {
 		return result.GetData(), nil
 	}

 	return nil, nil
 }

 // Remove will delete an entry at the specified location
 func (p *Proxy) Remove(ctx context.Context, path string, txid string) (interface{}, error) {
 	if !strings.HasPrefix(path, "/") {
 		logger.Errorf("invalid path: %s", path)
 		return nil, fmt.Errorf("invalid path: %s", path)
 	}
 	var fullPath string
 	var effectivePath string
 	if path == "/" {
 		fullPath = p.getPath()
 		effectivePath = p.getFullPath()
 	} else {
 		fullPath = p.getPath() + path
 		effectivePath = p.getFullPath() + path
 	}

 	p.SetOperation(ProxyRemove)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-remove", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"full":      fullPath,
 		"operation": p.GetOperation(),
 	})

 	result := p.getRoot().Remove(ctx, fullPath, txid, nil)

 	if result != nil {
 		return result.GetData(), nil
 	}

 	return nil, nil
 }

 // CreateProxy to interact with specific path directly
 func (p *Proxy) CreateProxy(ctx context.Context, path string, exclusive bool) (*Proxy, error) {
 	if !strings.HasPrefix(path, "/") {
 		logger.Errorf("invalid path: %s", path)
 		return nil, fmt.Errorf("invalid path: %s", path)
 	}

 	var fullPath string
 	var effectivePath string
 	if path == "/" {
 		fullPath = p.getPath()
 		effectivePath = p.getFullPath()
 	} else {
 		fullPath = p.getPath() + path
 		effectivePath = p.getFullPath() + path
 	}

 	p.SetOperation(ProxyCreate)
 	defer p.SetOperation(ProxyNone)

 	logger.Debugw("proxy-create", log.Fields{
 		"path":      path,
 		"effective": effectivePath,
 		"full":      fullPath,
 		"operation": p.GetOperation(),
 	})

 	return p.getRoot().CreateProxy(ctx, fullPath, exclusive)
 }

 // OpenTransaction creates a new transaction branch to isolate operations made to the data model
 func (p *Proxy) OpenTransaction() *Transaction {
 	txid := p.getRoot().MakeTxBranch()
 	return NewTransaction(p, txid)
 }

 // commitTransaction will apply and merge modifications made in the transaction branch to the data model
 func (p *Proxy) commitTransaction(ctx context.Context, txid string) {
 	p.getRoot().FoldTxBranch(ctx, txid)
 }

 // cancelTransaction will terminate a transaction branch along will all changes within it
 func (p *Proxy) cancelTransaction(txid string) {
 	p.getRoot().DeleteTxBranch(txid)
 }

 // CallbackFunction is a type used to define callback functions
 type CallbackFunction func(ctx context.Context, args ...interface{}) interface{}

 // CallbackTuple holds the function and arguments details of a callback
 type CallbackTuple struct {
 	callback CallbackFunction
 	args     []interface{}
 }

 // Execute will process the a callback with its provided arguments
 func (tuple *CallbackTuple) Execute(ctx context.Context, contextArgs []interface{}) interface{} {
 	args := []interface{}{}

 	args = append(args, tuple.args...)

 	args = append(args, contextArgs...)

 	return tuple.callback(ctx, args...)
 }

 // RegisterCallback associates a callback to the proxy
 func (p *Proxy) RegisterCallback(callbackType CallbackType, callback CallbackFunction, args ...interface{}) {
 	if p.getCallbacks(callbackType) == nil {
 		p.setCallbacks(callbackType, make(map[string]*CallbackTuple))
 	}
 	funcName := runtime.FuncForPC(reflect.ValueOf(callback).Pointer()).Name()
 	logger.Debugf("value of function: %s", funcName)
 	funcHash := fmt.Sprintf("%x", md5.Sum([]byte(funcName)))[:12]

 	p.setCallback(callbackType, funcHash, &CallbackTuple{callback, args})
 }

 // UnregisterCallback removes references to a callback within a proxy
 func (p *Proxy) UnregisterCallback(callbackType CallbackType, callback CallbackFunction, args ...interface{}) {
 	if p.getCallbacks(callbackType) == nil {
 		logger.Errorf("no such callback type - %s", callbackType.String())
 		return
 	}

 	funcName := runtime.FuncForPC(reflect.ValueOf(callback).Pointer()).Name()
 	funcHash := fmt.Sprintf("%x", md5.Sum([]byte(funcName)))[:12]

 	logger.Debugf("value of function: %s", funcName)

 	if p.getCallback(callbackType, funcHash) == nil {
 		logger.Errorf("function with hash value: '%s' not registered with callback type: '%s'", funcHash, callbackType)
 		return
 	}

 	p.DeleteCallback(callbackType, funcHash)
 }

 func (p *Proxy) invoke(ctx context.Context, callback *CallbackTuple, context []interface{}) (result interface{}, err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			errStr := fmt.Sprintf("callback error occurred: %+v", r)
 			err = errors.New(errStr)
 			logger.Error(errStr)
 		}
 	}()

 	result = callback.Execute(ctx, context)

 	return result, err
 }

 // InvokeCallbacks executes all callbacks associated to a specific type
 func (p *Proxy) InvokeCallbacks(ctx context.Context, args ...interface{}) (result interface{}) {
 	callbackType := args[0].(CallbackType)
 	proceedOnError := args[1].(bool)
 	context := args[2:]

 	var err error

 	if callbacks := p.getCallbacks(callbackType); callbacks != nil {
 		p.mutex.Lock()
 		for _, callback := range callbacks {
 			if result, err = p.invoke(ctx, callback, context); err != nil {
 				if !proceedOnError {
 					logger.Info("An error occurred.  Stopping callback invocation")
 					break
 				}
 				logger.Info("An error occurred.  Invoking next callback")
 			}
 		}
 		p.mutex.Unlock()
 	}

 	return result
 }
	/*
	* Copyright 2018-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 model

	import (
	"context"
	"crypto/md5"
	"errors"
	"fmt"
	"reflect"
	"runtime"
	"strings"
	"sync"

	"github.com/opencord/voltha-lib-go/v3/pkg/log"
	)

	// OperationContext holds details on the information used during an operation
	type OperationContext struct {
	Path string
	Data interface{}
	FieldName string
	ChildKey string
	}

	// NewOperationContext instantiates a new OperationContext structure
	func NewOperationContext(path string, data interface{}, fieldName string, childKey string) *OperationContext {
	oc := &OperationContext{
	Path: path,
	Data: data,
	FieldName: fieldName,
	ChildKey: childKey,
	}
	return oc
	}

	// Update applies new data to the context structure
	func (oc OperationContext) Update(data interface{}) OperationContext {
	oc.Data = data
	return oc
	}

	// Proxy holds the information for a specific location with the data model
	type Proxy struct {
	mutex sync.RWMutex
	Root *root
	Node *node
	ParentNode *node
	Path string
	FullPath string
	Exclusive bool
	Callbacks map[CallbackType]map[string]*CallbackTuple
	operation ProxyOperation
	}

	// NewProxy instantiates a new proxy to a specific location
	func NewProxy(root root, node node, parentNode node, path string, fullPath string, exclusive bool) Proxy {
	callbacks := make(map[CallbackType]map[string]*CallbackTuple)
	if fullPath == "/" {
	fullPath = ""
	}
	p := &Proxy{
	Root: root,
	Node: node,
	ParentNode: parentNode,
	Exclusive: exclusive,
	Path: path,
	FullPath: fullPath,
	Callbacks: callbacks,
	}
	return p
	}

	// getRoot returns the root attribute of the proxy
	func (p Proxy) getRoot() root {
	return p.Root
	}

	// getPath returns the path attribute of the proxy
	func (p *Proxy) getPath() string {
	return p.Path
	}

	// getFullPath returns the full path attribute of the proxy
	func (p *Proxy) getFullPath() string {
	return p.FullPath
	}

	// getCallbacks returns the full list of callbacks associated to the proxy
	func (p Proxy) getCallbacks(callbackType CallbackType) map[string]CallbackTuple {
	p.mutex.RLock()
	defer p.mutex.RUnlock()

	if p != nil {
	if cb, exists := p.Callbacks[callbackType]; exists {
	return cb
	}
	} else {
	logger.Debugw("proxy-is-nil", log.Fields{"callback-type": callbackType.String()})
	}
	return nil
	}

	// getCallback returns a specific callback matching the type and function hash
	func (p Proxy) getCallback(callbackType CallbackType, funcHash string) CallbackTuple {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	if tuple, exists := p.Callbacks[callbackType][funcHash]; exists {
	return tuple
	}
	return nil
	}

	// setCallbacks applies a callbacks list to a type
	func (p Proxy) setCallbacks(callbackType CallbackType, callbacks map[string]CallbackTuple) {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	p.Callbacks[callbackType] = callbacks
	}

	// setCallback applies a callback to a type and hash value
	func (p Proxy) setCallback(callbackType CallbackType, funcHash string, tuple CallbackTuple) {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	p.Callbacks[callbackType][funcHash] = tuple
	}

	// DeleteCallback removes a callback matching the type and hash
	func (p *Proxy) DeleteCallback(callbackType CallbackType, funcHash string) {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	delete(p.Callbacks[callbackType], funcHash)
	}

	// ProxyOperation callbackType is an enumerated value to express when a callback should be executed
	type ProxyOperation uint8

	// Enumerated list of callback types
	const (
	ProxyNone ProxyOperation = iota
	ProxyGet
	ProxyList
	ProxyAdd
	ProxyUpdate
	ProxyRemove
	ProxyCreate
	ProxyWatch
	)

	var proxyOperationTypes = []string{
	"PROXY_NONE",
	"PROXY_GET",
	"PROXY_LIST",
	"PROXY_ADD",
	"PROXY_UPDATE",
	"PROXY_REMOVE",
	"PROXY_CREATE",
	"PROXY_WATCH",
	}

	func (t ProxyOperation) String() string {
	return proxyOperationTypes[t]
	}

	// GetOperation -
	func (p *Proxy) GetOperation() ProxyOperation {
	p.mutex.RLock()
	defer p.mutex.RUnlock()
	return p.operation
	}

	// SetOperation -
	func (p *Proxy) SetOperation(operation ProxyOperation) {
	p.mutex.Lock()
	defer p.mutex.Unlock()
	p.operation = operation
	}

	// List will retrieve information from the data model at the specified path location
	// A list operation will force access to persistence storage
	func (p *Proxy) List(ctx context.Context, path string, depth int, deep bool, txid string) (interface{}, error) {
	var effectivePath string
	if path == "/" {
	effectivePath = p.getFullPath()
	} else {
	effectivePath = p.getFullPath() + path
	}

	p.SetOperation(ProxyList)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-list", log.Fields{
	"path": path,
	"effective": effectivePath,
	"operation": p.GetOperation(),
	})
	return p.getRoot().List(ctx, path, "", depth, deep, txid)
	}

	// Get will retrieve information from the data model at the specified path location
	func (p *Proxy) Get(ctx context.Context, path string, depth int, deep bool, txid string) (interface{}, error) {
	var effectivePath string
	if path == "/" {
	effectivePath = p.getFullPath()
	} else {
	effectivePath = p.getFullPath() + path
	}

	p.SetOperation(ProxyGet)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-get", log.Fields{
	"path": path,
	"effective": effectivePath,
	"operation": p.GetOperation(),
	})

	return p.getRoot().Get(ctx, path, "", depth, deep, txid)
	}

	// Update will modify information in the data model at the specified location with the provided data
	func (p *Proxy) Update(ctx context.Context, path string, data interface{}, strict bool, txid string) (interface{}, error) {
	if !strings.HasPrefix(path, "/") {
	logger.Errorf("invalid path: %s", path)
	return nil, fmt.Errorf("invalid path: %s", path)
	}
	var fullPath string
	var effectivePath string
	if path == "/" {
	fullPath = p.getPath()
	effectivePath = p.getFullPath()
	} else {
	fullPath = p.getPath() + path
	effectivePath = p.getFullPath() + path
	}

	p.SetOperation(ProxyUpdate)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-update", log.Fields{
	"path": path,
	"effective": effectivePath,
	"full": fullPath,
	"operation": p.GetOperation(),
	})

	result := p.getRoot().Update(ctx, fullPath, data, strict, txid, nil)

	if result != nil {
	return result.GetData(), nil
	}

	return nil, nil
	}

	// AddWithID will insert new data at specified location.
	// This method also allows the user to specify the ID of the data entry to ensure
	// that access control is active while inserting the information.
	func (p *Proxy) AddWithID(ctx context.Context, path string, id string, data interface{}, txid string) (interface{}, error) {
	if !strings.HasPrefix(path, "/") {
	logger.Errorf("invalid path: %s", path)
	return nil, fmt.Errorf("invalid path: %s", path)
	}
	var fullPath string
	var effectivePath string
	if path == "/" {
	fullPath = p.getPath()
	effectivePath = p.getFullPath()
	} else {
	fullPath = p.getPath() + path
	effectivePath = p.getFullPath() + path + "/" + id
	}

	p.SetOperation(ProxyAdd)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-add-with-id", log.Fields{
	"path": path,
	"effective": effectivePath,
	"full": fullPath,
	"operation": p.GetOperation(),
	})

	result := p.getRoot().Add(ctx, fullPath, data, txid, nil)

	if result != nil {
	return result.GetData(), nil
	}

	return nil, nil
	}

	// Add will insert new data at specified location.
	func (p *Proxy) Add(ctx context.Context, path string, data interface{}, txid string) (interface{}, error) {
	if !strings.HasPrefix(path, "/") {
	logger.Errorf("invalid path: %s", path)
	return nil, fmt.Errorf("invalid path: %s", path)
	}
	var fullPath string
	var effectivePath string
	if path == "/" {
	fullPath = p.getPath()
	effectivePath = p.getFullPath()
	} else {
	fullPath = p.getPath() + path
	effectivePath = p.getFullPath() + path
	}

	p.SetOperation(ProxyAdd)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-add", log.Fields{
	"path": path,
	"effective": effectivePath,
	"full": fullPath,
	"operation": p.GetOperation(),
	})

	result := p.getRoot().Add(ctx, fullPath, data, txid, nil)

	if result != nil {
	return result.GetData(), nil
	}

	return nil, nil
	}

	// Remove will delete an entry at the specified location
	func (p *Proxy) Remove(ctx context.Context, path string, txid string) (interface{}, error) {
	if !strings.HasPrefix(path, "/") {
	logger.Errorf("invalid path: %s", path)
	return nil, fmt.Errorf("invalid path: %s", path)
	}
	var fullPath string
	var effectivePath string
	if path == "/" {
	fullPath = p.getPath()
	effectivePath = p.getFullPath()
	} else {
	fullPath = p.getPath() + path
	effectivePath = p.getFullPath() + path
	}

	p.SetOperation(ProxyRemove)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-remove", log.Fields{
	"path": path,
	"effective": effectivePath,
	"full": fullPath,
	"operation": p.GetOperation(),
	})

	result := p.getRoot().Remove(ctx, fullPath, txid, nil)

	if result != nil {
	return result.GetData(), nil
	}

	return nil, nil
	}

	// CreateProxy to interact with specific path directly
	func (p Proxy) CreateProxy(ctx context.Context, path string, exclusive bool) (Proxy, error) {
	if !strings.HasPrefix(path, "/") {
	logger.Errorf("invalid path: %s", path)
	return nil, fmt.Errorf("invalid path: %s", path)
	}

	var fullPath string
	var effectivePath string
	if path == "/" {
	fullPath = p.getPath()
	effectivePath = p.getFullPath()
	} else {
	fullPath = p.getPath() + path
	effectivePath = p.getFullPath() + path
	}

	p.SetOperation(ProxyCreate)
	defer p.SetOperation(ProxyNone)

	logger.Debugw("proxy-create", log.Fields{
	"path": path,
	"effective": effectivePath,
	"full": fullPath,
	"operation": p.GetOperation(),
	})

	return p.getRoot().CreateProxy(ctx, fullPath, exclusive)
	}

	// OpenTransaction creates a new transaction branch to isolate operations made to the data model
	func (p Proxy) OpenTransaction() Transaction {
	txid := p.getRoot().MakeTxBranch()
	return NewTransaction(p, txid)
	}

	// commitTransaction will apply and merge modifications made in the transaction branch to the data model
	func (p *Proxy) commitTransaction(ctx context.Context, txid string) {
	p.getRoot().FoldTxBranch(ctx, txid)
	}

	// cancelTransaction will terminate a transaction branch along will all changes within it
	func (p *Proxy) cancelTransaction(txid string) {
	p.getRoot().DeleteTxBranch(txid)
	}

	// CallbackFunction is a type used to define callback functions
	type CallbackFunction func(ctx context.Context, args ...interface{}) interface{}

	// CallbackTuple holds the function and arguments details of a callback
	type CallbackTuple struct {
	callback CallbackFunction
	args []interface{}
	}

	// Execute will process the a callback with its provided arguments
	func (tuple *CallbackTuple) Execute(ctx context.Context, contextArgs []interface{}) interface{} {
	args := []interface{}{}

	args = append(args, tuple.args...)

	args = append(args, contextArgs...)

	return tuple.callback(ctx, args...)
	}

	// RegisterCallback associates a callback to the proxy
	func (p *Proxy) RegisterCallback(callbackType CallbackType, callback CallbackFunction, args ...interface{}) {
	if p.getCallbacks(callbackType) == nil {
	p.setCallbacks(callbackType, make(map[string]*CallbackTuple))
	}
	funcName := runtime.FuncForPC(reflect.ValueOf(callback).Pointer()).Name()
	logger.Debugf("value of function: %s", funcName)
	funcHash := fmt.Sprintf("%x", md5.Sum([]byte(funcName)))[:12]

	p.setCallback(callbackType, funcHash, &CallbackTuple{callback, args})
	}

	// UnregisterCallback removes references to a callback within a proxy
	func (p *Proxy) UnregisterCallback(callbackType CallbackType, callback CallbackFunction, args ...interface{}) {
	if p.getCallbacks(callbackType) == nil {
	logger.Errorf("no such callback type - %s", callbackType.String())
	return
	}

	funcName := runtime.FuncForPC(reflect.ValueOf(callback).Pointer()).Name()
	funcHash := fmt.Sprintf("%x", md5.Sum([]byte(funcName)))[:12]

	logger.Debugf("value of function: %s", funcName)

	if p.getCallback(callbackType, funcHash) == nil {
	logger.Errorf("function with hash value: '%s' not registered with callback type: '%s'", funcHash, callbackType)
	return
	}

	p.DeleteCallback(callbackType, funcHash)
	}

	func (p Proxy) invoke(ctx context.Context, callback CallbackTuple, context []interface{}) (result interface{}, err error) {
	defer func() {
	if r := recover(); r != nil {
	errStr := fmt.Sprintf("callback error occurred: %+v", r)
	err = errors.New(errStr)
	logger.Error(errStr)
	}
	}()

	result = callback.Execute(ctx, context)

	return result, err
	}

	// InvokeCallbacks executes all callbacks associated to a specific type
	func (p *Proxy) InvokeCallbacks(ctx context.Context, args ...interface{}) (result interface{}) {
	callbackType := args[0].(CallbackType)
	proceedOnError := args[1].(bool)
	context := args[2:]

	var err error

	if callbacks := p.getCallbacks(callbackType); callbacks != nil {
	p.mutex.Lock()
	for _, callback := range callbacks {
	if result, err = p.invoke(ctx, callback, context); err != nil {
	if !proceedOnError {
	logger.Info("An error occurred. Stopping callback invocation")
	break
	}
	logger.Info("An error occurred. Invoking next callback")
	}
	}
	p.mutex.Unlock()
	}

	return result
	}