11package device
22
33import (
4- "encoding/json"
4+ "sync"
5+ "sync/atomic"
56
67 "github.com/segmentio/ksuid"
78 "github.com/spf13/cast"
@@ -28,107 +29,101 @@ func init() {
2829}
2930
3031// Metadata contains information such as security credentials
31- // related to a device.
32- type Metadata map [string ]interface {}
33-
34- // JWTClaims returns the JWT claims attached to a device. If no claims exist,
35- // they are initialized appropiately.
36- func (m Metadata ) JWTClaims () JWTClaims { // returns the type and such type has getter/setter
37- if jwtClaims , ok := m [JWTClaimsKey ].(JWTClaims ); ok {
38- return deepCopyMap (jwtClaims )
39- }
40- return deepCopyMap (m .initJWTClaims ())
41- }
42-
43- // SetJWTClaims sets the JWT claims attached to a device.
44- func (m Metadata ) SetJWTClaims (jwtClaims JWTClaims ) {
45- m [JWTClaimsKey ] = jwtClaims
32+ // related to a device. Read operations are optimized with a
33+ // copy-on-write strategy. Client code must further synchronize concurrent
34+ // writers to avoid stale data.
35+ // Metadata uses an atomic.Value internally and thus it should not be copied
36+ // after creation.
37+ type Metadata struct {
38+ v atomic.Value
39+ once sync.Once
4640}
4741
4842// SessionID returns the UUID associated with a device's current connection
49- // to the cluster.
50- func (m Metadata ) SessionID () string {
51- if sessionID , ok := m [SessionIDKey ].(string ); ok {
52- return sessionID
53- }
54-
55- return m .initSessionID ()
56- }
57-
58- func (m Metadata ) initSessionID () string {
59- sessionID := ksuid .New ().String ()
60- m [SessionIDKey ] = sessionID
61- return sessionID
43+ // to the cluster if one has been set. The zero value is returned as default.
44+ func (m * Metadata ) SessionID () (sessionID string ) {
45+ sessionID , _ = m .loadData ()[SessionIDKey ].(string )
46+ return
6247}
6348
64- func (m Metadata ) initJWTClaims () JWTClaims {
65- jwtClaims := JWTClaims (make (map [string ]interface {}))
66- m .SetJWTClaims (jwtClaims )
67- return jwtClaims
49+ // SetSessionID sets the UUID associated the device's current connection to the cluster.
50+ // It uses sync.Once to ensure the sessionID is unchanged through the metadata's lifecycle.
51+ func (m * Metadata ) SetSessionID (sessionID string ) {
52+ m .once .Do (func () {
53+ m .copyAndStore (SessionIDKey , sessionID )
54+ })
6855}
6956
70- // Load allows retrieving values from a device's metadata
71- func (m Metadata ) Load (key string ) interface {} {
72- return m [key ]
57+ // Load returns the value associated with the given key in the metadata map.
58+ // It is not recommended modifying values returned by reference.
59+ func (m * Metadata ) Load (key string ) interface {} {
60+ return m .loadData ()[key ]
7361}
7462
75- // Store allows writing values into the device's metadata given
76- // a key. Boolean results indicates whether the operation was successful.
77- // Note: operations will fail for reserved keys.
78- func (m Metadata ) Store (key string , value interface {}) bool {
63+ // Store updates the key value mapping in the device metadata map.
64+ // A boolean result is given indicating whether the operation was successful.
65+ // Operations will fail for reserved keys.
66+ // To avoid updating keys with stale data/value, client code will need to
67+ // synchronize the entire transaction of reading, copying, modifying and
68+ // writing back the value.
69+ func (m * Metadata ) Store (key string , value interface {}) bool {
7970 if reservedMetadataKeys [key ] {
8071 return false
8172 }
82- m [ key ] = value
73+ m . copyAndStore ( key , value )
8374 return true
8475}
8576
86- // NewDeviceMetadata returns a metadata object ready for use.
87- func NewDeviceMetadata () Metadata {
88- return NewDeviceMetadataWithClaims (make (map [string ]interface {}))
77+ // SetClaims updates the claims associated with the device that's
78+ // owner of the metadata.
79+ // To avoid updating the claims with stale data, client code will need to
80+ // synchronize the entire transaction of reading, copying, modifying and
81+ // writing back the value.
82+ func (m * Metadata ) SetClaims (claims map [string ]interface {}) {
83+ m .copyAndStore (JWTClaimsKey , deepCopyMap (claims ))
8984}
9085
91- // NewDeviceMetadataWithClaims returns a metadata object ready for use with the
92- // given claims.
93- func NewDeviceMetadataWithClaims (claims map [string ]interface {}) Metadata {
94- m := make (Metadata )
95- m .SetJWTClaims (deepCopyMap (claims ))
96- m .initSessionID ()
97- return m
86+ // Claims returns the claims attached to a device. The returned map
87+ // should not be modified to avoid any race conditions. To update the claims,
88+ // take a look at the ClaimsCopy() function
89+ func (m * Metadata ) Claims () (claims map [string ]interface {}) {
90+ claims , _ = m .loadData ()[JWTClaimsKey ].(map [string ]interface {})
91+ return
9892}
9993
100- // JWTClaims defines the interface of a device's security claims.
101- // One current use case is providing security credentials the device
102- // presented at registration time.
103- type JWTClaims map [string ]interface {}
94+ // ClaimsCopy returns a deep copy of the claims. Use this, along with the
95+ // SetClaims() method to update the claims.
96+ func (m * Metadata ) ClaimsCopy () map [string ]interface {} {
97+ return deepCopyMap (m .Claims ())
98+ }
10499
105- // Trust returns the device's trust level claim
100+ // TrustClaim returns the device's trust level claim.
106101// By Default, a device is untrusted (trust = 0).
107- func (c JWTClaims ) Trust () int {
108- if trust , ok := c [TrustClaimKey ].(int ); ok {
109- return trust
110- }
111- return 0
102+ func (m * Metadata ) TrustClaim () (trust int ) {
103+ trust , _ = m .Claims ()[TrustClaimKey ].(int )
104+ return
112105}
113106
114- // PartnerID returns the partner ID claim.
107+ // PartnerIDClaim returns the partner ID claim.
115108// If no claim is found, the zero value is returned.
116- func (c JWTClaims ) PartnerID () string {
117- if partnerID , ok := c [PartnerIDClaimKey ].(string ); ok {
118- return partnerID
119- }
120- return "" // no partner by default
109+ func (m * Metadata ) PartnerIDClaim () (partnerID string ) {
110+ partnerID , _ = m .Claims ()[PartnerIDClaimKey ].(string )
111+ return
112+ }
113+
114+ func (m * Metadata ) loadData () (data map [string ]interface {}) {
115+ data , _ = m .v .Load ().(map [string ]interface {})
116+ return
121117}
122118
123- // SetTrust modifies the trust level of the device which owns these
124- // claims.
125- func (c JWTClaims ) SetTrust (trust int ) {
126- c [TrustClaimKey ] = trust
119+ func (m * Metadata ) storeData (data map [string ]interface {}) {
120+ m .v .Store (data )
127121}
128122
129- // MarshalJSON allows easy JSON representation of the JWTClaims underlying claims map.
130- func (c JWTClaims ) MarshalJSON () ([]byte , error ) {
131- return json .Marshal (c )
123+ func (m * Metadata ) copyAndStore (key string , val interface {}) {
124+ data := deepCopyMap (m .loadData ())
125+ data [key ] = val
126+ m .storeData (data )
132127}
133128
134129func deepCopyMap (m map [string ]interface {}) map [string ]interface {} {
0 commit comments