ducky/subscriptions
ducky/subscriptions/subscription.go
Implement PostgreSQL support, drop subscription IDs. Create a Postgres object that wraps database/sql, so we can attach methods to it and fulfill interfaces. Create a postgres_init.sql script that will create the subscriptions table in a PostgreSQL database. Make our period type fulfill the driver.Valuer and driver.Scanner types, so it can be stored in and retrieved from SQL databases. Create a SubscriptionStats type, and add a method to our subscriptionStore interface that will allow us to retrieve current stats about the Subscriptions it is storing. Deprecated the ID property of our Subscription type, and use the Subscription.UserID property instead as our primary key. Subscriptions should be unique per user and we generally will want to access Subscriptions in the context of the User they belong to, so the UserID is a better primary key. This also means we removed the getSubscriptionByUserID method (and implementations) from our subscriptionStore, as getSubscriptions now fills that role. Implement our getSubscriptionStats method in the memstore. Implement the subscriptionStore interface on our new Postgres type. Run the subscription store tests on our Postgres type, as well, if the PG_TEST_DB environment variable is set. Round all our timestamps in our tests to the nearest millisecond, as Postgres silently truncates all timestamps to the nearest millisecond, and it was causing false test failures. Remove the tests for our getSubscriptionStoreByUser method, as that was removed.
| paddy@0 | 1 package subscriptions |
| paddy@0 | 2 |
| paddy@0 | 3 import ( |
| paddy@1 | 4 "database/sql/driver" |
| paddy@0 | 5 "errors" |
| paddy@0 | 6 "time" |
| paddy@0 | 7 |
| paddy@0 | 8 "code.secondbit.org/uuid.hg" |
| paddy@0 | 9 ) |
| paddy@0 | 10 |
| paddy@0 | 11 const ( |
| paddy@0 | 12 // MonthlyPeriod represents a period of once a month. |
| paddy@0 | 13 MonthlyPeriod period = "monthly" |
| paddy@0 | 14 ) |
| paddy@0 | 15 |
| paddy@0 | 16 var ( |
| paddy@0 | 17 // ErrSubscriptionAlreadyExists is returned when a Subscription |
| paddy@0 | 18 // with an identical ID already exists in the subscriptionStore. |
| paddy@0 | 19 ErrSubscriptionAlreadyExists = errors.New("Subscription already exists") |
| paddy@0 | 20 // ErrSubscriptionNotFound is returned when a single Subscription |
| paddy@0 | 21 // is acted upon or requested, but cannot be found. |
| paddy@0 | 22 ErrSubscriptionNotFound = errors.New("Subscription not found") |
| paddy@0 | 23 // ErrStripeCustomerAlreadyExists is returned when a Subscription |
| paddy@0 | 24 // is created or updates its StripeCustomer property, but that |
| paddy@0 | 25 // StripeCustomer is already associated with another Subscription. |
| paddy@0 | 26 ErrStripeCustomerAlreadyExists = errors.New("Stripe customer already assigned to another Subscription") |
| paddy@0 | 27 // ErrSubscriptionChangeEmpty is returned when a SubscriptionChange |
| paddy@0 | 28 // is empty but is passed to subscriptionStore.UpdateSubscription |
| paddy@0 | 29 // anyways. |
| paddy@0 | 30 ErrSubscriptionChangeEmpty = errors.New("SubscriptionChange is empty") |
| paddy@0 | 31 // ErrNoSubscriptionID is returned when one or more Subscription IDs |
| paddy@0 | 32 // are required, but none are provided. |
| paddy@0 | 33 ErrNoSubscriptionID = errors.New("no Subscription ID provided") |
| paddy@1 | 34 // ErrPeriodInvalid is returned when attempting to use a period that |
| paddy@1 | 35 // is not a valid period. |
| paddy@1 | 36 ErrPeriodInvalid = errors.New("invalid period") |
| paddy@0 | 37 ) |
| paddy@0 | 38 |
| paddy@0 | 39 type period string |
| paddy@0 | 40 |
| paddy@1 | 41 func (p period) Value() (driver.Value, error) { |
| paddy@1 | 42 return string(p), nil |
| paddy@1 | 43 } |
| paddy@1 | 44 |
| paddy@1 | 45 func (p *period) Scan(src interface{}) error { |
| paddy@1 | 46 if src == nil { |
| paddy@1 | 47 *p = period("") |
| paddy@1 | 48 return nil |
| paddy@1 | 49 } |
| paddy@1 | 50 switch src.(type) { |
| paddy@1 | 51 case []byte: |
| paddy@1 | 52 *p = period(string(src.([]byte))) |
| paddy@1 | 53 return nil |
| paddy@1 | 54 case string: |
| paddy@1 | 55 *p = period(src.(string)) |
| paddy@1 | 56 return nil |
| paddy@1 | 57 default: |
| paddy@1 | 58 return ErrPeriodInvalid |
| paddy@1 | 59 } |
| paddy@1 | 60 } |
| paddy@1 | 61 |
| paddy@0 | 62 // Subscription represents the state of a user's payments. It holds |
| paddy@0 | 63 // metadata about the last time a user was charged, how much a user |
| paddy@0 | 64 // should be charged, how to charge a user and how much to charge |
| paddy@0 | 65 // the user. |
| paddy@0 | 66 type Subscription struct { |
| paddy@0 | 67 UserID uuid.ID |
| paddy@0 | 68 StripeCustomer string |
| paddy@0 | 69 Amount int |
| paddy@0 | 70 Period period |
| paddy@0 | 71 Created time.Time |
| paddy@0 | 72 BeginCharging time.Time |
| paddy@0 | 73 LastCharged time.Time |
| paddy@0 | 74 LastNotified time.Time |
| paddy@0 | 75 InLockout bool |
| paddy@0 | 76 } |
| paddy@0 | 77 |
| paddy@0 | 78 // SubscriptionChange represents desired changes to a Subscription |
| paddy@0 | 79 // object. A nil value means that property should remain unchanged. |
| paddy@0 | 80 type SubscriptionChange struct { |
| paddy@0 | 81 StripeCustomer *string |
| paddy@0 | 82 Amount *int |
| paddy@0 | 83 Period *period |
| paddy@0 | 84 BeginCharging *time.Time |
| paddy@0 | 85 LastCharged *time.Time |
| paddy@0 | 86 LastNotified *time.Time |
| paddy@0 | 87 InLockout *bool |
| paddy@0 | 88 } |
| paddy@0 | 89 |
| paddy@0 | 90 // IsEmpty returns true if the SubscriptionChange doesn't request |
| paddy@0 | 91 // a change to any property of the Subscription. |
| paddy@0 | 92 func (change SubscriptionChange) IsEmpty() bool { |
| paddy@0 | 93 if change.StripeCustomer != nil { |
| paddy@0 | 94 return false |
| paddy@0 | 95 } |
| paddy@0 | 96 if change.Amount != nil { |
| paddy@0 | 97 return false |
| paddy@0 | 98 } |
| paddy@0 | 99 if change.Period != nil { |
| paddy@0 | 100 return false |
| paddy@0 | 101 } |
| paddy@0 | 102 if change.BeginCharging != nil { |
| paddy@0 | 103 return false |
| paddy@0 | 104 } |
| paddy@0 | 105 if change.LastCharged != nil { |
| paddy@0 | 106 return false |
| paddy@0 | 107 } |
| paddy@0 | 108 if change.LastNotified != nil { |
| paddy@0 | 109 return false |
| paddy@0 | 110 } |
| paddy@0 | 111 if change.InLockout != nil { |
| paddy@0 | 112 return false |
| paddy@0 | 113 } |
| paddy@0 | 114 return true |
| paddy@0 | 115 } |
| paddy@0 | 116 |
| paddy@0 | 117 // ApplyChange updates a Subscription based on the changes requested |
| paddy@0 | 118 // by a SubscriptionChange. |
| paddy@0 | 119 func (s *Subscription) ApplyChange(change SubscriptionChange) { |
| paddy@0 | 120 if change.StripeCustomer != nil { |
| paddy@0 | 121 s.StripeCustomer = *change.StripeCustomer |
| paddy@0 | 122 } |
| paddy@0 | 123 if change.Amount != nil { |
| paddy@0 | 124 s.Amount = *change.Amount |
| paddy@0 | 125 } |
| paddy@0 | 126 if change.Period != nil { |
| paddy@0 | 127 s.Period = *change.Period |
| paddy@0 | 128 } |
| paddy@0 | 129 if change.BeginCharging != nil { |
| paddy@0 | 130 s.BeginCharging = *change.BeginCharging |
| paddy@0 | 131 } |
| paddy@0 | 132 if change.LastCharged != nil { |
| paddy@0 | 133 s.LastCharged = *change.LastCharged |
| paddy@0 | 134 } |
| paddy@0 | 135 if change.LastNotified != nil { |
| paddy@0 | 136 s.LastNotified = *change.LastNotified |
| paddy@0 | 137 } |
| paddy@0 | 138 if change.InLockout != nil { |
| paddy@0 | 139 s.InLockout = *change.InLockout |
| paddy@0 | 140 } |
| paddy@0 | 141 } |
| paddy@0 | 142 |
| paddy@0 | 143 // ByLastChargeDate allows us to sort a []Subscription by the LastCharged |
| paddy@0 | 144 // property, with the lowest LastCharged date first. |
| paddy@0 | 145 type ByLastChargeDate []Subscription |
| paddy@0 | 146 |
| paddy@0 | 147 // Len returns the length the SubscriptionsByLastChargeDate. It fulfills |
| paddy@0 | 148 // the sort.Interface interface. |
| paddy@0 | 149 func (s ByLastChargeDate) Len() int { |
| paddy@0 | 150 return len(s) |
| paddy@0 | 151 } |
| paddy@0 | 152 |
| paddy@0 | 153 // Swap puts the item in position i in position j, and the item in position |
| paddy@0 | 154 // j in position i. It fulfills the sort.Interface interface. |
| paddy@0 | 155 func (s ByLastChargeDate) Swap(i, j int) { |
| paddy@0 | 156 s[i], s[j] = s[j], s[i] |
| paddy@0 | 157 } |
| paddy@0 | 158 |
| paddy@0 | 159 // Less returns true if the item in position i should be sorted before the |
| paddy@0 | 160 // item in position j. |
| paddy@0 | 161 func (s ByLastChargeDate) Less(i, j int) bool { |
| paddy@0 | 162 return s[i].LastCharged.Before(s[j].LastCharged) |
| paddy@0 | 163 } |
| paddy@0 | 164 |
| paddy@1 | 165 // SubscriptionStats represents a set of statistics about our Subscription |
| paddy@1 | 166 // data that will be exposed to the Prometheus scraper. |
| paddy@1 | 167 type SubscriptionStats struct { |
| paddy@1 | 168 Number int64 |
| paddy@1 | 169 TotalAmount int64 |
| paddy@1 | 170 MeanAmount float64 |
| paddy@1 | 171 // BUG(paddy): Currently, Kubernetes doesn't offer any way to contact _all_ nodes in a service. |
| paddy@1 | 172 // Because of this, we can only report stats that will be identical across nodes, e.g. stats |
| paddy@1 | 173 // that come from the database. More info here: https://github.com/GoogleCloudPlatform/kubernetes/issues/6666 |
| paddy@1 | 174 // In the future, we'll need per-node metrics. For now, we'll make do. |
| paddy@1 | 175 // |
| paddy@1 | 176 // Actually, as of https://github.com/GoogleCloudPlatform/kubernetes/pull/9073, we may be all set: |
| paddy@1 | 177 // "SRV Records are created for named ports that are part of normal or Headless Services. For each named port, |
| paddy@1 | 178 // the SRV record would have the form _my-port-name._my-port-protocol.my-svc.my-namespace.svc.cluster.local. |
| paddy@1 | 179 // For a regular service, this resolves to the port number and the CNAME: my-svc.my-namespace.svc.cluster.local. |
| paddy@1 | 180 // For a headless service, this resolves to multiple answers, one for each pod that is backing the service, and |
| paddy@1 | 181 // contains the port number and a CNAME of the pod with the format auto-generated-name.my-svc.my-namespace.svc.cluster.local |
| paddy@1 | 182 // SRV records always contain the 'svc' segment in them and are not supported for old-style CNAMEs where the 'svc' segment |
| paddy@1 | 183 // was omitted." |
| paddy@1 | 184 } |
| paddy@1 | 185 |
| paddy@0 | 186 type subscriptionStore interface { |
| paddy@0 | 187 reset() error |
| paddy@0 | 188 createSubscription(sub Subscription) error |
| paddy@0 | 189 updateSubscription(id uuid.ID, change SubscriptionChange) error |
| paddy@0 | 190 deleteSubscription(id uuid.ID) error |
| paddy@0 | 191 listSubscriptionsLastChargedBefore(time.Time) ([]Subscription, error) |
| paddy@0 | 192 getSubscriptions(ids []uuid.ID) (map[string]Subscription, error) |
| paddy@1 | 193 getSubscriptionStats() (SubscriptionStats, error) |
| paddy@0 | 194 } |