open-consul/agent/consul/state/usage.go

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package state
import (
"fmt"
"github.com/hashicorp/consul/agent/structs"
memdb "github.com/hashicorp/go-memdb"
)
const (
serviceNamesUsageTable = "service-names"
)
// usageTableSchema returns a new table schema used for tracking various indexes
// for the Raft log.
func usageTableSchema() *memdb.TableSchema {
return &memdb.TableSchema{
Name: "usage",
Indexes: map[string]*memdb.IndexSchema{
"id": {
Name: "id",
AllowMissing: false,
Unique: true,
Indexer: &memdb.StringFieldIndex{
Field: "ID",
Lowercase: true,
},
},
},
}
}
func init() {
registerSchema(usageTableSchema)
}
// UsageEntry represents a count of some arbitrary identifier within the
// state store, along with the last seen index.
type UsageEntry struct {
ID string
Index uint64
Count int
}
// ServiceUsage contains all of the usage data related to services
type ServiceUsage struct {
Services int
ServiceInstances int
EnterpriseServiceUsage
}
type uniqueServiceState int
const (
NoChange uniqueServiceState = 0
Deleted uniqueServiceState = 1
Created uniqueServiceState = 2
)
// updateUsage takes a set of memdb changes and computes a delta for specific
// usage metrics that we track.
func updateUsage(tx WriteTxn, changes Changes) error {
usageDeltas := make(map[string]int)
for _, change := range changes.Changes {
var delta int
if change.Created() {
delta = 1
} else if change.Deleted() {
delta = -1
}
switch change.Table {
case "nodes":
usageDeltas[change.Table] += delta
case "services":
svc := changeObject(change).(*structs.ServiceNode)
usageDeltas[change.Table] += delta
serviceIter, err := getWithTxn(tx, servicesTableName, "service", svc.ServiceName, &svc.EnterpriseMeta)
if err != nil {
return err
}
var serviceState uniqueServiceState
if serviceIter.Next() == nil {
// If no services exist, we know we deleted the last service
// instance.
serviceState = Deleted
usageDeltas[serviceNamesUsageTable] -= 1
} else if serviceIter.Next() == nil {
// If a second call to Next() returns nil, we know only a single
// instance exists. If, in addition, a new service name has been
// registered, either via creating a new service instance or via
// renaming an existing service, than we update our service count.
//
// We only care about two cases here:
// 1. A new service instance has been created with a unique name
// 2. An existing service instance has been updated with a new unique name
//
// These are the only ways a new unique service can be created. The
// other valid cases here: an update that does not change the service
// name, and a deletion, both do not impact the count of unique service
// names in the system.
if change.Created() {
// Given a single existing service instance of the service: If a
// service has just been created, then we know this is a new unique
// service.
serviceState = Created
usageDeltas[serviceNamesUsageTable] += 1
} else if serviceNameChanged(change) {
// Given a single existing service instance of the service: If a
// service has been updated with a new service name, then we know
// this is a new unique service.
serviceState = Created
usageDeltas[serviceNamesUsageTable] += 1
// Check whether the previous name was deleted in this rename, this
// is a special case of renaming a service which does not result in
// changing the count of unique service names.
before := change.Before.(*structs.ServiceNode)
beforeSvc, err := firstWithTxn(tx, servicesTableName, "service", before.ServiceName, &before.EnterpriseMeta)
if err != nil {
return err
}
if beforeSvc == nil {
usageDeltas[serviceNamesUsageTable] -= 1
// set serviceState to NoChange since we have both gained and lost a
// service, cancelling each other out
serviceState = NoChange
}
}
}
addEnterpriseServiceUsage(usageDeltas, change, serviceState)
}
}
idx := changes.Index
// This will happen when restoring from a snapshot, just take the max index
// of the tables we are tracking.
if idx == 0 {
idx = maxIndexTxn(tx, "nodes", servicesTableName)
}
return writeUsageDeltas(tx, idx, usageDeltas)
}
// serviceNameChanged returns a boolean that indicates whether the
// provided change resulted in an update to the service's service name.
func serviceNameChanged(change memdb.Change) bool {
if change.Updated() {
before := change.Before.(*structs.ServiceNode)
after := change.After.(*structs.ServiceNode)
return before.ServiceName != after.ServiceName
}
return false
}
// writeUsageDeltas will take in a map of IDs to deltas and update each
// entry accordingly, checking for integer underflow. The index that is
// passed in will be recorded on the entry as well.
func writeUsageDeltas(tx WriteTxn, idx uint64, usageDeltas map[string]int) error {
for id, delta := range usageDeltas {
u, err := tx.First("usage", "id", id)
if err != nil {
return fmt.Errorf("failed to retrieve existing usage entry: %s", err)
}
if u == nil {
if delta < 0 {
return fmt.Errorf("failed to insert usage entry for %q: delta will cause a negative count", id)
}
err := tx.Insert("usage", &UsageEntry{
ID: id,
Count: delta,
Index: idx,
})
if err != nil {
return fmt.Errorf("failed to update usage entry: %s", err)
}
} else if cur, ok := u.(*UsageEntry); ok {
if cur.Count+delta < 0 {
return fmt.Errorf("failed to insert usage entry for %q: delta will cause a negative count", id)
}
err := tx.Insert("usage", &UsageEntry{
ID: id,
Count: cur.Count + delta,
Index: idx,
})
if err != nil {
return fmt.Errorf("failed to update usage entry: %s", err)
}
}
}
return nil
}
// NodeCount returns the latest seen Raft index, a count of the number of nodes
// registered, and any errors.
func (s *Store) NodeCount() (uint64, int, error) {
tx := s.db.ReadTxn()
defer tx.Abort()
nodeUsage, err := firstUsageEntry(tx, "nodes")
if err != nil {
return 0, 0, fmt.Errorf("failed nodes lookup: %s", err)
}
return nodeUsage.Index, nodeUsage.Count, nil
}
// ServiceUsage returns the latest seen Raft index, a compiled set of service
// usage data, and any errors.
func (s *Store) ServiceUsage() (uint64, ServiceUsage, error) {
tx := s.db.ReadTxn()
defer tx.Abort()
serviceInstances, err := firstUsageEntry(tx, servicesTableName)
if err != nil {
return 0, ServiceUsage{}, fmt.Errorf("failed services lookup: %s", err)
}
services, err := firstUsageEntry(tx, serviceNamesUsageTable)
if err != nil {
return 0, ServiceUsage{}, fmt.Errorf("failed services lookup: %s", err)
}
usage := ServiceUsage{
ServiceInstances: serviceInstances.Count,
Services: services.Count,
}
results, err := compileEnterpriseUsage(tx, usage)
if err != nil {
return 0, ServiceUsage{}, fmt.Errorf("failed services lookup: %s", err)
}
return serviceInstances.Index, results, nil
}
func firstUsageEntry(tx ReadTxn, id string) (*UsageEntry, error) {
usage, err := tx.First("usage", "id", id)
if err != nil {
return nil, err
}
// If no elements have been inserted, the usage entry will not exist. We
// return a valid value so that can be certain the return value is not nil
// when no error has occurred.
if usage == nil {
return &UsageEntry{ID: id, Count: 0}, nil
}
realUsage, ok := usage.(*UsageEntry)
if !ok {
return nil, fmt.Errorf("failed usage lookup: type %T is not *UsageEntry", usage)
}
return realUsage, nil
}