forked from wundergraph/graphql-go-tools
/
datasource_nats.go
134 lines (111 loc) · 2.67 KB
/
datasource_nats.go
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package datasource
import (
"context"
"encoding/json"
"io"
"sync"
"time"
log "github.com/jensneuse/abstractlogger"
"github.com/nats-io/nats.go"
"github.com/dchukmasov/graphql-go-tools/pkg/lexer/literal"
)
type NatsDataSourceConfig struct {
Addr string
Topic string
}
type NatsDataSourcePlannerFactoryFactory struct {
}
func (n NatsDataSourcePlannerFactoryFactory) Initialize(base BasePlanner, configReader io.Reader) (PlannerFactory, error) {
factory := &NatsDataSourcePlannerFactory{
base: base,
}
return factory, json.NewDecoder(configReader).Decode(&factory.config)
}
type NatsDataSourcePlannerFactory struct {
base BasePlanner
config NatsDataSourceConfig
}
func (n NatsDataSourcePlannerFactory) DataSourcePlanner() Planner {
return SimpleDataSourcePlanner(&NatsDataSourcePlanner{
BasePlanner: n.base,
dataSourceConfig: n.config,
})
}
type NatsDataSourcePlanner struct {
BasePlanner
dataSourceConfig NatsDataSourceConfig
}
func (n *NatsDataSourcePlanner) Plan([]Argument) (DataSource, []Argument) {
n.Args = append(n.Args, &StaticVariableArgument{
Name: literal.ADDR,
Value: []byte(n.dataSourceConfig.Addr),
})
n.Args = append(n.Args, &StaticVariableArgument{
Name: literal.TOPIC,
Value: []byte(n.dataSourceConfig.Topic),
})
return &NatsDataSource{
log: n.Log,
}, n.Args
}
type NatsDataSource struct {
log log.Logger
conn *nats.Conn
sub *nats.Subscription
once sync.Once
}
func (d *NatsDataSource) Resolve(ctx context.Context, args ResolverArgs, out io.Writer) (n int, err error) {
d.once.Do(func() {
addrArg := args.ByKey(literal.ADDR)
topicArg := args.ByKey(literal.TOPIC)
addr := nats.DefaultURL
topic := string(topicArg)
if len(addrArg) != 0 {
addr = string(addrArg)
}
go func() {
<-ctx.Done()
if d.sub != nil {
d.log.Debug("NatsDataSource.unsubscribing",
log.String("addr", addr),
log.String("topic", topic),
)
err := d.sub.Unsubscribe()
if err != nil {
d.log.Error("Unsubscribe", log.Error(err))
}
}
if d.conn != nil {
d.log.Debug("NatsDataSource.closing",
log.String("addr", addr),
log.String("topic", topic),
)
d.conn.Close()
}
}()
d.log.Debug("NatsDataSource.connecting",
log.String("addr", addr),
log.String("topic", topic),
)
d.conn, err = nats.Connect(addr)
if err != nil {
panic(err)
}
d.log.Debug("NatsDataSource.subscribing",
log.String("addr", addr),
log.String("topic", topic),
)
d.sub, err = d.conn.SubscribeSync(topic)
if err != nil {
panic(err)
}
})
if err != nil {
return n, err
}
message, err := d.sub.NextMsg(time.Minute)
if err != nil {
return n, err
}
return out.Write(message.Data)
}