Add some examples

operation.go

@@ -28,6 +28,25 @@ type OperationData struct {
 	Ref       string    `bson:"-,omitempty" json:"ref,omitempty"`
 }
 
+// NewOperation creates an new operation from given information.
+//
+// The event argument can be one of "insert", "update" or "delete". The time
+// defines the exact modification date of the object (must be the exact same time
+// as stored in the database).
+func NewOperation(event string, time time.Time, objID, objType string, objParents []string) *Operation {
+	id := bson.NewObjectId()
+	return &Operation{
+		ID:    &id,
+		Event: event,
+		Data: &OperationData{
+			Timestamp: time,
+			ID:        objID,
+			Type:      objType,
+			Parents:   objParents,
+		},
+	}
+}
+
 // GetEventID returns an SSE last event id for the operation
 func (op Operation) GetEventID() LastID {
 	return &OperationLastID{op.ID}

oplog_example_test.go

@@ -0,0 +1,52 @@
+package oplog_test
+
+import (
+	"log"
+	"os"
+	"strconv"
+	"time"
+
+	"github.com/dailymotion/oplog"
+)
+
+func ExampleOpLog_Append() {
+	ol, err := oplog.New("mongodb://localhost/oplog", 1048576)
+	if err != nil {
+		log.Fatal(err)
+	}
+	op := oplog.NewOperation("insert", time.Now(), "123", "user", nil)
+	ol.Append(op)
+}
+
+func ExampleOpLog_Ingest() {
+	ol, err := oplog.New("mongodb://localhost/oplog", 1048576)
+	if err != nil {
+		log.Fatal(err)
+	}
+	ops := make(chan *oplog.Operation)
+	done := make(chan bool, 1)
+	go ol.Ingest(ops, nil)
+	// Insert a large number of operations
+	for i := 0; i < 1000; i++ {
+		ops <- oplog.NewOperation("insert", time.Now(), strconv.FormatInt(int64(i), 10), "user", nil)
+	}
+	done <- true
+}
+
+func ExampleOpLog_Tail() {
+	ol, err := oplog.New("mongodb://localhost/oplog", 1048576)
+	if err != nil {
+		log.Fatal(err)
+	}
+	ops := make(chan oplog.GenericEvent)
+	stop := make(chan bool)
+	// Tail all future events with no filters
+	go ol.Tail(nil, oplog.Filter{}, ops, stop)
+	// Read 100 events
+	for i := 0; i < 100; i++ {
+		op := <-ops
+		op.WriteTo(os.Stdout)
+	}
+	// Stop the tail
+	stop <- true
+}