split example file

Author: whhe

README.md

@@ -13,19 +13,19 @@ For ChangeStreamOptions, [startAtOperationTime](https://docs.mongodb.com/manual/
 
 ## Concepts
 
-Mongo Replicator is built on structure of Collector, Replicator and Operator.
+Mongo Replicator consists of Collector, Replicator and Operator.
 
 ### Collector
 
-Collector represent the data source to watch. 
+Collector represents the data source to watch. 
 
 You can set the watch scope when creating a Collector instance. According to the params, the data source can be a deployment (either a replica set or a sharded cluster), several databases or collections.
 
 ```go
 NewCollector(uri string, databases []string, collections []string) *Collector 
 ```
 
-The Collector instance has a `Collect` method to perform the watch action.
+Collector has a `Collect` method to perform the watch action.
 
 ```go
 (c *Collector) Collect(opts ...*options.ChangeStreamOptions) (*mongo.ChangeStream, error)
@@ -43,7 +43,7 @@ func (r *Replicator) Replicate(e model.ChangeEvent) error
 
 ### Operator
 
-Operator defined the functions need to be implemented for the target container to replicate data.
+Operator interface defined the methods need to be implemented for the target container to deal with [change event](https://docs.mongodb.com/manual/reference/change-events/) documents.
 
 ```go
 type Operator interface {
@@ -60,16 +60,10 @@ type Operator interface {
 
 You can implement your own Operator to customize the replication logic.
 
-## Getting Started
+## Usage and Example
 
-Import packages of Mongo Replicator into your project.
-
-```go
-import "github.com/whhe/mongo-replicator"
-```
-
-See [example_test.go](example_test.go) for reference.
+See [example](example_test.go) and [godoc](https://godoc.org/github.com/whhe/mongo-replicator) for reference.
 
 ## License
 
-Mongo Replicator is released under the Apache 2.0 license. See [LICENSE](LICENSE)
+[Apache 2.0 License](LICENSE)

collector_test.go

@@ -0,0 +1,36 @@
+package replicator_test
+
+import (
+	"context"
+	"log"
+
+	"github.com/whhe/mongo-replicator"
+)
+
+var collector = &replicator.Collector{}
+
+func doCollect(*replicator.Collector)         {}
+func newCollectorFunc() *replicator.Collector { return collector }
+
+func ExampleNewCollector() {
+	// set source mongodb and watch scope
+	uri := "mongodb://username@password@host:port"
+	db := []string{"db"}
+	coll := []string{"coll_1", "coll_2"}
+
+	collector := replicator.NewCollector(uri, db, coll)
+
+	doCollect(collector)
+}
+
+func ExampleCollector_Collect() {
+	collector := newCollectorFunc()
+
+	stream, err := collector.Collect()
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer stream.Close(context.TODO())
+
+	// ... do some work ...
+}

example_test.go

@@ -4,40 +4,42 @@ import (
 	"context"
 	"log"
 
-	"go.mongodb.org/mongo-driver/bson"
-
 	"github.com/whhe/mongo-replicator"
 	"github.com/whhe/mongo-replicator/model"
-	"github.com/whhe/mongo-replicator/operator/mongo"
-	"github.com/whhe/mongo-replicator/token/redis"
 )
 
-var changeEvent = model.ChangeEvent{}
-var newResumeToken = bson.Raw{}
+var exampleReplicator = &replicator.Replicator{}
+
+func newReplicatorFunc() *replicator.Replicator { return exampleReplicator }
 
-func ExampleNewCollector() {
-	// set source mongodb and watch scope
-	uri := "mongodb://username@password@host:port"
-	db := []string{"db"}
-	coll := []string{"coll_1", "coll_2"}
+func Example() {
+	// create a collector
+	collector := newCollectorFunc()
 
-	// create a collector instance and start collecting change stream
-	collector := replicator.NewCollector(uri, db, coll)
+	// start collecting change streams
 	stream, err := collector.Collect()
 	if err != nil {
 		log.Fatal(err)
 	}
 	defer stream.Close(context.TODO())
 
-	// iterate the change stream and do some work with the change event document until
-	// the change stream is closed by the server or there is an error getting the next event
+	// create a replicator
+	repl := newReplicatorFunc()
+
+	// iterate the change stream and sync change event until the change stream is
+	// closed by the server or there is an error getting the next event document
 	for {
 		if stream.TryNext(context.TODO()) {
 			var event model.ChangeEvent
 			if err := stream.Decode(&event); err != nil {
 				log.Fatal(err)
 			}
-			// ... do some work ...
+
+			// replicate data using change event
+			if err := repl.Replicate(event); err != nil {
+				log.Fatal(err)
+			}
+
 			continue
 		}
 
@@ -50,44 +52,3 @@ func ExampleNewCollector() {
 		}
 	}
 }
-
-func ExampleNewReplicator() {
-	// create an mongo operator to be used by the replicator
-	mo, err := mongo.NewOperator("mongodb://localhost:27017")
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	// create a replicator instance and replicate a change event
-	repl := replicator.NewReplicator(mo)
-	err = repl.Replicate(changeEvent)
-	if err != nil {
-		log.Fatal(err)
-	}
-}
-
-func ExampleNewTokenManager() {
-	// set redis uri and resume token key
-	uri := "redis://:password@host:port/db"
-	key := "resumeToken"
-
-	// create a token manager instance
-	manager, err := redis.NewTokenManager(uri, key)
-	if err != nil {
-		log.Fatal(err)
-	}
-	defer manager.Close()
-
-	// get the latest resume token
-	resumeToken, err := manager.Get()
-	if err != nil {
-		log.Fatal(err)
-	}
-	log.Print("resume token:", resumeToken)
-
-	// save the latest resume token
-	err = manager.Set(newResumeToken)
-	if err != nil {
-		log.Fatal(err)
-	}
-}

replicator_test.go

@@ -0,0 +1,23 @@
+package replicator_test
+
+import (
+	"log"
+
+	"github.com/whhe/mongo-replicator"
+	"github.com/whhe/mongo-replicator/operator/mongo"
+)
+
+func doReplicate(*replicator.Replicator) {}
+
+func ExampleNewReplicator_mongo() {
+	// create a mongo operator to be used by the replicator
+	mo, err := mongo.NewOperator("mongodb://localhost:27017")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// create a replicator using mongo operator
+	exampleReplicator := replicator.NewReplicator(mo)
+
+	doReplicate(exampleReplicator)
+}

token/redis/redis_test.go

@@ -0,0 +1,22 @@
+package redis_test
+
+import (
+	"log"
+
+	"github.com/whhe/mongo-replicator/token/redis"
+)
+
+func ExampleNewTokenManager() {
+	// set redis uri and resume token key
+	uri := "redis://:password@host:port/db"
+	key := "resumeToken"
+
+	// create a token manager instance
+	manager, err := redis.NewTokenManager(uri, key)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer manager.Close()
+
+	// ... get and set resume token ...
+}