Add pessimistic locking, more tests

CURLs.txt

@@ -8,7 +8,8 @@ GET:
 
 POST (Create):
 
- curl -v -H "Content-Type: application/json" -d '{"name":"test recipe","preptime":1.11,"difficulty":1,"vegetarian":false}' localhost/v1/recipes
+ curl -v -H "Content-Type: application/json" -d '{"id":1,"name":"test recipe","preptime":1.11,"difficulty":1,"vegetarian":false}' localhost/v1/recipes
+ curl -v -H "Content-Type: application/json" -d '{"id":2,"name":"test recipe 2","preptime":1.22,"difficulty":2,"vegetarian":true}' localhost/v1/recipes
 
 PUT (Update):
 

README.md

@@ -77,6 +77,8 @@ returning JSON documents.
 Similiar to __redis__ and __Cassandra__, data may be assigned arbitrary
 expiry times.
 
+Couchbase offers both [optimistic and pessimistic locking](http://docs.couchbase.com/go-sdk/1.5/concurrent-mutations-cluster.html).
+
 Couchbase is packaged with an Admin Console GUI.
 
 #### Getting familiar with Couchbase
@@ -364,10 +366,15 @@ Query Optimization Using Prepared (Optimized) Statements:
 
  http://docs.couchbase.com/go-sdk/1.5/n1ql-query.html#prepare-stmts
 
+Concurrent Document Mutations
+
+ http://docs.couchbase.com/go-sdk/1.5/concurrent-mutations-cluster.html
+
 ## To Do
 
 - [x] Learn [N1QL](http://docs.couchbase.com/server/6.0/getting-started/try-a-query.html)
 - [ ] Investigate using views to enforce constraints (indexes are a performance nightmare)
 - [x] Add Travis CI build process & code coverage reporting
+- [x] Add pessimistic locking to updates
 - [ ] Update build process to `vgo`
 - [ ] Add tests for data TTL

src/application/app.go

@@ -79,7 +79,11 @@ func (a *App) modifyRecipeEndpoint(w http.ResponseWriter, req *http.Request) {
  }
  defer req.Body.Close()
  if err := r.UpdateRecipe(recipeID, a.DB); err != nil {
- respondWithError(w, http.StatusInternalServerError, err.Error())
+ if gocb.IsKeyNotFoundError(err) {
+ respondWithError(w, http.StatusNotFound, err.Error())
+ } else {
+ respondWithError(w, http.StatusInternalServerError, err.Error())
+ }
  return
  }
  respondWithJSON(w, http.StatusOK, r)
@@ -115,8 +119,12 @@ func (a *App) addRatingEndpoint(w http.ResponseWriter, req *http.Request) {
  }
  defer req.Body.Close()
  if err := rr.AddRecipeRating(a.DB); err != nil {
- respondWithError(w, http.StatusInternalServerError, err.Error())
- return
+ if gocb.IsKeyNotFoundError(err) {
+ respondWithError(w, http.StatusNotFound, err.Error())
+ } else {
+ respondWithError(w, http.StatusInternalServerError, err.Error())
+ return
+ }
  }
  respondWithJSON(w, http.StatusCreated, rr)
 }

src/recipes/models.go

@@ -56,16 +56,21 @@ func (r *Recipe) GetRecipe(id string, db *gocb.Bucket) error {
 // The recipe ID and the recipe ratings will not be changed.
 func (r *Recipe) UpdateRecipe(id string, db *gocb.Bucket) error {
 
- updateRecipeQuery := gocb.NewN1qlQuery("UPDATE recipes USE KEYS $1 SET name = $2, preptime = $3, difficulty = $4, vegetarian = $5").AdHoc(false)
+ var recipe Recipe
 
- var params []interface{}
- params = append(params, id)
- params = append(params, r.Name)
- params = append(params, r.PrepTime)
- params = append(params, r.Difficulty)
- params = append(params, r.Vegetarian)
+ // Get document, 3 second lock
+ cas, err := db.GetAndLock(id, 3, &recipe)
+ if err != nil {
+ return err
+ }
+
+ recipe.Name = r.Name
+ recipe.PrepTime = r.PrepTime
+ recipe.Difficulty = r.Difficulty
+ recipe.Vegetarian = r.Vegetarian
 
- _, err := db.ExecuteN1qlQuery(updateRecipeQuery, params)
+ // Mutating unlocks the document
+ _, err = db.Replace(id, recipe, cas, 0)
  if err != nil {
  return err
  }
@@ -178,30 +183,22 @@ func GetRecipesRated(db *gocb.Bucket, start int, count int, preptime float32) ([
 // and the ratings are never overwritten.
 func (rr *RecipeRating) AddRecipeRating(db *gocb.Bucket) error {
 
- getRecipeQuery := gocb.NewN1qlQuery("SELECT ratings FROM recipes AS results USE KEYS $1").AdHoc(false)
-
  id := strconv.Itoa(int(rr.RecipeID))
 
- var params []interface{}
- params = append(params, id)
+ var recipe Recipe
 
- rs, err := db.ExecuteN1qlQuery(getRecipeQuery, params)
+ // Get document, 3 second lock
+ cas, err := db.GetAndLock(id, 3, &recipe)
  if err != nil {
  return err
  }
- defer rs.Close()
-
- var row n1qlRatings
- rs.One(&row)
 
- ratings := row.Ratings
+ ratings := recipe.Ratings
  ratings = append(ratings, rr.Rating)
+ recipe.Ratings = ratings
 
- updateRecipeQuery := gocb.NewN1qlQuery("UPDATE recipes USE KEYS $1 SET ratings = $2").AdHoc(false)
-
- params = append(params, ratings)
-
- _, err = db.ExecuteN1qlQuery(updateRecipeQuery, params)
+ // Mutating unlocks the document
+ _, err = db.Replace(id, recipe, cas, 0)
  if err != nil {
  return err
  }

src/test/main_test.go

@@ -17,6 +17,10 @@ import (
  "gopkg.in/couchbase/gocb.v1"
 )
 
+const (
+ sleepTime = 6 // 6 seconds
+)
+
 var app application.App
 
 func TestMain(m *testing.M) {
@@ -63,6 +67,61 @@ func TestGetNonExistentRecipe(t *testing.T) {
  }
 }
 
+func TestUpdatePutNonExistentRecipe(t *testing.T) {
+ clearTables()
+
+ payload := []byte(`{"name":"test recipe - put","preptime":11.11,"difficulty":3,"vegetarian":false}`)
+
+ req, err := http.NewRequest("PUT", "/v1/recipes/1", bytes.NewBuffer(payload))
+ if err != nil {
+ t.Errorf("Error on http.NewRequest (PUT): %s", err)
+ }
+ response := executeRequest(req)
+ checkResponseCode(t, http.StatusNotFound, response)
+
+ var m map[string]string
+ json.Unmarshal(response.Body.Bytes(), &m)
+ if m["error"] != "key not found" {
+ t.Errorf("Expected the 'error' of the response to be set to 'key not found'. Got '%s'", m["error"])
+ }
+}
+
+func TestUpdatePatchNonExistentRecipe(t *testing.T) {
+ clearTables()
+
+ payload := []byte(`{"name":"test recipe - patch","preptime":22.22,"difficulty":4,"vegetarian":false}`)
+
+ req, err := http.NewRequest("PATCH", "/v1/recipes/1", bytes.NewBuffer(payload))
+ if err != nil {
+ t.Errorf("Error on http.NewRequest (PATCH): %s", err)
+ }
+ response := executeRequest(req)
+ checkResponseCode(t, http.StatusNotFound, response)
+
+ var m map[string]string
+ json.Unmarshal(response.Body.Bytes(), &m)
+ if m["error"] != "key not found" {
+ t.Errorf("Expected the 'error' of the response to be set to 'key not found'. Got '%s'", m["error"])
+ }
+}
+
+func TestDeleteNonExistentRecipe(t *testing.T) {
+ clearTables()
+
+ req, err := http.NewRequest("DELETE", "/v1/recipes/1", nil)
+ if err != nil {
+ t.Errorf("Error on http.NewRequest (Second DELETE): %s", err)
+ }
+ response := executeRequest(req)
+ checkResponseCode(t, http.StatusNotFound, response)
+
+ var m map[string]string
+ json.Unmarshal(response.Body.Bytes(), &m)
+ if m["error"] != "key not found" {
+ t.Errorf("Expected the 'error' of the response to be set to 'key not found'. Got '%s'", m["error"])
+ }
+}
+
 func TestCreateRecipe(t *testing.T) {
  clearTables()
 
@@ -315,12 +374,25 @@ func TestAddRating(t *testing.T) {
  checkResponseCode(t, http.StatusCreated, response)
 }
 
+func TestAddRatingNonExistentRecipe(t *testing.T) {
+ clearTables()
+
+ payload := []byte(`{"rating":3}`)
+
+ req, err := http.NewRequest("POST", "/v1/recipes/1/rating", bytes.NewBuffer(payload))
+ if err != nil {
+ t.Errorf("Error on http.NewRequest (2nd POST): %s", err)
+ }
+ response := executeRequest(req)
+ checkResponseCode(t, http.StatusNotFound, response)
+}
+
 func TestGetRecipes(t *testing.T) {
  clearTables()
  addRecipes(1, 2)
 
- // Sleep for 5 seconds to allow Couchbase time to commit
- time.Sleep(5 * time.Second)
+ // Sleep the specified number of seconds to allow Couchbase time to commit
+ time.Sleep(sleepTime * time.Second)
 
  var bb bytes.Buffer
  mw := multipart.NewWriter(&bb)
@@ -376,8 +448,8 @@ func TestSearch(t *testing.T) {
  response = executeRequest(req)
  checkResponseCode(t, http.StatusCreated, response)
 
- // Sleep for 5 seconds to allow Couchbase time to commit
- time.Sleep(5 * time.Second)
+ // Sleep the specified number of seconds to allow Couchbase time to commit
+ time.Sleep(sleepTime * time.Second)
 
  var bb bytes.Buffer
  mw := multipart.NewWriter(&bb)
@@ -429,8 +501,8 @@ func TestSearch(t *testing.T) {
 
  addRecipes(2, 12)
 
- // Sleep for 5 seconds to allow Couchbase time to commit
- time.Sleep(5 * time.Second)
+ // Sleep the specified number of seconds to allow Couchbase time to commit
+ time.Sleep(sleepTime * time.Second)
 
  mw = multipart.NewWriter(&bb)
  mw.WriteField("count", "20") // Should get reset to 10