Make remote joins use parallel http requests

docs/guide.md

@@ -345,13 +345,17 @@ class AddSearchColumn < ActiveRecord::Migration[5.1]
 end
 ```
 
-## Join with remote REST APIs
+## Remote Joins
 
-It often happens that after fetching some data from the DB we need to call another API to fetch some more data and all this combined into a single JSON response. For example along with a list of users you need their last 5 payments from Stripe. This requires you to query your DB for the users and Stripe for the payments. Super Graph handles all this for you also only the fields you requested from the Stripe API are returned. All this is a very performance focused way.
+It often happens that after fetching some data from the DB we need to call another API to fetch some more data and all this combined into a single JSON response. For example along with a list of users you need their last 5 payments from Stripe. This requires you to query your DB for the users and Stripe for the payments. Super Graph handles all this for you also only the fields you requested from the Stripe API are returned. 
+
+::: tip Is this fast?
+Super Graph is able fetch remote data and merge it with the DB response in an efficient manner. Several optimizations such as parallel HTTP requests and a zero-allocation JSON merge algorithm makes this very fast. All of this without you having to write a line of code.
+:::
 
 For example you need to list the last 3 payments made by a user. You will first need to look up the user in the database and then call the Stripe API to fetch his last 3 payments. For this to work your user table in the db has a `customer_id` column that contains his Stripe customer ID.
 
-Similiarly you might also have the need to fetch the users last tweet and include that too. Super Graph can handle this for you using it's `API Stitching` feature.
+Similiarly you could also fetch the users last tweet, lead info from Salesforce or whatever else you need. It's fine to mix up several different `remote joins` into a single GraphQL query.
 
 ### Stripe API example
 

psql/bench.0

@@ -1,6 +1,7 @@
 goos: darwin
 goarch: amd64
 pkg: github.com/dosco/super-graph/psql
-BenchmarkCompileGQLToSQL-8   	   50000	     38882 ns/op	   15177 B/op	     266 allocs/op
+BenchmarkCompile-8           	   50000	     38531 ns/op	    5175 B/op	     148 allocs/op
+BenchmarkCompileParallel-8   	  200000	     11472 ns/op	    5237 B/op	     148 allocs/op
 PASS
-ok  	github.com/dosco/super-graph/psql	2.473s
+ok  	github.com/dosco/super-graph/psql	4.686s

psql/bench.1

@@ -1,6 +0,0 @@
-goos: darwin
-goarch: amd64
-pkg: github.com/dosco/super-graph/psql
-BenchmarkCompileGQLToSQL-8   	   50000	     39601 ns/op	   20165 B/op	     263 allocs/op
-PASS
-ok  	github.com/dosco/super-graph/psql	2.549s

psql/bench.2

@@ -1,6 +0,0 @@
-goos: darwin
-goarch: amd64
-pkg: github.com/dosco/super-graph/psql
-BenchmarkCompileGQLToSQL-8   	   50000	     35559 ns/op	    8453 B/op	     228 allocs/op
-PASS
-ok  	github.com/dosco/super-graph/psql	2.162s

psql/bench.3

@@ -1,6 +0,0 @@
-goos: darwin
-goarch: amd64
-pkg: github.com/dosco/super-graph/psql
-BenchmarkCompileGQLToSQL-8   	   50000	     28320 ns/op	    7698 B/op	     154 allocs/op
-PASS
-ok  	github.com/dosco/super-graph/psql	1.724s

psql/psql.go

@@ -91,7 +91,7 @@ func (c *Compiler) Compile(qc *qcode.QCode, w *bytes.Buffer) (uint32, error) {
 			ignored |= skipped
 
 			for _, id := range v.sel.Children {
-				if hasBit(skipped, id) {
+				if hasBit(skipped, uint16(id)) {
 					continue
 				}
 				child := &qc.Query.Selects[id]
@@ -377,7 +377,7 @@ func (v *selectBlock) renderJoinedColumns(w *bytes.Buffer, skipped uint32) error
 	colsRendered := len(v.sel.Cols) != 0
 
 	for _, id := range v.sel.Children {
-		skipThis := hasBit(skipped, id)
+		skipThis := hasBit(skipped, uint16(id))
 
 		if colsRendered && !skipThis {
 			io.WriteString(w, ", ")
@@ -884,7 +884,7 @@ func alias(w *bytes.Buffer, alias string) {
 	w.WriteString(`"`)
 }
 
-func aliasWithID(w *bytes.Buffer, alias string, id uint16) {
+func aliasWithID(w *bytes.Buffer, alias string, id int16) {
 	w.WriteString(` AS "`)
 	w.WriteString(alias)
 	w.WriteString(`_`)
@@ -892,7 +892,7 @@ func aliasWithID(w *bytes.Buffer, alias string, id uint16) {
 	w.WriteString(`"`)
 }
 
-func aliasWithIDSuffix(w *bytes.Buffer, alias string, id uint16, suffix string) {
+func aliasWithIDSuffix(w *bytes.Buffer, alias string, id int16, suffix string) {
 	w.WriteString(` AS "`)
 	w.WriteString(alias)
 	w.WriteString(`_`)
@@ -917,7 +917,7 @@ func colWithTable(w *bytes.Buffer, table, col string) {
 	w.WriteString(`"`)
 }
 
-func colWithTableID(w *bytes.Buffer, table string, id uint16, col string) {
+func colWithTableID(w *bytes.Buffer, table string, id int16, col string) {
 	w.WriteString(`"`)
 	w.WriteString(table)
 	w.WriteString(`_`)
@@ -927,7 +927,7 @@ func colWithTableID(w *bytes.Buffer, table string, id uint16, col string) {
 	w.WriteString(`"`)
 }
 
-func colWithTableIDAlias(w *bytes.Buffer, table string, id uint16, col, alias string) {
+func colWithTableIDAlias(w *bytes.Buffer, table string, id int16, col, alias string) {
 	w.WriteString(`"`)
 	w.WriteString(table)
 	w.WriteString(`_`)
@@ -939,7 +939,7 @@ func colWithTableIDAlias(w *bytes.Buffer, table string, id uint16, col, alias st
 	w.WriteString(`"`)
 }
 
-func colWithTableIDSuffixAlias(w *bytes.Buffer, table string, id uint16,
+func colWithTableIDSuffixAlias(w *bytes.Buffer, table string, id int16,
 	suffix, col, alias string) {
 	w.WriteString(`"`)
 	w.WriteString(table)
@@ -953,7 +953,7 @@ func colWithTableIDSuffixAlias(w *bytes.Buffer, table string, id uint16,
 	w.WriteString(`"`)
 }
 
-func tableIDColSuffix(w *bytes.Buffer, table string, id uint16, col, suffix string) {
+func tableIDColSuffix(w *bytes.Buffer, table string, id int16, col, suffix string) {
 	w.WriteString(`"`)
 	w.WriteString(table)
 	w.WriteString(`_`)
@@ -966,18 +966,18 @@ func tableIDColSuffix(w *bytes.Buffer, table string, id uint16, col, suffix stri
 
 const charset = "0123456789"
 
-func int2string(w *bytes.Buffer, val uint16) {
+func int2string(w *bytes.Buffer, val int16) {
 	if val < 10 {
 		w.WriteByte(charset[val])
 		return
 	}
 
-	temp := uint16(0)
+	temp := int16(0)
 	val2 := val
 	for val2 > 0 {
 		temp *= 10
 		temp += val2 % 10
-		val2 = uint16(math.Floor(float64(val2 / 10)))
+		val2 = int16(math.Floor(float64(val2 / 10)))
 	}
 
 	val3 := temp

psql/psql_test.go

@@ -480,45 +480,68 @@ func TestCompileGQL(t *testing.T) {
 	t.Run("syntheticTables", syntheticTables)
 }
 
-func BenchmarkCompileGQLToSQL(b *testing.B) {
+var benchGQL = `query {
-	gql := `query {
+	products(
-		products(
+		# returns only 30 items
-			# returns only 30 items
+		limit: 30,
-			limit: 30,
 
-			# starts from item 10, commented out for now
+		# starts from item 10, commented out for now
-			# offset: 10,
+		# offset: 10,
 
-			# orders the response items by highest price
+		# orders the response items by highest price
-			order_by: { price: desc },
+		order_by: { price: desc },
 
-			# only items with an id >= 30 and < 30 are returned
+		# only items with an id >= 30 and < 30 are returned
-			where: { id: { and: { greater_or_equals: 20, lt: 28 } } }) {
+		where: { id: { and: { greater_or_equals: 20, lt: 28 } } }) {
-			id
+		id
-			name
+		name
-			price
+		price
-			user {
+		user {
-				full_name
+			full_name
-				picture : avatar
+			picture : avatar
-			}
 		}
-	}`
+	}
+}`
 
-	w := &bytes.Buffer()
+func BenchmarkCompile(b *testing.B) {
+	w := &bytes.Buffer{}
 
 	b.ResetTimer()
 	b.ReportAllocs()
 
 	for n := 0; n < b.N; n++ {
-		qc, err := qcompile.CompileQuery(gql)
+		w.Reset()
+
+		qc, err := qcompile.CompileQuery(benchGQL)
 		if err != nil {
 			b.Fatal(err)
 		}
 
-		_, sqlStmt, err := pcompile.Compile(qc, w)
+		_, err = pcompile.Compile(qc, w)
 		if err != nil {
 			b.Fatal(err)
 		}
-		w.Reset()
 	}
 }
+
+func BenchmarkCompileParallel(b *testing.B) {
+	b.ReportAllocs()
+
+	b.RunParallel(func(pb *testing.PB) {
+		w := &bytes.Buffer{}
+
+		for pb.Next() {
+			w.Reset()
+
+			qc, err := qcompile.CompileQuery(benchGQL)
+			if err != nil {
+				b.Fatal(err)
+			}
+
+			_, err = pcompile.Compile(qc, w)
+			if err != nil {
+				b.Fatal(err)
+			}
+		}
+	})
+}

qcode/parse.go

@@ -48,14 +48,14 @@ func (o *Operation) Reset() {
 }
 
 type Field struct {
-	ID        uint16
+	ID        int16
 	Name      string
 	Alias     string
 	Args      []Arg
 	argsA     [10]Arg
-	ParentID  uint16
+	ParentID  int16
-	Children  []uint16
+	Children  []int16
-	childrenA [10]uint16
+	childrenA [10]int16
 }
 
 type Arg struct {
@@ -277,7 +277,7 @@ func (p *Parser) parseFields(fields []Field) ([]Field, error) {
 			return nil, errors.New("expecting an alias or field name")
 		}
 
-		fields = append(fields, Field{ID: uint16(len(fields))})
+		fields = append(fields, Field{ID: int16(len(fields))})
 		f := &fields[(len(fields) - 1)]
 		f.Args = f.argsA[:0]
 		f.Children = f.childrenA[:0]
@@ -288,7 +288,7 @@ func (p *Parser) parseFields(fields []Field) ([]Field, error) {
 
 		if f.ID != 0 {
 			intf := st.Peek()
-			pid, ok := intf.(uint16)
+			pid, ok := intf.(int16)
 
 			if !ok {
 				return nil, fmt.Errorf("14: unexpected value %v (%t)", intf, intf)

qcode/qcode.go

@@ -29,8 +29,8 @@ type Column struct {
 }
 
 type Select struct {
-	ID         uint16
+	ID         int16
-	ParentID   uint16
+	ParentID   int16
 	RelID      uint64
 	Args       map[string]*Node
 	AsList     bool
@@ -42,7 +42,7 @@ type Select struct {
 	OrderBy    []*OrderBy
 	DistinctOn []string
 	Paging     Paging
-	Children   []uint16
+	Children   []int16
 }
 
 type Exp struct {
@@ -197,7 +197,8 @@ func (com *Compiler) CompileQuery(query string) (*QCode, error) {
 }
 
 func (com *Compiler) compileQuery(op *Operation) (*Query, error) {
-	var id, parentID uint16
+	id := int16(0)
+	parentID := int16(-1)
 
 	selects := make([]Select, 0, 5)
 	st := util.NewStack()
@@ -218,7 +219,7 @@ func (com *Compiler) compileQuery(op *Operation) (*Query, error) {
 		}
 
 		intf := st.Pop()
-		fid, ok := intf.(uint16)
+		fid, ok := intf.(int16)
 
 		if !ok {
 			return nil, fmt.Errorf("15: unexpected value %v (%t)", intf, intf)
@@ -235,7 +236,7 @@ func (com *Compiler) compileQuery(op *Operation) (*Query, error) {
 			ID:       id,
 			ParentID: parentID,
 			Table:    tn,
-			Children: make([]uint16, 0, 5),
+			Children: make([]int16, 0, 5),
 		}
 
 		if s.ID != 0 {

serv/core.go

@@ -8,6 +8,7 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"sync"
 	"time"
 
 	"github.com/cespare/xxhash/v2"
@@ -74,10 +75,6 @@ func (c *coreContext) handleReq(w io.Writer, req *http.Request) error {
 		return errors.New("something wrong no remote ids found in db response")
 	}
 
-	if err != nil {
-		return err
-	}
-
 	var ob bytes.Buffer
 
 	err = jsn.Replace(&ob, data, from, to)
@@ -131,7 +128,7 @@ func (c *coreContext) resolveRemote(
 	}
 
 	if conf.EnableTracing {
-		c.addTrace(s, st)
+		c.addTrace(sel, s.ID, st)
 	}
 
 	if len(r.Path) != 0 {
@@ -163,9 +160,14 @@ func (c *coreContext) resolveRemotes(
 
 	// replacement data for the marked insertion points
 	// key and value will be replaced by whats below
-	to := make([]jsn.Field, 0, len(from))
+	to := make([]jsn.Field, len(from))
 
-	for _, id := range from {
+	var wg sync.WaitGroup
+	wg.Add(len(from))
+
+	var cerr error
+
+	for i, id := range from {
 
 		// use the json key to find the related Select object
 		k1 := xxhash.Sum64(id.Key)
@@ -190,39 +192,48 @@ func (c *coreContext) resolveRemotes(
 			return nil, nil
 		}
 
-		st := time.Now()
+		go func(n int) {
+			defer wg.Done()
 
-		b, err := r.Fn(req, id)
+			st := time.Now()
-		if err != nil {
-			return nil, err
-		}
 
-		if conf.EnableTracing {
+			b, err := r.Fn(req, id)
-			c.addTrace(s, st)
-		}
-
-		if len(r.Path) != 0 {
-			b = jsn.Strip(b, r.Path)
-		}
-
-		var ob bytes.Buffer
-
-		if len(s.Cols) != 0 {
-			err = jsn.Filter(&ob, b, colsToList(s.Cols))
 			if err != nil {
-				return nil, err
+				cerr = err
+				return
 			}
 
-		} else {
+			if conf.EnableTracing {
-			ob.WriteString("null")
+				c.addTrace(sel, s.ID, st)
-		}
+			}
 
-		to = append(to, jsn.Field{[]byte(s.FieldName), ob.Bytes()})
+			if len(r.Path) != 0 {
+				b = jsn.Strip(b, r.Path)
+			}
+
+			var ob bytes.Buffer
+
+			if len(s.Cols) != 0 {
+				err = jsn.Filter(&ob, b, colsToList(s.Cols))
+				if err != nil {
+					cerr = err
+					return
+				}
+
+			} else {
+				ob.WriteString("null")
+			}
+
+			to[n] = jsn.Field{[]byte(s.FieldName), ob.Bytes()}
+		}(i)
 	}
-	return to, nil
+	wg.Wait()
+
+	return to, cerr
 }
 
-func (c *coreContext) resolveSQL(qc *qcode.QCode, vars variables) ([]byte, uint32, error) {
+func (c *coreContext) resolveSQL(qc *qcode.QCode, vars variables) (
+	[]byte, uint32, error) {
 
 	// var entry []byte
 	// var key string
@@ -291,7 +302,10 @@ func (c *coreContext) resolveSQL(qc *qcode.QCode, vars variables) ([]byte, uint3
 	}
 
 	if conf.EnableTracing && len(qc.Query.Selects) != 0 {
-		c.addTrace(&qc.Query.Selects[0], st)
+		c.addTrace(
+			qc.Query.Selects,
+			qc.Query.Selects[0].ID,
+			st)
 	}
 
 	return []byte(root), skipped, nil
@@ -302,7 +316,7 @@ func (c *coreContext) render(w io.Writer, data []byte) error {
 	return json.NewEncoder(w).Encode(c.res)
 }
 
-func (c *coreContext) addTrace(sel *qcode.Select, st time.Time) {
+func (c *coreContext) addTrace(sel []qcode.Select, id int16, st time.Time) {
 	et := time.Now()
 	du := et.Sub(st)
 
@@ -317,10 +331,22 @@ func (c *coreContext) addTrace(sel *qcode.Select, st time.Time) {
 	c.res.Extensions.Tracing.EndTime = et
 	c.res.Extensions.Tracing.Duration = du
 
+	n := 0
+	for i := id; i != -1; i = sel[i].ParentID {
+		n++
+	}
+
+	path := make([]string, n)
+	n--
+	for i := id; i != -1; i = sel[i].ParentID {
+		path[n] = sel[i].Table
+		n--
+	}
+
 	tr := resolver{
-		Path:        []string{sel.Table},
+		Path:        path,
 		ParentType:  "Query",
-		FieldName:   sel.Table,
+		FieldName:   sel[id].Table,
 		ReturnType:  "object",
 		StartOffset: 1,
 		Duration:    du,
@@ -337,7 +363,7 @@ func parentFieldIds(h *xxhash.Digest, sel []qcode.Select, skipped uint32) (
 	c := 0
 	for i := range sel {
 		s := &sel[i]
-		if isSkipped(skipped, s.ID) {
+		if isSkipped(skipped, uint16(s.ID)) {
 			c++
 		}
 	}
@@ -354,7 +380,7 @@ func parentFieldIds(h *xxhash.Digest, sel []qcode.Select, skipped uint32) (
 	for i := range sel {
 		s := &sel[i]
 
-		if isSkipped(skipped, s.ID) == false {
+		if isSkipped(skipped, uint16(s.ID)) == false {
 			continue
 		}