fix: race in node pool object cleanup

core/bench.11

@@ -1,41 +0,0 @@
-INF roles_query not defined: attribute based access control disabled
-all expectations were already fulfilled, call to Query 'SELECT jsonb_build_object('users', "__sj_0"."json", 'products', "__sj_1"."json") as "__root" FROM (SELECT coalesce(jsonb_agg("__sj_1"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_1".*) AS "json"FROM (SELECT "products_1"."id" AS "id", "products_1"."name" AS "name", "__sj_2"."json" AS "customers", "__sj_3"."json" AS "user" FROM (SELECT "products"."id", "products"."name", "products"."user_id" FROM "products" LIMIT ('20') :: integer) AS "products_1" LEFT OUTER JOIN LATERAL (SELECT to_jsonb("__sr_3".*) AS "json"FROM (SELECT "users_3"."full_name" AS "full_name", "users_3"."phone" AS "phone", "users_3"."email" AS "email" FROM (SELECT "users"."full_name", "users"."phone", "users"."email" FROM "users" WHERE ((("users"."id") = ("products_1"."user_id"))) LIMIT ('1') :: integer) AS "users_3") AS "__sr_3") AS "__sj_3" ON ('true') LEFT OUTER JOIN LATERAL (SELECT coalesce(jsonb_agg("__sj_2"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_2".*) AS "json"FROM (SELECT "customers_2"."id" AS "id", "customers_2"."email" AS "email" FROM (SELECT "customers"."id", "customers"."email" FROM "customers" LEFT OUTER JOIN "purchases" ON (("purchases"."product_id") = ("products_1"."id")) WHERE ((("customers"."id") = ("purchases"."customer_id"))) LIMIT ('20') :: integer) AS "customers_2") AS "__sr_2") AS "__sj_2") AS "__sj_2" ON ('true')) AS "__sr_1") AS "__sj_1") AS "__sj_1", (SELECT coalesce(jsonb_agg("__sj_0"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_0".*) AS "json"FROM (SELECT "users_0"."id" AS "id", "users_0"."name" AS "name" FROM (SELECT "users"."id" FROM "users" GROUP BY "users"."id" LIMIT ('20') :: integer) AS "users_0") AS "__sr_0") AS "__sj_0") AS "__sj_0"' with args [] was not expected
-goos: darwin
-goarch: amd64
-pkg: github.com/dosco/super-graph/core
-BenchmarkGraphQL-16    	INF roles_query not defined: attribute based access control disabled
-all expectations were already fulfilled, call to Query 'SELECT jsonb_build_object('users', "__sj_0"."json", 'products', "__sj_1"."json") as "__root" FROM (SELECT coalesce(jsonb_agg("__sj_1"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_1".*) AS "json"FROM (SELECT "products_1"."id" AS "id", "products_1"."name" AS "name", "__sj_2"."json" AS "customers", "__sj_3"."json" AS "user" FROM (SELECT "products"."id", "products"."name", "products"."user_id" FROM "products" LIMIT ('20') :: integer) AS "products_1" LEFT OUTER JOIN LATERAL (SELECT to_jsonb("__sr_3".*) AS "json"FROM (SELECT "users_3"."full_name" AS "full_name", "users_3"."phone" AS "phone", "users_3"."email" AS "email" FROM (SELECT "users"."full_name", "users"."phone", "users"."email" FROM "users" WHERE ((("users"."id") = ("products_1"."user_id"))) LIMIT ('1') :: integer) AS "users_3") AS "__sr_3") AS "__sj_3" ON ('true') LEFT OUTER JOIN LATERAL (SELECT coalesce(jsonb_agg("__sj_2"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_2".*) AS "json"FROM (SELECT "customers_2"."id" AS "id", "customers_2"."email" AS "email" FROM (SELECT "customers"."id", "customers"."email" FROM "customers" LEFT OUTER JOIN "purchases" ON (("purchases"."product_id") = ("products_1"."id")) WHERE ((("customers"."id") = ("purchases"."customer_id"))) LIMIT ('20') :: integer) AS "customers_2") AS "__sr_2") AS "__sj_2") AS "__sj_2" ON ('true')) AS "__sr_1") AS "__sj_1") AS "__sj_1", (SELECT coalesce(jsonb_agg("__sj_0"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_0".*) AS "json"FROM (SELECT "users_0"."id" AS "id", "users_0"."name" AS "name" FROM (SELECT "users"."id" FROM "users" GROUP BY "users"."id" LIMIT ('20') :: integer) AS "users_0") AS "__sr_0") AS "__sj_0") AS "__sj_0"' with args [] was not expected
-INF roles_query not defined: attribute based access control disabled
-all expectations were already fulfilled, call to Query 'SELECT jsonb_build_object('users', "__sj_0"."json", 'products', "__sj_1"."json") as "__root" FROM (SELECT coalesce(jsonb_agg("__sj_1"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_1".*) AS "json"FROM (SELECT "products_1"."id" AS "id", "products_1"."name" AS "name", "__sj_2"."json" AS "customers", "__sj_3"."json" AS "user" FROM (SELECT "products"."id", "products"."name", "products"."user_id" FROM "products" LIMIT ('20') :: integer) AS "products_1" LEFT OUTER JOIN LATERAL (SELECT to_jsonb("__sr_3".*) AS "json"FROM (SELECT "users_3"."full_name" AS "full_name", "users_3"."phone" AS "phone", "users_3"."email" AS "email" FROM (SELECT "users"."full_name", "users"."phone", "users"."email" FROM "users" WHERE ((("users"."id") = ("products_1"."user_id"))) LIMIT ('1') :: integer) AS "users_3") AS "__sr_3") AS "__sj_3" ON ('true') LEFT OUTER JOIN LATERAL (SELECT coalesce(jsonb_agg("__sj_2"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_2".*) AS "json"FROM (SELECT "customers_2"."id" AS "id", "customers_2"."email" AS "email" FROM (SELECT "customers"."id", "customers"."email" FROM "customers" LEFT OUTER JOIN "purchases" ON (("purchases"."product_id") = ("products_1"."id")) WHERE ((("customers"."id") = ("purchases"."customer_id"))) LIMIT ('20') :: integer) AS "customers_2") AS "__sr_2") AS "__sj_2") AS "__sj_2" ON ('true')) AS "__sr_1") AS "__sj_1") AS "__sj_1", (SELECT coalesce(jsonb_agg("__sj_0"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_0".*) AS "json"FROM (SELECT "users_0"."id" AS "id", "users_0"."name" AS "name" FROM (SELECT "users"."id" FROM "users" GROUP BY "users"."id" LIMIT ('20') :: integer) AS "users_0") AS "__sr_0") AS "__sj_0") AS "__sj_0"' with args [] was not expected
-INF roles_query not defined: attribute based access control disabled
-all expectations were already fulfilled, call to Query 'SELECT jsonb_build_object('users', "__sj_0"."json", 'products', "__sj_1"."json") as "__root" FROM (SELECT coalesce(jsonb_agg("__sj_1"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_1".*) AS "json"FROM (SELECT "products_1"."id" AS "id", "products_1"."name" AS "name", "__sj_2"."json" AS "customers", "__sj_3"."json" AS "user" FROM (SELECT "products"."id", "products"."name", "products"."user_id" FROM "products" LIMIT ('20') :: integer) AS "products_1" LEFT OUTER JOIN LATERAL (SELECT to_jsonb("__sr_3".*) AS "json"FROM (SELECT "users_3"."full_name" AS "full_name", "users_3"."phone" AS "phone", "users_3"."email" AS "email" FROM (SELECT "users"."full_name", "users"."phone", "users"."email" FROM "users" WHERE ((("users"."id") = ("products_1"."user_id"))) LIMIT ('1') :: integer) AS "users_3") AS "__sr_3") AS "__sj_3" ON ('true') LEFT OUTER JOIN LATERAL (SELECT coalesce(jsonb_agg("__sj_2"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_2".*) AS "json"FROM (SELECT "customers_2"."id" AS "id", "customers_2"."email" AS "email" FROM (SELECT "customers"."id", "customers"."email" FROM "customers" LEFT OUTER JOIN "purchases" ON (("purchases"."product_id") = ("products_1"."id")) WHERE ((("customers"."id") = ("purchases"."customer_id"))) LIMIT ('20') :: integer) AS "customers_2") AS "__sr_2") AS "__sj_2") AS "__sj_2" ON ('true')) AS "__sr_1") AS "__sj_1") AS "__sj_1", (SELECT coalesce(jsonb_agg("__sj_0"."json"), '[]') as "json" FROM (SELECT to_jsonb("__sr_0".*) AS "json"FROM (SELECT "users_0"."id" AS "id", "users_0"."name" AS "name" FROM (SELECT "users"."id" FROM "users" GROUP BY "users"."id" LIMIT ('20') :: integer) AS "users_0") AS "__sr_0") AS "__sj_0") AS "__sj_0"' with args [] was not expected
-  105048	     10398 ns/op	   18342 B/op	      55 allocs/op
-PASS
-ok  	github.com/dosco/super-graph/core	1.328s
-PASS
-ok  	github.com/dosco/super-graph/core/internal/allow	0.088s
-?   	github.com/dosco/super-graph/core/internal/crypto	[no test files]
-?   	github.com/dosco/super-graph/core/internal/integration_tests	[no test files]
-PASS
-ok  	github.com/dosco/super-graph/core/internal/integration_tests/cockroachdb	0.121s
-PASS
-ok  	github.com/dosco/super-graph/core/internal/integration_tests/postgresql	0.118s
-goos: darwin
-goarch: amd64
-pkg: github.com/dosco/super-graph/core/internal/psql
-BenchmarkCompile-16            	   79845	     14428 ns/op	    4584 B/op	      39 allocs/op
-BenchmarkCompileParallel-16    	  326205	      3918 ns/op	    4633 B/op	      39 allocs/op
-PASS
-ok  	github.com/dosco/super-graph/core/internal/psql	2.696s
-goos: darwin
-goarch: amd64
-pkg: github.com/dosco/super-graph/core/internal/qcode
-BenchmarkQCompile-16        	  146953	      8049 ns/op	    3756 B/op	      28 allocs/op
-BenchmarkQCompileP-16       	  475936	      2447 ns/op	    3790 B/op	      28 allocs/op
-BenchmarkParse-16           	  140811	      8163 ns/op	    3902 B/op	      18 allocs/op
-BenchmarkParseP-16          	  571345	      2041 ns/op	    3903 B/op	      18 allocs/op
-BenchmarkSchemaParse-16     	  230715	      5012 ns/op	    3968 B/op	      57 allocs/op
-BenchmarkSchemaParseP-16    	  802426	      1565 ns/op	    3968 B/op	      57 allocs/op
-PASS
-ok  	github.com/dosco/super-graph/core/internal/qcode	8.427s
-?   	github.com/dosco/super-graph/core/internal/util	[no test files]

core/internal/allow/allow.go

@@ -299,9 +299,13 @@ func (al *List) save(item Item) error {
 
 	for _, v := range list {
 		if v.Comment != "" {
-			f.WriteString(fmt.Sprintf("/* %s */\n\n", v.Comment))
+			_, err = f.WriteString(fmt.Sprintf("/* %s */\n\n", v.Comment))
 		} else {
-			f.WriteString(fmt.Sprintf("/* %s */\n\n", v.Name))
+			_, err = f.WriteString(fmt.Sprintf("/* %s */\n\n", v.Name))
+		}
+
+		if err != nil {
+			return err
 		}
 
 		if v.Vars != "" {
@@ -320,18 +324,6 @@ func (al *List) save(item Item) error {
 	return nil
 }
 
-func matchPrefix(b []byte, i int, s string) bool {
-	if (len(b) - i) < len(s) {
-		return false
-	}
-	for n := 0; n < len(s); n++ {
-		if b[(i+n)] != s[n] {
-			return false
-		}
-	}
-	return true
-}
-
 func QueryName(b string) string {
 	state, s := 0, 0
 

core/internal/psql/query.go

@@ -220,10 +220,8 @@ func (co *Compiler) compileQueryWithMetadata(
 			}
 
 			if len(sel.Args) != 0 {
-				i := 0
 				for _, v := range sel.Args {
-					qcode.FreeNode(v, 500)
+					qcode.FreeNode(v)
-					i++
 				}
 			}
 		}

core/internal/qcode/bench.11

@@ -0,0 +1,13 @@
+goos: darwin
+goarch: amd64
+pkg: github.com/dosco/super-graph/core/internal/qcode
+BenchmarkQCompile-16            	  118282	      9686 ns/op	    4031 B/op	      30 allocs/op
+BenchmarkQCompileP-16           	  427531	      2710 ns/op	    4077 B/op	      30 allocs/op
+BenchmarkQCompileFragment-16    	  140588	      8328 ns/op	    8903 B/op	      13 allocs/op
+BenchmarkParse-16               	  131396	      9212 ns/op	    4175 B/op	      18 allocs/op
+BenchmarkParseP-16              	  503778	      2310 ns/op	    4176 B/op	      18 allocs/op
+BenchmarkParseFragment-16       	  143725	      8158 ns/op	   10193 B/op	       9 allocs/op
+BenchmarkSchemaParse-16         	  240609	      5060 ns/op	    3968 B/op	      57 allocs/op
+BenchmarkSchemaParseP-16        	  785116	      1534 ns/op	    3968 B/op	      57 allocs/op
+PASS
+ok  	github.com/dosco/super-graph/core/internal/qcode	11.092s

core/internal/qcode/parse.go

@@ -1,7 +1,6 @@
 package qcode
 
 import (
-	"encoding/binary"
 	"errors"
 	"fmt"
 	"hash/maphash"
@@ -80,6 +79,7 @@ type Field struct {
 type Arg struct {
 	Name string
 	Val  *Node
+	df   bool
 }
 
 type Node struct {
@@ -182,8 +182,8 @@ func (p *Parser) parseFragment(op *Operation) error {
 	frag := fragPool.Get().(*Fragment)
 	frag.Reset()
 
-	frag.Fields = frag.fieldsA[:0]
+	frag.Fields = frag.SelectionSet.fieldsA[:0]
-	frag.Args = frag.argsA[:0]
+	frag.Args = frag.SelectionSet.argsA[:0]
 
 	if p.peek(itemName) {
 		frag.Name = p.val(p.next())
@@ -273,7 +273,7 @@ func (p *Parser) parseOpTypeAndArgs(op *Operation) error {
 		op.Type = opSub
 	}
 
-	op.Args = op.argsA[:0]
+	op.Args = op.SelectionSet.argsA[:0]
 
 	var err error
 
@@ -370,11 +370,11 @@ func (p *Parser) parseFields(fields []Field) ([]Field, error) {
 
 		if isFrag {
 			name := p.val(p.next())
-			p.h.WriteString(name)
+			_, _ = p.h.WriteString(name)
-			k := p.h.Sum64()
+			id := p.h.Sum64()
 			p.h.Reset()
 
-			fr, ok := p.frags[k]
+			fr, ok := p.frags[id]
 			if !ok {
 				return nil, fmt.Errorf("no fragment named '%s' defined", name)
 			}
@@ -403,6 +403,9 @@ func (p *Parser) parseFields(fields []Field) ([]Field, error) {
 				f.Children = make([]int32, len(f.Children))
 				copy(f.Children, fr.Fields[i].Children)
 
+				f.Args = make([]Arg, len(f.Args))
+				copy(f.Args, fr.Fields[i].Args)
+
 				// Update all the children which is needed.
 				for j := range f.Children {
 					f.Children[j] += n
@@ -676,11 +679,6 @@ func (p *Parser) ignore() {
 	p.pos = n
 }
 
-func (p *Parser) peekCurrent() string {
-	item := p.items[p.pos]
-	return b2s(p.input[item.pos:item.end])
-}
-
 func (p *Parser) peekNext() string {
 	item := p.items[p.pos+1]
 	return b2s(p.input[item.pos:item.end])
@@ -690,16 +688,6 @@ func (p *Parser) reset(to int) {
 	p.pos = to
 }
 
-func (p *Parser) fHash(name string, parentID int32) uint64 {
-	var b []byte
-	binary.LittleEndian.PutUint32(b, uint32(parentID))
-	p.h.WriteString(name)
-	p.h.Write(b)
-	v := p.h.Sum64()
-	p.h.Reset()
-	return v
-}
-
 func b2s(b []byte) string {
 	return *(*string)(unsafe.Pointer(&b))
 }
@@ -736,31 +724,6 @@ func (t parserType) String() string {
 	return v
 }
 
-// type Frees struct {
+func FreeNode(n *Node) {
-// 	n   *Node
-// 	loc int
-// }
-
-// var freeList []Frees
-
-// func FreeNode(n *Node, loc int) {
-// 	j := -1
-
-// 	for i := range freeList {
-// 		if n == freeList[i].n {
-// 			j = i
-// 			break
-// 		}
-// 	}
-
-// 	if j == -1 {
-// 		nodePool.Put(n)
-// 		freeList = append(freeList, Frees{n, loc})
-// 	} else {
-// 		fmt.Printf("(%d) RE_FREE %d %p %s %s\n", loc, freeList[j].loc, freeList[j].n, n.Name, n.Type)
-// 	}
-// }
-
-func FreeNode(n *Node, loc int) {
 	nodePool.Put(n)
 }

core/internal/qcode/qcode.go

@@ -277,6 +277,7 @@ func (com *Compiler) Compile(query []byte, role string) (*QCode, error) {
 		return nil, err
 	}
 
+	freeNodes(op)
 	opPool.Put(op)
 
 	return &qc, nil
@@ -492,50 +493,42 @@ func (com *Compiler) AddFilters(qc *QCode, sel *Select, role string) {
 func (com *Compiler) compileArgs(qc *QCode, sel *Select, args []Arg, role string) error {
 	var err error
 
-	// don't free this arg either previously done or will be free'd
-	// in the future like in psql
-	var df bool
-
 	for i := range args {
 		arg := &args[i]
 
 		switch arg.Name {
 		case "id":
-			err, df = com.compileArgID(sel, arg)
+			err = com.compileArgID(sel, arg)
 
 		case "search":
-			err, df = com.compileArgSearch(sel, arg)
+			err = com.compileArgSearch(sel, arg)
 
 		case "where":
-			err, df = com.compileArgWhere(sel, arg, role)
+			err = com.compileArgWhere(sel, arg, role)
 
 		case "orderby", "order_by", "order":
-			err, df = com.compileArgOrderBy(sel, arg)
+			err = com.compileArgOrderBy(sel, arg)
 
 		case "distinct_on", "distinct":
-			err, df = com.compileArgDistinctOn(sel, arg)
+			err = com.compileArgDistinctOn(sel, arg)
 
 		case "limit":
-			err, df = com.compileArgLimit(sel, arg)
+			err = com.compileArgLimit(sel, arg)
 
 		case "offset":
-			err, df = com.compileArgOffset(sel, arg)
+			err = com.compileArgOffset(sel, arg)
 
 		case "first":
-			err, df = com.compileArgFirstLast(sel, arg, PtForward)
+			err = com.compileArgFirstLast(sel, arg, PtForward)
 
 		case "last":
-			err, df = com.compileArgFirstLast(sel, arg, PtBackward)
+			err = com.compileArgFirstLast(sel, arg, PtBackward)
 
 		case "after":
-			err, df = com.compileArgAfterBefore(sel, arg, PtForward)
+			err = com.compileArgAfterBefore(sel, arg, PtForward)
 
 		case "before":
-			err, df = com.compileArgAfterBefore(sel, arg, PtBackward)
+			err = com.compileArgAfterBefore(sel, arg, PtBackward)
-		}
-
-		if !df {
-			FreeNode(arg.Val, 5)
 		}
 
 		if err != nil {
@@ -646,39 +639,20 @@ func (com *Compiler) compileArgNode(st *util.Stack, node *Node, usePool bool) (*
 		}
 	}
 
-	if usePool {
-		st.Push(node)
-
-		for {
-			if st.Len() == 0 {
-				break
-			}
-			intf := st.Pop()
-			node, ok := intf.(*Node)
-			if !ok || node == nil {
-				continue
-			}
-			for i := range node.Children {
-				st.Push(node.Children[i])
-			}
-			FreeNode(node, 1)
-		}
-	}
-
 	return root, needsUser, nil
 }
 
-func (com *Compiler) compileArgID(sel *Select, arg *Arg) (error, bool) {
+func (com *Compiler) compileArgID(sel *Select, arg *Arg) error {
 	if sel.ID != 0 {
-		return nil, false
+		return nil
 	}
 
 	if sel.Where != nil && sel.Where.Op == OpEqID {
-		return nil, false
+		return nil
 	}
 
 	if arg.Val.Type != NodeVar {
-		return argErr("id", "variable"), false
+		return argErr("id", "variable")
 	}
 
 	ex := expPool.Get().(*Exp)
@@ -689,12 +663,12 @@ func (com *Compiler) compileArgID(sel *Select, arg *Arg) (error, bool) {
 	ex.Val = arg.Val.Val
 
 	sel.Where = ex
-	return nil, false
+	return nil
 }
 
-func (com *Compiler) compileArgSearch(sel *Select, arg *Arg) (error, bool) {
+func (com *Compiler) compileArgSearch(sel *Select, arg *Arg) error {
 	if arg.Val.Type != NodeVar {
-		return argErr("search", "variable"), false
+		return argErr("search", "variable")
 	}
 
 	ex := expPool.Get().(*Exp)
@@ -709,18 +683,19 @@ func (com *Compiler) compileArgSearch(sel *Select, arg *Arg) (error, bool) {
 	}
 
 	sel.Args[arg.Name] = arg.Val
+	arg.df = true
 	AddFilter(sel, ex)
 
-	return nil, true
+	return nil
 }
 
-func (com *Compiler) compileArgWhere(sel *Select, arg *Arg, role string) (error, bool) {
+func (com *Compiler) compileArgWhere(sel *Select, arg *Arg, role string) error {
 	st := util.NewStack()
 	var err error
 
 	ex, nu, err := com.compileArgObj(st, arg)
 	if err != nil {
-		return err, false
+		return err
 	}
 
 	if nu && role == "anon" {
@@ -728,12 +703,12 @@ func (com *Compiler) compileArgWhere(sel *Select, arg *Arg, role string) (error,
 	}
 	AddFilter(sel, ex)
 
-	return nil, true
+	return nil
 }
 
-func (com *Compiler) compileArgOrderBy(sel *Select, arg *Arg) (error, bool) {
+func (com *Compiler) compileArgOrderBy(sel *Select, arg *Arg) error {
 	if arg.Val.Type != NodeObj {
-		return fmt.Errorf("expecting an object"), false
+		return fmt.Errorf("expecting an object")
 	}
 
 	st := util.NewStack()
@@ -751,16 +726,15 @@ func (com *Compiler) compileArgOrderBy(sel *Select, arg *Arg) (error, bool) {
 		node, ok := intf.(*Node)
 
 		if !ok || node == nil {
-			return fmt.Errorf("17: unexpected value %v (%t)", intf, intf), false
+			return fmt.Errorf("17: unexpected value %v (%t)", intf, intf)
 		}
 
 		if _, ok := com.bl[node.Name]; ok {
-			FreeNode(node, 2)
 			continue
 		}
 
 		if node.Type != NodeStr && node.Type != NodeVar {
-			return fmt.Errorf("expecting a string or variable"), false
+			return fmt.Errorf("expecting a string or variable")
 		}
 
 		ob := &OrderBy{}
@@ -779,25 +753,24 @@ func (com *Compiler) compileArgOrderBy(sel *Select, arg *Arg) (error, bool) {
 		case "desc_nulls_last":
 			ob.Order = OrderDescNullsLast
 		default:
-			return fmt.Errorf("valid values include asc, desc, asc_nulls_first and desc_nulls_first"), false
+			return fmt.Errorf("valid values include asc, desc, asc_nulls_first and desc_nulls_first")
 		}
 
 		setOrderByColName(ob, node)
 		sel.OrderBy = append(sel.OrderBy, ob)
-		FreeNode(node, 3)
 	}
-	return nil, false
+	return nil
 }
 
-func (com *Compiler) compileArgDistinctOn(sel *Select, arg *Arg) (error, bool) {
+func (com *Compiler) compileArgDistinctOn(sel *Select, arg *Arg) error {
 	node := arg.Val
 
 	if _, ok := com.bl[node.Name]; ok {
-		return nil, false
+		return nil
 	}
 
 	if node.Type != NodeList && node.Type != NodeStr {
-		return fmt.Errorf("expecting a list of strings or just a string"), false
+		return fmt.Errorf("expecting a list of strings or just a string")
 	}
 
 	if node.Type == NodeStr {
@@ -806,58 +779,57 @@ func (com *Compiler) compileArgDistinctOn(sel *Select, arg *Arg) (error, bool) {
 
 	for i := range node.Children {
 		sel.DistinctOn = append(sel.DistinctOn, node.Children[i].Val)
-		FreeNode(node.Children[i], 5)
 	}
 
-	return nil, false
+	return nil
 }
 
-func (com *Compiler) compileArgLimit(sel *Select, arg *Arg) (error, bool) {
+func (com *Compiler) compileArgLimit(sel *Select, arg *Arg) error {
 	node := arg.Val
 
 	if node.Type != NodeInt {
-		return argErr("limit", "number"), false
+		return argErr("limit", "number")
 	}
 
 	sel.Paging.Limit = node.Val
 
-	return nil, false
+	return nil
 }
 
-func (com *Compiler) compileArgOffset(sel *Select, arg *Arg) (error, bool) {
+func (com *Compiler) compileArgOffset(sel *Select, arg *Arg) error {
 	node := arg.Val
 
 	if node.Type != NodeVar {
-		return argErr("offset", "variable"), false
+		return argErr("offset", "variable")
 	}
 
 	sel.Paging.Offset = node.Val
-	return nil, false
+	return nil
 }
 
-func (com *Compiler) compileArgFirstLast(sel *Select, arg *Arg, pt PagingType) (error, bool) {
+func (com *Compiler) compileArgFirstLast(sel *Select, arg *Arg, pt PagingType) error {
 	node := arg.Val
 
 	if node.Type != NodeInt {
-		return argErr(arg.Name, "number"), false
+		return argErr(arg.Name, "number")
 	}
 
 	sel.Paging.Type = pt
 	sel.Paging.Limit = node.Val
 
-	return nil, false
+	return nil
 }
 
-func (com *Compiler) compileArgAfterBefore(sel *Select, arg *Arg, pt PagingType) (error, bool) {
+func (com *Compiler) compileArgAfterBefore(sel *Select, arg *Arg, pt PagingType) error {
 	node := arg.Val
 
 	if node.Type != NodeVar || node.Val != "cursor" {
-		return fmt.Errorf("value for argument '%s' must be a variable named $cursor", arg.Name), false
+		return fmt.Errorf("value for argument '%s' must be a variable named $cursor", arg.Name)
 	}
 	sel.Paging.Type = pt
 	sel.Paging.Cursor = true
 
-	return nil, false
+	return nil
 }
 
 // var zeroTrv = &trval{}
@@ -1237,3 +1209,81 @@ func FreeExp(ex *Exp) {
 func argErr(name, ty string) error {
 	return fmt.Errorf("value for argument '%s' must be a %s", name, ty)
 }
+
+func freeNodes(op *Operation) {
+	var st *util.Stack
+	fm := make(map[*Node]struct{})
+
+	for i := range op.Args {
+		arg := op.Args[i]
+		if arg.df {
+			continue
+		}
+
+		for i := range arg.Val.Children {
+			if st == nil {
+				st = util.NewStack()
+			}
+			c := arg.Val.Children[i]
+			if _, ok := fm[c]; !ok {
+				st.Push(c)
+			}
+		}
+
+		if _, ok := fm[arg.Val]; !ok {
+			nodePool.Put(arg.Val)
+			fm[arg.Val] = struct{}{}
+		}
+
+	}
+
+	for i := range op.Fields {
+		f := op.Fields[i]
+
+		for j := range f.Args {
+			arg := f.Args[j]
+			if arg.df {
+				continue
+			}
+
+			for k := range arg.Val.Children {
+				if st == nil {
+					st = util.NewStack()
+				}
+				c := arg.Val.Children[k]
+				if _, ok := fm[c]; !ok {
+					st.Push(c)
+				}
+			}
+
+			if _, ok := fm[arg.Val]; !ok {
+				nodePool.Put(arg.Val)
+				fm[arg.Val] = struct{}{}
+			}
+		}
+	}
+
+	if st == nil {
+		return
+	}
+
+	for {
+		if st.Len() == 0 {
+			break
+		}
+		intf := st.Pop()
+		node, ok := intf.(*Node)
+		if !ok || node == nil {
+			continue
+		}
+
+		for i := range node.Children {
+			st.Push(node.Children[i])
+		}
+
+		if _, ok := fm[node]; !ok {
+			nodePool.Put(node)
+			fm[node] = struct{}{}
+		}
+	}
+}