chore: generate dbmetrics automatically when adding new queries (#7999)

* chore: rename dbgen package files and remove small file

* chore: automatically generate dbmetrics when new queries are added

coderd/database/gen/metrics/main.go

@@ -0,0 +1,210 @@
+package main
+
+import (
+	"fmt"
+	"go/format"
+	"go/token"
+	"log"
+	"os"
+	"strings"
+
+	"github.com/dave/dst"
+	"github.com/dave/dst/decorator"
+	"github.com/dave/dst/decorator/resolver/goast"
+	"github.com/dave/dst/decorator/resolver/guess"
+	"golang.org/x/xerrors"
+)
+
+func main() {
+	err := run()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run() error {
+	funcs, err := readStoreInterface()
+	if err != nil {
+		return err
+	}
+	funcByName := map[string]struct{}{}
+	for _, f := range funcs {
+		funcByName[f.Name] = struct{}{}
+	}
+	declByName := map[string]*dst.FuncDecl{}
+
+	dbmetrics, err := os.ReadFile("./dbmetrics/dbmetrics.go")
+	if err != nil {
+		return xerrors.Errorf("read dbfake: %w", err)
+	}
+
+	// Required to preserve imports!
+	f, err := decorator.NewDecoratorWithImports(token.NewFileSet(), "dbmetrics", goast.New()).Parse(dbmetrics)
+	if err != nil {
+		return xerrors.Errorf("parse dbfake: %w", err)
+	}
+
+	for i := 0; i < len(f.Decls); i++ {
+		funcDecl, ok := f.Decls[i].(*dst.FuncDecl)
+		if !ok || funcDecl.Recv == nil || len(funcDecl.Recv.List) == 0 {
+			continue
+		}
+		// Check if the receiver is the struct we're interested in
+		_, ok = funcDecl.Recv.List[0].Type.(*dst.Ident)
+		if !ok {
+			continue
+		}
+		if _, ok := funcByName[funcDecl.Name.Name]; !ok {
+			continue
+		}
+		declByName[funcDecl.Name.Name] = funcDecl
+		f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
+		i--
+	}
+
+	for _, fn := range funcs {
+		decl, ok := declByName[fn.Name]
+		if !ok {
+			params := make([]string, 0)
+			if fn.Func.Params != nil {
+				for _, p := range fn.Func.Params.List {
+					for _, name := range p.Names {
+						params = append(params, name.Name)
+					}
+				}
+			}
+			returns := make([]string, 0)
+			if fn.Func.Results != nil {
+				for i := range fn.Func.Results.List {
+					returns = append(returns, fmt.Sprintf("r%d", i))
+				}
+			}
+
+			code := fmt.Sprintf(`
+package stub
+
+func stub() {
+	start := time.Now()
+	%s := m.s.%s(%s)
+	m.queryLatencies.WithLabelValues("%s").Observe(time.Since(start).Seconds())
+	return %s
+}
+`, strings.Join(returns, ","), fn.Name, strings.Join(params, ","), fn.Name, strings.Join(returns, ","))
+			file, err := decorator.Parse(code)
+			if err != nil {
+				return xerrors.Errorf("parse code: %w", err)
+			}
+			stmt, ok := file.Decls[0].(*dst.FuncDecl)
+			if !ok {
+				return xerrors.Errorf("not ok %T", file.Decls[0])
+			}
+
+			// Not implemented!
+			// When a function isn't implemented, we automatically stub it!
+			decl = &dst.FuncDecl{
+				Name: dst.NewIdent(fn.Name),
+				Type: fn.Func,
+				Recv: &dst.FieldList{
+					List: []*dst.Field{{
+						Names: []*dst.Ident{dst.NewIdent("m")},
+						Type:  dst.NewIdent("metricsStore"),
+					}},
+				},
+				Decs: dst.FuncDeclDecorations{
+					NodeDecs: dst.NodeDecs{
+						Before: dst.EmptyLine,
+						After:  dst.EmptyLine,
+					},
+				},
+				Body: stmt.Body,
+			}
+		}
+		f.Decls = append(f.Decls, decl)
+	}
+
+	file, err := os.OpenFile("./dbmetrics/dbmetrics.go", os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o755)
+	if err != nil {
+		return xerrors.Errorf("open dbfake: %w", err)
+	}
+	defer file.Close()
+
+	// Required to preserve imports!
+	restorer := decorator.NewRestorerWithImports("dbmetrics", guess.New())
+	restored, err := restorer.RestoreFile(f)
+	if err != nil {
+		return xerrors.Errorf("restore dbfake: %w", err)
+	}
+	err = format.Node(file, restorer.Fset, restored)
+	return err
+}
+
+type storeMethod struct {
+	Name string
+	Func *dst.FuncType
+}
+
+func readStoreInterface() ([]storeMethod, error) {
+	querier, err := os.ReadFile("./querier.go")
+	if err != nil {
+		return nil, xerrors.Errorf("read querier: %w", err)
+	}
+	f, err := decorator.Parse(querier)
+	if err != nil {
+		return nil, err
+	}
+
+	var sqlcQuerier *dst.InterfaceType
+	for _, decl := range f.Decls {
+		genDecl, ok := decl.(*dst.GenDecl)
+		if !ok {
+			continue
+		}
+
+		for _, spec := range genDecl.Specs {
+			typeSpec, ok := spec.(*dst.TypeSpec)
+			if !ok {
+				continue
+			}
+			if typeSpec.Name.Name != "sqlcQuerier" {
+				continue
+			}
+			sqlcQuerier, ok = typeSpec.Type.(*dst.InterfaceType)
+			if !ok {
+				return nil, xerrors.Errorf("unexpected sqlcQuerier type: %T", typeSpec.Type)
+			}
+			break
+		}
+	}
+	if sqlcQuerier == nil {
+		return nil, xerrors.Errorf("sqlcQuerier not found")
+	}
+	funcs := []storeMethod{}
+	for _, method := range sqlcQuerier.Methods.List {
+		funcType, ok := method.Type.(*dst.FuncType)
+		if !ok {
+			continue
+		}
+
+		for _, t := range []*dst.FieldList{funcType.Params, funcType.Results} {
+			if t == nil {
+				continue
+			}
+			for _, f := range t.List {
+				ident, ok := f.Type.(*dst.Ident)
+				if !ok {
+					continue
+				}
+				if !ident.IsExported() {
+					continue
+				}
+				ident.Path = "github.com/coder/coder/coderd/database"
+			}
+		}
+
+		funcs = append(funcs, storeMethod{
+			Name: method.Names[0].Name,
+			Func: funcType,
+		})
+	}
+	return funcs, nil
+}