| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package atomic defines an Analyzer that checks for common mistakes |
| 6 | // using the sync/atomic package. |
| 7 | package atomic |
| 8 | |
| 9 | import ( |
| 10 | "go/ast" |
| 11 | "go/token" |
| 12 | "go/types" |
| 13 | |
| 14 | "golang.org/x/tools/go/analysis" |
| 15 | "golang.org/x/tools/go/analysis/passes/inspect" |
| 16 | "golang.org/x/tools/go/analysis/passes/internal/analysisutil" |
| 17 | "golang.org/x/tools/go/ast/inspector" |
| 18 | ) |
| 19 | |
| 20 | const Doc = `check for common mistakes using the sync/atomic package |
| 21 | |
| 22 | The atomic checker looks for assignment statements of the form: |
| 23 | |
| 24 | x = atomic.AddUint64(&x, 1) |
| 25 | |
| 26 | which are not atomic.` |
| 27 | |
| 28 | var Analyzer = &analysis.Analyzer{ |
| 29 | Name: "atomic", |
| 30 | Doc: Doc, |
| 31 | Requires: []*analysis.Analyzer{inspect.Analyzer}, |
| 32 | RunDespiteErrors: true, |
| 33 | Run: run, |
| 34 | } |
| 35 | |
| 36 | func run(pass *analysis.Pass) (interface{}, error) { |
| 37 | inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector) |
| 38 | |
| 39 | nodeFilter := []ast.Node{ |
| 40 | (*ast.AssignStmt)(nil), |
| 41 | } |
| 42 | inspect.Preorder(nodeFilter, func(node ast.Node) { |
| 43 | n := node.(*ast.AssignStmt) |
| 44 | if len(n.Lhs) != len(n.Rhs) { |
| 45 | return |
| 46 | } |
| 47 | if len(n.Lhs) == 1 && n.Tok == token.DEFINE { |
| 48 | return |
| 49 | } |
| 50 | |
| 51 | for i, right := range n.Rhs { |
| 52 | call, ok := right.(*ast.CallExpr) |
| 53 | if !ok { |
| 54 | continue |
| 55 | } |
| 56 | sel, ok := call.Fun.(*ast.SelectorExpr) |
| 57 | if !ok { |
| 58 | continue |
| 59 | } |
| 60 | pkgIdent, _ := sel.X.(*ast.Ident) |
| 61 | pkgName, ok := pass.TypesInfo.Uses[pkgIdent].(*types.PkgName) |
| 62 | if !ok || pkgName.Imported().Path() != "sync/atomic" { |
| 63 | continue |
| 64 | } |
| 65 | |
| 66 | switch sel.Sel.Name { |
| 67 | case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr": |
| 68 | checkAtomicAddAssignment(pass, n.Lhs[i], call) |
| 69 | } |
| 70 | } |
| 71 | }) |
| 72 | return nil, nil |
| 73 | } |
| 74 | |
| 75 | // checkAtomicAddAssignment walks the atomic.Add* method calls checking |
| 76 | // for assigning the return value to the same variable being used in the |
| 77 | // operation |
| 78 | func checkAtomicAddAssignment(pass *analysis.Pass, left ast.Expr, call *ast.CallExpr) { |
| 79 | if len(call.Args) != 2 { |
| 80 | return |
| 81 | } |
| 82 | arg := call.Args[0] |
| 83 | broken := false |
| 84 | |
| 85 | gofmt := func(e ast.Expr) string { return analysisutil.Format(pass.Fset, e) } |
| 86 | |
| 87 | if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND { |
| 88 | broken = gofmt(left) == gofmt(uarg.X) |
| 89 | } else if star, ok := left.(*ast.StarExpr); ok { |
| 90 | broken = gofmt(star.X) == gofmt(arg) |
| 91 | } |
| 92 | |
| 93 | if broken { |
| 94 | pass.ReportRangef(left, "direct assignment to atomic value") |
| 95 | } |
| 96 | } |
| 97 |
Members