github.com/xushiwei/go@v0.0.0-20130601165731-2b9d83f45bc9/src/cmd/vet/atomic.go (about)

     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 main
     6  
     7  import (
     8  	"go/ast"
     9  	"go/token"
    10  )
    11  
    12  // checkAtomicAssignment walks the assignment statement checking for common
    13  // mistaken usage of atomic package, such as: x = atomic.AddUint64(&x, 1)
    14  func (f *File) checkAtomicAssignment(n *ast.AssignStmt) {
    15  	if !vet("atomic") {
    16  		return
    17  	}
    18  
    19  	if len(n.Lhs) != len(n.Rhs) {
    20  		return
    21  	}
    22  
    23  	for i, right := range n.Rhs {
    24  		call, ok := right.(*ast.CallExpr)
    25  		if !ok {
    26  			continue
    27  		}
    28  		sel, ok := call.Fun.(*ast.SelectorExpr)
    29  		if !ok {
    30  			continue
    31  		}
    32  		pkg, ok := sel.X.(*ast.Ident)
    33  		if !ok || pkg.Name != "atomic" {
    34  			continue
    35  		}
    36  
    37  		switch sel.Sel.Name {
    38  		case "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr":
    39  			f.checkAtomicAddAssignment(n.Lhs[i], call)
    40  		}
    41  	}
    42  }
    43  
    44  // checkAtomicAddAssignment walks the atomic.Add* method calls checking for assigning the return value
    45  // to the same variable being used in the operation
    46  func (f *File) checkAtomicAddAssignment(left ast.Expr, call *ast.CallExpr) {
    47  	arg := call.Args[0]
    48  	broken := false
    49  
    50  	if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
    51  		broken = f.gofmt(left) == f.gofmt(uarg.X)
    52  	} else if star, ok := left.(*ast.StarExpr); ok {
    53  		broken = f.gofmt(star.X) == f.gofmt(arg)
    54  	}
    55  
    56  	if broken {
    57  		f.Warn(left.Pos(), "direct assignment to atomic value")
    58  	}
    59  }