76 lines
1.8 KiB
Go
76 lines
1.8 KiB
Go
package checkers
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import (
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"go/ast"
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"github.com/go-lintpack/lintpack"
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"github.com/go-lintpack/lintpack/astwalk"
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)
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func init() {
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var info lintpack.CheckerInfo
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info.Name = "rangeValCopy"
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info.Tags = []string{"performance"}
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info.Params = lintpack.CheckerParams{
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"sizeThreshold": {
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Value: 128,
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Usage: "size in bytes that makes the warning trigger",
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},
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"skipTestFuncs": {
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Value: true,
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Usage: "whether to check test functions",
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},
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}
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info.Summary = "Detects loops that copy big objects during each iteration"
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info.Details = "Suggests to use index access or take address and make use pointer instead."
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info.Before = `
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xs := make([][1024]byte, length)
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for _, x := range xs {
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// Loop body.
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}`
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info.After = `
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xs := make([][1024]byte, length)
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for i := range xs {
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x := &xs[i]
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// Loop body.
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}`
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collection.AddChecker(&info, func(ctx *lintpack.CheckerContext) lintpack.FileWalker {
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c := &rangeValCopyChecker{ctx: ctx}
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c.sizeThreshold = int64(info.Params.Int("sizeThreshold"))
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c.skipTestFuncs = info.Params.Bool("skipTestFuncs")
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return astwalk.WalkerForStmt(c)
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})
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}
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type rangeValCopyChecker struct {
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astwalk.WalkHandler
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ctx *lintpack.CheckerContext
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sizeThreshold int64
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skipTestFuncs bool
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}
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func (c *rangeValCopyChecker) EnterFunc(fn *ast.FuncDecl) bool {
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return fn.Body != nil &&
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!(c.skipTestFuncs && isUnitTestFunc(c.ctx, fn))
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}
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func (c *rangeValCopyChecker) VisitStmt(stmt ast.Stmt) {
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rng, ok := stmt.(*ast.RangeStmt)
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if !ok || rng.Value == nil {
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return
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}
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typ := c.ctx.TypesInfo.TypeOf(rng.Value)
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if typ == nil {
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return
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}
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if size := c.ctx.SizesInfo.Sizeof(typ); size >= c.sizeThreshold {
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c.warn(rng, size)
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}
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}
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func (c *rangeValCopyChecker) warn(node ast.Node, size int64) {
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c.ctx.Warn(node, "each iteration copies %d bytes (consider pointers or indexing)", size)
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}
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