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go/internal/lsp/cache/analysis.go
Rebecca Stambler 67a4523381 internal/lsp: determine parse mode based on workspace packages
Our current invariant is that all workspace packages are parsed in full
mode, and all dependencies are parsed in exported mode. We can rely on
this, as well as the fact that workspace packages are set during
metadata loads, to reduce the amount of plumbing the mode requires.W

Change-Id: Ib9406ca3c0dc2c81c7ee3158407f28022924d4d0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/217139
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
2020-02-04 23:03:16 +00:00

385 lines
11 KiB
Go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cache
import (
"context"
"fmt"
"go/token"
"go/types"
"reflect"
"sort"
"sync"
"golang.org/x/sync/errgroup"
"golang.org/x/tools/go/analysis"
"golang.org/x/tools/internal/lsp/source"
"golang.org/x/tools/internal/lsp/telemetry"
"golang.org/x/tools/internal/memoize"
"golang.org/x/tools/internal/telemetry/log"
"golang.org/x/tools/internal/telemetry/tag"
errors "golang.org/x/xerrors"
)
func (s *snapshot) Analyze(ctx context.Context, id string, analyzers []*analysis.Analyzer) ([]*source.Error, error) {
var roots []*actionHandle
for _, a := range analyzers {
ah, err := s.actionHandle(ctx, packageID(id), a)
if err != nil {
return nil, err
}
roots = append(roots, ah)
}
// Check if the context has been canceled before running the analyses.
if ctx.Err() != nil {
return nil, ctx.Err()
}
var results []*source.Error
for _, ah := range roots {
diagnostics, _, err := ah.analyze(ctx)
if err != nil {
return nil, err
}
results = append(results, diagnostics...)
}
return results, nil
}
type actionHandleKey string
// An action represents one unit of analysis work: the application of
// one analysis to one package. Actions form a DAG, both within a
// package (as different analyzers are applied, either in sequence or
// parallel), and across packages (as dependencies are analyzed).
type actionHandle struct {
handle *memoize.Handle
analyzer *analysis.Analyzer
pkg *pkg
}
type actionData struct {
diagnostics []*source.Error
result interface{}
objectFacts map[objectFactKey]analysis.Fact
packageFacts map[packageFactKey]analysis.Fact
err error
}
type objectFactKey struct {
obj types.Object
typ reflect.Type
}
type packageFactKey struct {
pkg *types.Package
typ reflect.Type
}
func (s *snapshot) actionHandle(ctx context.Context, id packageID, a *analysis.Analyzer) (*actionHandle, error) {
ph := s.getPackage(id)
if ph == nil {
return nil, errors.Errorf("no PackageHandle for %s", id)
}
expectMode(ph, source.ParseFull)
act := s.getActionHandle(id, ph.mode, a)
if act != nil {
return act, nil
}
if len(ph.key) == 0 {
return nil, errors.Errorf("no key for PackageHandle %s", id)
}
pkg, err := ph.check(ctx)
if err != nil {
return nil, err
}
act = &actionHandle{
analyzer: a,
pkg: pkg,
}
var deps []*actionHandle
// Add a dependency on each required analyzers.
for _, req := range a.Requires {
reqActionHandle, err := s.actionHandle(ctx, id, req)
if err != nil {
return nil, err
}
deps = append(deps, reqActionHandle)
}
// TODO(golang/go#35089): Re-enable this when we doesn't use ParseExported
// mode for dependencies. In the meantime, disable analysis for dependencies,
// since we don't get anything useful out of it.
if false {
// An analysis that consumes/produces facts
// must run on the package's dependencies too.
if len(a.FactTypes) > 0 {
importIDs := make([]string, 0, len(ph.m.deps))
for _, importID := range ph.m.deps {
importIDs = append(importIDs, string(importID))
}
sort.Strings(importIDs) // for determinism
for _, importID := range importIDs {
depActionHandle, err := s.actionHandle(ctx, packageID(importID), a)
if err != nil {
return nil, err
}
deps = append(deps, depActionHandle)
}
}
}
fset := s.view.session.cache.fset
h := s.view.session.cache.store.Bind(buildActionKey(a, ph), func(ctx context.Context) interface{} {
// Analyze dependencies first.
results, err := execAll(ctx, fset, deps)
if err != nil {
return &actionData{
err: err,
}
}
return runAnalysis(ctx, fset, a, pkg, results)
})
act.handle = h
s.addActionHandle(act)
return act, nil
}
func (act *actionHandle) analyze(ctx context.Context) ([]*source.Error, interface{}, error) {
v := act.handle.Get(ctx)
if v == nil {
return nil, nil, ctx.Err()
}
data, ok := v.(*actionData)
if !ok {
return nil, nil, errors.Errorf("unexpected type for %s:%s", act.pkg.ID(), act.analyzer.Name)
}
if data == nil {
return nil, nil, errors.Errorf("unexpected nil analysis for %s:%s", act.pkg.ID(), act.analyzer.Name)
}
return data.diagnostics, data.result, data.err
}
func buildActionKey(a *analysis.Analyzer, ph *packageHandle) actionHandleKey {
return actionHandleKey(hashContents([]byte(fmt.Sprintf("%p %s", a, string(ph.key)))))
}
func (act *actionHandle) String() string {
return fmt.Sprintf("%s@%s", act.analyzer, act.pkg.PkgPath())
}
func execAll(ctx context.Context, fset *token.FileSet, actions []*actionHandle) (map[*actionHandle]*actionData, error) {
var mu sync.Mutex
results := make(map[*actionHandle]*actionData)
g, ctx := errgroup.WithContext(ctx)
for _, act := range actions {
act := act
g.Go(func() error {
v := act.handle.Get(ctx)
if v == nil {
return errors.Errorf("no analyses for %s", act.pkg.ID())
}
data, ok := v.(*actionData)
if !ok {
return errors.Errorf("unexpected type for %s: %T", act, v)
}
mu.Lock()
defer mu.Unlock()
results[act] = data
return nil
})
}
return results, g.Wait()
}
func runAnalysis(ctx context.Context, fset *token.FileSet, analyzer *analysis.Analyzer, pkg *pkg, deps map[*actionHandle]*actionData) (data *actionData) {
data = &actionData{
objectFacts: make(map[objectFactKey]analysis.Fact),
packageFacts: make(map[packageFactKey]analysis.Fact),
}
defer func() {
if r := recover(); r != nil {
log.Print(ctx, fmt.Sprintf("analysis panicked: %s", r), telemetry.Package.Of(pkg.PkgPath))
data.err = errors.Errorf("analysis %s for package %s panicked: %v", analyzer.Name, pkg.PkgPath(), r)
}
}()
// Plumb the output values of the dependencies
// into the inputs of this action. Also facts.
inputs := make(map[*analysis.Analyzer]interface{})
for depHandle, depData := range deps {
if depHandle.pkg == pkg {
// Same package, different analysis (horizontal edge):
// in-memory outputs of prerequisite analyzers
// become inputs to this analysis pass.
inputs[depHandle.analyzer] = depData.result
} else if depHandle.analyzer == analyzer { // (always true)
// Same analysis, different package (vertical edge):
// serialized facts produced by prerequisite analysis
// become available to this analysis pass.
for key, fact := range depData.objectFacts {
// Filter out facts related to objects
// that are irrelevant downstream
// (equivalently: not in the compiler export data).
if !exportedFrom(key.obj, depHandle.pkg.types) {
continue
}
data.objectFacts[key] = fact
}
for key, fact := range depData.packageFacts {
// TODO: filter out facts that belong to
// packages not mentioned in the export data
// to prevent side channels.
data.packageFacts[key] = fact
}
}
}
var diagnostics []*analysis.Diagnostic
// Run the analysis.
pass := &analysis.Pass{
Analyzer: analyzer,
Fset: fset,
Files: pkg.GetSyntax(),
Pkg: pkg.GetTypes(),
TypesInfo: pkg.GetTypesInfo(),
TypesSizes: pkg.GetTypesSizes(),
ResultOf: inputs,
Report: func(d analysis.Diagnostic) {
// Prefix the diagnostic category with the analyzer's name.
if d.Category == "" {
d.Category = analyzer.Name
} else {
d.Category = analyzer.Name + "." + d.Category
}
diagnostics = append(diagnostics, &d)
},
ImportObjectFact: func(obj types.Object, ptr analysis.Fact) bool {
if obj == nil {
panic("nil object")
}
key := objectFactKey{obj, factType(ptr)}
if v, ok := data.objectFacts[key]; ok {
reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
return true
}
return false
},
ExportObjectFact: func(obj types.Object, fact analysis.Fact) {
if obj.Pkg() != pkg.types {
panic(fmt.Sprintf("internal error: in analysis %s of package %s: Fact.Set(%s, %T): can't set facts on objects belonging another package",
analyzer, pkg.ID(), obj, fact))
}
key := objectFactKey{obj, factType(fact)}
data.objectFacts[key] = fact // clobber any existing entry
},
ImportPackageFact: func(pkg *types.Package, ptr analysis.Fact) bool {
if pkg == nil {
panic("nil package")
}
key := packageFactKey{pkg, factType(ptr)}
if v, ok := data.packageFacts[key]; ok {
reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
return true
}
return false
},
ExportPackageFact: func(fact analysis.Fact) {
key := packageFactKey{pkg.types, factType(fact)}
data.packageFacts[key] = fact // clobber any existing entry
},
AllObjectFacts: func() []analysis.ObjectFact {
facts := make([]analysis.ObjectFact, 0, len(data.objectFacts))
for k := range data.objectFacts {
facts = append(facts, analysis.ObjectFact{Object: k.obj, Fact: data.objectFacts[k]})
}
return facts
},
AllPackageFacts: func() []analysis.PackageFact {
facts := make([]analysis.PackageFact, 0, len(data.packageFacts))
for k := range data.packageFacts {
facts = append(facts, analysis.PackageFact{Package: k.pkg, Fact: data.packageFacts[k]})
}
return facts
},
}
if pkg.IsIllTyped() {
data.err = errors.Errorf("analysis skipped due to errors in package: %v", pkg.GetErrors())
return data
}
data.result, data.err = pass.Analyzer.Run(pass)
if data.err != nil {
return data
}
if got, want := reflect.TypeOf(data.result), pass.Analyzer.ResultType; got != want {
data.err = errors.Errorf(
"internal error: on package %s, analyzer %s returned a result of type %v, but declared ResultType %v",
pass.Pkg.Path(), pass.Analyzer, got, want)
return data
}
// disallow calls after Run
pass.ExportObjectFact = func(obj types.Object, fact analysis.Fact) {
panic(fmt.Sprintf("%s:%s: Pass.ExportObjectFact(%s, %T) called after Run", analyzer.Name, pkg.PkgPath(), obj, fact))
}
pass.ExportPackageFact = func(fact analysis.Fact) {
panic(fmt.Sprintf("%s:%s: Pass.ExportPackageFact(%T) called after Run", analyzer.Name, pkg.PkgPath(), fact))
}
for _, diag := range diagnostics {
srcErr, err := sourceError(ctx, fset, pkg, diag)
if err != nil {
log.Error(ctx, "unable to compute analysis error position", err, tag.Of("category", diag.Category), telemetry.Package.Of(pkg.ID()))
continue
}
data.diagnostics = append(data.diagnostics, srcErr)
}
return data
}
// exportedFrom reports whether obj may be visible to a package that imports pkg.
// This includes not just the exported members of pkg, but also unexported
// constants, types, fields, and methods, perhaps belonging to oether packages,
// that find there way into the API.
// This is an overapproximation of the more accurate approach used by
// gc export data, which walks the type graph, but it's much simpler.
//
// TODO(adonovan): do more accurate filtering by walking the type graph.
func exportedFrom(obj types.Object, pkg *types.Package) bool {
switch obj := obj.(type) {
case *types.Func:
return obj.Exported() && obj.Pkg() == pkg ||
obj.Type().(*types.Signature).Recv() != nil
case *types.Var:
return obj.Exported() && obj.Pkg() == pkg ||
obj.IsField()
case *types.TypeName, *types.Const:
return true
}
return false // Nil, Builtin, Label, or PkgName
}
func factType(fact analysis.Fact) reflect.Type {
t := reflect.TypeOf(fact)
if t.Kind() != reflect.Ptr {
panic(fmt.Sprintf("invalid Fact type: got %T, want pointer", t))
}
return t
}