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Make checker state concurrency safe #702

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merged 1 commit into from
May 5, 2023
Merged

Make checker state concurrency safe #702

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55 changes: 36 additions & 19 deletions cel/env.go
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Original file line number Diff line number Diff line change
Expand Up @@ -109,10 +109,11 @@ type Env struct {
prsrOpts []parser.Option

// Internal checker representation
chk *checker.Env
chkErr error
chkOnce sync.Once
chkOpts []checker.Option
chkMutex sync.Mutex
chk *checker.Env
chkErr error
chkOnce sync.Once
chkOpts []checker.Option

// Program options tied to the environment
progOpts []ProgramOption
Expand Down Expand Up @@ -178,14 +179,14 @@ func (e *Env) Check(ast *Ast) (*Ast, *Issues) {
pe, _ := AstToParsedExpr(ast)

// Construct the internal checker env, erroring if there is an issue adding the declarations.
err := e.initChecker()
chk, err := e.initChecker()
if err != nil {
errs := common.NewErrors(ast.Source())
errs.ReportError(common.NoLocation, e.chkErr.Error())
errs.ReportError(common.NoLocation, err.Error())
return nil, NewIssues(errs)
}

res, errs := checker.Check(pe, ast.Source(), e.chk)
res, errs := checker.Check(pe, ast.Source(), chk)
if len(errs.GetErrors()) > 0 {
return nil, NewIssues(errs)
}
Expand Down Expand Up @@ -239,8 +240,9 @@ func (e *Env) CompileSource(src Source) (*Ast, *Issues) {
// TypeProvider are immutable, or that their underlying implementations are based on the
// ref.TypeRegistry which provides a Copy method which will be invoked by this method.
func (e *Env) Extend(opts ...EnvOption) (*Env, error) {
if e.chkErr != nil {
return nil, e.chkErr
chk, chkErr := e.getCheckerOrError()
if chkErr != nil {
return nil, chkErr
}

prsrOptsCopy := make([]parser.Option, len(e.prsrOpts))
Expand All @@ -254,10 +256,10 @@ func (e *Env) Extend(opts ...EnvOption) (*Env, error) {

// Copy the declarations if needed.
decsCopy := []*exprpb.Decl{}
if e.chk != nil {
if chk != nil {
// If the type-checker has already been instantiated, then the e.declarations have been
// validated within the chk instance.
chkOptsCopy = append(chkOptsCopy, checker.ValidatedDeclarations(e.chk))
chkOptsCopy = append(chkOptsCopy, checker.ValidatedDeclarations(chk))
} else {
// If the type-checker has not been instantiated, ensure the unvalidated declarations are
// provided to the extended Env instance.
Expand Down Expand Up @@ -509,7 +511,7 @@ func (e *Env) configure(opts []EnvOption) (*Env, error) {

// Ensure that the checker init happens eagerly rather than lazily.
if e.HasFeature(featureEagerlyValidateDeclarations) {
err := e.initChecker()
_, err := e.initChecker()
if err != nil {
return nil, err
}
Expand All @@ -518,7 +520,7 @@ func (e *Env) configure(opts []EnvOption) (*Env, error) {
return e, nil
}

func (e *Env) initChecker() error {
func (e *Env) initChecker() (*checker.Env, error) {
e.chkOnce.Do(func() {
chkOpts := []checker.Option{}
chkOpts = append(chkOpts, e.chkOpts...)
Expand All @@ -530,32 +532,47 @@ func (e *Env) initChecker() error {

ce, err := checker.NewEnv(e.Container, e.provider, chkOpts...)
if err != nil {
e.chkErr = err
e.setCheckerOrError(nil, err)
return
}
// Add the statically configured declarations.
err = ce.Add(e.declarations...)
if err != nil {
e.chkErr = err
e.setCheckerOrError(nil, err)
return
}
// Add the function declarations which are derived from the FunctionDecl instances.
for _, fn := range e.functions {
fnDecl, err := functionDeclToExprDecl(fn)
if err != nil {
e.chkErr = err
e.setCheckerOrError(nil, err)
return
}
err = ce.Add(fnDecl)
if err != nil {
e.chkErr = err
e.setCheckerOrError(nil, err)
return
}
}
// Add function declarations here separately.
e.chk = ce
e.setCheckerOrError(ce, nil)
})
return e.chkErr
return e.getCheckerOrError()
}

// setCheckerOrError sets the checker.Env or error state in a concurrency-safe manner
func (e *Env) setCheckerOrError(chk *checker.Env, chkErr error) {
e.chkMutex.Lock()
e.chk = chk
e.chkErr = chkErr
e.chkMutex.Unlock()
}

// getCheckerOrError gets the checker.Env or error state in a concurrency-safe manner
func (e *Env) getCheckerOrError() (*checker.Env, error) {
e.chkMutex.Lock()
defer e.chkMutex.Unlock()
return e.chk, e.chkErr
}

// maybeApplyFeature determines whether the feature-guarded option is enabled, and if so applies
Expand Down
27 changes: 27 additions & 0 deletions cel/env_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,9 @@
package cel

import (
"fmt"
"reflect"
"sync"
"testing"

"github.com/google/cel-go/common"
Expand Down Expand Up @@ -82,6 +84,31 @@ ERROR: <input>:1:2: Syntax error: mismatched input '<EOF>' expecting {'[', '{',
}
}

func TestEnvCheckExtendRace(t *testing.T) {
t.Parallel()
for i := 0; i < 500; i++ {
wg := &sync.WaitGroup{}
wg.Add(2)
env, err := NewCustomEnv(StdLib())
if err != nil {
t.Fatalf("NewCustomEnv() failed: %v", err)
}
t.Run(fmt.Sprintf("Compile[%d]", i), func(t *testing.T) {
go func() {
defer wg.Done()
_, _ = env.Compile(`1 + 1 * 20 < 400`)
}()
})
t.Run(fmt.Sprintf("Extend[%d]", i), func(t *testing.T) {
go func() {
defer wg.Done()
_, _ = env.Extend(Variable("bar", BoolType))
}()
})
wg.Wait()
}
}

func BenchmarkNewCustomEnvLazy(b *testing.B) {
b.ResetTimer()
for i := 0; i < b.N; i++ {
Expand Down