Merge pull request kubernetes#129749 from pohly/dra-cel-cost-estimate-during-validation

DRA:  CEL cost estimate during validation

Author: k8s-ci-robot

staging/src/k8s.io/dynamic-resource-allocation/cel/cache.go

@@ -43,6 +43,8 @@ func NewCache(maxCacheEntries int) *Cache {
 // GetOrCompile checks whether the cache already has a compilation result
 // and returns that if available. Otherwise it compiles, stores successful
 // results and returns the new result.
+//
+// Cost estimation is disabled.
 func (c *Cache) GetOrCompile(expression string) CompilationResult {
 	// Compiling a CEL expression is expensive enough that it is cheaper
 	// to lock a mutex than doing it several times in parallel.
@@ -55,7 +57,7 @@ func (c *Cache) GetOrCompile(expression string) CompilationResult {
 		return *cached
 	}
 
-	expr := GetCompiler().CompileCELExpression(expression, Options{})
+	expr := GetCompiler().CompileCELExpression(expression, Options{DisableCostEstimation: true})
 	if expr.Error == nil {
 		c.add(expression, &expr)
 	}

staging/src/k8s.io/dynamic-resource-allocation/cel/cache_test.go

@@ -18,6 +18,7 @@ package cel
 
 import (
 	"fmt"
+	"math"
 	"sync"
 	"testing"
 
@@ -73,6 +74,11 @@ func TestCacheSemantic(t *testing.T) {
 	if resultFalse == resultFalseAgain {
 		t.Fatal("result of compiling `false` should have been evicted from the cache")
 	}
+
+	// Cost estimation must be off (not needed by scheduler).
+	if resultFalseAgain.MaxCost != math.MaxUint64 {
+		t.Error("cost estimation should have been disabled, was enabled")
+	}
 }
 
 func TestCacheConcurrency(t *testing.T) {

staging/src/k8s.io/dynamic-resource-allocation/cel/compile.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"math"
 	"reflect"
 	"strings"
 	"sync"
@@ -120,6 +121,10 @@ type Options struct {
 
 	// CostLimit allows overriding the default runtime cost limit [resourceapi.CELSelectorExpressionMaxCost].
 	CostLimit *uint64
+
+	// DisableCostEstimation can be set to skip estimating the worst-case CEL cost.
+	// If disabled or after an error, [CompilationResult.MaxCost] will be set to [math.Uint64].
+	DisableCostEstimation bool
 }
 
 // CompileCELExpression returns a compiled CEL expression. It evaluates to bool.
@@ -133,6 +138,7 @@ func (c compiler) CompileCELExpression(expression string, options Options) Compi
 				Detail: errorString,
 			},
 			Expression: expression,
+			MaxCost:    math.MaxUint64,
 		}
 	}
 
@@ -141,10 +147,6 @@ func (c compiler) CompileCELExpression(expression string, options Options) Compi
 		return resultError(fmt.Sprintf("unexpected error loading CEL environment: %v", err), apiservercel.ErrorTypeInternal)
 	}
 
-	// We don't have a SizeEstimator. The potential size of the input (= a
-	// device) is already declared in the definition of the environment.
-	estimator := c.newCostEstimator()
-
 	ast, issues := env.Compile(expression)
 	if issues != nil {
 		return resultError("compilation failed: "+issues.String(), apiservercel.ErrorTypeInvalid)
@@ -176,15 +178,21 @@ func (c compiler) CompileCELExpression(expression string, options Options) Compi
 		OutputType:  ast.OutputType(),
 		Environment: env,
 		emptyMapVal: env.CELTypeAdapter().NativeToValue(map[string]any{}),
+		MaxCost:     math.MaxUint64,
 	}
 
-	costEst, err := env.EstimateCost(ast, estimator)
-	if err != nil {
-		compilationResult.Error = &apiservercel.Error{Type: apiservercel.ErrorTypeInternal, Detail: "cost estimation failed: " + err.Error()}
-		return compilationResult
+	if !options.DisableCostEstimation {
+		// We don't have a SizeEstimator. The potential size of the input (= a
+		// device) is already declared in the definition of the environment.
+		estimator := c.newCostEstimator()
+		costEst, err := env.EstimateCost(ast, estimator)
+		if err != nil {
+			compilationResult.Error = &apiservercel.Error{Type: apiservercel.ErrorTypeInternal, Detail: "cost estimation failed: " + err.Error()}
+			return compilationResult
+		}
+		compilationResult.MaxCost = costEst.Max
 	}
 
-	compilationResult.MaxCost = costEst.Max
 	return compilationResult
 }