Make dataplane system test behave deterministically (#849)

Make dataplane system test deterministic by injecting capacity constraints

api/agent/pure_runner.go

@@ -194,6 +194,17 @@ func (ch *callHandle) cancel(ctx context.Context, err error) {
 	}
 }
 
+type CapacityGate interface {
+	// CheckAndReserveCapacity must perform an atomic check plus reservation. If an error is returned, then it is
+	// guaranteed that no capacity has been committed. If nil is returned, then it is guaranteed that the provided units
+	// of capacity have been committed.
+	CheckAndReserveCapacity(units uint64) error
+
+	// ReleaseCapacity must perform an atomic release of capacity. The units provided must not bring the capacity under
+	// zero; implementations are free to panic in that case.
+	ReleaseCapacity(units uint64)
+}
+
 type pureRunnerCapacityManager struct {
 	totalCapacityUnits     uint64
 	committedCapacityUnits uint64
@@ -202,24 +213,24 @@ type pureRunnerCapacityManager struct {
 
 type capacityDeallocator func()
 
-func newPureRunnerCapacityManager(units uint64) pureRunnerCapacityManager {
+func newPureRunnerCapacityManager(units uint64) *pureRunnerCapacityManager {
-	return pureRunnerCapacityManager{
+	return &pureRunnerCapacityManager{
 		totalCapacityUnits:     units,
 		committedCapacityUnits: 0,
 	}
 }
 
-func (prcm *pureRunnerCapacityManager) checkAndReserveCapacity(units uint64) error {
+func (prcm *pureRunnerCapacityManager) CheckAndReserveCapacity(units uint64) error {
 	prcm.mtx.Lock()
 	defer prcm.mtx.Unlock()
-	if prcm.committedCapacityUnits+units < prcm.totalCapacityUnits {
+	if prcm.totalCapacityUnits-prcm.committedCapacityUnits >= units {
 		prcm.committedCapacityUnits = prcm.committedCapacityUnits + units
 		return nil
 	}
 	return models.ErrCallTimeoutServerBusy
 }
 
-func (prcm *pureRunnerCapacityManager) releaseCapacity(units uint64) {
+func (prcm *pureRunnerCapacityManager) ReleaseCapacity(units uint64) {
 	prcm.mtx.Lock()
 	defer prcm.mtx.Unlock()
 	if units <= prcm.committedCapacityUnits {
@@ -236,7 +247,7 @@ type pureRunner struct {
 	listen     string
 	a          Agent
 	inflight   int32
-	capacity   pureRunnerCapacityManager
+	capacity   CapacityGate
 }
 
 func (pr *pureRunner) GetCall(opts ...CallOpt) (Call, error) {
@@ -368,7 +379,7 @@ func (pr *pureRunner) handleTryCall(ctx context.Context, tc *runner.TryCall, sta
 	}
 
 	// Capacity check first
-	err = pr.capacity.checkAndReserveCapacity(c.Memory)
+	err = pr.capacity.CheckAndReserveCapacity(c.Memory)
 	if err != nil {
 		return func() {}, err
 	}
@@ -379,13 +390,13 @@ func (pr *pureRunner) handleTryCall(ctx context.Context, tc *runner.TryCall, sta
 	inR, inW := io.Pipe()
 	agent_call, err := pr.a.GetCall(FromModelAndInput(&c, inR), WithWriter(w))
 	if err != nil {
-		return func() { pr.capacity.releaseCapacity(c.Memory) }, err
+		return func() { pr.capacity.ReleaseCapacity(c.Memory) }, err
 	}
 	state.c = agent_call.(*call)
 	state.input = inW
 	state.allocatedTime = strfmt.DateTime(time.Now())
 
-	return func() { pr.capacity.releaseCapacity(c.Memory) }, nil
+	return func() { pr.capacity.ReleaseCapacity(c.Memory) }, nil
 }
 
 // Handles a client engagement
@@ -535,7 +546,15 @@ func (pr *pureRunner) Start() error {
 	return err
 }
 
-func NewPureRunner(cancel context.CancelFunc, addr string, a Agent, cert string, key string, ca string) (*pureRunner, error) {
+func UnsecuredPureRunner(cancel context.CancelFunc, addr string, a Agent) (*pureRunner, error) {
+	return NewPureRunner(cancel, addr, a, "", "", "", nil)
+}
+
+func DefaultPureRunner(cancel context.CancelFunc, addr string, a Agent, cert string, key string, ca string) (*pureRunner, error) {
+	return NewPureRunner(cancel, addr, a, cert, key, ca, nil)
+}
+
+func NewPureRunner(cancel context.CancelFunc, addr string, a Agent, cert string, key string, ca string, gate CapacityGate) (*pureRunner, error) {
 	var pr *pureRunner
 	var err error
 	if cert != "" && key != "" && ca != "" {
@@ -544,13 +563,13 @@ func NewPureRunner(cancel context.CancelFunc, addr string, a Agent, cert string,
 			logrus.WithField("runner_addr", addr).Warn("Failed to create credentials!")
 			return nil, err
 		}
-		pr, err = createPureRunner(addr, a, c)
+		pr, err = createPureRunner(addr, a, c, gate)
 		if err != nil {
 			return nil, err
 		}
 	} else {
 		logrus.Warn("Running pure runner in insecure mode!")
-		pr, err = createPureRunner(addr, a, nil)
+		pr, err = createPureRunner(addr, a, nil, gate)
 		if err != nil {
 			return nil, err
 		}
@@ -592,19 +611,22 @@ func creds(cert string, key string, ca string) (credentials.TransportCredentials
 	}), nil
 }
 
-func createPureRunner(addr string, a Agent, creds credentials.TransportCredentials) (*pureRunner, error) {
+func createPureRunner(addr string, a Agent, creds credentials.TransportCredentials, gate CapacityGate) (*pureRunner, error) {
 	var srv *grpc.Server
 	if creds != nil {
 		srv = grpc.NewServer(grpc.Creds(creds))
 	} else {
 		srv = grpc.NewServer()
 	}
-	memUnits := getAvailableMemoryUnits()
+	if gate == nil {
+		memUnits := getAvailableMemoryUnits()
+		gate = newPureRunnerCapacityManager(memUnits)
+	}
 	pr := &pureRunner{
 		gRPCServer: srv,
 		listen:     addr,
 		a:          a,
-		capacity:   newPureRunnerCapacityManager(memUnits),
+		capacity:   gate,
 	}
 
 	runner.RegisterRunnerProtocolServer(srv, pr)

api/server/server.go

@@ -409,7 +409,7 @@ func WithAgentFromEnv() ServerOption {
 			grpcAddr := fmt.Sprintf(":%d", s.grpcListenPort)
 			delegatedAgent := agent.NewSyncOnly(agent.NewCachedDataAccess(ds))
 			cancelCtx, cancel := context.WithCancel(ctx)
-			prAgent, err := agent.NewPureRunner(cancel, grpcAddr, delegatedAgent, s.cert, s.certKey, s.certAuthority)
+			prAgent, err := agent.DefaultPureRunner(cancel, grpcAddr, delegatedAgent, s.cert, s.certKey, s.certAuthority)
 			if err != nil {
 				return err
 			}

test/fn-system-tests/system_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/fnproject/fn/api/agent"
 	"github.com/fnproject/fn/api/agent/hybrid"
 	agent_grpc "github.com/fnproject/fn/api/agent/nodepool/grpc"
+	"github.com/fnproject/fn/api/models"
 	"github.com/fnproject/fn/api/server"
 
 	"github.com/sirupsen/logrus"
@@ -17,6 +18,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 )
@@ -154,6 +156,39 @@ func SetUpLBNode(ctx context.Context) (*server.Server, error) {
 	return server.New(ctx, opts...), nil
 }
 
+type testCapacityGate struct {
+	runnerNumber           int
+	committedCapacityUnits uint64
+	mtx                    sync.Mutex
+}
+
+const (
+	FixedTestCapacityUnitsPerRunner = 512
+)
+
+func (tcg *testCapacityGate) CheckAndReserveCapacity(units uint64) error {
+	tcg.mtx.Lock()
+	defer tcg.mtx.Unlock()
+	if tcg.committedCapacityUnits+units <= FixedTestCapacityUnitsPerRunner {
+		logrus.WithField("nodeNumber", tcg.runnerNumber).WithField("units", units).WithField("currentlyCommitted", tcg.committedCapacityUnits).Info("Runner is committing capacity")
+		tcg.committedCapacityUnits = tcg.committedCapacityUnits + units
+		return nil
+	}
+	logrus.WithField("nodeNumber", tcg.runnerNumber).WithField("currentlyCommitted", tcg.committedCapacityUnits).Info("Runner is out of capacity")
+	return models.ErrCallTimeoutServerBusy
+}
+
+func (tcg *testCapacityGate) ReleaseCapacity(units uint64) {
+	tcg.mtx.Lock()
+	defer tcg.mtx.Unlock()
+	if units <= tcg.committedCapacityUnits {
+		logrus.WithField("nodeNumber", tcg.runnerNumber).WithField("units", units).WithField("currentlyCommitted", tcg.committedCapacityUnits).Info("Runner is releasing capacity")
+		tcg.committedCapacityUnits = tcg.committedCapacityUnits - units
+		return
+	}
+	panic("Fatal error in test capacity calculation, getting to sub-zero capacity")
+}
+
 func SetUpPureRunnerNode(ctx context.Context, nodeNum int) (*server.Server, error) {
 	nodeType := server.ServerTypePureRunner
 	opts := make([]server.ServerOption, 0)
@@ -174,7 +209,7 @@ func SetUpPureRunnerNode(ctx context.Context, nodeNum int) (*server.Server, erro
 	grpcAddr := fmt.Sprintf(":%d", 9190+nodeNum)
 	delegatedAgent := agent.NewSyncOnly(agent.NewCachedDataAccess(ds))
 	cancelCtx, cancel := context.WithCancel(ctx)
-	prAgent, err := agent.NewPureRunner(cancel, grpcAddr, delegatedAgent, "", "", "")
+	prAgent, err := agent.NewPureRunner(cancel, grpcAddr, delegatedAgent, "", "", "", &testCapacityGate{runnerNumber: nodeNum})
 	if err != nil {
 		return nil, err
 	}