Make thriftbp.NewBaseplateClientPool() behave more like the grpcbp one

clientpool/bench_test.go

@@ -1,6 +1,7 @@
 package clientpool_test
 
 import (
+	"context"
 	"testing"
 
 	"github.com/reddit/baseplate.go/clientpool"
@@ -11,8 +12,8 @@ func BenchmarkPoolGetRelease(b *testing.B) {
 		return &testClient{}, nil
 	}
 
-	const min, max = 0, 100
-	channelPool, _ := clientpool.NewChannelPool(min, max, opener)
+	const min, init, max = 0, 0, 100
+	channelPool, _ := clientpool.NewChannelPool(context.Background(), min, init, max, opener)
 
 	for label, pool := range map[string]clientpool.Pool{
 		"channel": channelPool,

clientpool/channel.go

@@ -1,8 +1,13 @@
 package clientpool
 
 import (
+	"context"
 	"fmt"
 	"sync/atomic"
+	"time"
+
+	"github.com/reddit/baseplate.go/log"
+	"golang.org/x/time/rate"
 )
 
 type channelPool struct {
@@ -19,25 +24,58 @@ var _ Pool = (*channelPool)(nil)
 // NewChannelPool creates a new client pool implemented via channel.
 //
 // Note that this function could return both non-nil Pool and error,
-// when we failed to create all asked initialClients.
-// In such case the returned Pool would have the clients we already established.
-func NewChannelPool(initialClients, maxClients int, opener ClientOpener) (Pool, error) {
-	if initialClients > maxClients {
+// when we failed to create all asked bestEffortInitialClients.
+// In such case the returned Pool would have at least requiredInitialClients
+// clients we already established.
+func NewChannelPool(ctx context.Context, requiredInitialClients, bestEffortInitialClients, maxClients int, opener ClientOpener) (Pool, error) {
+	if !(requiredInitialClients <= bestEffortInitialClients && bestEffortInitialClients <= maxClients) {
 		return nil, &ConfigError{
-			InitialClients: initialClients,
-			MaxClients:     maxClients,
+			BestEffortInitialClients: bestEffortInitialClients,
+			RequiredInitialClients:   requiredInitialClients,
+			MaxClients:               maxClients,
 		}
 	}
 
-	var finalErr error
+	var lastAttemptErr error
 	pool := make(chan Client, maxClients)
-	for i := 0; i < initialClients; i++ {
+	chatty := rate.NewLimiter(rate.Every(2*time.Second), 1)
+
+	for i := 0; i < requiredInitialClients; {
+		if ctxErr := ctx.Err(); ctxErr != nil {
+			if lastAttemptErr == nil {
+				// In case the user sets a deadline so short that we don't have
+				// time to open all the client serially despite all of them working.
+				// In that case lastAttempErr would be nil so we need to indicate to
+				// the user that their timeout being too short is the issue.
+				lastAttemptErr = ctxErr
+			}
+			return &channelPool{
+				pool:           pool,
+				opener:         opener,
+				initialClients: len(pool),
+				maxClients:     maxClients,
+			}, lastAttemptErr
+		}
+		c, err := opener()
+		if err == nil {
+			pool <- c
+			i++
+		} else {
+			lastAttemptErr = err
+			if chatty.Allow() {
+				log.Warnf("clientpool: error creating required client (will retry): %w", err)
+			}
+		}
+	}
+	lastAttemptErr = nil
+
+	for i := requiredInitialClients; i < bestEffortInitialClients; i++ {
 		c, err := opener()
 		if err != nil {
-			finalErr = fmt.Errorf(
-				"clientpool: error creating client #%d/%d: %w",
+			lastAttemptErr = fmt.Errorf(
+				"clientpool: error creating best-effort client #%d/%d: %w",
 				i,
-				initialClients,
+				bestEffortInitialClients,
 				err,
 			)
 			break
@@ -48,9 +86,9 @@ func NewChannelPool(initialClients, maxClients int, opener ClientOpener) (Pool,
 	return &channelPool{
 		pool:           pool,
 		opener:         opener,
-		initialClients: initialClients,
+		initialClients: bestEffortInitialClients,
 		maxClients:     maxClients,
-	}, finalErr
+	}, lastAttemptErr
 }
 
 // Get returns a client from the pool.

clientpool/channel_test.go

@@ -1,6 +1,7 @@
 package clientpool_test
 
 import (
+	"context"
 	"errors"
 	"sync/atomic"
 	"testing"
@@ -9,8 +10,8 @@ import (
 )
 
 func TestChannelPoolInvalidConfig(t *testing.T) {
-	const min, max = 5, 1
-	_, err := clientpool.NewChannelPool(min, max, nil)
+	const min, init, max = 5, 1, 1
+	_, err := clientpool.NewChannelPool(context.Background(), min, init, max, nil)
 	if err == nil {
 		t.Errorf(
 			"NewChannelPool with min %d and max %d expected an error, got nil.",
@@ -30,15 +31,15 @@ func TestChannelPool(t *testing.T) {
 		}
 	}
 
-	const min, max = 2, 5
+	const min, init, max = 1, 2, 5
 	var openerCalled atomic.Int32
-	pool, err := clientpool.NewChannelPool(min, max, opener(&openerCalled))
+	pool, err := clientpool.NewChannelPool(context.Background(), min, init, max, opener(&openerCalled))
 	if err != nil {
 		t.Fatal(err)
 	}
-	t.Logf("min: %d, max: %d", min, max)
+	t.Logf("min: %d, init: %d, max: %d", min, init, max)
 
-	testPool(t, pool, &openerCalled, min, max)
+	testPool(t, pool, &openerCalled, init, max)
 }
 
 func TestChannelPoolWithOpenerFailure(t *testing.T) {
@@ -54,11 +55,11 @@ func TestChannelPoolWithOpenerFailure(t *testing.T) {
 		}
 	}
 
-	const min, max = 1, 5
+	const min, init, max = 0, 1, 5
 	t.Run(
 		"new-with-min-2-should-fail-initialization",
 		func(t *testing.T) {
-			pool, err := clientpool.NewChannelPool(2, max, opener())
+			pool, err := clientpool.NewChannelPool(context.Background(), min, 2, max, opener())
 			if err == nil {
 				t.Error("NewChannelPool with min = 2 should fail but did not.")
 			}
@@ -68,7 +69,7 @@ func TestChannelPoolWithOpenerFailure(t *testing.T) {
 		},
 	)
 
-	pool, err := clientpool.NewChannelPool(min, max, opener())
+	pool, err := clientpool.NewChannelPool(context.Background(), min, init, max, opener())
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -77,14 +78,14 @@ func TestChannelPoolWithOpenerFailure(t *testing.T) {
 	t.Run(
 		"drain-the-pool",
 		func(t *testing.T) {
-			for i := 0; i < min; i++ {
+			for i := 0; i < init; i++ {
 				_, err := pool.Get()
 				if err != nil {
 					t.Errorf("pool.Get returned error: %v", err)
 				}
 			}
 
-			checkActiveAndAllocated(t, pool, min, 0)
+			checkActiveAndAllocated(t, pool, init, 0)
 		},
 	)
 
@@ -97,7 +98,7 @@ func TestChannelPoolWithOpenerFailure(t *testing.T) {
 				t.Error("pool.Get should return error, got nil")
 			}
 
-			checkActiveAndAllocated(t, pool, min, 0)
+			checkActiveAndAllocated(t, pool, init, 0)
 		},
 	)
 }

clientpool/errors.go

@@ -23,16 +23,18 @@ func (exhaustedError) Retryable() int {
 // ConfigError is the error type returned when trying to open a new
 // client pool, but the configuration values passed in won't work.
 type ConfigError struct {
-	InitialClients int
-	MaxClients     int
+	BestEffortInitialClients int
+	RequiredInitialClients   int
+	MaxClients               int
 }
 
 var _ error = (*ConfigError)(nil)
 
 func (e *ConfigError) Error() string {
 	return fmt.Sprintf(
-		"clientpool: initialClients (%d) > maxClients (%d)",
-		e.InitialClients,
+		"clientpool: need requiredClients (%d) <= initialClients (%d) <= maxClients (%d)",
+		e.RequiredInitialClients,
+		e.BestEffortInitialClients,
 		e.MaxClients,
 	)
 }

go.mod

@@ -23,6 +23,7 @@ require (
 	go.uber.org/automaxprocs v1.5.1
 	go.uber.org/zap v1.21.0
 	golang.org/x/sys v0.5.0
+	golang.org/x/time v0.0.0-20220609170525-579cf78fd858
 	google.golang.org/grpc v1.47.0
 	gopkg.in/yaml.v2 v2.4.0
 	sigs.k8s.io/secrets-store-csi-driver v1.3.0

go.sum

@@ -645,6 +645,8 @@ golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
+golang.org/x/time v0.0.0-20220609170525-579cf78fd858 h1:Dpdu/EMxGMFgq0CeYMh4fazTD2vtlZRYE7wyynxJb9U=
+golang.org/x/time v0.0.0-20220609170525-579cf78fd858/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20181221001348-537d06c36207/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

thriftbp/client_pool.go

@@ -355,6 +355,9 @@ func SingleAddressGenerator(addr string) AddressGenerator {
 // It always uses SingleAddressGenerator with the server address configured in
 // cfg, and THeader+TCompact as the protocol factory.
 func NewBaseplateClientPool(cfg ClientPoolConfig, middlewares ...thrift.ClientMiddleware) (ClientPool, error) {
+	return NewBaseplateClientPoolWithContext(context.Background(), cfg, middlewares...)
+}
+func NewBaseplateClientPoolWithContext(ctx context.Context, cfg ClientPoolConfig, middlewares ...thrift.ClientMiddleware) (ClientPool, error) {
 	err := BaseplateClientPoolConfig(cfg).Validate()
 	if err != nil {
 		return nil, fmt.Errorf("thriftbp.NewBaseplateClientPool: %w", err)
@@ -370,7 +373,11 @@ func NewBaseplateClientPool(cfg ClientPoolConfig, middlewares ...thrift.ClientMi
 		},
 	)
 	middlewares = append(middlewares, defaults...)
-	return NewCustomClientPool(
+	if err := cfg.Validate(); err != nil {
+		return nil, fmt.Errorf("thriftbp.NewCustomClientPool: %w", err)
+	}
+	return newClientPool(
+		ctx,
 		cfg,
 		SingleAddressGenerator(cfg.Addr),
 		thrift.NewTHeaderProtocolFactoryConf(cfg.ToTConfiguration()),
@@ -388,14 +395,24 @@ func NewCustomClientPool(
 	genAddr AddressGenerator,
 	protoFactory thrift.TProtocolFactory,
 	middlewares ...thrift.ClientMiddleware,
+) (ClientPool, error) {
+	return NewCustomClientPoolWithContext(context.Background(), cfg, genAddr, protoFactory, middlewares...)
+}
+func NewCustomClientPoolWithContext(
+	ctx context.Context,
+	cfg ClientPoolConfig,
+	genAddr AddressGenerator,
+	protoFactory thrift.TProtocolFactory,
+	middlewares ...thrift.ClientMiddleware,
 ) (ClientPool, error) {
 	if err := cfg.Validate(); err != nil {
 		return nil, fmt.Errorf("thriftbp.NewCustomClientPool: %w", err)
 	}
-	return newClientPool(cfg, genAddr, protoFactory, middlewares...)
+	return newClientPool(ctx, cfg, genAddr, protoFactory, middlewares...)
 }
 
 func newClientPool(
+	ctx context.Context,
 	cfg ClientPoolConfig,
 	genAddr AddressGenerator,
 	proto thrift.TProtocolFactory,
@@ -433,6 +450,8 @@ func newClientPool(
 		)
 	}
 	pool, err := clientpool.NewChannelPool(
+		ctx,
+		cfg.RequiredInitialConnections,
 		cfg.InitialConnections,
 		cfg.MaxConnections,
 		opener,
@@ -446,13 +465,13 @@ func newClientPool(
 				err = batch.Compile()
 			}
 			return nil, fmt.Errorf(
-				"thriftbp: error initializing thrift clientpool for %q: %w",
+				"thriftbp: error initializing the required number of connections in the thrift clientpool for %q: %w",
 				cfg.ServiceSlug,
 				err,
 			)
 		}
 
-		cfg.InitialConnectionsFallbackLogger.Log(context.Background(), fmt.Sprintf(
+		cfg.InitialConnectionsFallbackLogger.Log(ctx, fmt.Sprintf(
 			"thriftbp: Established %d of %d InitialConnections asked for thrift clientpool for %q: %v",
 			pool.NumAllocated(),
 			cfg.InitialConnections,