Reuse senders (#571)

* Reuse senders

The change to support TLS renegotiation types inadvertently removed
sharing transports, leading to a growing number of goroutines for
workloads that create a lot of different clients.
Create senders per TLS renegotiation type.  Each sender is created on
demand and cached for reuse.

* update CHANGELOG with notice about per module change info

CHANGELOG.md

@@ -1,5 +1,7 @@
 # CHANGELOG
 
+**NOTE** Please see a module's release notes for change details.
+
 ## v14.2.1
 
 - In `Future.WaitForCompletionRef()`, if the initial async response includes a `Retry-After` header, sleep for the specified amount of time before starting to poll.

autorest/go.mod

@@ -4,9 +4,9 @@ go 1.12
 
 require (
 	github.com/Azure/go-autorest v14.2.0+incompatible
-	github.com/Azure/go-autorest/autorest/adal v0.9.4
+	github.com/Azure/go-autorest/autorest/adal v0.9.5
 	github.com/Azure/go-autorest/autorest/mocks v0.4.1
 	github.com/Azure/go-autorest/logger v0.2.0
 	github.com/Azure/go-autorest/tracing v0.6.0
-	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
+	golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0
 )

autorest/go.sum

@@ -1,7 +1,7 @@
 github.com/Azure/go-autorest v14.2.0+incompatible h1:V5VMDjClD3GiElqLWO7mz2MxNAK/vTfRHdAubSIPRgs=
 github.com/Azure/go-autorest v14.2.0+incompatible/go.mod h1:r+4oMnoxhatjLLJ6zxSWATqVooLgysK6ZNox3g/xq24=
-github.com/Azure/go-autorest/autorest/adal v0.9.4 h1:1/DtH4Szusk4psLBrJn/gocMRIf1ji30WAz3GfyULRQ=
-github.com/Azure/go-autorest/autorest/adal v0.9.4/go.mod h1:/3SMAM86bP6wC9Ev35peQDUeqFZBMH07vvUOmg4z/fE=
+github.com/Azure/go-autorest/autorest/adal v0.9.5 h1:Y3bBUV4rTuxenJJs41HU3qmqsb+auo+a3Lz+PlJPpL0=
+github.com/Azure/go-autorest/autorest/adal v0.9.5/go.mod h1:B7KF7jKIeC9Mct5spmyCB/A8CG/sEz1vwIRGv/bbw7A=
 github.com/Azure/go-autorest/autorest/date v0.3.0 h1:7gUk1U5M/CQbp9WoqinNzJar+8KY+LPI6wiWrP/myHw=
 github.com/Azure/go-autorest/autorest/date v0.3.0/go.mod h1:BI0uouVdmngYNUzGWeSYnokU+TrmwEsOqdt8Y6sso74=
 github.com/Azure/go-autorest/autorest/mocks v0.4.1 h1:K0laFcLE6VLTOwNgSxaGbUcLPuGXlNkbVvq4cW4nIHk=
@@ -10,12 +10,12 @@ github.com/Azure/go-autorest/logger v0.2.0 h1:e4RVHVZKC5p6UANLJHkM4OfR1UKZPj8Wt8
 github.com/Azure/go-autorest/logger v0.2.0/go.mod h1:T9E3cAhj2VqvPOtCYAvby9aBXkZmbF5NWuPV8+WeEW8=
 github.com/Azure/go-autorest/tracing v0.6.0 h1:TYi4+3m5t6K48TGI9AUdb+IzbnSxvnvUMfuitfgcfuo=
 github.com/Azure/go-autorest/tracing v0.6.0/go.mod h1:+vhtPC754Xsa23ID7GlGsrdKBpUA79WCAKPPZVC2DeU=
-github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
-github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
+github.com/form3tech-oss/jwt-go v3.2.2+incompatible h1:TcekIExNqud5crz4xD2pavyTgWiPvpYe4Xau31I0PRk=
+github.com/form3tech-oss/jwt-go v3.2.2+incompatible/go.mod h1:pbq4aXjuKjdthFRnoDwaVPLA+WlJuPGy+QneDUgJi2k=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnkZWQJsqcURM6tKiBApRjXI=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 h1:hb9wdF1z5waM+dSIICn1l0DkLVDT3hqhhQsDNUmHPRE=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a h1:1BGLXjeY4akVXGgbC9HugT3Jv3hCI0z56oJR5vAMgBU=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

autorest/sender.go

@@ -23,11 +23,29 @@ import (
 	"net/http"
 	"net/http/cookiejar"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/Azure/go-autorest/tracing"
 )
 
+// there is one sender per TLS renegotiation type, i.e. count of tls.RenegotiationSupport enums
+const defaultSendersCount = 3
+
+type defaultSender struct {
+	sender Sender
+	init   *sync.Once
+}
+
+// each type of sender will be created on demand in sender()
+var defaultSenders [defaultSendersCount]defaultSender
+
+func init() {
+	for i := 0; i < defaultSendersCount; i++ {
+		defaultSenders[i].init = &sync.Once{}
+	}
+}
+
 // used as a key type in context.WithValue()
 type ctxSendDecorators struct{}
 
@@ -107,26 +125,31 @@ func SendWithSender(s Sender, r *http.Request, decorators ...SendDecorator) (*ht
 }
 
 func sender(renengotiation tls.RenegotiationSupport) Sender {
-	// Use behaviour compatible with DefaultTransport, but require TLS minimum version.
-	defaultTransport := http.DefaultTransport.(*http.Transport)
-	transport := &http.Transport{
-		Proxy:                 defaultTransport.Proxy,
-		DialContext:           defaultTransport.DialContext,
-		MaxIdleConns:          defaultTransport.MaxIdleConns,
-		IdleConnTimeout:       defaultTransport.IdleConnTimeout,
-		TLSHandshakeTimeout:   defaultTransport.TLSHandshakeTimeout,
-		ExpectContinueTimeout: defaultTransport.ExpectContinueTimeout,
-		TLSClientConfig: &tls.Config{
-			MinVersion:    tls.VersionTLS12,
-			Renegotiation: renengotiation,
-		},
-	}
-	var roundTripper http.RoundTripper = transport
-	if tracing.IsEnabled() {
-		roundTripper = tracing.NewTransport(transport)
-	}
-	j, _ := cookiejar.New(nil)
-	return &http.Client{Jar: j, Transport: roundTripper}
+	// note that we can't init defaultSenders in init() since it will
+	// execute before calling code has had a chance to enable tracing
+	defaultSenders[renengotiation].init.Do(func() {
+		// Use behaviour compatible with DefaultTransport, but require TLS minimum version.
+		defaultTransport := http.DefaultTransport.(*http.Transport)
+		transport := &http.Transport{
+			Proxy:                 defaultTransport.Proxy,
+			DialContext:           defaultTransport.DialContext,
+			MaxIdleConns:          defaultTransport.MaxIdleConns,
+			IdleConnTimeout:       defaultTransport.IdleConnTimeout,
+			TLSHandshakeTimeout:   defaultTransport.TLSHandshakeTimeout,
+			ExpectContinueTimeout: defaultTransport.ExpectContinueTimeout,
+			TLSClientConfig: &tls.Config{
+				MinVersion:    tls.VersionTLS12,
+				Renegotiation: renengotiation,
+			},
+		}
+		var roundTripper http.RoundTripper = transport
+		if tracing.IsEnabled() {
+			roundTripper = tracing.NewTransport(transport)
+		}
+		j, _ := cookiejar.New(nil)
+		defaultSenders[renengotiation].sender = &http.Client{Jar: j, Transport: roundTripper}
+	})
+	return defaultSenders[renengotiation].sender
 }
 
 // AfterDelay returns a SendDecorator that delays for the passed time.Duration before