From c165311f4270e8a2d75d9a610abdfb54d72ae4e5 Mon Sep 17 00:00:00 2001
From: ale <ale@incal.net>
Date: Mon, 6 Jan 2020 11:09:19 +0000
Subject: [PATCH] Let the configuration override connection and max request
timeouts
Add the 'connect_timeout' and 'request_max_timeout' configuration
fields, to control respectively the initial connection timeout, and
the maximum time for each individual request. This allows fine-tuning
of the expected performance of specific backends, for example to let
optional backends fail fast.
---
clientutil/backend.go | 7 ++++++
clientutil/balancer.go | 43 ++++++++++++++++++++++++++++---------
clientutil/dialer.go | 20 +++++++++++++++++
clientutil/dialer_legacy.go | 23 ++++++++++++++++++++
clientutil/transport.go | 37 ++++++++++++++++---------------
5 files changed, 101 insertions(+), 29 deletions(-)
create mode 100644 clientutil/dialer.go
create mode 100644 clientutil/dialer_legacy.go
diff --git a/clientutil/backend.go b/clientutil/backend.go
index 9e08fa0..cdde33b 100644
--- a/clientutil/backend.go
+++ b/clientutil/backend.go
@@ -16,6 +16,13 @@ type BackendConfig struct {
TLSConfig *TLSClientConfig `yaml:"tls"`
Sharded bool `yaml:"sharded"`
Debug bool `yaml:"debug"`
+
+ // Connection timeout (if unset, use default value).
+ ConnectTimeout string `yaml:"connect_timeout"`
+
+ // Maximum timeout for each individual request to this backend
+ // (if unset, use the Context timeout).
+ RequestMaxTimeout string `yaml:"request_max_timeout"`
}
// Backend is a runtime class that provides http Clients for use with
diff --git a/clientutil/balancer.go b/clientutil/balancer.go
index d2ca827..8f6e99f 100644
--- a/clientutil/balancer.go
+++ b/clientutil/balancer.go
@@ -60,10 +60,11 @@ func newExponentialBackOff() *backoff.ExponentialBackOff {
type balancedBackend struct {
*backendTracker
*transportCache
- baseURI *url.URL
- sharded bool
- resolver resolver
- log logger
+ baseURI *url.URL
+ sharded bool
+ resolver resolver
+ log logger
+ requestMaxTimeout time.Duration
}
func newBalancedBackend(config *BackendConfig, resolver resolver) (*balancedBackend, error) {
@@ -80,17 +81,36 @@ func newBalancedBackend(config *BackendConfig, resolver resolver) (*balancedBack
}
}
+ var connectTimeout time.Duration
+ if config.ConnectTimeout != "" {
+ t, err := time.ParseDuration(config.ConnectTimeout)
+ if err != nil {
+ return nil, fmt.Errorf("error in connect_timeout: %v", err)
+ }
+ connectTimeout = t
+ }
+
+ var reqTimeout time.Duration
+ if config.RequestMaxTimeout != "" {
+ t, err := time.ParseDuration(config.RequestMaxTimeout)
+ if err != nil {
+ return nil, fmt.Errorf("error in request_max_timeout: %v", err)
+ }
+ reqTimeout = t
+ }
+
var logger logger = &nilLogger{}
if config.Debug {
logger = log.New(os.Stderr, fmt.Sprintf("backend %s: ", u.Host), 0)
}
return &balancedBackend{
- backendTracker: newBackendTracker(u.Host, resolver, logger),
- transportCache: newTransportCache(tlsConfig),
- sharded: config.Sharded,
- baseURI: u,
- resolver: resolver,
- log: logger,
+ backendTracker: newBackendTracker(u.Host, resolver, logger),
+ transportCache: newTransportCache(tlsConfig, connectTimeout),
+ requestMaxTimeout: reqTimeout,
+ sharded: config.Sharded,
+ baseURI: u,
+ resolver: resolver,
+ log: logger,
}, nil
}
@@ -115,6 +135,9 @@ func (b *balancedBackend) Call(ctx context.Context, shard, path string, req, res
if deadline, ok := ctx.Deadline(); ok {
innerTimeout = time.Until(deadline) / time.Duration(seq.Len())
}
+ if b.requestMaxTimeout > 0 && innerTimeout > b.requestMaxTimeout {
+ innerTimeout = b.requestMaxTimeout
+ }
// Call the backends in the sequence until one succeeds, with an
// exponential backoff policy controlled by the outer Context.
diff --git a/clientutil/dialer.go b/clientutil/dialer.go
new file mode 100644
index 0000000..c8e7390
--- /dev/null
+++ b/clientutil/dialer.go
@@ -0,0 +1,20 @@
+// +build go1.9
+
+package clientutil
+
+import (
+ "context"
+ "net"
+ "time"
+)
+
+func netDialContext(addr string, connectTimeout time.Duration) func(context.Context, string, string) (net.Conn, error) {
+ dialer := &net.Dialer{
+ Timeout: connectTimeout,
+ KeepAlive: 30 * time.Second,
+ DualStack: true,
+ }
+ return func(ctx context.Context, net string, _ string) (net.Conn, error) {
+ return dialer.DialContext(ctx, net, addr)
+ }
+}
diff --git a/clientutil/dialer_legacy.go b/clientutil/dialer_legacy.go
new file mode 100644
index 0000000..f257990
--- /dev/null
+++ b/clientutil/dialer_legacy.go
@@ -0,0 +1,23 @@
+// +build !go1.9
+
+package clientutil
+
+import (
+ "context"
+ "net"
+ "time"
+)
+
+// Go < 1.9 does not have net.DialContext, reimplement it in terms of
+// net.DialTimeout.
+func netDialContext(addr string, connectTimeout time.Duration) func(context.Context, string, string) (net.Conn, error) {
+ return func(ctx context.Context, net string, _ string) (net.Conn, error) {
+ if deadline, ok := ctx.Deadline(); ok {
+ ctxTimeout := time.Until(deadline)
+ if ctxTimeout < connectTimeout {
+ connectTimeout = ctxTimeout
+ }
+ }
+ return net.DialTimeout(network, addr, connectTimeout)
+ }
+}
diff --git a/clientutil/transport.go b/clientutil/transport.go
index 1cc6c6d..39b1b3d 100644
--- a/clientutil/transport.go
+++ b/clientutil/transport.go
@@ -1,9 +1,7 @@
package clientutil
import (
- "context"
"crypto/tls"
- "net"
"net/http"
"sync"
"time"
@@ -11,31 +9,42 @@ import (
"git.autistici.org/ai3/go-common/tracing"
)
+var defaultConnectTimeout = 30 * time.Second
+
// The transportCache is just a cache of http transports, each
// connecting to a specific address.
//
// We use this to control the HTTP Host header and the TLS ServerName
// independently of the target address.
type transportCache struct {
- tlsConfig *tls.Config
+ tlsConfig *tls.Config
+ connectTimeout time.Duration
mx sync.RWMutex
transports map[string]http.RoundTripper
}
-func newTransportCache(tlsConfig *tls.Config) *transportCache {
+func newTransportCache(tlsConfig *tls.Config, connectTimeout time.Duration) *transportCache {
+ if connectTimeout == 0 {
+ connectTimeout = defaultConnectTimeout
+ }
return &transportCache{
- tlsConfig: tlsConfig,
- transports: make(map[string]http.RoundTripper),
+ tlsConfig: tlsConfig,
+ connectTimeout: connectTimeout,
+ transports: make(map[string]http.RoundTripper),
}
}
func (m *transportCache) newTransport(addr string) http.RoundTripper {
return tracing.WrapTransport(&http.Transport{
TLSClientConfig: m.tlsConfig,
- DialContext: func(ctx context.Context, network, _ string) (net.Conn, error) {
- return netDialContext(ctx, network, addr)
- },
+ DialContext: netDialContext(addr, m.connectTimeout),
+
+ // Parameters match those of net/http.DefaultTransport.
+ MaxIdleConns: 100,
+ IdleConnTimeout: 90 * time.Second,
+ TLSHandshakeTimeout: 10 * time.Second,
+ ExpectContinueTimeout: 1 * time.Second,
})
}
@@ -55,13 +64,3 @@ func (m *transportCache) getTransport(addr string) http.RoundTripper {
return t
}
-
-// Go < 1.9 does not have net.DialContext, reimplement it in terms of
-// net.DialTimeout.
-func netDialContext(ctx context.Context, network, addr string) (net.Conn, error) {
- timeout := 60 * time.Second // some arbitrary max timeout
- if deadline, ok := ctx.Deadline(); ok {
- timeout = time.Until(deadline)
- }
- return net.DialTimeout(network, addr, timeout)
-}
--
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