Open source a generic http client module to garr

go.mod

@@ -1,3 +1,8 @@
 module go.linecorp.com/garr
 
 require github.com/valyala/fastrand v1.1.0
+
+require (
+	github.com/hashicorp/errwrap v1.0.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1
+)

go.sum

@@ -1,2 +1,6 @@
+github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/valyala/fastrand v1.1.0 h1:f+5HkLW4rsgzdNoleUOB69hyT9IlD2ZQh9GyDMfb5G8=
 github.com/valyala/fastrand v1.1.0/go.mod h1:HWqCzkrkg6QXT8V2EXWvXCoow7vLwOFN002oeRzjapQ=

http-client/README.md

@@ -0,0 +1 @@
+# http client

http-client/actions.go

@@ -0,0 +1,47 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+import "net/http"
+
+// EndpointAction specifies in which cases a request should be passed
+// to the next endpoint or retrying on current endpoint.
+//
+// Similar to: http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_next_upstream
+type EndpointAction byte
+
+const (
+	// None indicates that there is no need for taking any actions.
+	None EndpointAction = iota
+
+	// NextEndpoint indicates that client should retry request on next endpoint.
+	NextEndpoint
+
+	// Retrying indicates that client could retry request on same endpoint.
+	Retrying
+)
+
+// OnStatus5xx is builtin decider which judge on 5xx status code.
+func OnStatus5xx(statusCode int, _ http.Header) (action EndpointAction) {
+	switch statusCode {
+	case http.StatusBadGateway:
+		action = Retrying
+	case http.StatusInternalServerError, http.StatusServiceUnavailable:
+		action = NextEndpoint
+	default:
+		action = None
+	}
+	return
+}

http-client/actions_test.go

@@ -0,0 +1,38 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+import (
+	"net/http"
+	"testing"
+)
+
+func TestOnStatus5xx(t *testing.T) {
+	if action := OnStatus5xx(http.StatusBadGateway, nil); action != Retrying {
+		t.FailNow()
+	}
+
+	if action := OnStatus5xx(http.StatusInternalServerError, nil); action != NextEndpoint {
+		t.FailNow()
+	}
+
+	if action := OnStatus5xx(http.StatusServiceUnavailable, nil); action != NextEndpoint {
+		t.FailNow()
+	}
+
+	if action := OnStatus5xx(http.StatusOK, nil); action != None {
+		t.FailNow()
+	}
+}

http-client/balancer.go

@@ -0,0 +1,36 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+// LB is load balancer for endpoints.
+type LB interface {
+	// Initialize endpoints for LB.
+	Initialize(endpoints Endpoints)
+
+	// Endpoints returned saved/ordered endpoints of LB.
+	Endpoints() Endpoints
+
+	// Pick returned index of picked endpoint.
+	Pick() (index int)
+}
+
+// LBBuilder is builder for LB.
+type LBBuilder interface {
+	Build() LB
+}
+
+func defaultLBBuilder() LBBuilder {
+	return &RoundRobinLBBuilder{}
+}

http-client/balancer_pf.go

@@ -0,0 +1,43 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+// PickfirstLB is pickfirst load balancer.
+type PickfirstLB struct {
+	endpoints Endpoints
+}
+
+// Initialize endpoints for PickfirstLB.
+func (p *PickfirstLB) Initialize(endpoints Endpoints) {
+	p.endpoints = endpoints
+}
+
+// Endpoints returned saved endpoints inside PickfirstLB
+func (p *PickfirstLB) Endpoints() Endpoints {
+	return p.endpoints
+}
+
+// Pick returns index of picked endpoint.
+func (p *PickfirstLB) Pick() int {
+	return 0
+}
+
+// PickfirstLBBuilder is builder for Pickfirst load-balancer
+type PickfirstLBBuilder struct{}
+
+// Build pickfirst balancer.
+func (p *PickfirstLBBuilder) Build() LB {
+	return &PickfirstLB{}
+}

http-client/balancer_pf_test.go

@@ -0,0 +1,78 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+import (
+	"testing"
+	"time"
+)
+
+func TestPickFirst(t *testing.T) {
+	builder := &PickfirstLBBuilder{}
+
+	lb := builder.Build()
+	lb.Initialize(validEndpoints())
+
+	endpoints := lb.Endpoints()
+	valid := validEndpoints()
+	if len(endpoints) != len(valid) {
+		t.FailNow()
+	}
+	for i := range endpoints {
+		if !endpoints[i].Equal(valid[i]) {
+			t.FailNow()
+		}
+	}
+	if lb.Pick()+lb.Pick()+lb.Pick() != 0 {
+		t.FailNow()
+	}
+}
+
+func TestPickFirstRace(t *testing.T) {
+	builder := PickfirstLBBuilder{}
+
+	lb := builder.Build()
+	lb.Initialize(validEndpoints())
+
+	type counter struct {
+		v [3]int
+	}
+	ch := make(chan counter, 5)
+	for i := 0; i < 5; i++ {
+		go func() {
+			time.Sleep(200 * time.Millisecond)
+
+			var counting counter
+			for j := 0; j < 18000; j++ {
+				counting.v[lb.Pick()]++
+			}
+
+			ch <- counting
+		}()
+	}
+
+	var sum counter
+	for i := 0; i < 5; i++ {
+		v := <-ch
+		sum.v[0] += v.v[0]
+		sum.v[1] += v.v[1]
+		sum.v[2] += v.v[2]
+	}
+
+	// 90000 = 18000 * 5
+	if sum.v[0] != 90000 || sum.v[1] != 0 || sum.v[2] != 0 {
+		t.FailNow()
+	}
+}

http-client/balancer_rr.go

@@ -0,0 +1,55 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+import (
+	"sync/atomic"
+
+	"github.com/valyala/fastrand"
+)
+
+// RoundRobinLB is round robin strategy.
+type RoundRobinLB struct {
+	endpoints Endpoints
+	index     uint32
+	n         uint32
+}
+
+// Initialize endpoints for RoundRobinLB.
+func (p *RoundRobinLB) Initialize(endpoints Endpoints) {
+	p.endpoints = endpoints
+	p.n = uint32(len(endpoints))
+}
+
+// Endpoints returned saved endpoints inside RoundRobinLB
+func (p *RoundRobinLB) Endpoints() Endpoints {
+	return p.endpoints
+}
+
+// Pick returns index of picked endpoint.
+func (p *RoundRobinLB) Pick() (chosen int) {
+	if p.n > 0 {
+		chosen = int(atomic.AddUint32(&p.index, 1) % p.n)
+	}
+	return
+}
+
+// RoundRobinLBBuilder is builder for RoundRobin load-balancer
+type RoundRobinLBBuilder struct{}
+
+// Build round robin balancer.
+func (p *RoundRobinLBBuilder) Build() LB {
+	return &RoundRobinLB{index: fastrand.Uint32()}
+}

http-client/balancer_rr_test.go

@@ -0,0 +1,78 @@
+// Copyright 2022 LINE Corporation
+//
+// LINE Corporation licenses this file to you under the Apache License,
+// version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at:
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+package httpclient
+
+import (
+	"testing"
+	"time"
+)
+
+func TestRoundRobin(t *testing.T) {
+	builder := defaultLBBuilder()
+
+	lb := builder.Build()
+	lb.Initialize(validEndpoints())
+
+	endpoints := lb.Endpoints()
+	valid := validEndpoints()
+	if len(endpoints) != len(valid) {
+		t.FailNow()
+	}
+	for i := range endpoints {
+		if !endpoints[i].Equal(valid[i]) {
+			t.FailNow()
+		}
+	}
+	if lb.Pick()+lb.Pick()+lb.Pick() != 3 {
+		t.FailNow()
+	}
+}
+
+func TestRoundRobinRace(t *testing.T) {
+	builder := defaultLBBuilder()
+
+	lb := builder.Build()
+	lb.Initialize(validEndpoints())
+
+	type counter struct {
+		v [3]int
+	}
+	ch := make(chan counter, 5)
+	for i := 0; i < 7; i++ {
+		go func() {
+			time.Sleep(200 * time.Millisecond)
+
+			var counting counter
+			for j := 0; j < 18000; j++ {
+				counting.v[lb.Pick()]++
+			}
+
+			ch <- counting
+		}()
+	}
+
+	var sum counter
+	for i := 0; i < 7; i++ {
+		v := <-ch
+		sum.v[0] += v.v[0]
+		sum.v[1] += v.v[1]
+		sum.v[2] += v.v[2]
+	}
+
+	// 42000 = 18000 / 3 * 7
+	if sum.v[0] != 42000 || sum.v[1] != 42000 || sum.v[2] != 42000 {
+		t.FailNow()
+	}
+}