Add API support for cancelation contexts passed via QueryOptions and …

…WriteOptions (hashicorp#8836)

Copy Consul API's format: QueryOptions.WithContext(context) will now return
a new QueryOption whose HTTP requests will be canceled with the context
provided (and similar for WriteOptions)

api/api.go

@@ -3,6 +3,7 @@ package api
 import (
 	"bytes"
 	"compress/gzip"
+	"context"
 	"crypto/tls"
 	"encoding/json"
 	"errors"
@@ -63,6 +64,10 @@ type QueryOptions struct {
 
 	// AuthToken is the secret ID of an ACL token
 	AuthToken string
+
+	// ctx is an optional context pass through to the underlying HTTP
+	// request layer. Use Context() and WithContext() to manage this.
+	ctx context.Context
 }
 
 // WriteOptions are used to parametrize a write
@@ -76,6 +81,10 @@ type WriteOptions struct {
 
 	// AuthToken is the secret ID of an ACL token
 	AuthToken string
+
+	// ctx is an optional context pass through to the underlying HTTP
+	// request layer. Use Context() and WithContext() to manage this.
+	ctx context.Context
 }
 
 // QueryMeta is used to return meta data about a query
@@ -517,6 +526,7 @@ type request struct {
 	token  string
 	body   io.Reader
 	obj    interface{}
+	ctx    context.Context
 }
 
 // setQueryOptions is used to annotate the request with
@@ -549,6 +559,7 @@ func (r *request) setQueryOptions(q *QueryOptions) {
 	for k, v := range q.Params {
 		r.params.Set(k, v)
 	}
+	r.ctx = q.Context()
 }
 
 // durToMsec converts a duration to a millisecond specified string
@@ -571,6 +582,7 @@ func (r *request) setWriteOptions(q *WriteOptions) {
 	if q.AuthToken != "" {
 		r.token = q.AuthToken
 	}
+	r.ctx = q.Context()
 }
 
 // toHTTP converts the request to an HTTP request
@@ -587,8 +599,15 @@ func (r *request) toHTTP() (*http.Request, error) {
 		}
 	}
 
+	ctx := func() context.Context {
+		if r.ctx != nil {
+			return r.ctx
+		}
+		return context.Background()
+	}()
+
 	// Create the HTTP request
-	req, err := http.NewRequest(r.method, r.url.RequestURI(), r.body)
+	req, err := http.NewRequestWithContext(ctx, r.method, r.url.RequestURI(), r.body)
 	if err != nil {
 		return nil, err
 	}
@@ -982,3 +1001,39 @@ func requireOK(d time.Duration, resp *http.Response, e error) (time.Duration, *h
 	}
 	return d, resp, nil
 }
+
+// Context returns the context used for canceling HTTP requests related to this query
+func (o *QueryOptions) Context() context.Context {
+	if o != nil && o.ctx != nil {
+		return o.ctx
+	}
+	return context.Background()
+}
+
+// WithContext creates a copy of the query options using the provided context to cancel related HTTP requests
+func (o *QueryOptions) WithContext(ctx context.Context) *QueryOptions {
+	o2 := new(QueryOptions)
+	if o != nil {
+		*o2 = *o
+	}
+	o2.ctx = ctx
+	return o2
+}
+
+// Context returns the context used for canceling HTTP requests related to this write
+func (o *WriteOptions) Context() context.Context {
+	if o != nil && o.ctx != nil {
+		return o.ctx
+	}
+	return context.Background()
+}
+
+// WithContext creates a copy of the write options using the provided context to cancel related HTTP requests
+func (o *WriteOptions) WithContext(ctx context.Context) *WriteOptions {
+	o2 := new(WriteOptions)
+	if o != nil {
+		*o2 = *o
+	}
+	o2.ctx = ctx
+	return o2
+}

api/api_test.go

@@ -1,7 +1,9 @@
 package api
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -198,6 +200,53 @@ func TestSetQueryOptions(t *testing.T) {
 	}
 }
 
+func TestQueryOptionsContext(t *testing.T) {
+	t.Parallel()
+	ctx, cancel := context.WithCancel(context.Background())
+	c, s := makeClient(t, nil, nil)
+	defer s.Stop()
+	q := (&QueryOptions{
+		WaitIndex: 10000,
+	}).WithContext(ctx)
+
+	if q.ctx != ctx {
+		t.Fatalf("expected context to be set")
+	}
+
+	go func() {
+		cancel()
+	}()
+	_, _, err := c.Jobs().List(q)
+	if !errors.Is(err, context.Canceled) {
+		t.Fatalf("expected job wait to fail with canceled, got %s", err)
+	}
+}
+
+func TestWriteOptionsContext(t *testing.T) {
+	// No blocking query to test a real cancel of a pending request so
+	// just test that if we pass a pre-canceled context, writes fail quickly
+	t.Parallel()
+
+	c, err := NewClient(DefaultConfig())
+	if err != nil {
+		t.Fatalf("failed to initialize client: %s", err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	w := (&WriteOptions{}).WithContext(ctx)
+
+	if w.ctx != ctx {
+		t.Fatalf("expected context to be set")
+	}
+
+	cancel()
+
+	_, _, err = c.Jobs().Deregister("jobid", true, w)
+	if !errors.Is(err, context.Canceled) {
+		t.Fatalf("expected job to fail with canceled, got %s", err)
+	}
+}
+
 func TestSetWriteOptions(t *testing.T) {
 	t.Parallel()
 	c, s := makeClient(t, nil, nil)