snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

internal/testutils/channel.go

@@ -0,0 +1,118 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed 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
+ *
+ *     http://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 testutils
+
+import (
+	"context"
+)
+
+// DefaultChanBufferSize is the default buffer size of the underlying channel.
+const DefaultChanBufferSize = 1
+
+// Channel wraps a generic channel and provides a timed receive operation.
+type Channel struct {
+	// C is the underlying channel on which values sent using the SendXxx()
+	// methods are delivered. Tests which cannot use ReceiveXxx() for whatever
+	// reasons can use C to read the values.
+	C chan any
+}
+
+// Send sends value on the underlying channel.
+func (c *Channel) Send(value any) {
+	c.C <- value
+}
+
+// SendContext sends value on the underlying channel, or returns an error if
+// the context expires.
+func (c *Channel) SendContext(ctx context.Context, value any) error {
+	select {
+	case c.C <- value:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+// SendOrFail attempts to send value on the underlying channel.  Returns true
+// if successful or false if the channel was full.
+func (c *Channel) SendOrFail(value any) bool {
+	select {
+	case c.C <- value:
+		return true
+	default:
+		return false
+	}
+}
+
+// ReceiveOrFail returns the value on the underlying channel and true, or nil
+// and false if the channel was empty.
+func (c *Channel) ReceiveOrFail() (any, bool) {
+	select {
+	case got := <-c.C:
+		return got, true
+	default:
+		return nil, false
+	}
+}
+
+// Drain drains the channel by repeatedly reading from it until it is empty.
+func (c *Channel) Drain() {
+	for {
+		select {
+		case <-c.C:
+		default:
+			return
+		}
+	}
+}
+
+// Receive returns the value received on the underlying channel, or the error
+// returned by ctx if it is closed or cancelled.
+func (c *Channel) Receive(ctx context.Context) (any, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	case got := <-c.C:
+		return got, nil
+	}
+}
+
+// Replace clears the value on the underlying channel, and sends the new value.
+//
+// It's expected to be used with a size-1 channel, to only keep the most
+// up-to-date item. This method is inherently racy when invoked concurrently
+// from multiple goroutines.
+func (c *Channel) Replace(value any) {
+	for {
+		select {
+		case c.C <- value:
+			return
+		case <-c.C:
+		}
+	}
+}
+
+// NewChannel returns a new Channel.
+func NewChannel() *Channel {
+	return NewChannelWithSize(DefaultChanBufferSize)
+}
+
+// NewChannelWithSize returns a new Channel with a buffer of bufSize.
+func NewChannelWithSize(bufSize int) *Channel {
+	return &Channel{C: make(chan any, bufSize)}
+}