From f9ee579dcbaa4bf803194279ea76a3080802487a Mon Sep 17 00:00:00 2001
From: Sushan Bhattarai <sushantsusan@google.com>
Date: Mon, 16 Mar 2026 14:02:34 -0400
Subject: [PATCH] for experiment

---
 bigtable/direct_access_check.go | 65 +++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/bigtable/direct_access_check.go b/bigtable/direct_access_check.go
index 95ca6ef36e0d..abd74731aaf1 100644
--- a/bigtable/direct_access_check.go
+++ b/bigtable/direct_access_check.go
@@ -19,11 +19,16 @@ package bigtable
 import (
 	"context"
 	"fmt"
+	"log"
 	"strings"
+	"sync"
+	"time"
 
+	internal "cloud.google.com/go/bigtable/internal/transport"
 	"google.golang.org/api/option"
 	"google.golang.org/api/option/internaloption"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/credentials/google"
 	"google.golang.org/grpc/peer"
 )
 
@@ -117,3 +122,63 @@ func CheckDirectAccessSupported(ctx context.Context, project, instance, appProfi
 
 	return isDirectPathUsed, nil
 }
+
+// CallSingleChannel connects to Bigtable using the DirectPath C2P scheme,
+// and continuously maintains 200 in-flight Prime requests on the same channel
+// until the provided context is canceled.
+func CallSingleChannel(ctx context.Context, project, instance, appProfile, target string, requestsInFlight int) error {
+	fullInstanceName := fmt.Sprintf("projects/%s/instances/%s", project, instance)
+
+	log.Printf("Creating single channel to %s", target)
+
+	// 1. Create the gRPC Client
+	conn, err := grpc.NewClient(target,
+		grpc.WithCredentialsBundle(google.NewDefaultCredentials()),
+	)
+	if err != nil {
+		return fmt.Errorf("failed to create client for C2P target %s: %w", target, err)
+	}
+	defer conn.Close()
+
+	// 2. Wrap it in the internal BigtableConn
+	btc := internal.NewBigtableConn(conn)
+
+	// 3. Maintain 200 in-flight requests continuously
+	log.Printf("Starting %d workers to maintain continuous in-flight Prime() requests...", requestsInFlight)
+
+	var wg sync.WaitGroup
+
+	for i := 0; i < requestsInFlight; i++ {
+		wg.Add(1)
+		go func(workerID int) {
+			defer wg.Done()
+
+			// Infinite loop to keep firing requests
+			for {
+				// Exit the loop if the parent context is canceled
+				select {
+				case <-ctx.Done():
+					return
+				default:
+				}
+
+				// Execute a single request with its own 10s timeout
+				primeCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+				ffMd := createFeatureFlagsMD(true, false, true)
+				err := btc.Prime(primeCtx, fullInstanceName, appProfile, ffMd)
+				cancel() // Always cancel to prevent context leaks
+
+				if err != nil {
+					log.Printf("[Worker %d] Prime() failed: %v", workerID, err)
+					// Tiny backoff to prevent CPU thrashing if the connection fully drops
+				}
+			}
+		}(i)
+	}
+
+	// 4. Block until the context is canceled and all workers exit
+	wg.Wait()
+
+	log.Println("Stopped maintaining requests. Exiting CallSingleChannel.")
+	return ctx.Err()
+}