From d154d71e4ad57a593c805a09c5edb56d746e291b Mon Sep 17 00:00:00 2001
From: Yutong Sean <yutongsean@gmail.com>
Date: Tue, 18 May 2021 10:28:57 +0800
Subject: [PATCH] Replace semaphore with mutex

---
 client.go | 18 ++----------------
 rpc.go    |  4 ++--
 2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/client.go b/client.go
index 0d340561..af8553cf 100644
--- a/client.go
+++ b/client.go
@@ -11,8 +11,6 @@ import (
 	"sync"
 	"time"
 
-	"golang.org/x/sync/semaphore"
-
 	log "github.com/sirupsen/logrus"
 	"github.com/tsuna/gohbase/compression"
 	"github.com/tsuna/gohbase/hrpc"
@@ -29,7 +27,6 @@ const (
 	defaultZkRoot        = "/hbase"
 	defaultZkTimeout     = 30 * time.Second
 	defaultEffectiveUser = "root"
-	defaultMetaLimit     = 50
 )
 
 // Client a regular HBase client
@@ -93,11 +90,8 @@ type client struct {
 	// regionReadTimeout is the maximum amount of time to wait for regionserver reply
 	regionReadTimeout time.Duration
 
-	// The max number of the goroutines that look up meta table simultaneously.
-	metaLimit int64
-
-	// The corresponding semaphore of metaLimit
-	sema *semaphore.Weighted
+	// The lock to control meta table lookup
+	lock sync.Mutex
 
 	done      chan struct{}
 	closeOnce sync.Once
@@ -135,7 +129,6 @@ func newClient(zkquorum string, options ...Option) *client {
 		zkRoot:              defaultZkRoot,
 		zkTimeout:           defaultZkTimeout,
 		effectiveUser:       defaultEffectiveUser,
-		metaLimit:           defaultMetaLimit,
 		regionLookupTimeout: region.DefaultLookupTimeout,
 		regionReadTimeout:   region.DefaultReadTimeout,
 		done:                make(chan struct{}),
@@ -149,13 +142,6 @@ func newClient(zkquorum string, options ...Option) *client {
 	//since the zkTimeout could be changed as an option
 	c.zkClient = zk.NewClient(zkquorum, c.zkTimeout)
 
-	if c.metaLimit > 0 {
-		c.sema = semaphore.NewWeighted(c.metaLimit)
-	} else {
-		c.sema = semaphore.NewWeighted(defaultMetaLimit)
-		c.metaLimit = defaultMetaLimit
-	}
-
 	return c
 }
 
diff --git a/rpc.go b/rpc.go
index ec33aedc..d47705a7 100644
--- a/rpc.go
+++ b/rpc.go
@@ -342,10 +342,10 @@ func (c *client) metaLookup(ctx context.Context,
 		return nil, "", err
 	}
 
-	c.sema.Acquire(context.Background(), 1)
+	c.lock.Lock()
 	scanner := c.Scan(rpc)
 	resp, err := scanner.Next()
-	c.sema.Release(1)
+	c.lock.Unlock()
 	if err == io.EOF {
 		return nil, "", TableNotFound
 	}