Per pool.Conn preallocated resources

This removes the pool wide mutexes for preallocated resources.

pool/conn.go

@@ -66,5 +66,17 @@ func (c *Conn) Begin(ctx context.Context, txOptions *pgx.TxOptions) (*pgx.Tx, er
 }
 
 func (c *Conn) Conn() *pgx.Conn {
-	return c.res.Value().(*pgx.Conn)
+	return c.res.Value().(*connResource).conn
+}
+
+func (c *Conn) connResource() *connResource {
+	return c.res.Value().(*connResource)
+}
+
+func (c *Conn) getPoolRow(r pgx.Row) *poolRow {
+	return c.connResource().getPoolRow(c, r)
+}
+
+func (c *Conn) getPoolRows(r pgx.Rows) *poolRows {
+	return c.connResource().getPoolRows(c, r)
 }

pool/pool.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"runtime"
 	"strconv"
-	"sync"
 	"time"
 
 	"github.com/jackc/pgconn"
@@ -17,6 +16,55 @@ var defaultMaxConns = int32(4)
 var defaultMaxConnLifetime = time.Hour
 var defaultHealthCheckPeriod = time.Minute
 
+type connResource struct {
+	conn      *pgx.Conn
+	conns     []Conn
+	poolRows  []poolRow
+	poolRowss []poolRows
+}
+
+func (cr *connResource) getConn(p *Pool, res *puddle.Resource) *Conn {
+	if len(cr.conns) == 0 {
+		cr.conns = make([]Conn, 128)
+	}
+
+	c := &cr.conns[len(cr.conns)-1]
+	cr.conns = cr.conns[0 : len(cr.conns)-1]
+
+	c.res = res
+	c.p = p
+
+	return c
+}
+
+func (cr *connResource) getPoolRow(c *Conn, r pgx.Row) *poolRow {
+	if len(cr.poolRows) == 0 {
+		cr.poolRows = make([]poolRow, 128)
+	}
+
+	pr := &cr.poolRows[len(cr.poolRows)-1]
+	cr.poolRows = cr.poolRows[0 : len(cr.poolRows)-1]
+
+	pr.c = c
+	pr.r = r
+
+	return pr
+}
+
+func (cr *connResource) getPoolRows(c *Conn, r pgx.Rows) *poolRows {
+	if len(cr.poolRowss) == 0 {
+		cr.poolRowss = make([]poolRows, 128)
+	}
+
+	pr := &cr.poolRowss[len(cr.poolRowss)-1]
+	cr.poolRowss = cr.poolRowss[0 : len(cr.poolRowss)-1]
+
+	pr.c = c
+	pr.r = r
+
+	return pr
+}
+
 type Pool struct {
 	p                 *puddle.Pool
 	afterConnect      func(context.Context, *pgx.Conn) error
@@ -25,15 +73,6 @@ type Pool struct {
 	maxConnLifetime   time.Duration
 	healthCheckPeriod time.Duration
 	closeChan         chan struct{}
-
-	preallocatedConnsMux sync.Mutex
-	preallocatedConns    []Conn
-
-	preallocatedPoolRowsMux sync.Mutex
-	preallocatedPoolRows    []poolRow
-
-	preallocatedPoolRowssMux sync.Mutex
-	preallocatedPoolRowss    []poolRows
 }
 
 // Config is the configuration struct for creating a pool. It is highly recommended to modify a Config returned by
@@ -101,11 +140,18 @@ func ConnectConfig(ctx context.Context, config *Config) (*Pool, error) {
 				}
 			}
 
-			return conn, nil
+			cr := &connResource{
+				conn:      conn,
+				conns:     make([]Conn, 64),
+				poolRows:  make([]poolRow, 64),
+				poolRowss: make([]poolRows, 64),
+			}
+
+			return cr, nil
 		},
 		func(value interface{}) {
 			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-			value.(*pgx.Conn).Close(ctx)
+			value.(*connResource).conn.Close(ctx)
 			cancel()
 		},
 		config.MaxConns,
@@ -222,60 +268,6 @@ func (p *Pool) checkIdleConnsHealth() {
 	}
 }
 
-func (p *Pool) getConn(res *puddle.Resource) *Conn {
-	p.preallocatedConnsMux.Lock()
-
-	if len(p.preallocatedConns) == 0 {
-		p.preallocatedConns = make([]Conn, 128)
-	}
-
-	c := &p.preallocatedConns[len(p.preallocatedConns)-1]
-	p.preallocatedConns = p.preallocatedConns[0 : len(p.preallocatedConns)-1]
-
-	p.preallocatedConnsMux.Unlock()
-
-	c.res = res
-	c.p = p
-
-	return c
-}
-
-func (p *Pool) getPoolRow(c *Conn, r pgx.Row) *poolRow {
-	p.preallocatedPoolRowsMux.Lock()
-
-	if len(p.preallocatedPoolRows) == 0 {
-		p.preallocatedPoolRows = make([]poolRow, 128)
-	}
-
-	pr := &p.preallocatedPoolRows[len(p.preallocatedPoolRows)-1]
-	p.preallocatedPoolRows = p.preallocatedPoolRows[0 : len(p.preallocatedPoolRows)-1]
-
-	p.preallocatedPoolRowsMux.Unlock()
-
-	pr.c = c
-	pr.r = r
-
-	return pr
-}
-
-func (p *Pool) getPoolRows(c *Conn, r pgx.Rows) *poolRows {
-	p.preallocatedPoolRowssMux.Lock()
-
-	if len(p.preallocatedPoolRowss) == 0 {
-		p.preallocatedPoolRowss = make([]poolRows, 128)
-	}
-
-	pr := &p.preallocatedPoolRowss[len(p.preallocatedPoolRowss)-1]
-	p.preallocatedPoolRowss = p.preallocatedPoolRowss[0 : len(p.preallocatedPoolRowss)-1]
-
-	p.preallocatedPoolRowssMux.Unlock()
-
-	pr.c = c
-	pr.r = r
-
-	return pr
-}
-
 func (p *Pool) Acquire(ctx context.Context) (*Conn, error) {
 	for {
 		res, err := p.p.Acquire(ctx)
@@ -283,8 +275,9 @@ func (p *Pool) Acquire(ctx context.Context) (*Conn, error) {
 			return nil, err
 		}
 
-		if p.beforeAcquire == nil || p.beforeAcquire(res.Value().(*pgx.Conn)) {
-			return p.getConn(res), nil
+		cr := res.Value().(*connResource)
+		if p.beforeAcquire == nil || p.beforeAcquire(cr.conn) {
+			return cr.getConn(p, res), nil
 		}
 
 		res.Destroy()
@@ -297,8 +290,9 @@ func (p *Pool) AcquireAllIdle() []*Conn {
 	resources := p.p.AcquireAllIdle()
 	conns := make([]*Conn, 0, len(resources))
 	for _, res := range resources {
-		if p.beforeAcquire == nil || p.beforeAcquire(res.Value().(*pgx.Conn)) {
-			conns = append(conns, p.getConn(res))
+		cr := res.Value().(*connResource)
+		if p.beforeAcquire == nil || p.beforeAcquire(cr.conn) {
+			conns = append(conns, cr.getConn(p, res))
 		} else {
 			res.Destroy()
 		}
@@ -333,7 +327,7 @@ func (p *Pool) Query(ctx context.Context, sql string, args ...interface{}) (pgx.
 		return errRows{err: err}, err
 	}
 
-	return p.getPoolRows(c, rows), nil
+	return c.getPoolRows(rows), nil
 }
 
 func (p *Pool) QueryRow(ctx context.Context, sql string, args ...interface{}) pgx.Row {
@@ -343,7 +337,7 @@ func (p *Pool) QueryRow(ctx context.Context, sql string, args ...interface{}) pg
 	}
 
 	row := c.QueryRow(ctx, sql, args...)
-	return p.getPoolRow(c, row)
+	return c.getPoolRow(row)
 }
 
 func (p *Pool) SendBatch(ctx context.Context, b *pgx.Batch) pgx.BatchResults {