switch from github.com/lib/pq to github.com/jackc/pgx/v5HEAD20240905master

lib/pq is out of maintenance for some time now, so switch to the newer
more active library. Looks like it finally stabilized after a long time.

1 files changed, 717 insertions, 0 deletions

diff --git a/vendor/github.com/jackc/pgx/v5/pgxpool/pool.go b/vendor/github.com/jackc/pgx/v5/pgxpool/pool.go
new file mode 100644
index 0000000..fdcba72
--- /dev/null
+++ b/vendor/github.com/jackc/pgx/v5/pgxpool/pool.go
@@ -0,0 +1,717 @@
+package pgxpool
+
+import (
+	"context"
+	"fmt"
+	"math/rand"
+	"runtime"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/jackc/pgx/v5"
+	"github.com/jackc/pgx/v5/pgconn"
+	"github.com/jackc/puddle/v2"
+)
+
+var defaultMaxConns = int32(4)
+var defaultMinConns = int32(0)
+var defaultMaxConnLifetime = time.Hour
+var defaultMaxConnIdleTime = time.Minute * 30
+var defaultHealthCheckPeriod = time.Minute
+
+type connResource struct {
+	conn       *pgx.Conn
+	conns      []Conn
+	poolRows   []poolRow
+	poolRowss  []poolRows
+	maxAgeTime time.Time
+}
+
+func (cr *connResource) getConn(p *Pool, res *puddle.Resource[*connResource]) *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
+}
+
+// Pool allows for connection reuse.
+type Pool struct {
+	// 64 bit fields accessed with atomics must be at beginning of struct to guarantee alignment for certain 32-bit
+	// architectures. See BUGS section of https://pkg.go.dev/sync/atomic and https://github.com/jackc/pgx/issues/1288.
+	newConnsCount        int64
+	lifetimeDestroyCount int64
+	idleDestroyCount     int64
+
+	p                     *puddle.Pool[*connResource]
+	config                *Config
+	beforeConnect         func(context.Context, *pgx.ConnConfig) error
+	afterConnect          func(context.Context, *pgx.Conn) error
+	beforeAcquire         func(context.Context, *pgx.Conn) bool
+	afterRelease          func(*pgx.Conn) bool
+	beforeClose           func(*pgx.Conn)
+	minConns              int32
+	maxConns              int32
+	maxConnLifetime       time.Duration
+	maxConnLifetimeJitter time.Duration
+	maxConnIdleTime       time.Duration
+	healthCheckPeriod     time.Duration
+
+	healthCheckChan chan struct{}
+
+	acquireTracer AcquireTracer
+	releaseTracer ReleaseTracer
+
+	closeOnce sync.Once
+	closeChan chan struct{}
+}
+
+// Config is the configuration struct for creating a pool. It must be created by [ParseConfig] and then it can be
+// modified.
+type Config struct {
+	ConnConfig *pgx.ConnConfig
+
+	// BeforeConnect is called before a new connection is made. It is passed a copy of the underlying pgx.ConnConfig and
+	// will not impact any existing open connections.
+	BeforeConnect func(context.Context, *pgx.ConnConfig) error
+
+	// AfterConnect is called after a connection is established, but before it is added to the pool.
+	AfterConnect func(context.Context, *pgx.Conn) error
+
+	// BeforeAcquire is called before a connection is acquired from the pool. It must return true to allow the
+	// acquisition or false to indicate that the connection should be destroyed and a different connection should be
+	// acquired.
+	BeforeAcquire func(context.Context, *pgx.Conn) bool
+
+	// AfterRelease is called after a connection is released, but before it is returned to the pool. It must return true to
+	// return the connection to the pool or false to destroy the connection.
+	AfterRelease func(*pgx.Conn) bool
+
+	// BeforeClose is called right before a connection is closed and removed from the pool.
+	BeforeClose func(*pgx.Conn)
+
+	// MaxConnLifetime is the duration since creation after which a connection will be automatically closed.
+	MaxConnLifetime time.Duration
+
+	// MaxConnLifetimeJitter is the duration after MaxConnLifetime to randomly decide to close a connection.
+	// This helps prevent all connections from being closed at the exact same time, starving the pool.
+	MaxConnLifetimeJitter time.Duration
+
+	// MaxConnIdleTime is the duration after which an idle connection will be automatically closed by the health check.
+	MaxConnIdleTime time.Duration
+
+	// MaxConns is the maximum size of the pool. The default is the greater of 4 or runtime.NumCPU().
+	MaxConns int32
+
+	// MinConns is the minimum size of the pool. After connection closes, the pool might dip below MinConns. A low
+	// number of MinConns might mean the pool is empty after MaxConnLifetime until the health check has a chance
+	// to create new connections.
+	MinConns int32
+
+	// HealthCheckPeriod is the duration between checks of the health of idle connections.
+	HealthCheckPeriod time.Duration
+
+	createdByParseConfig bool // Used to enforce created by ParseConfig rule.
+}
+
+// Copy returns a deep copy of the config that is safe to use and modify.
+// The only exception is the tls.Config:
+// according to the tls.Config docs it must not be modified after creation.
+func (c *Config) Copy() *Config {
+	newConfig := new(Config)
+	*newConfig = *c
+	newConfig.ConnConfig = c.ConnConfig.Copy()
+	return newConfig
+}
+
+// ConnString returns the connection string as parsed by pgxpool.ParseConfig into pgxpool.Config.
+func (c *Config) ConnString() string { return c.ConnConfig.ConnString() }
+
+// New creates a new Pool. See [ParseConfig] for information on connString format.
+func New(ctx context.Context, connString string) (*Pool, error) {
+	config, err := ParseConfig(connString)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewWithConfig(ctx, config)
+}
+
+// NewWithConfig creates a new Pool. config must have been created by [ParseConfig].
+func NewWithConfig(ctx context.Context, config *Config) (*Pool, error) {
+	// Default values are set in ParseConfig. Enforce initial creation by ParseConfig rather than setting defaults from
+	// zero values.
+	if !config.createdByParseConfig {
+		panic("config must be created by ParseConfig")
+	}
+
+	p := &Pool{
+		config:                config,
+		beforeConnect:         config.BeforeConnect,
+		afterConnect:          config.AfterConnect,
+		beforeAcquire:         config.BeforeAcquire,
+		afterRelease:          config.AfterRelease,
+		beforeClose:           config.BeforeClose,
+		minConns:              config.MinConns,
+		maxConns:              config.MaxConns,
+		maxConnLifetime:       config.MaxConnLifetime,
+		maxConnLifetimeJitter: config.MaxConnLifetimeJitter,
+		maxConnIdleTime:       config.MaxConnIdleTime,
+		healthCheckPeriod:     config.HealthCheckPeriod,
+		healthCheckChan:       make(chan struct{}, 1),
+		closeChan:             make(chan struct{}),
+	}
+
+	if t, ok := config.ConnConfig.Tracer.(AcquireTracer); ok {
+		p.acquireTracer = t
+	}
+
+	if t, ok := config.ConnConfig.Tracer.(ReleaseTracer); ok {
+		p.releaseTracer = t
+	}
+
+	var err error
+	p.p, err = puddle.NewPool(
+		&puddle.Config[*connResource]{
+			Constructor: func(ctx context.Context) (*connResource, error) {
+				atomic.AddInt64(&p.newConnsCount, 1)
+				connConfig := p.config.ConnConfig.Copy()
+
+				// Connection will continue in background even if Acquire is canceled. Ensure that a connect won't hang forever.
+				if connConfig.ConnectTimeout <= 0 {
+					connConfig.ConnectTimeout = 2 * time.Minute
+				}
+
+				if p.beforeConnect != nil {
+					if err := p.beforeConnect(ctx, connConfig); err != nil {
+						return nil, err
+					}
+				}
+
+				conn, err := pgx.ConnectConfig(ctx, connConfig)
+				if err != nil {
+					return nil, err
+				}
+
+				if p.afterConnect != nil {
+					err = p.afterConnect(ctx, conn)
+					if err != nil {
+						conn.Close(ctx)
+						return nil, err
+					}
+				}
+
+				jitterSecs := rand.Float64() * config.MaxConnLifetimeJitter.Seconds()
+				maxAgeTime := time.Now().Add(config.MaxConnLifetime).Add(time.Duration(jitterSecs) * time.Second)
+
+				cr := &connResource{
+					conn:       conn,
+					conns:      make([]Conn, 64),
+					poolRows:   make([]poolRow, 64),
+					poolRowss:  make([]poolRows, 64),
+					maxAgeTime: maxAgeTime,
+				}
+
+				return cr, nil
+			},
+			Destructor: func(value *connResource) {
+				ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+				conn := value.conn
+				if p.beforeClose != nil {
+					p.beforeClose(conn)
+				}
+				conn.Close(ctx)
+				select {
+				case <-conn.PgConn().CleanupDone():
+				case <-ctx.Done():
+				}
+				cancel()
+			},
+			MaxSize: config.MaxConns,
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	go func() {
+		p.createIdleResources(ctx, int(p.minConns))
+		p.backgroundHealthCheck()
+	}()
+
+	return p, nil
+}
+
+// ParseConfig builds a Config from connString. It parses connString with the same behavior as [pgx.ParseConfig] with the
+// addition of the following variables:
+//
+//   - pool_max_conns: integer greater than 0
+//   - pool_min_conns: integer 0 or greater
+//   - pool_max_conn_lifetime: duration string
+//   - pool_max_conn_idle_time: duration string
+//   - pool_health_check_period: duration string
+//   - pool_max_conn_lifetime_jitter: duration string
+//
+// See Config for definitions of these arguments.
+//
+//	# Example Keyword/Value
+//	user=jack password=secret host=pg.example.com port=5432 dbname=mydb sslmode=verify-ca pool_max_conns=10
+//
+//	# Example URL
+//	postgres://jack:secret@pg.example.com:5432/mydb?sslmode=verify-ca&pool_max_conns=10
+func ParseConfig(connString string) (*Config, error) {
+	connConfig, err := pgx.ParseConfig(connString)
+	if err != nil {
+		return nil, err
+	}
+
+	config := &Config{
+		ConnConfig:           connConfig,
+		createdByParseConfig: true,
+	}
+
+	if s, ok := config.ConnConfig.Config.RuntimeParams["pool_max_conns"]; ok {
+		delete(connConfig.Config.RuntimeParams, "pool_max_conns")
+		n, err := strconv.ParseInt(s, 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("cannot parse pool_max_conns: %w", err)
+		}
+		if n < 1 {
+			return nil, fmt.Errorf("pool_max_conns too small: %d", n)
+		}
+		config.MaxConns = int32(n)
+	} else {
+		config.MaxConns = defaultMaxConns
+		if numCPU := int32(runtime.NumCPU()); numCPU > config.MaxConns {
+			config.MaxConns = numCPU
+		}
+	}
+
+	if s, ok := config.ConnConfig.Config.RuntimeParams["pool_min_conns"]; ok {
+		delete(connConfig.Config.RuntimeParams, "pool_min_conns")
+		n, err := strconv.ParseInt(s, 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("cannot parse pool_min_conns: %w", err)
+		}
+		config.MinConns = int32(n)
+	} else {
+		config.MinConns = defaultMinConns
+	}
+
+	if s, ok := config.ConnConfig.Config.RuntimeParams["pool_max_conn_lifetime"]; ok {
+		delete(connConfig.Config.RuntimeParams, "pool_max_conn_lifetime")
+		d, err := time.ParseDuration(s)
+		if err != nil {
+			return nil, fmt.Errorf("invalid pool_max_conn_lifetime: %w", err)
+		}
+		config.MaxConnLifetime = d
+	} else {
+		config.MaxConnLifetime = defaultMaxConnLifetime
+	}
+
+	if s, ok := config.ConnConfig.Config.RuntimeParams["pool_max_conn_idle_time"]; ok {
+		delete(connConfig.Config.RuntimeParams, "pool_max_conn_idle_time")
+		d, err := time.ParseDuration(s)
+		if err != nil {
+			return nil, fmt.Errorf("invalid pool_max_conn_idle_time: %w", err)
+		}
+		config.MaxConnIdleTime = d
+	} else {
+		config.MaxConnIdleTime = defaultMaxConnIdleTime
+	}
+
+	if s, ok := config.ConnConfig.Config.RuntimeParams["pool_health_check_period"]; ok {
+		delete(connConfig.Config.RuntimeParams, "pool_health_check_period")
+		d, err := time.ParseDuration(s)
+		if err != nil {
+			return nil, fmt.Errorf("invalid pool_health_check_period: %w", err)
+		}
+		config.HealthCheckPeriod = d
+	} else {
+		config.HealthCheckPeriod = defaultHealthCheckPeriod
+	}
+
+	if s, ok := config.ConnConfig.Config.RuntimeParams["pool_max_conn_lifetime_jitter"]; ok {
+		delete(connConfig.Config.RuntimeParams, "pool_max_conn_lifetime_jitter")
+		d, err := time.ParseDuration(s)
+		if err != nil {
+			return nil, fmt.Errorf("invalid pool_max_conn_lifetime_jitter: %w", err)
+		}
+		config.MaxConnLifetimeJitter = d
+	}
+
+	return config, nil
+}
+
+// Close closes all connections in the pool and rejects future Acquire calls. Blocks until all connections are returned
+// to pool and closed.
+func (p *Pool) Close() {
+	p.closeOnce.Do(func() {
+		close(p.closeChan)
+		p.p.Close()
+	})
+}
+
+func (p *Pool) isExpired(res *puddle.Resource[*connResource]) bool {
+	return time.Now().After(res.Value().maxAgeTime)
+}
+
+func (p *Pool) triggerHealthCheck() {
+	go func() {
+		// Destroy is asynchronous so we give it time to actually remove itself from
+		// the pool otherwise we might try to check the pool size too soon
+		time.Sleep(500 * time.Millisecond)
+		select {
+		case p.healthCheckChan <- struct{}{}:
+		default:
+		}
+	}()
+}
+
+func (p *Pool) backgroundHealthCheck() {
+	ticker := time.NewTicker(p.healthCheckPeriod)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-p.closeChan:
+			return
+		case <-p.healthCheckChan:
+			p.checkHealth()
+		case <-ticker.C:
+			p.checkHealth()
+		}
+	}
+}
+
+func (p *Pool) checkHealth() {
+	for {
+		// If checkMinConns failed we don't destroy any connections since we couldn't
+		// even get to minConns
+		if err := p.checkMinConns(); err != nil {
+			// Should we log this error somewhere?
+			break
+		}
+		if !p.checkConnsHealth() {
+			// Since we didn't destroy any connections we can stop looping
+			break
+		}
+		// Technically Destroy is asynchronous but 500ms should be enough for it to
+		// remove it from the underlying pool
+		select {
+		case <-p.closeChan:
+			return
+		case <-time.After(500 * time.Millisecond):
+		}
+	}
+}
+
+// checkConnsHealth will check all idle connections, destroy a connection if
+// it's idle or too old, and returns true if any were destroyed
+func (p *Pool) checkConnsHealth() bool {
+	var destroyed bool
+	totalConns := p.Stat().TotalConns()
+	resources := p.p.AcquireAllIdle()
+	for _, res := range resources {
+		// We're okay going under minConns if the lifetime is up
+		if p.isExpired(res) && totalConns >= p.minConns {
+			atomic.AddInt64(&p.lifetimeDestroyCount, 1)
+			res.Destroy()
+			destroyed = true
+			// Since Destroy is async we manually decrement totalConns.
+			totalConns--
+		} else if res.IdleDuration() > p.maxConnIdleTime && totalConns > p.minConns {
+			atomic.AddInt64(&p.idleDestroyCount, 1)
+			res.Destroy()
+			destroyed = true
+			// Since Destroy is async we manually decrement totalConns.
+			totalConns--
+		} else {
+			res.ReleaseUnused()
+		}
+	}
+	return destroyed
+}
+
+func (p *Pool) checkMinConns() error {
+	// TotalConns can include ones that are being destroyed but we should have
+	// sleep(500ms) around all of the destroys to help prevent that from throwing
+	// off this check
+	toCreate := p.minConns - p.Stat().TotalConns()
+	if toCreate > 0 {
+		return p.createIdleResources(context.Background(), int(toCreate))
+	}
+	return nil
+}
+
+func (p *Pool) createIdleResources(parentCtx context.Context, targetResources int) error {
+	ctx, cancel := context.WithCancel(parentCtx)
+	defer cancel()
+
+	errs := make(chan error, targetResources)
+
+	for i := 0; i < targetResources; i++ {
+		go func() {
+			err := p.p.CreateResource(ctx)
+			// Ignore ErrNotAvailable since it means that the pool has become full since we started creating resource.
+			if err == puddle.ErrNotAvailable {
+				err = nil
+			}
+			errs <- err
+		}()
+	}
+
+	var firstError error
+	for i := 0; i < targetResources; i++ {
+		err := <-errs
+		if err != nil && firstError == nil {
+			cancel()
+			firstError = err
+		}
+	}
+
+	return firstError
+}
+
+// Acquire returns a connection (*Conn) from the Pool
+func (p *Pool) Acquire(ctx context.Context) (c *Conn, err error) {
+	if p.acquireTracer != nil {
+		ctx = p.acquireTracer.TraceAcquireStart(ctx, p, TraceAcquireStartData{})
+		defer func() {
+			var conn *pgx.Conn
+			if c != nil {
+				conn = c.Conn()
+			}
+			p.acquireTracer.TraceAcquireEnd(ctx, p, TraceAcquireEndData{Conn: conn, Err: err})
+		}()
+	}
+
+	for {
+		res, err := p.p.Acquire(ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		cr := res.Value()
+
+		if res.IdleDuration() > time.Second {
+			err := cr.conn.Ping(ctx)
+			if err != nil {
+				res.Destroy()
+				continue
+			}
+		}
+
+		if p.beforeAcquire == nil || p.beforeAcquire(ctx, cr.conn) {
+			return cr.getConn(p, res), nil
+		}
+
+		res.Destroy()
+	}
+}
+
+// AcquireFunc acquires a *Conn and calls f with that *Conn. ctx will only affect the Acquire. It has no effect on the
+// call of f. The return value is either an error acquiring the *Conn or the return value of f. The *Conn is
+// automatically released after the call of f.
+func (p *Pool) AcquireFunc(ctx context.Context, f func(*Conn) error) error {
+	conn, err := p.Acquire(ctx)
+	if err != nil {
+		return err
+	}
+	defer conn.Release()
+
+	return f(conn)
+}
+
+// AcquireAllIdle atomically acquires all currently idle connections. Its intended use is for health check and
+// keep-alive functionality. It does not update pool statistics.
+func (p *Pool) AcquireAllIdle(ctx context.Context) []*Conn {
+	resources := p.p.AcquireAllIdle()
+	conns := make([]*Conn, 0, len(resources))
+	for _, res := range resources {
+		cr := res.Value()
+		if p.beforeAcquire == nil || p.beforeAcquire(ctx, cr.conn) {
+			conns = append(conns, cr.getConn(p, res))
+		} else {
+			res.Destroy()
+		}
+	}
+
+	return conns
+}
+
+// Reset closes all connections, but leaves the pool open. It is intended for use when an error is detected that would
+// disrupt all connections (such as a network interruption or a server state change).
+//
+// It is safe to reset a pool while connections are checked out. Those connections will be closed when they are returned
+// to the pool.
+func (p *Pool) Reset() {
+	p.p.Reset()
+}
+
+// Config returns a copy of config that was used to initialize this pool.
+func (p *Pool) Config() *Config { return p.config.Copy() }
+
+// Stat returns a pgxpool.Stat struct with a snapshot of Pool statistics.
+func (p *Pool) Stat() *Stat {
+	return &Stat{
+		s:                    p.p.Stat(),
+		newConnsCount:        atomic.LoadInt64(&p.newConnsCount),
+		lifetimeDestroyCount: atomic.LoadInt64(&p.lifetimeDestroyCount),
+		idleDestroyCount:     atomic.LoadInt64(&p.idleDestroyCount),
+	}
+}
+
+// Exec acquires a connection from the Pool and executes the given SQL.
+// SQL can be either a prepared statement name or an SQL string.
+// Arguments should be referenced positionally from the SQL string as $1, $2, etc.
+// The acquired connection is returned to the pool when the Exec function returns.
+func (p *Pool) Exec(ctx context.Context, sql string, arguments ...any) (pgconn.CommandTag, error) {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return pgconn.CommandTag{}, err
+	}
+	defer c.Release()
+
+	return c.Exec(ctx, sql, arguments...)
+}
+
+// Query acquires a connection and executes a query that returns pgx.Rows.
+// Arguments should be referenced positionally from the SQL string as $1, $2, etc.
+// See pgx.Rows documentation to close the returned Rows and return the acquired connection to the Pool.
+//
+// If there is an error, the returned pgx.Rows will be returned in an error state.
+// If preferred, ignore the error returned from Query and handle errors using the returned pgx.Rows.
+//
+// For extra control over how the query is executed, the types QuerySimpleProtocol, QueryResultFormats, and
+// QueryResultFormatsByOID may be used as the first args to control exactly how the query is executed. This is rarely
+// needed. See the documentation for those types for details.
+func (p *Pool) Query(ctx context.Context, sql string, args ...any) (pgx.Rows, error) {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return errRows{err: err}, err
+	}
+
+	rows, err := c.Query(ctx, sql, args...)
+	if err != nil {
+		c.Release()
+		return errRows{err: err}, err
+	}
+
+	return c.getPoolRows(rows), nil
+}
+
+// QueryRow acquires a connection and executes a query that is expected
+// to return at most one row (pgx.Row). Errors are deferred until pgx.Row's
+// Scan method is called. If the query selects no rows, pgx.Row's Scan will
+// return ErrNoRows. Otherwise, pgx.Row's Scan scans the first selected row
+// and discards the rest. The acquired connection is returned to the Pool when
+// pgx.Row's Scan method is called.
+//
+// Arguments should be referenced positionally from the SQL string as $1, $2, etc.
+//
+// For extra control over how the query is executed, the types QuerySimpleProtocol, QueryResultFormats, and
+// QueryResultFormatsByOID may be used as the first args to control exactly how the query is executed. This is rarely
+// needed. See the documentation for those types for details.
+func (p *Pool) QueryRow(ctx context.Context, sql string, args ...any) pgx.Row {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return errRow{err: err}
+	}
+
+	row := c.QueryRow(ctx, sql, args...)
+	return c.getPoolRow(row)
+}
+
+func (p *Pool) SendBatch(ctx context.Context, b *pgx.Batch) pgx.BatchResults {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return errBatchResults{err: err}
+	}
+
+	br := c.SendBatch(ctx, b)
+	return &poolBatchResults{br: br, c: c}
+}
+
+// Begin acquires a connection from the Pool and starts a transaction. Unlike database/sql, the context only affects the begin command. i.e. there is no
+// auto-rollback on context cancellation. Begin initiates a transaction block without explicitly setting a transaction mode for the block (see BeginTx with TxOptions if transaction mode is required).
+// *pgxpool.Tx is returned, which implements the pgx.Tx interface.
+// Commit or Rollback must be called on the returned transaction to finalize the transaction block.
+func (p *Pool) Begin(ctx context.Context) (pgx.Tx, error) {
+	return p.BeginTx(ctx, pgx.TxOptions{})
+}
+
+// BeginTx acquires a connection from the Pool and starts a transaction with pgx.TxOptions determining the transaction mode.
+// Unlike database/sql, the context only affects the begin command. i.e. there is no auto-rollback on context cancellation.
+// *pgxpool.Tx is returned, which implements the pgx.Tx interface.
+// Commit or Rollback must be called on the returned transaction to finalize the transaction block.
+func (p *Pool) BeginTx(ctx context.Context, txOptions pgx.TxOptions) (pgx.Tx, error) {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	t, err := c.BeginTx(ctx, txOptions)
+	if err != nil {
+		c.Release()
+		return nil, err
+	}
+
+	return &Tx{t: t, c: c}, nil
+}
+
+func (p *Pool) CopyFrom(ctx context.Context, tableName pgx.Identifier, columnNames []string, rowSrc pgx.CopyFromSource) (int64, error) {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return 0, err
+	}
+	defer c.Release()
+
+	return c.Conn().CopyFrom(ctx, tableName, columnNames, rowSrc)
+}
+
+// Ping acquires a connection from the Pool and executes an empty sql statement against it.
+// If the sql returns without error, the database Ping is considered successful, otherwise, the error is returned.
+func (p *Pool) Ping(ctx context.Context) error {
+	c, err := p.Acquire(ctx)
+	if err != nil {
+		return err
+	}
+	defer c.Release()
+	return c.Ping(ctx)
+}