Bump Redigo to v1.8.2.

Signed-off-by: olegburov <oleg.burov@outlook.com>

vendor/github.com/gomodule/redigo/redis/pool.go

@@ -0,0 +1,635 @@
+// Copyright 2012 Gary Burd
+//
+// 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 redis
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"crypto/sha1"
+	"errors"
+	"io"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+var (
+	_ ConnWithTimeout = (*activeConn)(nil)
+	_ ConnWithTimeout = (*errorConn)(nil)
+)
+
+var nowFunc = time.Now // for testing
+
+// ErrPoolExhausted is returned from a pool connection method (Do, Send,
+// Receive, Flush, Err) when the maximum number of database connections in the
+// pool has been reached.
+var ErrPoolExhausted = errors.New("redigo: connection pool exhausted")
+
+var (
+	errPoolClosed = errors.New("redigo: connection pool closed")
+	errConnClosed = errors.New("redigo: connection closed")
+)
+
+// Pool maintains a pool of connections. The application calls the Get method
+// to get a connection from the pool and the connection's Close method to
+// return the connection's resources to the pool.
+//
+// The following example shows how to use a pool in a web application. The
+// application creates a pool at application startup and makes it available to
+// request handlers using a package level variable. The pool configuration used
+// here is an example, not a recommendation.
+//
+//  func newPool(addr string) *redis.Pool {
+//    return &redis.Pool{
+//      MaxIdle: 3,
+//      IdleTimeout: 240 * time.Second,
+//      // Dial or DialContext must be set. When both are set, DialContext takes precedence over Dial.
+//      Dial: func () (redis.Conn, error) { return redis.Dial("tcp", addr) },
+//    }
+//  }
+//
+//  var (
+//    pool *redis.Pool
+//    redisServer = flag.String("redisServer", ":6379", "")
+//  )
+//
+//  func main() {
+//    flag.Parse()
+//    pool = newPool(*redisServer)
+//    ...
+//  }
+//
+// A request handler gets a connection from the pool and closes the connection
+// when the handler is done:
+//
+//  func serveHome(w http.ResponseWriter, r *http.Request) {
+//      conn := pool.Get()
+//      defer conn.Close()
+//      ...
+//  }
+//
+// Use the Dial function to authenticate connections with the AUTH command or
+// select a database with the SELECT command:
+//
+//  pool := &redis.Pool{
+//    // Other pool configuration not shown in this example.
+//    Dial: func () (redis.Conn, error) {
+//      c, err := redis.Dial("tcp", server)
+//      if err != nil {
+//        return nil, err
+//      }
+//      if _, err := c.Do("AUTH", password); err != nil {
+//        c.Close()
+//        return nil, err
+//      }
+//      if _, err := c.Do("SELECT", db); err != nil {
+//        c.Close()
+//        return nil, err
+//      }
+//      return c, nil
+//    },
+//  }
+//
+// Use the TestOnBorrow function to check the health of an idle connection
+// before the connection is returned to the application. This example PINGs
+// connections that have been idle more than a minute:
+//
+//  pool := &redis.Pool{
+//    // Other pool configuration not shown in this example.
+//    TestOnBorrow: func(c redis.Conn, t time.Time) error {
+//      if time.Since(t) < time.Minute {
+//        return nil
+//      }
+//      _, err := c.Do("PING")
+//      return err
+//    },
+//  }
+//
+type Pool struct {
+	// Dial is an application supplied function for creating and configuring a
+	// connection.
+	//
+	// The connection returned from Dial must not be in a special state
+	// (subscribed to pubsub channel, transaction started, ...).
+	Dial func() (Conn, error)
+
+	// DialContext is an application supplied function for creating and configuring a
+	// connection with the given context.
+	//
+	// The connection returned from Dial must not be in a special state
+	// (subscribed to pubsub channel, transaction started, ...).
+	DialContext func(ctx context.Context) (Conn, error)
+
+	// TestOnBorrow is an optional application supplied function for checking
+	// the health of an idle connection before the connection is used again by
+	// the application. Argument t is the time that the connection was returned
+	// to the pool. If the function returns an error, then the connection is
+	// closed.
+	TestOnBorrow func(c Conn, t time.Time) error
+
+	// Maximum number of idle connections in the pool.
+	MaxIdle int
+
+	// Maximum number of connections allocated by the pool at a given time.
+	// When zero, there is no limit on the number of connections in the pool.
+	MaxActive int
+
+	// Close connections after remaining idle for this duration. If the value
+	// is zero, then idle connections are not closed. Applications should set
+	// the timeout to a value less than the server's timeout.
+	IdleTimeout time.Duration
+
+	// If Wait is true and the pool is at the MaxActive limit, then Get() waits
+	// for a connection to be returned to the pool before returning.
+	Wait bool
+
+	// Close connections older than this duration. If the value is zero, then
+	// the pool does not close connections based on age.
+	MaxConnLifetime time.Duration
+
+	chInitialized uint32 // set to 1 when field ch is initialized
+
+	mu           sync.Mutex    // mu protects the following fields
+	closed       bool          // set to true when the pool is closed.
+	active       int           // the number of open connections in the pool
+	ch           chan struct{} // limits open connections when p.Wait is true
+	idle         idleList      // idle connections
+	waitCount    int64         // total number of connections waited for.
+	waitDuration time.Duration // total time waited for new connections.
+}
+
+// NewPool creates a new pool.
+//
+// Deprecated: Initialize the Pool directly as shown in the example.
+func NewPool(newFn func() (Conn, error), maxIdle int) *Pool {
+	return &Pool{Dial: newFn, MaxIdle: maxIdle}
+}
+
+// Get gets a connection. The application must close the returned connection.
+// This method always returns a valid connection so that applications can defer
+// error handling to the first use of the connection. If there is an error
+// getting an underlying connection, then the connection Err, Do, Send, Flush
+// and Receive methods return that error.
+func (p *Pool) Get() Conn {
+	// GetContext returns errorConn in the first argument when an error occurs.
+	c, _ := p.GetContext(context.Background())
+	return c
+}
+
+// GetContext gets a connection using the provided context.
+//
+// The provided Context must be non-nil. If the context expires before the
+// connection is complete, an error is returned. Any expiration on the context
+// will not affect the returned connection.
+//
+// If the function completes without error, then the application must close the
+// returned connection.
+func (p *Pool) GetContext(ctx context.Context) (Conn, error) {
+	// Wait until there is a vacant connection in the pool.
+	waited, err := p.waitVacantConn(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	p.mu.Lock()
+
+	if waited > 0 {
+		p.waitCount++
+		p.waitDuration += waited
+	}
+
+	// Prune stale connections at the back of the idle list.
+	if p.IdleTimeout > 0 {
+		n := p.idle.count
+		for i := 0; i < n && p.idle.back != nil && p.idle.back.t.Add(p.IdleTimeout).Before(nowFunc()); i++ {
+			pc := p.idle.back
+			p.idle.popBack()
+			p.mu.Unlock()
+			pc.c.Close()
+			p.mu.Lock()
+			p.active--
+		}
+	}
+
+	// Get idle connection from the front of idle list.
+	for p.idle.front != nil {
+		pc := p.idle.front
+		p.idle.popFront()
+		p.mu.Unlock()
+		if (p.TestOnBorrow == nil || p.TestOnBorrow(pc.c, pc.t) == nil) &&
+			(p.MaxConnLifetime == 0 || nowFunc().Sub(pc.created) < p.MaxConnLifetime) {
+			return &activeConn{p: p, pc: pc}, nil
+		}
+		pc.c.Close()
+		p.mu.Lock()
+		p.active--
+	}
+
+	// Check for pool closed before dialing a new connection.
+	if p.closed {
+		p.mu.Unlock()
+		err := errors.New("redigo: get on closed pool")
+		return errorConn{err}, err
+	}
+
+	// Handle limit for p.Wait == false.
+	if !p.Wait && p.MaxActive > 0 && p.active >= p.MaxActive {
+		p.mu.Unlock()
+		return errorConn{ErrPoolExhausted}, ErrPoolExhausted
+	}
+
+	p.active++
+	p.mu.Unlock()
+	c, err := p.dial(ctx)
+	if err != nil {
+		c = nil
+		p.mu.Lock()
+		p.active--
+		if p.ch != nil && !p.closed {
+			p.ch <- struct{}{}
+		}
+		p.mu.Unlock()
+		return errorConn{err}, err
+	}
+	return &activeConn{p: p, pc: &poolConn{c: c, created: nowFunc()}}, nil
+}
+
+// PoolStats contains pool statistics.
+type PoolStats struct {
+	// ActiveCount is the number of connections in the pool. The count includes
+	// idle connections and connections in use.
+	ActiveCount int
+	// IdleCount is the number of idle connections in the pool.
+	IdleCount int
+
+	// WaitCount is the total number of connections waited for.
+	// This value is currently not guaranteed to be 100% accurate.
+	WaitCount int64
+
+	// WaitDuration is the total time blocked waiting for a new connection.
+	// This value is currently not guaranteed to be 100% accurate.
+	WaitDuration time.Duration
+}
+
+// Stats returns pool's statistics.
+func (p *Pool) Stats() PoolStats {
+	p.mu.Lock()
+	stats := PoolStats{
+		ActiveCount:  p.active,
+		IdleCount:    p.idle.count,
+		WaitCount:    p.waitCount,
+		WaitDuration: p.waitDuration,
+	}
+	p.mu.Unlock()
+
+	return stats
+}
+
+// ActiveCount returns the number of connections in the pool. The count
+// includes idle connections and connections in use.
+func (p *Pool) ActiveCount() int {
+	p.mu.Lock()
+	active := p.active
+	p.mu.Unlock()
+	return active
+}
+
+// IdleCount returns the number of idle connections in the pool.
+func (p *Pool) IdleCount() int {
+	p.mu.Lock()
+	idle := p.idle.count
+	p.mu.Unlock()
+	return idle
+}
+
+// Close releases the resources used by the pool.
+func (p *Pool) Close() error {
+	p.mu.Lock()
+	if p.closed {
+		p.mu.Unlock()
+		return nil
+	}
+	p.closed = true
+	p.active -= p.idle.count
+	pc := p.idle.front
+	p.idle.count = 0
+	p.idle.front, p.idle.back = nil, nil
+	if p.ch != nil {
+		close(p.ch)
+	}
+	p.mu.Unlock()
+	for ; pc != nil; pc = pc.next {
+		pc.c.Close()
+	}
+	return nil
+}
+
+func (p *Pool) lazyInit() {
+	// Fast path.
+	if atomic.LoadUint32(&p.chInitialized) == 1 {
+		return
+	}
+	// Slow path.
+	p.mu.Lock()
+	if p.chInitialized == 0 {
+		p.ch = make(chan struct{}, p.MaxActive)
+		if p.closed {
+			close(p.ch)
+		} else {
+			for i := 0; i < p.MaxActive; i++ {
+				p.ch <- struct{}{}
+			}
+		}
+		atomic.StoreUint32(&p.chInitialized, 1)
+	}
+	p.mu.Unlock()
+}
+
+// waitVacantConn waits for a vacant connection in pool if waiting
+// is enabled and pool size is limited, otherwise returns instantly.
+// If ctx expires before that, an error is returned.
+//
+// If there were no vacant connection in the pool right away it returns the time spent waiting
+// for that connection to appear in the pool.
+func (p *Pool) waitVacantConn(ctx context.Context) (waited time.Duration, err error) {
+	if !p.Wait || p.MaxActive <= 0 {
+		// No wait or no connection limit.
+		return 0, nil
+	}
+
+	p.lazyInit()
+
+	// wait indicates if we believe it will block so its not 100% accurate
+	// however for stats it should be good enough.
+	wait := len(p.ch) == 0
+	var start time.Time
+	if wait {
+		start = time.Now()
+	}
+
+	if ctx == nil {
+		<-p.ch
+	} else {
+		select {
+		case <-p.ch:
+			// Additionally check that context hasn't expired while we were waiting,
+			// because `select` picks a random `case` if several of them are "ready".
+			select {
+			case <-ctx.Done():
+				return 0, ctx.Err()
+			default:
+			}
+		case <-ctx.Done():
+			return 0, ctx.Err()
+		}
+	}
+
+	if wait {
+		return time.Since(start), nil
+	}
+	return 0, nil
+}
+
+func (p *Pool) dial(ctx context.Context) (Conn, error) {
+	if p.DialContext != nil {
+		return p.DialContext(ctx)
+	}
+	if p.Dial != nil {
+		return p.Dial()
+	}
+	return nil, errors.New("redigo: must pass Dial or DialContext to pool")
+}
+
+func (p *Pool) put(pc *poolConn, forceClose bool) error {
+	p.mu.Lock()
+	if !p.closed && !forceClose {
+		pc.t = nowFunc()
+		p.idle.pushFront(pc)
+		if p.idle.count > p.MaxIdle {
+			pc = p.idle.back
+			p.idle.popBack()
+		} else {
+			pc = nil
+		}
+	}
+
+	if pc != nil {
+		p.mu.Unlock()
+		pc.c.Close()
+		p.mu.Lock()
+		p.active--
+	}
+
+	if p.ch != nil && !p.closed {
+		p.ch <- struct{}{}
+	}
+	p.mu.Unlock()
+	return nil
+}
+
+type activeConn struct {
+	p     *Pool
+	pc    *poolConn
+	state int
+}
+
+var (
+	sentinel     []byte
+	sentinelOnce sync.Once
+)
+
+func initSentinel() {
+	p := make([]byte, 64)
+	if _, err := rand.Read(p); err == nil {
+		sentinel = p
+	} else {
+		h := sha1.New()
+		io.WriteString(h, "Oops, rand failed. Use time instead.")
+		io.WriteString(h, strconv.FormatInt(time.Now().UnixNano(), 10))
+		sentinel = h.Sum(nil)
+	}
+}
+
+func (ac *activeConn) Close() error {
+	pc := ac.pc
+	if pc == nil {
+		return nil
+	}
+	ac.pc = nil
+
+	if ac.state&connectionMultiState != 0 {
+		pc.c.Send("DISCARD")
+		ac.state &^= (connectionMultiState | connectionWatchState)
+	} else if ac.state&connectionWatchState != 0 {
+		pc.c.Send("UNWATCH")
+		ac.state &^= connectionWatchState
+	}
+	if ac.state&connectionSubscribeState != 0 {
+		pc.c.Send("UNSUBSCRIBE")
+		pc.c.Send("PUNSUBSCRIBE")
+		// To detect the end of the message stream, ask the server to echo
+		// a sentinel value and read until we see that value.
+		sentinelOnce.Do(initSentinel)
+		pc.c.Send("ECHO", sentinel)
+		pc.c.Flush()
+		for {
+			p, err := pc.c.Receive()
+			if err != nil {
+				break
+			}
+			if p, ok := p.([]byte); ok && bytes.Equal(p, sentinel) {
+				ac.state &^= connectionSubscribeState
+				break
+			}
+		}
+	}
+	pc.c.Do("")
+	ac.p.put(pc, ac.state != 0 || pc.c.Err() != nil)
+	return nil
+}
+
+func (ac *activeConn) Err() error {
+	pc := ac.pc
+	if pc == nil {
+		return errConnClosed
+	}
+	return pc.c.Err()
+}
+
+func (ac *activeConn) Do(commandName string, args ...interface{}) (reply interface{}, err error) {
+	pc := ac.pc
+	if pc == nil {
+		return nil, errConnClosed
+	}
+	ci := lookupCommandInfo(commandName)
+	ac.state = (ac.state | ci.Set) &^ ci.Clear
+	return pc.c.Do(commandName, args...)
+}
+
+func (ac *activeConn) DoWithTimeout(timeout time.Duration, commandName string, args ...interface{}) (reply interface{}, err error) {
+	pc := ac.pc
+	if pc == nil {
+		return nil, errConnClosed
+	}
+	cwt, ok := pc.c.(ConnWithTimeout)
+	if !ok {
+		return nil, errTimeoutNotSupported
+	}
+	ci := lookupCommandInfo(commandName)
+	ac.state = (ac.state | ci.Set) &^ ci.Clear
+	return cwt.DoWithTimeout(timeout, commandName, args...)
+}
+
+func (ac *activeConn) Send(commandName string, args ...interface{}) error {
+	pc := ac.pc
+	if pc == nil {
+		return errConnClosed
+	}
+	ci := lookupCommandInfo(commandName)
+	ac.state = (ac.state | ci.Set) &^ ci.Clear
+	return pc.c.Send(commandName, args...)
+}
+
+func (ac *activeConn) Flush() error {
+	pc := ac.pc
+	if pc == nil {
+		return errConnClosed
+	}
+	return pc.c.Flush()
+}
+
+func (ac *activeConn) Receive() (reply interface{}, err error) {
+	pc := ac.pc
+	if pc == nil {
+		return nil, errConnClosed
+	}
+	return pc.c.Receive()
+}
+
+func (ac *activeConn) ReceiveWithTimeout(timeout time.Duration) (reply interface{}, err error) {
+	pc := ac.pc
+	if pc == nil {
+		return nil, errConnClosed
+	}
+	cwt, ok := pc.c.(ConnWithTimeout)
+	if !ok {
+		return nil, errTimeoutNotSupported
+	}
+	return cwt.ReceiveWithTimeout(timeout)
+}
+
+type errorConn struct{ err error }
+
+func (ec errorConn) Do(string, ...interface{}) (interface{}, error) { return nil, ec.err }
+func (ec errorConn) DoWithTimeout(time.Duration, string, ...interface{}) (interface{}, error) {
+	return nil, ec.err
+}
+func (ec errorConn) Send(string, ...interface{}) error                     { return ec.err }
+func (ec errorConn) Err() error                                            { return ec.err }
+func (ec errorConn) Close() error                                          { return nil }
+func (ec errorConn) Flush() error                                          { return ec.err }
+func (ec errorConn) Receive() (interface{}, error)                         { return nil, ec.err }
+func (ec errorConn) ReceiveWithTimeout(time.Duration) (interface{}, error) { return nil, ec.err }
+
+type idleList struct {
+	count       int
+	front, back *poolConn
+}
+
+type poolConn struct {
+	c          Conn
+	t          time.Time
+	created    time.Time
+	next, prev *poolConn
+}
+
+func (l *idleList) pushFront(pc *poolConn) {
+	pc.next = l.front
+	pc.prev = nil
+	if l.count == 0 {
+		l.back = pc
+	} else {
+		l.front.prev = pc
+	}
+	l.front = pc
+	l.count++
+	return
+}
+
+func (l *idleList) popFront() {
+	pc := l.front
+	l.count--
+	if l.count == 0 {
+		l.front, l.back = nil, nil
+	} else {
+		pc.next.prev = nil
+		l.front = pc.next
+	}
+	pc.next, pc.prev = nil, nil
+}
+
+func (l *idleList) popBack() {
+	pc := l.back
+	l.count--
+	if l.count == 0 {
+		l.front, l.back = nil, nil
+	} else {
+		pc.prev.next = nil
+		l.back = pc.prev
+	}
+	pc.next, pc.prev = nil, nil
+}