1 files changed, 658 insertions, 0 deletions
diff --git a/src/dma/vendor/github.com/go-redis/redis/ring.go b/src/dma/vendor/github.com/go-redis/redis/ring.go
new file mode 100644
index 00000000..250e5f64
--- /dev/null
+++ b/src/dma/vendor/github.com/go-redis/redis/ring.go
@@ -0,0 +1,658 @@
+package redis
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"math/rand"
+	"strconv"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/go-redis/redis/internal"
+	"github.com/go-redis/redis/internal/consistenthash"
+	"github.com/go-redis/redis/internal/hashtag"
+	"github.com/go-redis/redis/internal/pool"
+)
+
+// Hash is type of hash function used in consistent hash.
+type Hash consistenthash.Hash
+
+var errRingShardsDown = errors.New("redis: all ring shards are down")
+
+// RingOptions are used to configure a ring client and should be
+// passed to NewRing.
+type RingOptions struct {
+	// Map of name => host:port addresses of ring shards.
+	Addrs map[string]string
+
+	// Frequency of PING commands sent to check shards availability.
+	// Shard is considered down after 3 subsequent failed checks.
+	HeartbeatFrequency time.Duration
+
+	// Hash function used in consistent hash.
+	// Default is crc32.ChecksumIEEE.
+	Hash Hash
+
+	// Number of replicas in consistent hash.
+	// Default is 100 replicas.
+	//
+	// Higher number of replicas will provide less deviation, that is keys will be
+	// distributed to nodes more evenly.
+	//
+	// Following is deviation for common nreplicas:
+	//  --------------------------------------------------------
+	//  | nreplicas | standard error | 99% confidence interval |
+	//  |     10    |     0.3152     |      (0.37, 1.98)       |
+	//  |    100    |     0.0997     |      (0.76, 1.28)       |
+	//  |   1000    |     0.0316     |      (0.92, 1.09)       |
+	//  --------------------------------------------------------
+	//
+	//  See https://arxiv.org/abs/1406.2294 for reference
+	HashReplicas int
+
+	// Following options are copied from Options struct.
+
+	OnConnect func(*Conn) error
+
+	DB       int
+	Password string
+
+	MaxRetries      int
+	MinRetryBackoff time.Duration
+	MaxRetryBackoff time.Duration
+
+	DialTimeout  time.Duration
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+
+	PoolSize           int
+	MinIdleConns       int
+	MaxConnAge         time.Duration
+	PoolTimeout        time.Duration
+	IdleTimeout        time.Duration
+	IdleCheckFrequency time.Duration
+}
+
+func (opt *RingOptions) init() {
+	if opt.HeartbeatFrequency == 0 {
+		opt.HeartbeatFrequency = 500 * time.Millisecond
+	}
+
+	if opt.HashReplicas == 0 {
+		opt.HashReplicas = 100
+	}
+
+	switch opt.MinRetryBackoff {
+	case -1:
+		opt.MinRetryBackoff = 0
+	case 0:
+		opt.MinRetryBackoff = 8 * time.Millisecond
+	}
+	switch opt.MaxRetryBackoff {
+	case -1:
+		opt.MaxRetryBackoff = 0
+	case 0:
+		opt.MaxRetryBackoff = 512 * time.Millisecond
+	}
+}
+
+func (opt *RingOptions) clientOptions() *Options {
+	return &Options{
+		OnConnect: opt.OnConnect,
+
+		DB:       opt.DB,
+		Password: opt.Password,
+
+		DialTimeout:  opt.DialTimeout,
+		ReadTimeout:  opt.ReadTimeout,
+		WriteTimeout: opt.WriteTimeout,
+
+		PoolSize:           opt.PoolSize,
+		MinIdleConns:       opt.MinIdleConns,
+		MaxConnAge:         opt.MaxConnAge,
+		PoolTimeout:        opt.PoolTimeout,
+		IdleTimeout:        opt.IdleTimeout,
+		IdleCheckFrequency: opt.IdleCheckFrequency,
+	}
+}
+
+//------------------------------------------------------------------------------
+
+type ringShard struct {
+	Client *Client
+	down   int32
+}
+
+func (shard *ringShard) String() string {
+	var state string
+	if shard.IsUp() {
+		state = "up"
+	} else {
+		state = "down"
+	}
+	return fmt.Sprintf("%s is %s", shard.Client, state)
+}
+
+func (shard *ringShard) IsDown() bool {
+	const threshold = 3
+	return atomic.LoadInt32(&shard.down) >= threshold
+}
+
+func (shard *ringShard) IsUp() bool {
+	return !shard.IsDown()
+}
+
+// Vote votes to set shard state and returns true if state was changed.
+func (shard *ringShard) Vote(up bool) bool {
+	if up {
+		changed := shard.IsDown()
+		atomic.StoreInt32(&shard.down, 0)
+		return changed
+	}
+
+	if shard.IsDown() {
+		return false
+	}
+
+	atomic.AddInt32(&shard.down, 1)
+	return shard.IsDown()
+}
+
+//------------------------------------------------------------------------------
+
+type ringShards struct {
+	opt *RingOptions
+
+	mu     sync.RWMutex
+	hash   *consistenthash.Map
+	shards map[string]*ringShard // read only
+	list   []*ringShard          // read only
+	len    int
+	closed bool
+}
+
+func newRingShards(opt *RingOptions) *ringShards {
+	return &ringShards{
+		opt: opt,
+
+		hash:   newConsistentHash(opt),
+		shards: make(map[string]*ringShard),
+	}
+}
+
+func (c *ringShards) Add(name string, cl *Client) {
+	shard := &ringShard{Client: cl}
+	c.hash.Add(name)
+	c.shards[name] = shard
+	c.list = append(c.list, shard)
+}
+
+func (c *ringShards) List() []*ringShard {
+	c.mu.RLock()
+	list := c.list
+	c.mu.RUnlock()
+	return list
+}
+
+func (c *ringShards) Hash(key string) string {
+	c.mu.RLock()
+	hash := c.hash.Get(key)
+	c.mu.RUnlock()
+	return hash
+}
+
+func (c *ringShards) GetByKey(key string) (*ringShard, error) {
+	key = hashtag.Key(key)
+
+	c.mu.RLock()
+
+	if c.closed {
+		c.mu.RUnlock()
+		return nil, pool.ErrClosed
+	}
+
+	hash := c.hash.Get(key)
+	if hash == "" {
+		c.mu.RUnlock()
+		return nil, errRingShardsDown
+	}
+
+	shard := c.shards[hash]
+	c.mu.RUnlock()
+
+	return shard, nil
+}
+
+func (c *ringShards) GetByHash(name string) (*ringShard, error) {
+	if name == "" {
+		return c.Random()
+	}
+
+	c.mu.RLock()
+	shard := c.shards[name]
+	c.mu.RUnlock()
+	return shard, nil
+}
+
+func (c *ringShards) Random() (*ringShard, error) {
+	return c.GetByKey(strconv.Itoa(rand.Int()))
+}
+
+// heartbeat monitors state of each shard in the ring.
+func (c *ringShards) Heartbeat(frequency time.Duration) {
+	ticker := time.NewTicker(frequency)
+	defer ticker.Stop()
+	for range ticker.C {
+		var rebalance bool
+
+		c.mu.RLock()
+
+		if c.closed {
+			c.mu.RUnlock()
+			break
+		}
+
+		shards := c.list
+		c.mu.RUnlock()
+
+		for _, shard := range shards {
+			err := shard.Client.Ping().Err()
+			if shard.Vote(err == nil || err == pool.ErrPoolTimeout) {
+				internal.Logf("ring shard state changed: %s", shard)
+				rebalance = true
+			}
+		}
+
+		if rebalance {
+			c.rebalance()
+		}
+	}
+}
+
+// rebalance removes dead shards from the Ring.
+func (c *ringShards) rebalance() {
+	hash := newConsistentHash(c.opt)
+	var shardsNum int
+	for name, shard := range c.shards {
+		if shard.IsUp() {
+			hash.Add(name)
+			shardsNum++
+		}
+	}
+
+	c.mu.Lock()
+	c.hash = hash
+	c.len = shardsNum
+	c.mu.Unlock()
+}
+
+func (c *ringShards) Len() int {
+	c.mu.RLock()
+	l := c.len
+	c.mu.RUnlock()
+	return l
+}
+
+func (c *ringShards) Close() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.closed {
+		return nil
+	}
+	c.closed = true
+
+	var firstErr error
+	for _, shard := range c.shards {
+		if err := shard.Client.Close(); err != nil && firstErr == nil {
+			firstErr = err
+		}
+	}
+	c.hash = nil
+	c.shards = nil
+	c.list = nil
+
+	return firstErr
+}
+
+//------------------------------------------------------------------------------
+
+// Ring is a Redis client that uses consistent hashing to distribute
+// keys across multiple Redis servers (shards). It's safe for
+// concurrent use by multiple goroutines.
+//
+// Ring monitors the state of each shard and removes dead shards from
+// the ring. When a shard comes online it is added back to the ring. This
+// gives you maximum availability and partition tolerance, but no
+// consistency between different shards or even clients. Each client
+// uses shards that are available to the client and does not do any
+// coordination when shard state is changed.
+//
+// Ring should be used when you need multiple Redis servers for caching
+// and can tolerate losing data when one of the servers dies.
+// Otherwise you should use Redis Cluster.
+type Ring struct {
+	cmdable
+
+	ctx context.Context
+
+	opt           *RingOptions
+	shards        *ringShards
+	cmdsInfoCache *cmdsInfoCache
+
+	process         func(Cmder) error
+	processPipeline func([]Cmder) error
+}
+
+func NewRing(opt *RingOptions) *Ring {
+	opt.init()
+
+	ring := &Ring{
+		opt:    opt,
+		shards: newRingShards(opt),
+	}
+	ring.cmdsInfoCache = newCmdsInfoCache(ring.cmdsInfo)
+
+	ring.process = ring.defaultProcess
+	ring.processPipeline = ring.defaultProcessPipeline
+	ring.cmdable.setProcessor(ring.Process)
+
+	for name, addr := range opt.Addrs {
+		clopt := opt.clientOptions()
+		clopt.Addr = addr
+		ring.shards.Add(name, NewClient(clopt))
+	}
+
+	go ring.shards.Heartbeat(opt.HeartbeatFrequency)
+
+	return ring
+}
+
+func (c *Ring) Context() context.Context {
+	if c.ctx != nil {
+		return c.ctx
+	}
+	return context.Background()
+}
+
+func (c *Ring) WithContext(ctx context.Context) *Ring {
+	if ctx == nil {
+		panic("nil context")
+	}
+	c2 := c.copy()
+	c2.ctx = ctx
+	return c2
+}
+
+func (c *Ring) copy() *Ring {
+	cp := *c
+	return &cp
+}
+
+// Options returns read-only Options that were used to create the client.
+func (c *Ring) Options() *RingOptions {
+	return c.opt
+}
+
+func (c *Ring) retryBackoff(attempt int) time.Duration {
+	return internal.RetryBackoff(attempt, c.opt.MinRetryBackoff, c.opt.MaxRetryBackoff)
+}
+
+// PoolStats returns accumulated connection pool stats.
+func (c *Ring) PoolStats() *PoolStats {
+	shards := c.shards.List()
+	var acc PoolStats
+	for _, shard := range shards {
+		s := shard.Client.connPool.Stats()
+		acc.Hits += s.Hits
+		acc.Misses += s.Misses
+		acc.Timeouts += s.Timeouts
+		acc.TotalConns += s.TotalConns
+		acc.IdleConns += s.IdleConns
+	}
+	return &acc
+}
+
+// Len returns the current number of shards in the ring.
+func (c *Ring) Len() int {
+	return c.shards.Len()
+}
+
+// Subscribe subscribes the client to the specified channels.
+func (c *Ring) Subscribe(channels ...string) *PubSub {
+	if len(channels) == 0 {
+		panic("at least one channel is required")
+	}
+
+	shard, err := c.shards.GetByKey(channels[0])
+	if err != nil {
+		// TODO: return PubSub with sticky error
+		panic(err)
+	}
+	return shard.Client.Subscribe(channels...)
+}
+
+// PSubscribe subscribes the client to the given patterns.
+func (c *Ring) PSubscribe(channels ...string) *PubSub {
+	if len(channels) == 0 {
+		panic("at least one channel is required")
+	}
+
+	shard, err := c.shards.GetByKey(channels[0])
+	if err != nil {
+		// TODO: return PubSub with sticky error
+		panic(err)
+	}
+	return shard.Client.PSubscribe(channels...)
+}
+
+// ForEachShard concurrently calls the fn on each live shard in the ring.
+// It returns the first error if any.
+func (c *Ring) ForEachShard(fn func(client *Client) error) error {
+	shards := c.shards.List()
+	var wg sync.WaitGroup
+	errCh := make(chan error, 1)
+	for _, shard := range shards {
+		if shard.IsDown() {
+			continue
+		}
+
+		wg.Add(1)
+		go func(shard *ringShard) {
+			defer wg.Done()
+			err := fn(shard.Client)
+			if err != nil {
+				select {
+				case errCh <- err:
+				default:
+				}
+			}
+		}(shard)
+	}
+	wg.Wait()
+
+	select {
+	case err := <-errCh:
+		return err
+	default:
+		return nil
+	}
+}
+
+func (c *Ring) cmdsInfo() (map[string]*CommandInfo, error) {
+	shards := c.shards.List()
+	firstErr := errRingShardsDown
+	for _, shard := range shards {
+		cmdsInfo, err := shard.Client.Command().Result()
+		if err == nil {
+			return cmdsInfo, nil
+		}
+		if firstErr == nil {
+			firstErr = err
+		}
+	}
+	return nil, firstErr
+}
+
+func (c *Ring) cmdInfo(name string) *CommandInfo {
+	cmdsInfo, err := c.cmdsInfoCache.Get()
+	if err != nil {
+		return nil
+	}
+	info := cmdsInfo[name]
+	if info == nil {
+		internal.Logf("info for cmd=%s not found", name)
+	}
+	return info
+}
+
+func (c *Ring) cmdShard(cmd Cmder) (*ringShard, error) {
+	cmdInfo := c.cmdInfo(cmd.Name())
+	pos := cmdFirstKeyPos(cmd, cmdInfo)
+	if pos == 0 {
+		return c.shards.Random()
+	}
+	firstKey := cmd.stringArg(pos)
+	return c.shards.GetByKey(firstKey)
+}
+
+// Do creates a Cmd from the args and processes the cmd.
+func (c *Ring) Do(args ...interface{}) *Cmd {
+	cmd := NewCmd(args...)
+	c.Process(cmd)
+	return cmd
+}
+
+func (c *Ring) WrapProcess(
+	fn func(oldProcess func(cmd Cmder) error) func(cmd Cmder) error,
+) {
+	c.process = fn(c.process)
+}
+
+func (c *Ring) Process(cmd Cmder) error {
+	return c.process(cmd)
+}
+
+func (c *Ring) defaultProcess(cmd Cmder) error {
+	for attempt := 0; attempt <= c.opt.MaxRetries; attempt++ {
+		if attempt > 0 {
+			time.Sleep(c.retryBackoff(attempt))
+		}
+
+		shard, err := c.cmdShard(cmd)
+		if err != nil {
+			cmd.setErr(err)
+			return err
+		}
+
+		err = shard.Client.Process(cmd)
+		if err == nil {
+			return nil
+		}
+		if !internal.IsRetryableError(err, cmd.readTimeout() == nil) {
+			return err
+		}
+	}
+	return cmd.Err()
+}
+
+func (c *Ring) Pipeline() Pipeliner {
+	pipe := Pipeline{
+		exec: c.processPipeline,
+	}
+	pipe.cmdable.setProcessor(pipe.Process)
+	return &pipe
+}
+
+func (c *Ring) Pipelined(fn func(Pipeliner) error) ([]Cmder, error) {
+	return c.Pipeline().Pipelined(fn)
+}
+
+func (c *Ring) WrapProcessPipeline(
+	fn func(oldProcess func([]Cmder) error) func([]Cmder) error,
+) {
+	c.processPipeline = fn(c.processPipeline)
+}
+
+func (c *Ring) defaultProcessPipeline(cmds []Cmder) error {
+	cmdsMap := make(map[string][]Cmder)
+	for _, cmd := range cmds {
+		cmdInfo := c.cmdInfo(cmd.Name())
+		hash := cmd.stringArg(cmdFirstKeyPos(cmd, cmdInfo))
+		if hash != "" {
+			hash = c.shards.Hash(hashtag.Key(hash))
+		}
+		cmdsMap[hash] = append(cmdsMap[hash], cmd)
+	}
+
+	for attempt := 0; attempt <= c.opt.MaxRetries; attempt++ {
+		if attempt > 0 {
+			time.Sleep(c.retryBackoff(attempt))
+		}
+
+		var mu sync.Mutex
+		var failedCmdsMap map[string][]Cmder
+		var wg sync.WaitGroup
+
+		for hash, cmds := range cmdsMap {
+			wg.Add(1)
+			go func(hash string, cmds []Cmder) {
+				defer wg.Done()
+
+				shard, err := c.shards.GetByHash(hash)
+				if err != nil {
+					setCmdsErr(cmds, err)
+					return
+				}
+
+				cn, err := shard.Client.getConn()
+				if err != nil {
+					setCmdsErr(cmds, err)
+					return
+				}
+
+				canRetry, err := shard.Client.pipelineProcessCmds(cn, cmds)
+				shard.Client.releaseConnStrict(cn, err)
+
+				if canRetry && internal.IsRetryableError(err, true) {
+					mu.Lock()
+					if failedCmdsMap == nil {
+						failedCmdsMap = make(map[string][]Cmder)
+					}
+					failedCmdsMap[hash] = cmds
+					mu.Unlock()
+				}
+			}(hash, cmds)
+		}
+
+		wg.Wait()
+		if len(failedCmdsMap) == 0 {
+			break
+		}
+		cmdsMap = failedCmdsMap
+	}
+
+	return cmdsFirstErr(cmds)
+}
+
+func (c *Ring) TxPipeline() Pipeliner {
+	panic("not implemented")
+}
+
+func (c *Ring) TxPipelined(fn func(Pipeliner) error) ([]Cmder, error) {
+	panic("not implemented")
+}
+
+// Close closes the ring client, releasing any open resources.
+//
+// It is rare to Close a Ring, as the Ring is meant to be long-lived
+// and shared between many goroutines.
+func (c *Ring) Close() error {
+	return c.shards.Close()
+}
+
+func newConsistentHash(opt *RingOptions) *consistenthash.Map {
+	return consistenthash.New(opt.HashReplicas, consistenthash.Hash(opt.Hash))
+}