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Copy pathcommand_metadata.go
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1369 lines (1272 loc) · 41.4 KB
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package redis
import (
"context"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"maps"
"math/rand"
"reflect"
"slices"
"sort"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/redis/go-redis/v9/internal"
)
// Per-client command-metadata resolution. A client resolves COMMAND metadata
// records into an immutable commandMetadataView (app overrides > built-in
// corrections > live COMMAND output > shipped snapshot) and publishes it
// through an atomic pointer. Every command invocation reads exactly one view.
// In PreferLive mode a background worker upgrades the static view with the
// server's live COMMAND output.
// CommandMetadataMode selects metadata resolution for CSC and Cluster routing.
//
// Experimental: this API may change in a minor release.
type CommandMetadataMode int
const (
// CommandMetadataStatic uses the snapshot and overrides without network
// calls or goroutines, unless a ClusterClient's Dynamic Resolver is used.
CommandMetadataStatic CommandMetadataMode = iota
// CommandMetadataPreferLive starts static and fetches live metadata after
// the first connection. Older Redis versions and servers not identified as
// Redis get conservative CSC exclusions.
//
// Security: live metadata controls routing and caching. Use TLS because a
// compromised source can misroute commands, serve stale data, or suppress a
// write by falsely classifying it as cacheable. Redis 8.10+ records are
// authoritative except for built-in corrections.
CommandMetadataPreferLive
)
// CommandMetadataConfig configures metadata for Options and ClusterOptions.
// Its zero value is static.
//
// Experimental: this API may change in a minor release.
type CommandMetadataConfig struct {
Mode CommandMetadataMode
// Overrides take precedence over every other metadata source. Keys are
// case-insensitive; use "parent|child" for subcommands. Nil marks a command
// unknown. Unsafe cacheable overrides can serve stale data. The map and
// records are copied at client creation.
Overrides map[string]*CommandInfo
// RefreshInterval periodically refreshes live metadata with jitter.
// Zero disables periodic refresh; detected server or topology changes
// still trigger a refresh.
RefreshInterval time.Duration
}
// commandMetadataView is one immutable resolution of command metadata.
type commandMetadataView struct {
// generation identifies this view across clients and refreshes.
generation uint64
// records holds resolved metadata by lowercase command name.
records map[string]*CommandInfo
// tombstones block fallback for malformed or explicitly disabled commands.
tombstones map[string]struct{}
// shadowedParents are bare records pruned to expose their subcommands.
subcommandParents map[string]struct{}
shadowedParents map[string]struct{}
// CSC and routing derive separate decisions from the shared records.
cscTable map[string]cscCommandMeta
routingTable map[string]*routingCommandMeta
// cscFingerprint identifies the eligibility decisions. It is part of
// every cache-entry key — never of the Redis-key invalidation index — so
// entries cached under different metadata never mix, while invalidations
// keep reaching every generation.
cscFingerprint string
// live is true when the view was built from live COMMAND output.
live bool
serverVersion string
}
// defaultCommandMetadataView is built only when CSC or metadata routing needs
// it, and is shared by clients without overrides or live mode.
var defaultCommandMetadataView = sync.OnceValue(func() *commandMetadataView {
return buildCommandMetadataView(nil, nil)
})
var commandMetadataGeneration atomic.Uint64
// The snapshot itself is static data. Only live compatibility resolution needs
// a name index; ordinary static view construction can iterate the records.
var commandInfoSnapshotByName = sync.OnceValue(func() map[string]*CommandInfo {
index := make(map[string]*CommandInfo, len(commandInfoSnapshotRecords))
for i := range commandInfoSnapshotRecords {
info := &commandInfoSnapshotRecords[i]
index[info.Name] = info
}
return index
})
// commandMetadataCompatibilityCorrection adds CSC exclusions missing before
// Redis 8.10.
type commandMetadataCompatibilityCorrection struct {
flags []string
tips []string
}
// commandMetadataPre810Corrections contains only pre-8.10 CSC exclusions.
// Redis 8.10+ metadata stays authoritative except for built-in corrections.
var commandMetadataPre810Corrections = sync.OnceValue(func() map[string]commandMetadataCompatibilityCorrection {
corrections := make(map[string]commandMetadataCompatibilityCorrection)
for i := range commandInfoSnapshotRecords {
info := &commandInfoSnapshotRecords[i]
var correction commandMetadataCompatibilityCorrection
if !commandRecordHas(info, "readonly", false) {
// Do not let old metadata make a known write command cacheable.
correction.tips = append(correction.tips, "dont_cache")
}
for _, flag := range info.Flags {
switch flag {
case "script_runner", "blocking":
correction.flags = append(correction.flags, flag)
}
}
for _, tip := range info.Tips {
switch tip {
case "dont_cache", "nondeterministic_output":
correction.tips = append(correction.tips, tip)
}
}
if len(correction.flags) > 0 || len(correction.tips) > 0 {
corrections[info.Name] = correction
}
}
return corrections
})
// buildCommandMetadataView builds a view, treating live input as Redis 8.10.
func buildCommandMetadataView(live, overrides map[string]*CommandInfo) *commandMetadataView {
return buildCommandMetadataViewForServer(live, overrides, "redis", "8.10")
}
// buildCommandMetadataViewForServer resolves records and derived decisions.
func buildCommandMetadataViewForServer(
live, overrides map[string]*CommandInfo,
serverName, serverVersion string,
) *commandMetadataView {
return buildCommandMetadataViewForServerWithLegacy(
live,
overrides,
serverName,
serverVersion,
nil,
)
}
func buildCommandMetadataViewForServerWithLegacy(
live, overrides map[string]*CommandInfo,
serverName, serverVersion string,
liveLegacyRecords map[string]struct{},
) *commandMetadataView {
records := make(map[string]*CommandInfo, len(commandInfoSnapshotRecords)+len(overrides))
tombstones := make(map[string]struct{})
parents := make(map[string]struct{})
markParent := func(name string) {
for offset := 0; ; {
i := strings.IndexByte(name[offset:], '|')
if i < 0 {
break
}
offset += i
if offset > 0 {
parents[name[:offset]] = struct{}{}
}
offset++
}
}
for i := range commandInfoSnapshotRecords {
// Generated records are normalized and immutable. Mutable layers below
// copy their inputs before applying changes.
info := &commandInfoSnapshotRecords[i]
records[info.Name] = info
markParent(info.Name)
}
legacyLive := make(map[string]struct{}, len(liveLegacyRecords))
for name := range liveLegacyRecords {
legacyLive[internal.ToLower(name)] = struct{}{}
}
liveSupportsCSC := commandMetadataSupportsCSC(serverName, serverVersion)
seenLive := make(map[string]struct{}, len(live))
for name, info := range live {
lower := internal.ToLower(name)
// Tombstoned children still prevent their parent from shadowing them.
markParent(lower)
if _, duplicate := seenLive[lower]; duplicate {
delete(records, lower)
tombstones[lower] = struct{}{}
continue
}
seenLive[lower] = struct{}{}
if info == nil {
// Live nil explicitly blocks snapshot fallback and corrections.
delete(records, lower)
tombstones[lower] = struct{}{}
continue
}
_, legacy := legacyLive[lower]
records[lower] = resolveLiveCommandMetadata(
lower,
info,
liveSupportsCSC,
legacy,
)
}
// Apply built-in corrections before deriving CSC and routing decisions.
for name, correction := range commandMetadataCorrections {
markParent(name)
if _, tombstoned := tombstones[name]; tombstoned {
continue
}
rec := &CommandInfo{Name: name}
if base := records[name]; base != nil {
rec = cloneCommandInfo(base)
}
rec.Tips = appendCommandMetadataTokens(rec.Tips, correction.tips...)
rec.Flags = removeCommandMetadataTokens(rec.Flags, correction.removeFlags...)
if correction.keySpecs != nil {
rec.KeySpecs = cloneCommandInfo(&CommandInfo{KeySpecs: correction.keySpecs}).KeySpecs
rec.FirstKeyPos = correction.firstKeyPos
rec.LastKeyPos = correction.lastKeyPos
rec.StepCount = correction.stepCount
}
rec.ReadOnly = commandRecordHas(rec, "readonly", false)
records[name] = rec
}
seenOverrides := make(map[string]struct{}, len(overrides))
for name, info := range overrides {
lower := internal.ToLower(name)
markParent(lower)
if _, duplicate := seenOverrides[lower]; duplicate {
delete(records, lower)
tombstones[lower] = struct{}{}
continue
}
seenOverrides[lower] = struct{}{}
if info == nil {
// nil means "unknown": fail closed, don't expose lower layers.
delete(records, lower)
tombstones[lower] = struct{}{}
continue
}
// Overrides replace all lower-priority records and corrections.
delete(tombstones, lower)
records[lower] = cloneCommandInfoForName(lower, info)
}
table := make(map[string]cscCommandMeta, len(records))
for name, info := range records {
table[name] = cscDeriveMeta(info)
}
// Keep only parents whose arity permits a bare invocation. Lookup still
// checks subcommands first, so a parent cannot shadow its children.
shadowedParents := make(map[string]struct{})
for parent := range parents {
if _, shadowed := table[parent]; shadowed && !commandMetadataAllowsBareInvocation(records[parent]) {
delete(table, parent)
shadowedParents[parent] = struct{}{}
}
}
view := &commandMetadataView{
generation: commandMetadataGeneration.Add(1),
records: records,
tombstones: tombstones,
subcommandParents: parents,
shadowedParents: shadowedParents,
cscTable: table,
routingTable: deriveRoutingTable(records, shadowedParents),
cscFingerprint: cscTableFingerprint(table),
serverVersion: serverVersion,
}
linkRoutingTemplates(view)
return view
}
func commandMetadataAllowsBareInvocation(info *CommandInfo) bool {
return info != nil && (info.Arity == 1 || info.Arity == -1)
}
// commandMetadataSupportsCSC reports whether live metadata has all CSC
// exclusion signals. Only Redis 8.10+ defines the complete set.
func commandMetadataSupportsCSC(serverName, version string) bool {
if serverName != "redis" {
return false
}
parts := strings.SplitN(version, ".", 3)
if len(parts) < 2 {
return false
}
major, err := strconv.Atoi(parts[0])
if err != nil {
return false
}
minor, err := strconv.Atoi(parts[1])
if err != nil {
return false
}
return major > 8 || major == 8 && minor >= 10
}
// resolveLiveCommandMetadata applies server-specific restrictions to the
// shared record before consumers derive decisions.
func resolveLiveCommandMetadata(
name string,
info *CommandInfo,
liveSupportsCSC bool,
legacy bool,
) *CommandInfo {
resolved := cloneCommandInfoForName(name, info)
snapshot, snapshotKnown := commandInfoSnapshotByName()[name]
if legacy && snapshotKnown {
// Redis 5/6 COMMAND records cannot advertise routing policies. Keep
// the known policies while retaining the server's flags and key positions.
for _, tip := range snapshot.Tips {
if strings.HasPrefix(tip, requestPolicy+":") || strings.HasPrefix(tip, responsePolicy+":") {
resolved.Tips = appendCommandMetadataTokens(resolved.Tips, tip)
}
}
}
if !liveSupportsCSC {
if correction, ok := commandMetadataPre810Corrections()[name]; ok {
resolved.Flags = appendCommandMetadataTokens(resolved.Flags, correction.flags...)
resolved.Tips = appendCommandMetadataTokens(resolved.Tips, correction.tips...)
}
}
// Preserve legacy records for routing, but exclude unprovable records from
// CSC. Snapshot-known pre-8.10 records keep their known exclusions above.
if (!liveSupportsCSC && !snapshotKnown) || (liveSupportsCSC && legacy) {
resolved.Tips = appendCommandMetadataTokens(resolved.Tips, "dont_cache")
}
return resolved
}
func cloneCommandInfoForName(name string, info *CommandInfo) *CommandInfo {
cloned := cloneCommandInfo(info)
cloned.Name = internal.ToLower(name)
for i, flag := range cloned.Flags {
cloned.Flags[i] = normalizeCommandMetadataFlag(flag)
}
for i, tip := range cloned.Tips {
cloned.Tips[i] = normalizeCommandMetadataTip(tip)
}
for i := range cloned.KeySpecs {
spec := &cloned.KeySpecs[i]
spec.BeginSearch = normalizeCommandMetadataEnum(
spec.BeginSearch,
"index", "keyword", "unknown",
)
spec.FindKeys = normalizeCommandMetadataEnum(
spec.FindKeys,
"range", "keynum", "unknown",
)
for j, flag := range spec.Flags {
spec.Flags[j] = normalizeCommandMetadataKeyFlag(flag)
}
}
cloned.ReadOnly = commandRecordHas(cloned, "readonly", false)
return cloned
}
func normalizeCommandMetadataFlag(flag string) string {
key, _, hasValue := strings.Cut(flag, ":")
lowerKey := internal.ToLower(key)
switch lowerKey {
case "blocking", "script_runner":
// Preserve malformed negative signals conservatively.
return lowerKey
case "readonly":
if !hasValue {
return lowerKey
}
return flag
default:
return flag
}
}
func normalizeCommandMetadataTip(tip string) string {
key, value, hasValue := strings.Cut(tip, ":")
lowerKey := internal.ToLower(key)
switch lowerKey {
case "dont_cache", "nondeterministic_output":
// Preserve malformed negative signals conservatively.
return lowerKey
case requestPolicy:
if hasValue {
return lowerKey + ":" + normalizeCommandMetadataEnum(
value,
"", "default", "none", "all_nodes", "all_shards", "multi_shard", "special",
)
}
return lowerKey
case responsePolicy:
if hasValue {
return lowerKey + ":" + normalizeCommandMetadataEnum(
value,
"default(keyless)", "default(hashslot)", "all_succeeded", "one_succeeded",
"agg_sum", "agg_min", "agg_max", "agg_logical_and", "agg_logical_or", "special",
)
}
return lowerKey
}
return tip
}
func normalizeCommandMetadataEnum(value string, known ...string) string {
lower := internal.ToLower(value)
if slices.Contains(known, lower) {
return lower
}
return value
}
func normalizeCommandMetadataKeyFlag(flag string) string {
upper := strings.ToUpper(flag)
switch upper {
case "RO", "RW", "OW", "RM":
return upper
}
lower := internal.ToLower(flag)
switch lower {
case "access", "update", "insert", "delete", "not_key", "incomplete", "variable_flags", "prefix":
return lower
default:
return flag
}
}
// commandMetadataKeySpecFlags is the validated key-spec meaning shared by CSC
// and Cluster routing. Unknown and prefix flags fail closed.
type commandMetadataKeySpecFlags struct {
routingUsable bool
cscComplete bool
planComplete bool
}
func classifyCommandMetadataKeySpecFlags(flags []string) commandMetadataKeySpecFlags {
seen := make(map[string]struct{}, len(flags))
accessModes := 0
actions := 0
incomplete := false
notKey := false
for _, flag := range flags {
if _, duplicate := seen[flag]; duplicate {
return commandMetadataKeySpecFlags{}
}
seen[flag] = struct{}{}
switch flag {
case "RO", "RW", "OW", "RM":
accessModes++
case "access", "update", "insert", "delete":
actions++
case "variable_flags":
case "incomplete":
incomplete = true
case "not_key":
notKey = true
case "prefix":
return commandMetadataKeySpecFlags{}
default:
return commandMetadataKeySpecFlags{}
}
}
// not_key arguments can route by slot but cannot prove CSC invalidation.
if notKey {
if accessModes != 0 || actions != 0 {
return commandMetadataKeySpecFlags{}
}
return commandMetadataKeySpecFlags{
routingUsable: true,
planComplete: !incomplete,
}
}
// Ordinary key specs require exactly one access mode.
if accessModes != 1 {
return commandMetadataKeySpecFlags{}
}
return commandMetadataKeySpecFlags{
routingUsable: true,
cscComplete: !incomplete,
planComplete: !incomplete,
}
}
func appendCommandMetadataTokens(tokens []string, additions ...string) []string {
for _, addition := range additions {
if !slices.Contains(tokens, addition) {
tokens = append(tokens, addition)
}
}
return tokens
}
func removeCommandMetadataTokens(tokens []string, removals ...string) []string {
if len(removals) == 0 {
return tokens
}
return slices.DeleteFunc(tokens, func(token string) bool {
return slices.Contains(removals, token)
})
}
// cloneCommandInfo deep-copies a record so the copy can be mutated or
// published independently of the source.
func cloneCommandInfo(info *CommandInfo) *CommandInfo {
cp := *info
cp.Flags = append([]string(nil), info.Flags...)
cp.ACLFlags = append([]string(nil), info.ACLFlags...)
cp.Tips = append([]string(nil), info.Tips...)
if info.KeySpecs != nil {
cp.KeySpecs = make([]KeySpec, len(info.KeySpecs))
for i, ks := range info.KeySpecs {
cp.KeySpecs[i] = ks
cp.KeySpecs[i].Flags = append([]string(nil), ks.Flags...)
}
}
if info.CommandPolicy != nil {
cp.CommandPolicy = cloneRoutingPolicy(info.CommandPolicy)
}
return &cp
}
// cscTableFingerprint hashes the derived eligibility table into a short
// stable token. Cryptographic (truncated SHA-256): in PreferLive mode the
// input is server-influenced, and a forged collision with an honest view's
// fingerprint would let a poisoned generation's entries survive a refresh.
func cscTableFingerprint(table map[string]cscCommandMeta) string {
names := make([]string, 0, len(table))
for name := range table {
names = append(names, name)
}
sort.Strings(names)
h := sha256.New()
buf := make([]byte, 0, 128)
for _, name := range names {
m := table[name]
buf = append(buf[:0], name...)
buf = append(buf, 0)
for _, value := range [...]int64{
int64(m.bits), int64(m.extract), int64(m.guard),
int64(m.firstKey), int64(m.lastKey), int64(m.step), int64(m.numkeysAt),
} {
buf = strconv.AppendInt(buf, value, 10)
buf = append(buf, ' ')
}
buf[len(buf)-1] = '\n'
h.Write(buf)
}
var digest [sha256.Size]byte
return hex.EncodeToString(h.Sum(digest[:0])[:16])
}
// commandMetadataFetchResult separates publication identity from the server
// name and version used for compatibility rules.
type commandMetadataFetchResult struct {
records map[string]*CommandInfo
legacyRecords map[string]struct{}
serverName string
serverVersion string
serverFingerprint string
}
func (m commandMetadataFetchResult) equal(other commandMetadataFetchResult) bool {
return m.serverName == other.serverName &&
m.serverVersion == other.serverVersion &&
m.serverFingerprint == other.serverFingerprint &&
maps.Equal(m.legacyRecords, other.legacyRecords) &&
maps.EqualFunc(m.records, other.records, func(a, b *CommandInfo) bool {
return reflect.DeepEqual(a, b)
})
}
// A successful fetch transfers ownership of its records to the store.
type commandMetadataFetchFunc func(context.Context) (commandMetadataFetchResult, error)
// commandMetadataStore publishes immutable views for one client. Its pointer
// is shared with clones; the attaching client owns the worker.
type commandMetadataStore struct {
current atomic.Pointer[commandMetadataView]
// A dynamic resolver activates live tracking on its first lookup, including
// for a statically configured store. Constructing an unused resolver does not.
liveRequested atomic.Bool
mode CommandMetadataMode
overrides map[string]*CommandInfo
refreshInterval time.Duration
fetch commandMetadataFetchFunc
// static is the initial and fallback view.
static *commandMetadataView
// lastFetch is the source of the last successfully published live view.
// Only the active refresh attempt reads or replaces it.
lastFetch commandMetadataFetchResult
// fetchCtx is cancelled by signalStop so Close never waits out an
// in-flight fetch's own timeout.
fetchCtx context.Context
fetchCancel context.CancelFunc
mu sync.Mutex
refreshDone chan struct{} // guarded by mu; non-nil while one attempt owns lastFetch
initialDone bool // one completed attempt ends foreground verification
retryAt time.Time // background cooldown survives new refresh requests
backoff time.Duration
started bool
refresh chan struct{}
refreshLive atomic.Bool // A node identity observation also needs a live-view refresh.
stop chan struct{}
done chan struct{}
stopOnce sync.Once
// serverFp identifies the current server. serverEpoch also rejects ABA
// changes during a refresh. Both are guarded by mu.
serverFp string
serverEpoch uint64
}
// newCommandMetadataStore returns nil for configs equivalent to the static
// default, letting those clients share defaultCommandMetadataView with zero
// allocations.
func newCommandMetadataStore(
cfg *CommandMetadataConfig,
fetch commandMetadataFetchFunc,
) *commandMetadataStore {
return newCommandMetadataStoreWithLiveRequirement(cfg, fetch, false)
}
// newCommandMetadataStoreForLive creates a store even for static configuration.
func newCommandMetadataStoreForLive(
cfg *CommandMetadataConfig,
fetch commandMetadataFetchFunc,
) *commandMetadataStore {
return newCommandMetadataStoreWithLiveRequirement(cfg, fetch, true)
}
func newCommandMetadataStoreWithLiveRequirement(
cfg *CommandMetadataConfig,
fetch commandMetadataFetchFunc,
requireLive bool,
) *commandMetadataStore {
if cfg == nil {
cfg = &CommandMetadataConfig{}
}
if !requireLive && cfg.Mode == CommandMetadataStatic && len(cfg.Overrides) == 0 {
return nil
}
// Deep-copy the overrides: refreshOnce re-reads them on every rebuild,
// and an application mutating its config map would race the worker.
var overrides map[string]*CommandInfo
if len(cfg.Overrides) > 0 {
overrides = make(map[string]*CommandInfo, len(cfg.Overrides))
for name, info := range cfg.Overrides {
name = internal.ToLower(name)
if _, duplicate := overrides[name]; duplicate {
// Tombstone ambiguous case-colliding overrides.
overrides[name] = nil
continue
}
if info == nil {
overrides[name] = nil
continue
}
overrides[name] = cloneCommandInfo(info)
}
}
s := &commandMetadataStore{
mode: cfg.Mode,
overrides: overrides,
refreshInterval: cfg.RefreshInterval,
fetch: fetch,
refresh: make(chan struct{}, 1),
stop: make(chan struct{}),
done: make(chan struct{}),
}
s.fetchCtx, s.fetchCancel = context.WithCancel(context.Background())
if len(overrides) == 0 {
s.static = defaultCommandMetadataView()
} else {
s.static = buildCommandMetadataView(nil, overrides)
}
s.current.Store(s.static)
// An override keyed by a bare container name ("memory") is pruned in
// favor of its subcommand entries and would otherwise vanish silently.
for name, info := range overrides {
if info == nil {
continue
}
if _, shadowed := s.static.shadowedParents[name]; shadowed {
internal.Logger.Printf(context.Background(),
"redis: CommandMetadata override %q targets a container command and has no effect; key it \"parent|child\"", name)
}
}
return s
}
func (s *commandMetadataStore) view() *commandMetadataView {
return s.current.Load()
}
func (s *commandMetadataStore) wantsServerHello() bool {
return s != nil && (s.mode == CommandMetadataPreferLive || s.liveRequested.Load())
}
// onConnInit runs after each successful connection initialization: in
// live mode it schedules the upgrade until one succeeds. Later drift without
// a new connection (module loads, upgrades) is covered by RefreshInterval.
func (s *commandMetadataStore) onConnInit() {
if !s.wantsServerHello() {
return
}
if v := s.current.Load(); v != nil && v.live {
return
}
s.requestRefresh()
}
// ensureLive waits for one initial verification. Later calls use the conservative
// view immediately while background retries finish compatibility checks.
func (s *commandMetadataStore) ensureLive(ctx context.Context) error {
if s == nil || s.fetch == nil {
return fmt.Errorf("redis: live command metadata fetch is unavailable")
}
if err := ctx.Err(); err != nil {
return err
}
if !s.liveRequested.Load() && s.liveRequested.CompareAndSwap(false, true) && s.refreshInterval > 0 {
// Periodic refresh is opt-in, including after an explicit dynamic lookup.
s.startWorker()
}
if v := s.current.Load(); v != nil && v.live {
return nil
}
err := s.refreshMetadata(ctx, commandMetadataInitialRefresh)
if err != nil {
s.requestRefresh()
}
return err
}
// onServerHello retires live metadata when the server identity changes.
func (s *commandMetadataStore) onServerHello(fp string) {
if !s.wantsServerHello() {
return
}
s.mu.Lock()
changed := fp != s.serverFp
if changed {
s.serverFp = fp
s.serverEpoch++
if v := s.current.Load(); v != nil && v.live {
// Decide on static metadata until the new server's arrives.
s.current.Store(s.static)
}
}
s.mu.Unlock()
if !changed {
s.onConnInit()
return
}
s.requestRefresh()
}
// onClusterServerHelloReply keeps node callbacks dormant until live metadata
// is requested. A nil reply represents a connection initialized without HELLO.
func (s *commandMetadataStore) onClusterServerHelloReply(hello map[string]interface{}) {
if !s.wantsServerHello() {
return
}
fingerprint := ""
if hello != nil {
fingerprint = helloServerFingerprint(hello)
}
s.onClusterServerHello(fingerprint)
}
// onClusterServerHello schedules verification without adopting one node's
// identity. The cluster fetch checks siblings before retiring the live view.
// An empty fingerprint always requests verification, including during a fetch.
func (s *commandMetadataStore) onClusterServerHello(fp string) {
if !s.wantsServerHello() {
return
}
if fp != "" && fp == s.serverFingerprint() {
s.onConnInit()
return
}
s.requestVerification()
}
// requestVerification checks identity even when metadata is already live.
// HELLO-fallback reconnects cannot prove that the previous identity still holds.
func (s *commandMetadataStore) requestVerification() {
if !s.wantsServerHello() {
return
}
s.refreshLive.Store(true)
s.requestRefresh()
}
func (s *commandMetadataStore) serverFingerprint() string {
fp, _ := s.serverIdentity()
return fp
}
func (s *commandMetadataStore) serverIdentity() (string, uint64) {
s.mu.Lock()
defer s.mu.Unlock()
return s.serverFp, s.serverEpoch
}
// publishLiveView atomically validates the server identity and publishes the
// fetched view. It adopts the fetched identity when none was known.
func (s *commandMetadataStore) publishLiveView(
expectedFp string,
expectedEpoch uint64,
fetchedFp string,
view *commandMetadataView,
) bool {
s.mu.Lock()
defer s.mu.Unlock()
if s.serverFp != expectedFp || s.serverEpoch != expectedEpoch {
return false
}
// Never publish metadata without a verifiable source identity.
if fetchedFp == "" || expectedFp != "" && expectedFp != fetchedFp {
return false
}
if expectedFp == "" && fetchedFp != "" {
s.serverFp = fetchedFp
}
s.current.Store(view)
return true
}
// requestRefresh schedules one background refresh; pending requests coalesce.
func (s *commandMetadataStore) requestRefresh() {
if !s.wantsServerHello() || s.fetch == nil {
return
}
s.startWorker()
select {
case s.refresh <- struct{}{}:
default:
}
}
// invalidateLiveAndRequestRefresh retires old metadata and schedules a refresh.
func (s *commandMetadataStore) invalidateLiveAndRequestRefresh() {
s.invalidateLive()
s.requestRefresh()
}
// beginParentSourceChange blocks refresh publication across a topology change.
func (s *commandMetadataStore) beginParentSourceChange() {
if s == nil {
return
}
s.mu.Lock()
s.invalidateLiveLocked()
}
func (s *commandMetadataStore) finishParentSourceChange() {
if s == nil {
return
}
s.mu.Unlock()
s.requestRefresh()
}
// invalidateLive retires the live view without starting a fetch.
func (s *commandMetadataStore) invalidateLive() {
if s == nil {
return
}
s.mu.Lock()
s.invalidateLiveLocked()
s.mu.Unlock()
}
func (s *commandMetadataStore) invalidateLiveLocked() {
s.serverFp = ""
s.serverEpoch++
if view := s.current.Load(); view != nil && view.live {
s.current.Store(s.static)
}
}
func (s *commandMetadataStore) startWorker() {
s.mu.Lock()
defer s.mu.Unlock()
if s.started {
return
}
select {
case <-s.stop:
return // already stopped; never start after Close
default:
}
s.started = true
go s.run()
}
// cmdMetaBackoffMin/Max bound the retry backoff after a failed refresh, and
// cmdMetaRetryCap bounds automatic retries (later external triggers —
// conn init, periodic refresh — still attempt once each). Vars so tests can
// shrink them.
var (
cmdMetaBackoffMin = time.Second
cmdMetaBackoffMax = 30 * time.Second
cmdMetaRetryCap = 5
)
const cmdMetaFetchTimeout = 30 * time.Second
var errCommandMetadataNotReady = errors.New("redis: live command metadata verification is pending")
type commandMetadataRefreshMode uint8
const (
commandMetadataInitialRefresh commandMetadataRefreshMode = iota
commandMetadataUpgrade
commandMetadataVerify
)
func (s *commandMetadataStore) run() {
defer close(s.done)
var periodicC <-chan time.Time
var periodic *time.Timer
if s.refreshInterval > 0 {
periodic = time.NewTimer(cmdMetaJitter(s.refreshInterval))
defer periodic.Stop()
periodicC = periodic.C
}
consecFail := 0
attempt := func(verifyLive bool) {
for {
mode := commandMetadataUpgrade
if verifyLive {
mode = commandMetadataVerify
}
err := s.refreshMetadata(s.fetchCtx, mode)
if err == nil {
consecFail = 0
return
}
consecFail++
// Damp the log for persistent failures (e.g. COMMAND denied by ACL).
if consecFail <= cmdMetaRetryCap || consecFail%10 == 0 {
internal.Logger.Printf(context.Background(),
"redis: command metadata refresh failed (attempt %d): %v", consecFail, err)
}
if consecFail >= cmdMetaRetryCap {
// Stop self-retrying; the next external trigger tries again.
return
}
}
}
for {
select {
case <-s.stop:
return
case <-periodicC:
periodic.Reset(cmdMetaJitter(s.refreshInterval))
attempt(true)
case <-s.refresh:
// Stop wins over a pending token, so Close never runs one more fetch.
select {
You can’t perform that action at this time.