dual check v0.1

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cancerai committed 2026-08-29 23:34:01 +08:00
1 parent 78bad1fa3d
commit c137299016
36 files changed
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package store
import (
"context"
"errors"
"fmt"
"sort"
"strings"
"time"
"github.com/redis/go-redis/v9"
)
// 包级错误,业务层可以 errors.Is 检查
var (
ErrSessionNotFound = errors.New("session not found or expired")
ErrDuplicateJoin = errors.New("nickname already joined this session")
ErrDuplicateSubmit = errors.New("this nickname has already submitted")
)
const (
redisKeyPrefix = "dualcheck:session:"
fieldCreatedAt = "created_at"
fieldInitHash = "initiator_hash"
fieldInitNick = "initiator_nickname"
fieldAllowResub = "allow_resubmit"
// participant:{nick} 存该参与者的哈希值;participant:{nick}:match 存 "1"/"0"
partFieldPrefix = "participant:"
)
// ── 五个 Lua 脚本 ──
// createLuaScript 原子创建 Hash 类型的会话 key
var createLuaScript = redis.NewScript(`
local key = KEYS[1]
if redis.call("EXISTS", key) ~= 0 then
return 0
end
redis.call("HSET", key, "created_at", ARGV[1])
redis.call("HSET", key, "allow_resubmit", "0")
redis.call("EXPIRE", key, ARGV[2])
return 1
`)
// joinParticipantLuaScript 登记参与者昵称(空哈希占位,表示已加入未提交)
// KEYS[1] = session key
// ARGV[1] = nickname
var joinParticipantLuaScript = redis.NewScript(`
local key = KEYS[1]
local nick = ARGV[1]
local exists = redis.call("EXISTS", key)
if exists == 0 then
return redis.error_reply("SESSION_NOT_FOUND")
end
local field = "participant:" .. nick
-- 昵称已存在视为已加入(幂等),直接返回 1
if redis.call("HEXISTS", key, field) == 1 then
return 1
end
redis.call("HSET", key, field, "")
return 1
`)
// submitParticipantLuaScript 参与者提交自己的哈希
// 原子完成:检查 → 写入 → 与 initiator_hash 比对(若发起方已提交)
// 若已提交但 allow_resubmit=1 则覆盖(重算 match)
// KEYS[1] = session key
// ARGV[1] = nickname
// ARGV[2] = hash hex
// 返回 {initiatorSubmitted (0/1), match ("1"/"0"/"")}
var submitParticipantLuaScript = redis.NewScript(`
local key = KEYS[1]
local nick = ARGV[1]
local hash_val = ARGV[2]
if redis.call("EXISTS", key) == 0 then
return redis.error_reply("SESSION_NOT_FOUND")
end
local field = "participant:" .. nick
if redis.call("HEXISTS", key, field) == 0 then
return redis.error_reply("NICKNAME_NOT_JOINED")
end
local existing = redis.call("HGET", key, field)
if existing ~= "" then
-- 已提交过:看是否允许重提交
local allow = redis.call("HGET", key, "allow_resubmit")
if allow ~= "1" then
return redis.error_reply("DUPLICATE_SUBMIT")
end
end
-- 写入(覆盖)哈希
redis.call("HSET", key, field, hash_val)
-- 清除旧的 match 字段,稍后按需重算
redis.call("HDEL", key, field .. ":match")
local init_hash = redis.call("HGET", key, "initiator_hash")
if init_hash and init_hash ~= "" then
local match = (hash_val == init_hash) and "1" or "0"
redis.call("HSET", key, field .. ":match", match)
return {1, match}
else
return {0, ""}
end
`)
// submitInitiatorLuaScript 发起方提交标准答案
// 写入 initiator_hash 后,遍历所有已提交的 participant,批量计算 match
// KEYS[1] = session key
// ARGV[1] = nickname
// ARGV[2] = initiator hash
var submitInitiatorLuaScript = redis.NewScript(`
local key = KEYS[1]
local nick = ARGV[1]
local init_hash = ARGV[2]
if redis.call("EXISTS", key) == 0 then
return redis.error_reply("SESSION_NOT_FOUND")
end
-- 发起方只允许提交一次(幂等:已提交过则跳过)
if redis.call("HEXISTS", key, "initiator_hash") == 1 then
return 1
end
redis.call("HSET", key, "initiator_hash", init_hash)
redis.call("HSET", key, "initiator_nickname", nick)
-- 遍历所有 participant:{nick} 且哈希非空的,计算 match
local all = redis.call("HGETALL", key)
for i = 1, #all, 2 do
local field = all[i]
local val = all[i + 1]
if string.sub(field, 1, #("participant:")) == "participant:"
and not string.find(field, ":match$")
and val ~= "" then
local match = (val == init_hash) and "1" or "0"
redis.call("HSET", key, field .. ":match", match)
end
end
return 1
`)
// ── RedisSessionStore 实现 ──
type RedisSessionStore struct {
rdb *redis.Client
ttl time.Duration
}
func NewRedisSessionStore(rdb *redis.Client, defaultTTL time.Duration) *RedisSessionStore {
return &RedisSessionStore{rdb: rdb, ttl: defaultTTL}
}
func key(sessionID string) string {
return redisKeyPrefix + sessionID
}
// Create 原子创建会话 Hash key
func (s *RedisSessionStore) Create(ctx context.Context, sessionID string, ttl time.Duration) error {
if ttl <= 0 {
ttl = s.ttl
}
now := time.Now().Unix()
ttlSeconds := int64(ttl.Seconds())
result, err := createLuaScript.Run(ctx, s.rdb, []string{key(sessionID)}, now, ttlSeconds).Int64()
if err != nil {
return fmt.Errorf("redis create session: %w", err)
}
if result == 0 {
return fmt.Errorf("session id collision: %s", sessionID)
}
return nil
}
// JoinParticipant 登记参与者(空哈希占位)
func (s *RedisSessionStore) JoinParticipant(ctx context.Context, sessionID, nickname string) error {
_, err := joinParticipantLuaScript.Run(ctx, s.rdb, []string{key(sessionID)}, nickname).Int64()
if err != nil {
msg := err.Error()
if strings.Contains(msg, "SESSION_NOT_FOUND") {
return ErrSessionNotFound
}
return fmt.Errorf("redis join participant: %w", err)
}
return nil
}
// SubmitParticipant 参与者提交自己的文本哈希
func (s *RedisSessionStore) SubmitParticipant(ctx context.Context, sessionID, nickname, hashHex string) (bool, *bool, error) {
result, err := submitParticipantLuaScript.Run(ctx, s.rdb, []string{key(sessionID)}, nickname, hashHex).Result()
if err != nil {
msg := err.Error()
switch {
case strings.Contains(msg, "SESSION_NOT_FOUND"):
return false, nil, ErrSessionNotFound
case strings.Contains(msg, "DUPLICATE_SUBMIT"):
return false, nil, ErrDuplicateSubmit
case strings.Contains(msg, "NICKNAME_NOT_JOINED"):
// 参与者没走 join 直接 submit,自动补登记
if err := s.JoinParticipant(ctx, sessionID, nickname); err != nil {
return false, nil, err
}
return s.SubmitParticipant(ctx, sessionID, nickname, hashHex)
default:
return false, nil, fmt.Errorf("redis submit participant: %w", err)
}
}
values := result.([]interface{})
initSubmitted := values[0].(int64) == 1
var match *bool
if initSubmitted {
b := values[1].(string) == "1"
match = &b
}
return initSubmitted, match, nil
}
// SubmitInitiator 发起方提交标准答案哈希
func (s *RedisSessionStore) SubmitInitiator(ctx context.Context, sessionID, nickname, hashHex string) error {
_, err := submitInitiatorLuaScript.Run(ctx, s.rdb, []string{key(sessionID)}, nickname, hashHex).Int64()
if err != nil {
if strings.Contains(err.Error(), "SESSION_NOT_FOUND") {
return ErrSessionNotFound
}
return fmt.Errorf("redis submit initiator: %w", err)
}
return nil
}
// SetResubmit 设置会话是否允许参与者重复提交
func (s *RedisSessionStore) SetResubmit(ctx context.Context, sessionID string, allow bool) error {
key := key(sessionID)
exists, err := s.rdb.Exists(ctx, key).Result()
if err != nil {
return fmt.Errorf("redis exists: %w", err)
}
if exists == 0 {
return ErrSessionNotFound
}
val := "0"
if allow {
val = "1"
}
return s.rdb.HSet(ctx, key, fieldAllowResub, val).Err()
}
// Get 获取会话当前状态全量快照
func (s *RedisSessionStore) Get(ctx context.Context, sessionID string) (*SessionSnapshot, error) {
exists, err := s.rdb.Exists(ctx, key(sessionID)).Result()
if err != nil {
return nil, fmt.Errorf("redis exists: %w", err)
}
if exists == 0 {
return nil, ErrSessionNotFound
}
hash, err := s.rdb.HGetAll(ctx, key(sessionID)).Result()
if err != nil {
return nil, fmt.Errorf("redis hgetall: %w", err)
}
ttl, err := s.rdb.TTL(ctx, key(sessionID)).Result()
if err != nil {
return nil, fmt.Errorf("redis ttl: %w", err)
}
snap := &SessionSnapshot{
SessionID: sessionID,
InitiatorHash: hash[fieldInitHash],
InitiatorNickname: hash[fieldInitNick],
InitiatorSubmitted: hash[fieldInitHash] != "",
AllowResubmit: hash[fieldAllowResub] == "1",
ExpiresAt: time.Now().Add(ttl),
}
// 收集所有 participant 条目,按 nickname 排序
var nicks []string
partMap := map[string]string{} // nick → hash
for k, v := range hash {
if strings.HasPrefix(k, partFieldPrefix) && !strings.HasSuffix(k, ":match") {
nick := strings.TrimPrefix(k, partFieldPrefix)
nicks = append(nicks, nick)
partMap[nick] = v
}
}
sort.Strings(nicks)
initiatorHash := hash[fieldInitHash]
for _, nick := range nicks {
h := partMap[nick]
p := ParticipantInfo{
Nickname: nick,
Submitted: h != "",
}
if h != "" && initiatorHash != "" {
m := h == initiatorHash
p.Match = &m
} else if mStr, ok := hash[partFieldPrefix+nick+":match"]; ok && mStr != "" {
m := mStr == "1"
p.Match = &m
}
snap.Participants = append(snap.Participants, p)
}
return snap, nil
}
// Delete 删除会话
func (s *RedisSessionStore) Delete(ctx context.Context, sessionID string) error {
if err := s.rdb.Del(ctx, key(sessionID)).Err(); err != nil {
return fmt.Errorf("redis del: %w", err)
}
return nil
}
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// Package store 提供会话存储接口
// 接口解耦使得可以在测试中用 mock 替换,生产用 Redis
package store
import (
"context"
"time"
)
// Session 存储的会话数据结构(不含敏感字段)
type Session struct {
ID string `json:"session_id"`
ExpiresAt time.Time `json:"expires_at"`
CreatedAt time.Time `json:"created_at"`
}
// ParticipantInfo 参与者在全量快照中的状态
type ParticipantInfo struct {
Nickname string `json:"nickname"`
Submitted bool `json:"submitted"`
Match *bool `json:"match,omitempty"`
}
// SessionSnapshot Get 返回的全量快照
type SessionSnapshot struct {
SessionID string `json:"session_id"`
InitiatorHash string `json:"-"` // 发起方标准答案哈希,不对外暴露
InitiatorNickname string `json:"initiator_nickname"`
InitiatorSubmitted bool `json:"initiator_submitted"`
AllowResubmit bool `json:"allow_resubmit"`
Participants []ParticipantInfo `json:"participants"`
ExpiresAt time.Time `json:"expires_at"`
}
// SessionStore 会话存储接口
type SessionStore interface {
// Create 原子创建会话(SET NX EX)
Create(ctx context.Context, id string, ttl time.Duration) error
// SubmitInitiator 发起方提交标准答案(initiator_hash + initiator_nickname)
// 同时立即为所有已提交的参与者计算 match
SubmitInitiator(ctx context.Context, sessionID, nickname, hashHex string) error
// SubmitParticipant 参与者提交自己的文本(按 nickname 唯一标识)
// 返回:initiatorSubmitted(发起方是否已提交,是则 match 已算出)、match
SubmitParticipant(ctx context.Context, sessionID, nickname, hashHex string) (
initiatorSubmitted bool, match *bool, err error)
// JoinParticipant 参与者加入会话(只登记昵称,不提交文本)
// 用于 WS 连接时实时广播 joined 事件
JoinParticipant(ctx context.Context, sessionID, nickname string) error
// SetResubmit 设置是否允许参与者重复提交
SetResubmit(ctx context.Context, sessionID string, allow bool) error
// Get 获取会话当前状态全量快照
Get(ctx context.Context, sessionID string) (*SessionSnapshot, error)
// Delete 删除会话
Delete(ctx context.Context, sessionID string) error
}