Joey Armstrong | 903c69d | 2024-02-01 19:46:39 -0500 | [diff] [blame] | 1 | package pool |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | "sync/atomic" |
| 8 | ) |
| 9 | |
| 10 | const ( |
| 11 | stateDefault = 0 |
| 12 | stateInited = 1 |
| 13 | stateClosed = 2 |
| 14 | ) |
| 15 | |
| 16 | type BadConnError struct { |
| 17 | wrapped error |
| 18 | } |
| 19 | |
| 20 | var _ error = (*BadConnError)(nil) |
| 21 | |
| 22 | func (e BadConnError) Error() string { |
| 23 | s := "redis: Conn is in a bad state" |
| 24 | if e.wrapped != nil { |
| 25 | s += ": " + e.wrapped.Error() |
| 26 | } |
| 27 | return s |
| 28 | } |
| 29 | |
| 30 | func (e BadConnError) Unwrap() error { |
| 31 | return e.wrapped |
| 32 | } |
| 33 | |
| 34 | //------------------------------------------------------------------------------ |
| 35 | |
| 36 | type StickyConnPool struct { |
| 37 | pool Pooler |
| 38 | shared int32 // atomic |
| 39 | |
| 40 | state uint32 // atomic |
| 41 | ch chan *Conn |
| 42 | |
| 43 | _badConnError atomic.Value |
| 44 | } |
| 45 | |
| 46 | var _ Pooler = (*StickyConnPool)(nil) |
| 47 | |
| 48 | func NewStickyConnPool(pool Pooler) *StickyConnPool { |
| 49 | p, ok := pool.(*StickyConnPool) |
| 50 | if !ok { |
| 51 | p = &StickyConnPool{ |
| 52 | pool: pool, |
| 53 | ch: make(chan *Conn, 1), |
| 54 | } |
| 55 | } |
| 56 | atomic.AddInt32(&p.shared, 1) |
| 57 | return p |
| 58 | } |
| 59 | |
| 60 | func (p *StickyConnPool) NewConn(ctx context.Context) (*Conn, error) { |
| 61 | return p.pool.NewConn(ctx) |
| 62 | } |
| 63 | |
| 64 | func (p *StickyConnPool) CloseConn(cn *Conn) error { |
| 65 | return p.pool.CloseConn(cn) |
| 66 | } |
| 67 | |
| 68 | func (p *StickyConnPool) Get(ctx context.Context) (*Conn, error) { |
| 69 | // In worst case this races with Close which is not a very common operation. |
| 70 | for i := 0; i < 1000; i++ { |
| 71 | switch atomic.LoadUint32(&p.state) { |
| 72 | case stateDefault: |
| 73 | cn, err := p.pool.Get(ctx) |
| 74 | if err != nil { |
| 75 | return nil, err |
| 76 | } |
| 77 | if atomic.CompareAndSwapUint32(&p.state, stateDefault, stateInited) { |
| 78 | return cn, nil |
| 79 | } |
| 80 | p.pool.Remove(ctx, cn, ErrClosed) |
| 81 | case stateInited: |
| 82 | if err := p.badConnError(); err != nil { |
| 83 | return nil, err |
| 84 | } |
| 85 | cn, ok := <-p.ch |
| 86 | if !ok { |
| 87 | return nil, ErrClosed |
| 88 | } |
| 89 | return cn, nil |
| 90 | case stateClosed: |
| 91 | return nil, ErrClosed |
| 92 | default: |
| 93 | panic("not reached") |
| 94 | } |
| 95 | } |
| 96 | return nil, fmt.Errorf("redis: StickyConnPool.Get: infinite loop") |
| 97 | } |
| 98 | |
| 99 | func (p *StickyConnPool) Put(ctx context.Context, cn *Conn) { |
| 100 | defer func() { |
| 101 | if recover() != nil { |
| 102 | p.freeConn(ctx, cn) |
| 103 | } |
| 104 | }() |
| 105 | p.ch <- cn |
| 106 | } |
| 107 | |
| 108 | func (p *StickyConnPool) freeConn(ctx context.Context, cn *Conn) { |
| 109 | if err := p.badConnError(); err != nil { |
| 110 | p.pool.Remove(ctx, cn, err) |
| 111 | } else { |
| 112 | p.pool.Put(ctx, cn) |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | func (p *StickyConnPool) Remove(ctx context.Context, cn *Conn, reason error) { |
| 117 | defer func() { |
| 118 | if recover() != nil { |
| 119 | p.pool.Remove(ctx, cn, ErrClosed) |
| 120 | } |
| 121 | }() |
| 122 | p._badConnError.Store(BadConnError{wrapped: reason}) |
| 123 | p.ch <- cn |
| 124 | } |
| 125 | |
| 126 | func (p *StickyConnPool) Close() error { |
| 127 | if shared := atomic.AddInt32(&p.shared, -1); shared > 0 { |
| 128 | return nil |
| 129 | } |
| 130 | |
| 131 | for i := 0; i < 1000; i++ { |
| 132 | state := atomic.LoadUint32(&p.state) |
| 133 | if state == stateClosed { |
| 134 | return ErrClosed |
| 135 | } |
| 136 | if atomic.CompareAndSwapUint32(&p.state, state, stateClosed) { |
| 137 | close(p.ch) |
| 138 | cn, ok := <-p.ch |
| 139 | if ok { |
| 140 | p.freeConn(context.TODO(), cn) |
| 141 | } |
| 142 | return nil |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | return errors.New("redis: StickyConnPool.Close: infinite loop") |
| 147 | } |
| 148 | |
| 149 | func (p *StickyConnPool) Reset(ctx context.Context) error { |
| 150 | if p.badConnError() == nil { |
| 151 | return nil |
| 152 | } |
| 153 | |
| 154 | select { |
| 155 | case cn, ok := <-p.ch: |
| 156 | if !ok { |
| 157 | return ErrClosed |
| 158 | } |
| 159 | p.pool.Remove(ctx, cn, ErrClosed) |
| 160 | p._badConnError.Store(BadConnError{wrapped: nil}) |
| 161 | default: |
| 162 | return errors.New("redis: StickyConnPool does not have a Conn") |
| 163 | } |
| 164 | |
| 165 | if !atomic.CompareAndSwapUint32(&p.state, stateInited, stateDefault) { |
| 166 | state := atomic.LoadUint32(&p.state) |
| 167 | return fmt.Errorf("redis: invalid StickyConnPool state: %d", state) |
| 168 | } |
| 169 | |
| 170 | return nil |
| 171 | } |
| 172 | |
| 173 | func (p *StickyConnPool) badConnError() error { |
| 174 | if v := p._badConnError.Load(); v != nil { |
| 175 | err := v.(BadConnError) |
| 176 | if err.wrapped != nil { |
| 177 | return err |
| 178 | } |
| 179 | } |
| 180 | return nil |
| 181 | } |
| 182 | |
| 183 | func (p *StickyConnPool) Len() int { |
| 184 | switch atomic.LoadUint32(&p.state) { |
| 185 | case stateDefault: |
| 186 | return 0 |
| 187 | case stateInited: |
| 188 | return 1 |
| 189 | case stateClosed: |
| 190 | return 0 |
| 191 | default: |
| 192 | panic("not reached") |
| 193 | } |
| 194 | } |
| 195 | |
| 196 | func (p *StickyConnPool) IdleLen() int { |
| 197 | return len(p.ch) |
| 198 | } |
| 199 | |
| 200 | func (p *StickyConnPool) Stats() *Stats { |
| 201 | return &Stats{} |
| 202 | } |