forked from hashicorp/consul
-
Notifications
You must be signed in to change notification settings - Fork 0
/
pool.go
388 lines (331 loc) · 8.52 KB
/
pool.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
package consul
import (
"container/list"
"crypto/tls"
"fmt"
"github.com/hashicorp/yamux"
"github.com/inconshreveable/muxado"
"github.com/ugorji/go/codec"
"io"
"net"
"net/rpc"
"sync"
"sync/atomic"
"time"
)
// msgpackHandle is a shared handle for encoding/decoding of RPC messages
var msgpackHandle = &codec.MsgpackHandle{}
// muxSession is used to provide an interface for either muxado or yamux
type muxSession interface {
Open() (net.Conn, error)
Close() error
}
type muxadoWrapper struct {
m muxado.Session
}
func (w *muxadoWrapper) Open() (net.Conn, error) {
return w.m.Open()
}
func (w *muxadoWrapper) Close() error {
return w.m.Close()
}
// streamClient is used to wrap a stream with an RPC client
type StreamClient struct {
stream net.Conn
client *rpc.Client
}
// Conn is a pooled connection to a Consul server
type Conn struct {
refCount int32
shouldClose int32
addr net.Addr
session muxSession
lastUsed time.Time
version int
pool *ConnPool
clients *list.List
clientLock sync.Mutex
}
func (c *Conn) Close() error {
return c.session.Close()
}
// getClient is used to get a cached or new client
func (c *Conn) getClient() (*StreamClient, error) {
// Check for cached client
c.clientLock.Lock()
front := c.clients.Front()
if front != nil {
c.clients.Remove(front)
}
c.clientLock.Unlock()
if front != nil {
return front.Value.(*StreamClient), nil
}
// Open a new session
stream, err := c.session.Open()
if err != nil {
return nil, err
}
// Create the RPC client
cc := codec.GoRpc.ClientCodec(stream, msgpackHandle)
client := rpc.NewClientWithCodec(cc)
// Return a new stream client
sc := &StreamClient{
stream: stream,
client: client,
}
return sc, nil
}
// returnStream is used when done with a stream
// to allow re-use by a future RPC
func (c *Conn) returnClient(client *StreamClient) {
didSave := false
c.clientLock.Lock()
if c.clients.Len() < c.pool.maxStreams && atomic.LoadInt32(&c.shouldClose) == 0 {
c.clients.PushFront(client)
didSave = true
}
c.clientLock.Unlock()
if !didSave {
client.stream.Close()
}
}
// ConnPool is used to maintain a connection pool to other
// Consul servers. This is used to reduce the latency of
// RPC requests between servers. It is only used to pool
// connections in the rpcConsul mode. Raft connections
// are pooled seperately.
type ConnPool struct {
sync.Mutex
// LogOutput is used to control logging
logOutput io.Writer
// The maximum time to keep a connection open
maxTime time.Duration
// The maximum number of open streams to keep
maxStreams int
// Pool maps an address to a open connection
pool map[string]*Conn
// TLS settings
tlsConfig *tls.Config
// Used to indicate the pool is shutdown
shutdown bool
shutdownCh chan struct{}
}
// NewPool is used to make a new connection pool
// Maintain at most one connection per host, for up to maxTime.
// Set maxTime to 0 to disable reaping. maxStreams is used to control
// the number of idle streams allowed.
// If TLS settings are provided outgoing connections use TLS.
func NewPool(logOutput io.Writer, maxTime time.Duration, maxStreams int, tlsConfig *tls.Config) *ConnPool {
pool := &ConnPool{
logOutput: logOutput,
maxTime: maxTime,
maxStreams: maxStreams,
pool: make(map[string]*Conn),
tlsConfig: tlsConfig,
shutdownCh: make(chan struct{}),
}
if maxTime > 0 {
go pool.reap()
}
return pool
}
// Shutdown is used to close the connection pool
func (p *ConnPool) Shutdown() error {
p.Lock()
defer p.Unlock()
for _, conn := range p.pool {
conn.Close()
}
p.pool = make(map[string]*Conn)
if p.shutdown {
return nil
}
p.shutdown = true
close(p.shutdownCh)
return nil
}
// Acquire is used to get a connection that is
// pooled or to return a new connection
func (p *ConnPool) acquire(addr net.Addr, version int) (*Conn, error) {
// Check for a pooled ocnn
if conn := p.getPooled(addr, version); conn != nil {
return conn, nil
}
// Create a new connection
return p.getNewConn(addr, version)
}
// getPooled is used to return a pooled connection
func (p *ConnPool) getPooled(addr net.Addr, version int) *Conn {
p.Lock()
c := p.pool[addr.String()]
if c != nil {
c.lastUsed = time.Now()
atomic.AddInt32(&c.refCount, 1)
}
p.Unlock()
return c
}
// getNewConn is used to return a new connection
func (p *ConnPool) getNewConn(addr net.Addr, version int) (*Conn, error) {
// Try to dial the conn
conn, err := net.DialTimeout("tcp", addr.String(), 10*time.Second)
if err != nil {
return nil, err
}
// Cast to TCPConn
if tcp, ok := conn.(*net.TCPConn); ok {
tcp.SetKeepAlive(true)
tcp.SetNoDelay(true)
}
// Check if TLS is enabled
if p.tlsConfig != nil {
// Switch the connection into TLS mode
if _, err := conn.Write([]byte{byte(rpcTLS)}); err != nil {
conn.Close()
return nil, err
}
// Wrap the connection in a TLS client
conn = tls.Client(conn, p.tlsConfig)
}
// Switch the multiplexing based on version
var session muxSession
if version < 2 {
// Write the Consul multiplex byte to set the mode
if _, err := conn.Write([]byte{byte(rpcMultiplex)}); err != nil {
conn.Close()
return nil, err
}
// Create a multiplexed session
session = &muxadoWrapper{muxado.Client(conn)}
} else {
// Write the Consul multiplex byte to set the mode
if _, err := conn.Write([]byte{byte(rpcMultiplexV2)}); err != nil {
conn.Close()
return nil, err
}
// Setup the logger
conf := yamux.DefaultConfig()
conf.LogOutput = p.logOutput
// Create a multiplexed session
session, _ = yamux.Client(conn, conf)
}
// Wrap the connection
c := &Conn{
refCount: 1,
addr: addr,
session: session,
clients: list.New(),
lastUsed: time.Now(),
version: version,
pool: p,
}
// Track this connection, handle potential race condition
p.Lock()
if existing := p.pool[addr.String()]; existing != nil {
c.Close()
p.Unlock()
return existing, nil
} else {
p.pool[addr.String()] = c
p.Unlock()
return c, nil
}
}
// clearConn is used to clear any cached connection, potentially in response to an erro
func (p *ConnPool) clearConn(conn *Conn) {
// Ensure returned streams are closed
atomic.StoreInt32(&conn.shouldClose, 1)
// Clear from the cache
p.Lock()
if c, ok := p.pool[conn.addr.String()]; ok && c == conn {
delete(p.pool, conn.addr.String())
}
p.Unlock()
// Close down immediately if idle
if refCount := atomic.LoadInt32(&conn.refCount); refCount == 0 {
conn.Close()
}
}
// releaseConn is invoked when we are done with a conn to reduce the ref count
func (p *ConnPool) releaseConn(conn *Conn) {
refCount := atomic.AddInt32(&conn.refCount, -1)
if refCount == 0 && atomic.LoadInt32(&conn.shouldClose) == 1 {
conn.Close()
}
}
// getClient is used to get a usable client for an address and protocol version
func (p *ConnPool) getClient(addr net.Addr, version int) (*Conn, *StreamClient, error) {
retries := 0
START:
// Try to get a conn first
conn, err := p.acquire(addr, version)
if err != nil {
return nil, nil, fmt.Errorf("failed to get conn: %v", err)
}
// Get a client
client, err := conn.getClient()
if err != nil {
p.clearConn(conn)
p.releaseConn(conn)
// Try to redial, possible that the TCP session closed due to timeout
if retries == 0 {
retries++
goto START
}
return nil, nil, fmt.Errorf("failed to start stream: %v", err)
}
return conn, client, nil
}
// RPC is used to make an RPC call to a remote host
func (p *ConnPool) RPC(addr net.Addr, version int, method string, args interface{}, reply interface{}) error {
// Get a usable client
conn, sc, err := p.getClient(addr, version)
if err != nil {
return fmt.Errorf("rpc error: %v", err)
}
// Make the RPC call
err = sc.client.Call(method, args, reply)
if err != nil {
p.clearConn(conn)
p.releaseConn(conn)
return fmt.Errorf("rpc error: %v", err)
}
// Done with the connection
conn.returnClient(sc)
p.releaseConn(conn)
return nil
}
// Reap is used to close conns open over maxTime
func (p *ConnPool) reap() {
for !p.shutdown {
// Sleep for a while
select {
case <-time.After(time.Second):
case <-p.shutdownCh:
return
}
// Reap all old conns
p.Lock()
var removed []string
now := time.Now()
for host, conn := range p.pool {
// Skip recently used connections
if now.Sub(conn.lastUsed) < p.maxTime {
continue
}
// Skip connections with active streams
if atomic.LoadInt32(&conn.refCount) > 0 {
continue
}
// Close the conn
conn.Close()
// Remove from pool
removed = append(removed, host)
}
for _, host := range removed {
delete(p.pool, host)
}
p.Unlock()
}
}