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
|
/*
*
* Copyright 2017 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package grpclb
import (
"sync"
"sync/atomic"
"google.golang.org/grpc/balancer"
lbpb "google.golang.org/grpc/balancer/grpclb/grpc_lb_v1"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/internal/grpcrand"
"google.golang.org/grpc/status"
)
// rpcStats is same as lbpb.ClientStats, except that numCallsDropped is a map
// instead of a slice.
type rpcStats struct {
// Only access the following fields atomically.
numCallsStarted int64
numCallsFinished int64
numCallsFinishedWithClientFailedToSend int64
numCallsFinishedKnownReceived int64
mu sync.Mutex
// map load_balance_token -> num_calls_dropped
numCallsDropped map[string]int64
}
func newRPCStats() *rpcStats {
return &rpcStats{
numCallsDropped: make(map[string]int64),
}
}
func isZeroStats(stats *lbpb.ClientStats) bool {
return len(stats.CallsFinishedWithDrop) == 0 &&
stats.NumCallsStarted == 0 &&
stats.NumCallsFinished == 0 &&
stats.NumCallsFinishedWithClientFailedToSend == 0 &&
stats.NumCallsFinishedKnownReceived == 0
}
// toClientStats converts rpcStats to lbpb.ClientStats, and clears rpcStats.
func (s *rpcStats) toClientStats() *lbpb.ClientStats {
stats := &lbpb.ClientStats{
NumCallsStarted: atomic.SwapInt64(&s.numCallsStarted, 0),
NumCallsFinished: atomic.SwapInt64(&s.numCallsFinished, 0),
NumCallsFinishedWithClientFailedToSend: atomic.SwapInt64(&s.numCallsFinishedWithClientFailedToSend, 0),
NumCallsFinishedKnownReceived: atomic.SwapInt64(&s.numCallsFinishedKnownReceived, 0),
}
s.mu.Lock()
dropped := s.numCallsDropped
s.numCallsDropped = make(map[string]int64)
s.mu.Unlock()
for token, count := range dropped {
stats.CallsFinishedWithDrop = append(stats.CallsFinishedWithDrop, &lbpb.ClientStatsPerToken{
LoadBalanceToken: token,
NumCalls: count,
})
}
return stats
}
func (s *rpcStats) drop(token string) {
atomic.AddInt64(&s.numCallsStarted, 1)
s.mu.Lock()
s.numCallsDropped[token]++
s.mu.Unlock()
atomic.AddInt64(&s.numCallsFinished, 1)
}
func (s *rpcStats) failedToSend() {
atomic.AddInt64(&s.numCallsStarted, 1)
atomic.AddInt64(&s.numCallsFinishedWithClientFailedToSend, 1)
atomic.AddInt64(&s.numCallsFinished, 1)
}
func (s *rpcStats) knownReceived() {
atomic.AddInt64(&s.numCallsStarted, 1)
atomic.AddInt64(&s.numCallsFinishedKnownReceived, 1)
atomic.AddInt64(&s.numCallsFinished, 1)
}
type errPicker struct {
// Pick always returns this err.
err error
}
func (p *errPicker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
return balancer.PickResult{}, p.err
}
// rrPicker does roundrobin on subConns. It's typically used when there's no
// response from remote balancer, and grpclb falls back to the resolved
// backends.
//
// It guaranteed that len(subConns) > 0.
type rrPicker struct {
mu sync.Mutex
subConns []balancer.SubConn // The subConns that were READY when taking the snapshot.
subConnsNext int
}
func newRRPicker(readySCs []balancer.SubConn) *rrPicker {
return &rrPicker{
subConns: readySCs,
subConnsNext: grpcrand.Intn(len(readySCs)),
}
}
func (p *rrPicker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
p.mu.Lock()
defer p.mu.Unlock()
sc := p.subConns[p.subConnsNext]
p.subConnsNext = (p.subConnsNext + 1) % len(p.subConns)
return balancer.PickResult{SubConn: sc}, nil
}
// lbPicker does two layers of picks:
//
// First layer: roundrobin on all servers in serverList, including drops and backends.
// - If it picks a drop, the RPC will fail as being dropped.
// - If it picks a backend, do a second layer pick to pick the real backend.
//
// Second layer: roundrobin on all READY backends.
//
// It's guaranteed that len(serverList) > 0.
type lbPicker struct {
mu sync.Mutex
serverList []*lbpb.Server
serverListNext int
subConns []balancer.SubConn // The subConns that were READY when taking the snapshot.
subConnsNext int
stats *rpcStats
}
func newLBPicker(serverList []*lbpb.Server, readySCs []balancer.SubConn, stats *rpcStats) *lbPicker {
return &lbPicker{
serverList: serverList,
subConns: readySCs,
subConnsNext: grpcrand.Intn(len(readySCs)),
stats: stats,
}
}
func (p *lbPicker) Pick(balancer.PickInfo) (balancer.PickResult, error) {
p.mu.Lock()
defer p.mu.Unlock()
// Layer one roundrobin on serverList.
s := p.serverList[p.serverListNext]
p.serverListNext = (p.serverListNext + 1) % len(p.serverList)
// If it's a drop, return an error and fail the RPC.
if s.Drop {
p.stats.drop(s.LoadBalanceToken)
return balancer.PickResult{}, status.Errorf(codes.Unavailable, "request dropped by grpclb")
}
// If not a drop but there's no ready subConns.
if len(p.subConns) <= 0 {
return balancer.PickResult{}, balancer.ErrNoSubConnAvailable
}
// Return the next ready subConn in the list, also collect rpc stats.
sc := p.subConns[p.subConnsNext]
p.subConnsNext = (p.subConnsNext + 1) % len(p.subConns)
done := func(info balancer.DoneInfo) {
if !info.BytesSent {
p.stats.failedToSend()
} else if info.BytesReceived {
p.stats.knownReceived()
}
}
return balancer.PickResult{SubConn: sc, Done: done}, nil
}
func (p *lbPicker) updateReadySCs(readySCs []balancer.SubConn) {
p.mu.Lock()
defer p.mu.Unlock()
p.subConns = readySCs
p.subConnsNext = p.subConnsNext % len(readySCs)
}
|
