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
|
/*
*
* 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 grpc
import (
"sync"
"sync/atomic"
"golang.org/x/net/context"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/codes"
lbpb "google.golang.org/grpc/grpclb/grpc_lb_v1/messages"
"google.golang.org/grpc/status"
)
type rpcStats struct {
NumCallsStarted int64
NumCallsFinished int64
NumCallsFinishedWithDropForRateLimiting int64
NumCallsFinishedWithDropForLoadBalancing int64
NumCallsFinishedWithClientFailedToSend int64
NumCallsFinishedKnownReceived int64
}
// 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),
NumCallsFinishedWithDropForRateLimiting: atomic.SwapInt64(&s.NumCallsFinishedWithDropForRateLimiting, 0),
NumCallsFinishedWithDropForLoadBalancing: atomic.SwapInt64(&s.NumCallsFinishedWithDropForLoadBalancing, 0),
NumCallsFinishedWithClientFailedToSend: atomic.SwapInt64(&s.NumCallsFinishedWithClientFailedToSend, 0),
NumCallsFinishedKnownReceived: atomic.SwapInt64(&s.NumCallsFinishedKnownReceived, 0),
}
return stats
}
func (s *rpcStats) dropForRateLimiting() {
atomic.AddInt64(&s.NumCallsStarted, 1)
atomic.AddInt64(&s.NumCallsFinishedWithDropForRateLimiting, 1)
atomic.AddInt64(&s.NumCallsFinished, 1)
}
func (s *rpcStats) dropForLoadBalancing() {
atomic.AddInt64(&s.NumCallsStarted, 1)
atomic.AddInt64(&s.NumCallsFinishedWithDropForLoadBalancing, 1)
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(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
return nil, nil, 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 (p *rrPicker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
p.mu.Lock()
defer p.mu.Unlock()
sc := p.subConns[p.subConnsNext]
p.subConnsNext = (p.subConnsNext + 1) % len(p.subConns)
return sc, nil, 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 (p *lbPicker) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), 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.DropForRateLimiting {
p.stats.dropForRateLimiting()
return nil, nil, status.Errorf(codes.Unavailable, "request dropped by grpclb")
}
if s.DropForLoadBalancing {
p.stats.dropForLoadBalancing()
return nil, nil, status.Errorf(codes.Unavailable, "request dropped by grpclb")
}
// If not a drop but there's no ready subConns.
if len(p.subConns) <= 0 {
return nil, nil, 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 sc, done, nil
}
|