1 /*
2 *
3 * Copyright 2020 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18 19 // Package serviceconfig contains utility functions to parse service config.
20 package serviceconfig
21 22 import (
23 "encoding/json"
24 "fmt"
25 "time"
26 27 "google.golang.org/grpc/balancer"
28 "google.golang.org/grpc/codes"
29 "google.golang.org/grpc/grpclog"
30 externalserviceconfig "google.golang.org/grpc/serviceconfig"
31 )
32 33 var logger = grpclog.Component("core")
34 35 // BalancerConfig wraps the name and config associated with one load balancing
36 // policy. It corresponds to a single entry of the loadBalancingConfig field
37 // from ServiceConfig.
38 //
39 // It implements the json.Unmarshaler interface.
40 //
41 // https://github.com/grpc/grpc-proto/blob/54713b1e8bc6ed2d4f25fb4dff527842150b91b2/grpc/service_config/service_config.proto#L247
42 type BalancerConfig struct {
43 Name string
44 Config externalserviceconfig.LoadBalancingConfig
45 }
46 47 type intermediateBalancerConfig []map[string]json.RawMessage
48 49 // MarshalJSON implements the json.Marshaler interface.
50 //
51 // It marshals the balancer and config into a length-1 slice
52 // ([]map[string]config).
53 func (bc *BalancerConfig) MarshalJSON() ([]byte, error) {
54 if bc.Config == nil {
55 // If config is nil, return empty config `{}`.
56 return []byte(fmt.Sprintf(`[{%q: %v}]`, bc.Name, "{}")), nil
57 }
58 c, err := json.Marshal(bc.Config)
59 if err != nil {
60 return nil, err
61 }
62 return []byte(fmt.Sprintf(`[{%q: %s}]`, bc.Name, c)), nil
63 }
64 65 // UnmarshalJSON implements the json.Unmarshaler interface.
66 //
67 // ServiceConfig contains a list of loadBalancingConfigs, each with a name and
68 // config. This method iterates through that list in order, and stops at the
69 // first policy that is supported.
70 // - If the config for the first supported policy is invalid, the whole service
71 // config is invalid.
72 // - If the list doesn't contain any supported policy, the whole service config
73 // is invalid.
74 func (bc *BalancerConfig) UnmarshalJSON(b []byte) error {
75 var ir intermediateBalancerConfig
76 err := json.Unmarshal(b, &ir)
77 if err != nil {
78 return err
79 }
80 81 var names []string
82 for i, lbcfg := range ir {
83 if len(lbcfg) != 1 {
84 return fmt.Errorf("invalid loadBalancingConfig: entry %v does not contain exactly 1 policy/config pair: %q", i, lbcfg)
85 }
86 87 var (
88 name string
89 jsonCfg json.RawMessage
90 )
91 // Get the key:value pair from the map. We have already made sure that
92 // the map contains a single entry.
93 for name, jsonCfg = range lbcfg {
94 }
95 96 names = append(names, name)
97 builder := balancer.Get(name)
98 if builder == nil {
99 // If the balancer is not registered, move on to the next config.
100 // This is not an error.
101 continue
102 }
103 bc.Name = name
104 105 parser, ok := builder.(balancer.ConfigParser)
106 if !ok {
107 if string(jsonCfg) != "{}" {
108 logger.Warningf("non-empty balancer configuration %q, but balancer does not implement ParseConfig", string(jsonCfg))
109 }
110 // Stop at this, though the builder doesn't support parsing config.
111 return nil
112 }
113 114 cfg, err := parser.ParseConfig(jsonCfg)
115 if err != nil {
116 return fmt.Errorf("error parsing loadBalancingConfig for policy %q: %v", name, err)
117 }
118 bc.Config = cfg
119 return nil
120 }
121 // This is reached when the for loop iterates over all entries, but didn't
122 // return. This means we had a loadBalancingConfig slice but did not
123 // encounter a registered policy. The config is considered invalid in this
124 // case.
125 return fmt.Errorf("invalid loadBalancingConfig: no supported policies found in %v", names)
126 }
127 128 // MethodConfig defines the configuration recommended by the service providers for a
129 // particular method.
130 type MethodConfig struct {
131 // WaitForReady indicates whether RPCs sent to this method should wait until
132 // the connection is ready by default (!failfast). The value specified via the
133 // gRPC client API will override the value set here.
134 WaitForReady *bool
135 // Timeout is the default timeout for RPCs sent to this method. The actual
136 // deadline used will be the minimum of the value specified here and the value
137 // set by the application via the gRPC client API. If either one is not set,
138 // then the other will be used. If neither is set, then the RPC has no deadline.
139 Timeout *time.Duration
140 // MaxReqSize is the maximum allowed payload size for an individual request in a
141 // stream (client->server) in bytes. The size which is measured is the serialized
142 // payload after per-message compression (but before stream compression) in bytes.
143 // The actual value used is the minimum of the value specified here and the value set
144 // by the application via the gRPC client API. If either one is not set, then the other
145 // will be used. If neither is set, then the built-in default is used.
146 MaxReqSize *int
147 // MaxRespSize is the maximum allowed payload size for an individual response in a
148 // stream (server->client) in bytes.
149 MaxRespSize *int
150 // RetryPolicy configures retry options for the method.
151 RetryPolicy *RetryPolicy
152 }
153 154 // RetryPolicy defines the go-native version of the retry policy defined by the
155 // service config here:
156 // https://github.com/grpc/proposal/blob/master/A6-client-retries.md#integration-with-service-config
157 type RetryPolicy struct {
158 // MaxAttempts is the maximum number of attempts, including the original RPC.
159 //
160 // This field is required and must be two or greater.
161 MaxAttempts int
162 163 // Exponential backoff parameters. The initial retry attempt will occur at
164 // random(0, initialBackoff). In general, the nth attempt will occur at
165 // random(0,
166 // min(initialBackoff*backoffMultiplier**(n-1), maxBackoff)).
167 //
168 // These fields are required and must be greater than zero.
169 InitialBackoff time.Duration
170 MaxBackoff time.Duration
171 BackoffMultiplier float64
172 173 // The set of status codes which may be retried.
174 //
175 // Status codes are specified as strings, e.g., "UNAVAILABLE".
176 //
177 // This field is required and must be non-empty.
178 // Note: a set is used to store this for easy lookup.
179 RetryableStatusCodes map[codes.Code]bool
180 }
181