Scott Baker | e7144bc | 2019-10-01 14:16:47 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2019-present Open Networking Foundation |
| 3 | |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package afrouter |
| 18 | |
| 19 | import ( |
| 20 | "errors" |
| 21 | "fmt" |
| 22 | "github.com/google/uuid" |
| 23 | "github.com/opencord/voltha-go/common/log" |
| 24 | "google.golang.org/grpc" |
| 25 | ) |
| 26 | |
| 27 | var clusters = make(map[string]*cluster) |
| 28 | |
| 29 | // cluster a collection of HA backends |
| 30 | type cluster struct { |
| 31 | name string |
| 32 | //backends map[string]*backend |
| 33 | backends []*backend |
| 34 | backendIDMap map[*backend]int |
| 35 | } |
| 36 | |
| 37 | //TODO: Move the backend type (active/active etc) to the cluster |
| 38 | // level. All backends should really be of the same type. |
| 39 | // Create a new backend cluster |
| 40 | func newBackendCluster(conf *BackendClusterConfig) (*cluster, error) { |
| 41 | var err error = nil |
| 42 | var rtrn_err = false |
| 43 | var be *backend |
| 44 | log.Debugf("Creating a backend cluster with %v", conf) |
| 45 | // Validate the configuration |
| 46 | if conf.Name == "" { |
| 47 | log.Error("A backend cluster must have a name") |
| 48 | rtrn_err = true |
| 49 | } |
| 50 | //bc := &cluster{name:conf.Name,backends:make(map[string]*backend)} |
| 51 | bc := &cluster{name: conf.Name, backendIDMap: make(map[*backend]int)} |
| 52 | clusters[bc.name] = bc |
| 53 | idx := 0 |
| 54 | for _, bec := range conf.Backends { |
| 55 | if bec.Name == "" { |
| 56 | log.Errorf("A backend must have a name in cluster %s\n", conf.Name) |
| 57 | rtrn_err = true |
| 58 | } |
| 59 | if be, err = newBackend(&bec, conf.Name); err != nil { |
| 60 | log.Errorf("Error creating backend %s", bec.Name) |
| 61 | rtrn_err = true |
| 62 | } |
| 63 | bc.backends = append(bc.backends, be) |
| 64 | bc.backendIDMap[bc.backends[idx]] = idx |
| 65 | idx++ |
| 66 | } |
| 67 | if rtrn_err { |
| 68 | return nil, errors.New("Error creating backend(s)") |
| 69 | } |
| 70 | return bc, nil |
| 71 | } |
| 72 | |
| 73 | func (c *cluster) getBackend(name string) *backend { |
| 74 | for _, v := range c.backends { |
| 75 | if v.name == name { |
| 76 | return v |
| 77 | } |
| 78 | } |
| 79 | return nil |
| 80 | } |
| 81 | |
| 82 | func (c *cluster) allocateSerialNumber() string { |
| 83 | return uuid.New().String() |
| 84 | } |
| 85 | |
| 86 | func (c *cluster) nextBackend(be *backend, seq backendSequence) (*backend, error) { |
| 87 | switch seq { |
| 88 | case BackendSequenceRoundRobin: // Round robin |
| 89 | in := be |
| 90 | // If no backend is found having a connection |
| 91 | // then return nil. |
| 92 | if be == nil { |
| 93 | log.Debug("Previous backend is nil") |
| 94 | be = c.backends[0] |
| 95 | in = be |
| 96 | if be.NumOpenConnections() != 0 { |
| 97 | return be, nil |
| 98 | } |
| 99 | } |
| 100 | for { |
| 101 | log.Debugf("Requesting a new backend starting from %s", be.name) |
| 102 | cur := c.backendIDMap[be] |
| 103 | cur++ |
| 104 | if cur >= len(c.backends) { |
| 105 | cur = 0 |
| 106 | } |
| 107 | log.Debugf("Next backend is %d:%s", cur, c.backends[cur].name) |
| 108 | if c.backends[cur].NumOpenConnections() > 0 { |
| 109 | return c.backends[cur], nil |
| 110 | } |
| 111 | if c.backends[cur] == in { |
| 112 | err := fmt.Errorf("No backend with open connections found") |
| 113 | log.Debug(err) |
| 114 | return nil, err |
| 115 | } |
| 116 | be = c.backends[cur] |
| 117 | log.Debugf("Backend '%s' has no open connections, trying next", c.backends[cur].name) |
| 118 | } |
| 119 | default: // Invalid, default to round robin |
| 120 | log.Errorf("Invalid backend sequence %d. Defaulting to round robin", seq) |
| 121 | return c.nextBackend(be, BackendSequenceRoundRobin) |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | func (c *cluster) handler(srv interface{}, serverStream grpc.ServerStream, r Router, methodInfo methodDetails, |
| 126 | mk string, mv string) error { |
| 127 | //func (c *cluster) handler(nbR * nbRequest) error { |
| 128 | |
| 129 | // The final backend cluster needs to be determined here. With non-affinity routed backends it could |
| 130 | // just be determined here and for affinity routed backends the first message must be received |
| 131 | // before the backend is determined. In order to keep things simple, the same approach is taken for |
| 132 | // now. |
| 133 | |
| 134 | // Get the backend to use. |
| 135 | // Allocate the requestFrame here since it holds the "context" of this communication |
| 136 | nf := &requestFrame{router: r, methodInfo: methodInfo, serialNo: c.allocateSerialNumber(), metaKey: mk, metaVal: mv} |
| 137 | log.Debugf("Nb frame allocate with method %s", nf.methodInfo.method) |
| 138 | |
| 139 | if be, err := c.assignBackend(serverStream, nf); err != nil { |
| 140 | // At this point, no backend streams have been initiated |
| 141 | // so just return the error. |
| 142 | return err |
| 143 | } else { |
| 144 | log.Debugf("Backend '%s' selected", be.name) |
| 145 | // Allocate a responseFrame here because it might be needed for return value intercept |
| 146 | sf := &responseFrame{router: r, backend: be, method: nf.methodInfo.method, metaKey: mk, metaVal: mv} |
| 147 | log.Debugf("Sb frame allocated with router %s", r.Name()) |
| 148 | return be.handler(srv, serverStream, nf, sf) |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | func (c *cluster) assignBackend(src grpc.ServerStream, f *requestFrame) (*backend, error) { |
| 153 | // Receive the first message from the server. This calls the assigned codec in which |
| 154 | // Unmarshal gets executed. That will use the assigned router to select a backend |
| 155 | // and add it to the frame |
| 156 | if err := src.RecvMsg(f); err != nil { |
| 157 | return nil, err |
| 158 | } |
| 159 | // Check that the backend was routable and actually has connections open. |
| 160 | // If it doesn't then return a nil backend to indicate this |
| 161 | if f.backend == nil { |
| 162 | err := fmt.Errorf("Unable to route method '%s'", f.methodInfo.method) |
| 163 | log.Error(err) |
| 164 | return nil, err |
| 165 | } else if len(f.backend.openConns) == 0 { |
| 166 | err := fmt.Errorf("No open connections on backend '%s'", f.backend.name) |
| 167 | log.Error(err) |
| 168 | return f.backend, err |
| 169 | } |
| 170 | log.Debugf("Assigned backend %s", f.backend.name) |
| 171 | return f.backend, nil |
| 172 | } |