a43dc81ea8
* Deleting permament error as it doesn't make sense. Just return a plain old error and that will be considered permanent. * Removing double closure at as it's unmaintainable and can be error prone. Separated back offs into a generic one and a thrift call specific one. * ZK leader finder now returns a temporary error instead of constantly no leader found and quitting. It could be that the leader info is being propagated so it's worth trying another time. * Adding more logging to the retry. * Wrapping lock and unlock in an anonymous function so that we can use defer on unlock such that it is called in the case of a panic.
105 lines
3 KiB
Go
105 lines
3 KiB
Go
/**
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package realis
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import (
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"encoding/json"
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"fmt"
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"strconv"
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"strings"
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"time"
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"github.com/pkg/errors"
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"github.com/samuel/go-zookeeper/zk"
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)
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type Endpoint struct {
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Host string `json:"host"`
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Port int `json:"port"`
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}
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type ServiceInstance struct {
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Service Endpoint `json:"serviceEndpoint"`
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AdditionalEndpoints map[string]Endpoint `json:"additionalEndpoints"`
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Status string `json:"status"`
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}
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// Retrieves current Aurora leader from ZK.
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func LeaderFromZK(cluster Cluster) (string, error) {
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var zkurl string
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retryErr := ExponentialBackoff(defaultBackoff, func() (bool, error) {
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endpoints := strings.Split(cluster.ZK, ",")
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//TODO (rdelvalle): When enabling debugging, change logger here
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c, _, err := zk.Connect(endpoints, time.Second*10, func(c *zk.Conn) { c.SetLogger(NoopLogger{}) })
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if err != nil {
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return false, NewTemporaryError(errors.Wrap(err, "Failed to connect to Zookeeper at "+cluster.ZK))
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}
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defer c.Close()
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// Open up descriptor for the ZK path given
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children, _, _, err := c.ChildrenW(cluster.SchedZKPath)
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if err != nil {
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return false, errors.Wrapf(err, "Path %s doesn't exist on Zookeeper ", cluster.SchedZKPath)
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}
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// Search for the leader through all the children in the given path
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serviceInst := new(ServiceInstance)
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for _, child := range children {
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// Only the leader will start with member_
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if strings.HasPrefix(child, "member_") {
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data, _, err := c.Get(cluster.SchedZKPath + "/" + child)
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if err != nil {
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return false, errors.Wrap(err, "Error fetching contents of leader")
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}
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err = json.Unmarshal([]byte(data), serviceInst)
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if err != nil {
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return false, NewTemporaryError(errors.Wrap(err, "Unable to unmarshall contents of leader"))
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}
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// Should only be one endpoint
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if len(serviceInst.AdditionalEndpoints) > 1 {
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fmt.Errorf("Ambiguous end points schemes")
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}
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var scheme, host, port string
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for k, v := range serviceInst.AdditionalEndpoints {
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scheme = k
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host = v.Host
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port = strconv.Itoa(v.Port)
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}
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zkurl = scheme + "://" + host + ":" + port
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return true, nil
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}
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}
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// Leader data might not be available yet, try to fetch again.
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return false, NewTemporaryError(errors.New("No leader found"))
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})
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if retryErr != nil {
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return "", NewTimeoutError(errors.Wrapf(retryErr, "Failed to determine leader after %v attempts", defaultBackoff.Steps))
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}
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return zkurl, nil
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}
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