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Stop retrying if we find a permanent url error. (#85)

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* Detecting if the transport error was not temporary in which case we stop retrying. Changed bug where get results was being called before we checked for an error.

* Adding exception for EOF error. All EOF errors will be retried.

* Addressing race conditions that may happen when client is closed or connection is re-established.

* Adding documentation about how this particular implemantion of the realis client uses retries in scenarios where a temporary error is found.
This commit is contained in:
Renan DelValle 2018-11-01 17:00:03 -07:00 • committed by GitHub
parent 6762c1784b
commit a09a18ea3b
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 54 additions and 27 deletions
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59
realis.go
View file

@ -251,6 +251,10 @@ func newTBinTransport(url string, timeout int, config *RealisConfig) (thrift.TTr
return trans, err
}
// This client implementation of the realis interface uses a retry mechanism for all Thrift Calls.
// It will retry all calls which result in a temporary failure as well as calls that fail due to an EOF
// being returned by the http client. Most permanent failures are now being caught by the thriftCallWithRetries
// function and not being retried but there may be corner cases not yet handled.
func NewRealisClient(options ...ClientOption) (Realis, error) {
config := &RealisConfig{}
@ -443,7 +447,7 @@ func newTJSONConfig(url string, timeoutms int, config *RealisConfig) (*RealisCon
httpTrans := (trans).(*thrift.THttpClient)
httpTrans.SetHeader("Content-Type", "application/x-thrift")
httpTrans.SetHeader("User-Agent", "GoRealis v"+VERSION)
httpTrans.SetHeader("User-Agent", "gorealis v"+VERSION)
return &RealisConfig{transport: trans, protoFactory: thrift.NewTJSONProtocolFactory()}, nil
}
@ -460,7 +464,7 @@ func newTBinaryConfig(url string, timeoutms int, config *RealisConfig) (*RealisC
httpTrans.SetHeader("Accept", "application/vnd.apache.thrift.binary")
httpTrans.SetHeader("Content-Type", "application/vnd.apache.thrift.binary")
httpTrans.SetHeader("User-Agent", "GoRealis v"+VERSION)
httpTrans.SetHeader("User-Agent", "gorealis v"+VERSION)
return &RealisConfig{transport: trans, protoFactory: thrift.NewTBinaryProtocolFactoryDefault()}, nil
@ -476,6 +480,9 @@ func (r *realisClient) ReestablishConn() error {
r.logger.Println("Re-establishing Connection to Aurora")
r.Close()
r.lock.Lock()
defer r.lock.Unlock()
// Recreate connection from scratch using original options
newRealis, err := NewRealisClient(r.config.options...)
if err != nil {
@ -498,6 +505,10 @@ func (r *realisClient) ReestablishConn() error {
// Releases resources associated with the realis client.
func (r *realisClient) Close() {
r.lock.Lock()
defer r.lock.Unlock()
r.client.Transport.Close()
r.readonlyClient.Transport.Close()
r.adminClient.Transport.Close()
@ -555,14 +566,14 @@ func (r *realisClient) GetJobs(role string) (*aurora.Response, *aurora.GetJobsRe
return r.readonlyClient.GetJobs(role)
})
if resp.GetResult_() != nil {
result = resp.GetResult_().GetJobsResult_
}
if retryErr != nil {
return nil, result, errors.Wrap(retryErr, "Error getting Jobs from Aurora Scheduler")
}
if resp.GetResult_() != nil {
result = resp.GetResult_().GetJobsResult_
}
return resp, result, nil
}
@ -635,7 +646,7 @@ func (r *realisClient) CreateService(auroraJob Job, settings *aurora.JobUpdateSe
return resp, nil, errors.Wrap(err, "unable to create service")
}
if resp != nil && resp.GetResult_() != nil {
if resp.GetResult_() != nil {
return resp, resp.GetResult_().GetStartJobUpdateResult_(), nil
}
@ -879,7 +890,7 @@ func (r *realisClient) GetPendingReason(query *aurora.TaskQuery) (pendingReasons
var result map[*aurora.PendingReason]bool
if resp != nil && resp.GetResult_() != nil {
if resp.GetResult_() != nil {
result = resp.GetResult_().GetGetPendingReasonResult_().GetReasons()
}
for reason := range result {
@ -999,14 +1010,14 @@ func (r *realisClient) DrainHosts(hosts ...string) (*aurora.Response, *aurora.Dr
return r.adminClient.DrainHosts(drainList)
})
if resp != nil && resp.GetResult_() != nil {
result = resp.GetResult_().GetDrainHostsResult_()
}
if retryErr != nil {
return resp, result, errors.Wrap(retryErr, "Unable to recover connection")
}
if resp.GetResult_() != nil {
result = resp.GetResult_().GetDrainHostsResult_()
}
return resp, result, nil
}
@ -1030,14 +1041,14 @@ func (r *realisClient) StartMaintenance(hosts ...string) (*aurora.Response, *aur
return r.adminClient.StartMaintenance(hostList)
})
if resp.GetResult_() != nil {
result = resp.GetResult_().GetStartMaintenanceResult_()
}
if retryErr != nil {
return resp, result, errors.Wrap(retryErr, "Unable to recover connection")
}
if resp.GetResult_() != nil {
result = resp.GetResult_().GetStartMaintenanceResult_()
}
return resp, result, nil
}
@ -1061,14 +1072,14 @@ func (r *realisClient) EndMaintenance(hosts ...string) (*aurora.Response, *auror
return r.adminClient.EndMaintenance(hostList)
})
if resp.GetResult_() != nil {
result = resp.GetResult_().GetEndMaintenanceResult_()
}
if retryErr != nil {
return resp, result, errors.Wrap(retryErr, "Unable to recover connection")
}
if resp.GetResult_() != nil {
result = resp.GetResult_().GetEndMaintenanceResult_()
}
return resp, result, nil
}
@ -1094,14 +1105,14 @@ func (r *realisClient) MaintenanceStatus(hosts ...string) (*aurora.Response, *au
return r.adminClient.MaintenanceStatus(hostList)
})
if resp.GetResult_() != nil {
result = resp.GetResult_().GetMaintenanceStatusResult_()
}
if retryErr != nil {
return resp, result, errors.Wrap(retryErr, "Unable to recover connection")
}
if resp.GetResult_() != nil {
result = resp.GetResult_().GetMaintenanceStatusResult_()
}
return resp, result, nil
}

22
retry.go
View file

@ -15,9 +15,12 @@
package realis
import (
"io"
"math/rand"
"net/url"
"time"
"git.apache.org/thrift.git/lib/go/thrift"
"github.com/paypal/gorealis/gen-go/apache/aurora"
"github.com/paypal/gorealis/response"
"github.com/pkg/errors"
@ -88,7 +91,6 @@ func ExponentialBackoff(backoff Backoff, logger Logger, condition ConditionFunc)
}
if err != nil {
// If the error is temporary, continue retrying.
if !IsTemporary(err) {
return err
@ -96,9 +98,7 @@ func ExponentialBackoff(backoff Backoff, logger Logger, condition ConditionFunc)
// Print out the temporary error we experienced.
logger.Println(err)
}
}
}
if curStep > 1 {
@ -158,6 +158,22 @@ func (r *realisClient) thriftCallWithRetries(thriftCall auroraThriftCall) (*auro
// Print out the error to the user
r.logger.Printf("Client Error: %v\n", clientErr)
// Determine if error is a temporary URL error by going up the stack
e, ok := clientErr.(thrift.TTransportException)
if ok {
r.logger.DebugPrint("Encountered a transport exception")
e, ok := e.Err().(*url.Error)
if ok {
// EOF error occurs when the server closes the read buffer of the client. This is common
// when the server is overloaded and should be retried. All other errors that are permanent
// will not be retried.
if e.Err != io.EOF && !e.Temporary() {
return nil, errors.Wrap(clientErr, "Permanent connection error")
}
}
}
// In the future, reestablish connection should be able to check if it is actually possible
// to make a thrift call to Aurora. For now, a reconnect should always lead to a retry.
r.ReestablishConn()