testing: retry MgoDial

testing/mgo.go

 package testing
 
 import (
         "fmt"
         "io/ioutil"
         "labix.org/v2/mgo"
         . "launchpad.net/gocheck"
         "launchpad.net/juju-core/log"
+        "launchpad.net/juju-core/trivial"
         "net"
         "os"
         "os/exec"
         "strconv"
         stdtesting "testing"
         "time"
 )
 
 var (
         // MgoAddr holds the address of the shared MongoDB server set up by
@@ skipping 64 matching lines @@
 
 func (s *MgoSuite) SetUpSuite(c *C) {
         if MgoAddr == "" {
                 panic("MgoSuite tests must be run with MgoTestPackage")
         }
         mgo.SetStats(true)
 }
 
 func (s *MgoSuite) TearDownSuite(c *C) {}
 
+var mgoDialAttempt = trivial.AttemptStrategy{
+        Total: 500 * time.Millisecond,
+        Delay: 100 * time.Millisecond,
+}
+
 // MgoDial returns a new connection to the shared MongoDB server.
 func MgoDial() *mgo.Session {
-        session, err := mgo.Dial(MgoAddr)
-        if err != nil {
-                panic(err)
+        var err error
+        for a := mgoDialAttempt.Start(); a.Next(); {

[niemeyer, 2012/11/01 14:32:38]

Have you seen mgo.DialWithTimeout? Does it not solve the problem?

+                var session *mgo.Session
+                session, err = mgo.Dial(MgoAddr)
+                if err == nil {
+                        return session
+                }
         }
-        return session
+        panic(err)
 }
 
 func (s *MgoSuite) SetUpTest(c *C) {
         mgo.ResetStats()
         s.Session = MgoDial()
 }
 
 // MgoReset deletes all content from the shared MongoDB server.
 func MgoReset() {
         session := MgoDial()
@@ skipping 56 matching lines @@
 // We hope that the probability is small enough during
 // testing to be negligible.
 func FindTCPPort() int {
         l, err := net.Listen("tcp", "127.0.0.1:0")
         if err != nil {
                 panic(err)
         }
         l.Close()
         return l.Addr().(*net.TCPAddr).Port
 }