9944: Tweak centos6 Dockerfiles to fall back to mirror if repoforge main is

[arvados.git] / services / keep-balance / balance.go

diff --git a/services/keep-balance/balance.go b/services/keep-balance/balance.go
index fa585d3aeb90e089e16ae041e0a3955f725b3f24..25b474b9ca0a475f81cc08db02ef007e9fe009f0 100644 (file)
--- a/services/keep-balance/balance.go
+++ b/services/keep-balance/balance.go
@@ -6,6 +6,7 @@ import (
        "math"
        "os"
        "runtime"
+       "sort"
        "strings"
        "sync"
        "time"
@@ -50,11 +51,17 @@ type Balancer struct {
 }
 
 // Run performs a balance operation using the given config and
-// runOptions. It should only be called once on a given Balancer
-// object. Typical usage:
+// runOptions, and returns RunOptions suitable for passing to a
+// subsequent balance operation.
 //
-//   err = (&Balancer{}).Run(config, runOptions)
-func (bal *Balancer) Run(config Config, runOptions RunOptions) (err error) {
+// Run should only be called once on a given Balancer object.
+//
+// Typical usage:
+//
+//   runOptions, err = (&Balancer{}).Run(config, runOptions)
+func (bal *Balancer) Run(config Config, runOptions RunOptions) (nextRunOptions RunOptions, err error) {
+       nextRunOptions = runOptions
+
        bal.Dumper = runOptions.Dumper
        bal.Logger = runOptions.Logger
        if bal.Logger == nil {
@@ -75,10 +82,20 @@ func (bal *Balancer) Run(config Config, runOptions RunOptions) (err error) {
        if err = bal.CheckSanityEarly(&config.Client); err != nil {
                return
        }
-       if runOptions.CommitTrash {
+       rs := bal.rendezvousState()
+       if runOptions.CommitTrash && rs != runOptions.SafeRendezvousState {
+               if runOptions.SafeRendezvousState != "" {
+                       bal.logf("notice: KeepServices list has changed since last run")
+               }
+               bal.logf("clearing existing trash lists, in case the new rendezvous order differs from previous run")
                if err = bal.ClearTrashLists(&config.Client); err != nil {
                        return
                }
+               // The current rendezvous state becomes "safe" (i.e.,
+               // OK to compute changes for that state without
+               // clearing existing trash lists) only now, after we
+               // succeed in clearing existing trash lists.
+               nextRunOptions.SafeRendezvousState = rs
        }
        if err = bal.GetCurrentState(&config.Client, config.CollectionBatchSize, config.CollectionBuffers); err != nil {
                return
@@ -158,6 +175,17 @@ func (bal *Balancer) CheckSanityEarly(c *arvados.Client) error {
        return nil
 }
 
+// rendezvousState returns a fingerprint (e.g., a sorted list of
+// UUID+host+port) of the current set of keep services.
+func (bal *Balancer) rendezvousState() string {
+       srvs := make([]string, 0, len(bal.KeepServices))
+       for _, srv := range bal.KeepServices {
+               srvs = append(srvs, srv.String())
+       }
+       sort.Strings(srvs)
+       return strings.Join(srvs, "; ")
+}
+
 // ClearTrashLists sends an empty trash list to each keep
 // service. Calling this before GetCurrentState avoids races.
 //
@@ -619,7 +647,7 @@ func (bal *Balancer) commitAsync(c *arvados.Client, label string, f func(srv *Ke
                }(srv)
        }
        var lastErr error
-       for _ = range bal.KeepServices {
+       for range bal.KeepServices {
                if err := <-errs; err != nil {
                        bal.logf("%v", err)
                        lastErr = err