Merge branch '15928-fs-deadlock'

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

diff --git a/services/keep-balance/collection.go b/services/keep-balance/collection.go
index 1e5fa5797855048bcb9db80487d7f6a8e4486787..c4ddc90c419ae7e0d9c4d1b5cbadd9011f2a31fd 100644 (file)
--- a/services/keep-balance/collection.go
+++ b/services/keep-balance/collection.go
@@ -8,7 +8,7 @@ import (
        "fmt"
        "time"
 
-       "git.curoverse.com/arvados.git/sdk/go/arvados"
+       "git.arvados.org/arvados.git/sdk/go/arvados"
 )
 
 func countCollections(c *arvados.Client, params arvados.ResourceListParams) (int, error) {
@@ -43,6 +43,18 @@ func EachCollection(c *arvados.Client, pageSize int, f func(arvados.Collection)
                return err
        }
 
+       // Note the obvious way to get all collections (sorting by
+       // UUID) would be much easier, but would lose data: If a
+       // client were to move files from collection with uuid="zzz"
+       // to a collection with uuid="aaa" around the time when we
+       // were fetching the "mmm" page, we would never see those
+       // files' block IDs at all -- even if the client is careful to
+       // save "aaa" before saving "zzz".
+       //
+       // Instead, we get pages in modified_at order. Collections
+       // that are modified during the run will be re-fetched in a
+       // subsequent page.
+
        limit := pageSize
        if limit <= 0 {
                // Use the maximum page size the server allows
@@ -68,7 +80,7 @@ func EachCollection(c *arvados.Client, pageSize int, f func(arvados.Collection)
                        return err
                }
                for _, coll := range page.Items {
-                       if last.ModifiedAt != nil && *last.ModifiedAt == *coll.ModifiedAt && last.UUID >= coll.UUID {
+                       if last.ModifiedAt == coll.ModifiedAt && last.UUID >= coll.UUID {
                                continue
                        }
                        callCount++
@@ -80,9 +92,9 @@ func EachCollection(c *arvados.Client, pageSize int, f func(arvados.Collection)
                }
                if len(page.Items) == 0 && !gettingExactTimestamp {
                        break
-               } else if last.ModifiedAt == nil {
+               } else if last.ModifiedAt.IsZero() {
                        return fmt.Errorf("BUG: Last collection on the page (%s) has no modified_at timestamp; cannot make progress", last.UUID)
-               } else if len(page.Items) > 0 && *last.ModifiedAt == filterTime {
+               } else if len(page.Items) > 0 && last.ModifiedAt == filterTime {
                        // If we requested time>=X and never got a
                        // time>X then we might not have received all
                        // items with time==X yet. Switch to
@@ -123,7 +135,7 @@ func EachCollection(c *arvados.Client, pageSize int, f func(arvados.Collection)
                        // avoiding that would add overhead in the
                        // overwhelmingly common cases, so we don't
                        // bother.
-                       filterTime = *last.ModifiedAt
+                       filterTime = last.ModifiedAt
                        params.Filters = []arvados.Filter{{
                                Attr:     "modified_at",
                                Operator: ">=",