Added comments about zero-replica blocks in underReplicated.

[arvados.git] / services / datamanager / summary / pull_list.go

diff --git a/services/datamanager/summary/pull_list.go b/services/datamanager/summary/pull_list.go
index 950d1d056b762e937a36d5d4c66c51f5f40a362c..d2eef9316ba8ab91794bb0f84822a9cac1ac7b7b 100644 (file)
--- a/services/datamanager/summary/pull_list.go
+++ b/services/datamanager/summary/pull_list.go
@@ -59,6 +59,10 @@ type PullServers struct {
 
 // Creates a map from block locator to PullServers with one entry for
 // each under-replicated block.
+//
+// This method ignores zero-replica blocks since there are no servers
+// to pull them from, so callers should feel free to omit them, but
+// this function will ignore them if they are provided.
 func ComputePullServers(kc *keepclient.KeepClient,
        keepServerInfo *keep.ReadServers,
        blockToDesiredReplication map[blockdigest.DigestWithSize]int,
@@ -81,10 +85,9 @@ func ComputePullServers(kc *keepclient.KeepClient,
                if numCopiesMissing > 0 {
                        // We expect this to always be true, since the block was listed
                        // in underReplicated.
-                       // TODO(misha): Consider asserting the above conditional.
 
                        if numCopies > 0 {
-                               // I believe that we should expect this to always be true.
+                               // Not much we can do with blocks with no copies.
 
                                // A server's host-port string appears as a key in this map
                                // iff it contains the block.