// Moves data from one server to another
// Does the following:
// 1. Lock all necessary clients
// 2. Move Data
// 3. Update router table on servers
// 4. Delete partion from origin
// 5. Unlock
func MovePartition(services *Services, routerTable *shards.RouterTable, partition int, from, to *shards.RouterEntry) error {
err := LockPartition(services, routerTable, partition)
if err != nil {
return err
}
//Unlock partition no matter what
defer UnlockPartition(services, routerTable, partition)
//copy the data
_, err = CopyData(services, routerTable, partition, from, to)
if err != nil {
return err
}
//update the router table.
parts := make([]int, 0)
for _, p := range from.Partitions {
if p != partition {
parts = append(parts, p)
}
}
from.Partitions = parts
to.Partitions = append(to.Partitions, partition)
routerTable, err = routerTable.AddEntries(from, to)
routerTable, ok := RouterTableUpdate(services, routerTable, len(routerTable.Entries))
if !ok {
services.Logger.Printf("Uh oh, Didnt update any router tables")
}
//Delete the data on the from server.
err = DeletePartition(services, from, partition)
if err != nil {
return err
}
return nil
}
// Moves a single partition from the largest entry to the smallest. only
// if the smallest entry is smaller then the rest.
// if all entries are the same size, then a random entry is chosen
func RebalanceSingle(services *Services, routerTable *shards.RouterTable) error {
var smallest *shards.RouterEntry = nil
var largest *shards.RouterEntry = nil
min := int(routerTable.TotalPartitions / len(routerTable.Entries))
services.Logger.Printf("Looking for entries with more then %d partitions", min)
//shuffle the entries array
entries := make([]*shards.RouterEntry, len(routerTable.Entries))
perm := rand.Perm(len(routerTable.Entries))
for i, v := range perm {
entries[v] = routerTable.Entries[i]
}
for _, entry := range entries {
if len(entry.Partitions) < min {
if smallest == nil {
smallest = entry
} else if len(entry.Partitions) < len(smallest.Partitions) {
smallest = entry
}
if largest == nil {
largest = entry
} else if len(entry.Partitions) > len(largest.Partitions) {
largest = entry
}
}
}
if smallest == nil || largest == nil {
services.Logger.Printf("Cluster appears to be balanced")
return nil
}
services.Logger.Printf("Moving from %s to %s", largest.Id(), smallest.Id())
return nil
}
// Checkin to an entry. will update their router table if it is out of date. will update our router table if out of date.
func EntryCheckin(routerTable *shards.RouterTable, entry *shards.RouterEntry) (*shards.RouterTable, bool, error) {
// make sure our routertable is up to date.
response, err := client.HttpApiCallSync(
fmt.Sprintf("%s:%d", entry.Address, entry.HttpPort),
cheshire.NewRequest(shards.CHECKIN, "GET"),
5*time.Second)
if err != nil {
return routerTable, false, fmt.Errorf("ERROR While contacting %s -- %s", entry.Address, err)
}
entry.LastSeenAt = time.Now()
rev := response.MustInt64("rt_revision", 0)
if rev == routerTable.Revision {
return routerTable, false, nil
}
if rev < routerTable.Revision {
//updating server.
//set the new routertable.
req := cheshire.NewRequest(shards.ROUTERTABLE_SET, "POST")
req.Params().Put("router_table", req.ToDynMap())
response, err = client.HttpApiCallSync(
fmt.Sprintf("%s:%d", entry.Address, entry.HttpPort),
req,
5*time.Second)
if err != nil {
return routerTable, false, fmt.Errorf("ERROR While contacting for router table update %s -- %s", entry.Address, err)
}
if response.StatusCode() != 200 {
return routerTable, false, fmt.Errorf("Error trying to Set router table %s -- %s", entry.Address, response.StatusMessage())
}
} else {
//updating local
log.Printf("Found updated router table at: %s", entry.Address)
//get the new routertable.
response, err = client.HttpApiCallSync(
fmt.Sprintf("%s:%d", entry.Address, entry.HttpPort),
cheshire.NewRequest(shards.ROUTERTABLE_GET, "GET"),
5*time.Second)
if err != nil {
return routerTable, false, fmt.Errorf("ERROR While contacting %s -- %s", entry.Address, err)
}
mp, ok := response.GetDynMap("router_table")
if !ok {
return routerTable, false, fmt.Errorf("ERROR from %s -- BAD ROUTER TABLE RESPONSE %s", entry.Address, response)
}
rt, err := shards.ToRouterTable(mp)
if err != nil {
return routerTable, false, fmt.Errorf("ERROR While parsing router table %s -- %s", entry.Address, err)
}
log.Printf("SUCCESSFULLY update router table to revision %d", rt.Revision)
routerTable = rt
return routerTable, true, nil
}
return routerTable, false, nil
}