// reestablishRegion will continually attempt to reestablish a connection to a
// given region
func (c *Client) reestablishRegion(reg *regioninfo.Info) {
// The meta client is not kept in the region client cache.
if reg != c.metaRegionInfo {
// This region is inaccessible, and a new client will be created, so the
// client will be removed from the region client cache.
c.clients.del(reg)
}
for {
log.WithFields(log.Fields{
"Table": reg.Table,
"RegionName": reg.RegionName,
"StartKey": reg.StartKey,
"StopKey": reg.StopKey,
}).Warn("Attempting to re-establish region.")
// A new context is created here because this is not specific to any
// request that the user of gohbase initiated, and is instead an
// internal goroutine that may be servicing any number of requests
// initiated by the user.
ctx, _ := context.WithTimeout(context.Background(), regionLookupTimeout)
var err error
if reg == c.metaRegionInfo { // If we're looking for the meta region..
err = c.locateMeta(ctx) // .. look it up in ZooKeeper.
} else { // Otherwise do a normal meta lookup.
_, _, err = c.locateRegion(ctx, reg.Table, reg.StartKey)
}
if err == nil {
reg.MarkAvailable()
return
}
// TODO: Make this configurable, or verify that it's a sane number
time.Sleep(time.Millisecond * 100)
}
}
func (c *Client) waitOnRegion(rpc hrpc.Call, reg *regioninfo.Info) (proto.Message, error) {
ch := reg.GetAvailabilityChan()
if ch == nil {
// WTF, this region is available? Maybe it was marked as such
// since waitOnRegion was called.
return c.sendRPC(rpc)
}
// The region is unavailable. Wait for it to become available,
// or for the deadline to be exceeded.
select {
case <-ch:
return c.sendRPC(rpc)
case <-rpc.GetContext().Done():
return nil, ErrDeadline
}
}
func (c *Client) establishRegion(originalReg *regioninfo.Info, host string, port uint16) {
var err error
reg := originalReg
backoff := backoffStart
for {
ctx, _ := context.WithTimeout(context.Background(), regionLookupTimeout)
if port != 0 && err == nil {
// If this isn't the admin or meta region, check if a client
// for this host/port already exists
if c.clientType != AdminClient && reg != c.metaRegionInfo {
client := c.clients.checkForClient(host, port)
if client != nil {
// There's already a client, add it to the
// cache and mark the new region as available.
c.clients.put(reg, client)
originalReg.MarkAvailable()
return
}
}
// Make this channel buffered so that if we time out we don't
// block the newRegion goroutine forever.
ch := make(chan newRegResult, 1)
var clientType region.ClientType
if c.clientType == StandardClient {
clientType = region.RegionClient
} else {
clientType = region.MasterClient
}
go newRegion(ctx, ch, clientType, host, port, c.rpcQueueSize, c.flushInterval)
select {
case res := <-ch:
if res.Err == nil {
if c.clientType == AdminClient {
c.adminClient = res.Client
} else if reg == c.metaRegionInfo {
c.metaClient = res.Client
} else {
c.clients.put(reg, res.Client)
if reg != originalReg {
// Here `reg' is guaranteed to be available, so we
// must publish the region->client mapping first,
// because as soon as we add it to the key->region
// mapping here, concurrent readers are gonna want
// to find the client.
c.regions.put(reg.RegionName, reg)
}
}
originalReg.MarkAvailable()
return
} else {
err = res.Err
}
case <-ctx.Done():
err = ErrDeadline
}
}
if err != nil {
if err == TableNotFound {
c.regions.del(originalReg.RegionName)
originalReg.MarkAvailable()
return
}
// This will be hit if either there was an error locating the
// region, or the region was located but there was an error
// connecting to it.
backoff, err = sleepAndIncreaseBackoff(ctx, backoff)
if err != nil {
continue
}
}
if c.clientType == AdminClient {
host, port, err = c.zkLookup(ctx, zk.Master)
} else if reg == c.metaRegionInfo {
host, port, err = c.zkLookup(ctx, zk.Meta)
} else {
reg, host, port, err = c.locateRegion(ctx, originalReg.Table, originalReg.StartKey)
}
}
}
func (c *Client) sendRPCToRegion(rpc hrpc.Call, reg *regioninfo.Info) (proto.Message, error) {
// On the first sendRPC to the meta or admin regions, a goroutine must be
// manually kicked off for the meta or admin region client
if c.adminClient == nil && reg == c.adminRegionInfo && !c.adminRegionInfo.IsUnavailable() ||
c.metaClient == nil && reg == c.metaRegionInfo && !c.metaRegionInfo.IsUnavailable() {
c.regionsLock.Lock()
if reg == c.metaRegionInfo && !c.metaRegionInfo.IsUnavailable() ||
reg == c.adminRegionInfo && !c.adminRegionInfo.IsUnavailable() {
reg.MarkUnavailable()
go c.reestablishRegion(reg)
}
c.regionsLock.Unlock()
}
// The region was in the cache, check
// if the region is marked as available
if !reg.IsUnavailable() {
// The region is available
rpc.SetRegion(reg)
// Queue the RPC to be sent to the region
client := c.clientFor(reg)
var err error
if client == nil {
err = errors.New("no client for this region")
} else {
err = client.QueueRPC(rpc)
}
if err != nil {
// There was an error queueing the RPC.
// Mark the region as unavailable.
first := reg.MarkUnavailable()
// If this was the first goroutine to mark the region as
// unavailable, start a goroutine to reestablish a connection
if first {
go c.reestablishRegion(reg)
}
// Block until the region becomes available.
return c.waitOnRegion(rpc, reg)
}
// Wait for the response
var res hrpc.RPCResult
select {
case res = <-rpc.GetResultChan():
case <-rpc.GetContext().Done():
return nil, ErrDeadline
}
// Check for errors
if _, ok := res.Error.(region.RetryableError); ok {
// There's an error specific to this region, but
// our region client is fine. Mark this region as
// unavailable (as opposed to all regions sharing
// the client), and start a goroutine to reestablish
// it.
first := reg.MarkUnavailable()
if first {
go c.reestablishRegion(reg)
}
if reg != c.metaRegionInfo && reg != c.adminRegionInfo {
// The client won't be in the cache if this is the
// meta or admin region
c.clients.del(reg)
}
return c.waitOnRegion(rpc, reg)
} else if _, ok := res.Error.(region.UnrecoverableError); ok {
// If it was an unrecoverable error, the region client is
// considered dead.
if reg == c.metaRegionInfo || reg == c.adminRegionInfo {
// If this is the admin client or the meta table, mark the
// region as unavailable and start up a goroutine to
// reconnect if it wasn't already marked as such.
first := reg.MarkUnavailable()
if first {
go c.reestablishRegion(reg)
}
} else {
// Else this is a normal region. Mark all the regions
// sharing this region's client as unavailable, and start
// a goroutine to reconnect for each of them.
downregions := c.clients.clientDown(reg)
for _, downreg := range downregions {
go c.reestablishRegion(downreg)
}
}
// Fall through to the case of the region being unavailable,
// which will result in blocking until it's available again.
return c.waitOnRegion(rpc, reg)
} else {
// RPC was successfully sent, or an unknown type of error
// occurred. In either case, return the results.
return res.Msg, res.Error
}
}
return c.waitOnRegion(rpc, reg)
}