// Queues an RPC targeted at a particular region for handling by the appropriate
// region client. Results will be written to the rpc's result and error
// channels.
func (c *Client) queueRPC(rpc hrpc.Call) error {
table := rpc.Table()
key := rpc.Key()
reg := c.getRegion(table, key)
// The first time an RPC is sent to the meta region, the meta client will
// have not yet been intialized. Check if this is the case, try to mark
// the meta region info as unavailable, and if it hadn't been marked as
// unavailable yet start a goroutine to connect to it.
if reg == c.metaRegionInfo && c.metaClient == nil {
marked := c.metaRegionInfo.MarkUnavailable()
if marked {
go c.reestablishRegion(c.metaRegionInfo)
}
}
var client *region.Client
if reg != nil {
ch := reg.GetAvailabilityChan()
if ch != nil {
select {
case <-ch:
return c.queueRPC(rpc)
case <-rpc.GetContext().Done():
return ErrDeadline
}
}
client = c.clientFor(reg)
} else {
var err error
client, reg, err = c.locateRegion(rpc.GetContext(), table, key)
if err != nil {
return err
}
}
rpc.SetRegion(reg)
return client.QueueRPC(rpc)
}
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)
}