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Misc comment improvements

This commit is contained in:
Sean Chittenden 2016-06-20 15:29:38 -07:00
parent 9bf6e61655
commit 72f7a4061c
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GPG Key ID: 4EBC9DC16C2E5E16
2 changed files with 22 additions and 23 deletions
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43
consul/servers/manager.go
View File

@ -50,14 +50,14 @@ const (
newRebalanceConnsPerSecPerServer = 64 newRebalanceConnsPerSecPerServer = 64
) )
// ConsulClusterInfo is an interface wrapper around serf and prevents a // ConsulClusterInfo is an interface wrapper around serf in order to prevent
// cyclic import dependency // a cyclic import dependency.
type ConsulClusterInfo interface { type ConsulClusterInfo interface {
NumNodes() int NumNodes() int
} }
// Pinger is an interface wrapping client.ConnPool to prevent a // Pinger is an interface wrapping client.ConnPool to prevent a cyclic import
// cyclic import dependency // dependency.
type Pinger interface { type Pinger interface {
PingConsulServer(s *agent.Server) (bool, error) PingConsulServer(s *agent.Server) (bool, error)
} }
@ -269,8 +269,8 @@ func (m *Manager) NumServers() int {
// fail for a particular server are rotated to the end of the list. This // fail for a particular server are rotated to the end of the list. This
// method reshuffles the list periodically in order to redistribute work // method reshuffles the list periodically in order to redistribute work
// across all known consul servers (i.e. guarantee that the order of servers // across all known consul servers (i.e. guarantee that the order of servers
// in the server list isn't positively correlated with the age of a server in // in the server list is not positively correlated with the age of a server
// the consul cluster). Periodically shuffling the server list prevents // in the Consul cluster). Periodically shuffling the server list prevents
// long-lived clients from fixating on long-lived servers. // long-lived clients from fixating on long-lived servers.
// //
// Unhealthy servers are removed when serf notices the server has been // Unhealthy servers are removed when serf notices the server has been
@ -280,16 +280,16 @@ func (m *Manager) RebalanceServers() {
// Obtain a copy of the current serverList // Obtain a copy of the current serverList
l := m.getServerList() l := m.getServerList()
// Early abort if there is no value to shuffling // Early abort if there is nothing to shuffle
if len(l.servers) < 2 { if len(l.servers) < 2 {
return return
} }
l.shuffleServers() l.shuffleServers()
// Iterate through the shuffled server list to find a healthy server. // Iterate through the shuffled server list to find an assumed
// Don't iterate on the list directly, this loop mutates the server // healthy server. NOTE: Do not iterate on the list directly because
// list. // this loop mutates the server list in-place.
var foundHealthyServer bool var foundHealthyServer bool
for i := 0; i < len(l.servers); i++ { for i := 0; i < len(l.servers); i++ {
// Always test the first server. Failed servers are cycled // Always test the first server. Failed servers are cycled
@ -320,8 +320,7 @@ func (m *Manager) RebalanceServers() {
// reconcileServerList failed because Serf removed the server // reconcileServerList failed because Serf removed the server
// that was at the front of the list that had successfully // that was at the front of the list that had successfully
// been Ping'ed. Between the Ping and reconcile, a Serf // been Ping'ed. Between the Ping and reconcile, a Serf
// event had shown up removing the node. Prevent an RPC // event had shown up removing the node.
// timeout by retrying RebalanceServers().
// //
// Instead of doing any heroics, "freeze in place" and // Instead of doing any heroics, "freeze in place" and
// continue to use the existing connection until the next // continue to use the existing connection until the next
@ -332,9 +331,9 @@ func (m *Manager) RebalanceServers() {
} }
// reconcileServerList returns true when the first server in serverList // reconcileServerList returns true when the first server in serverList
// exists in the receiver's serverList. If true, the merged serverList // exists in the receiver's serverList. If true, the merged serverList is
// is stored as the receiver's serverList. Returns false if the first // stored as the receiver's serverList. Returns false if the first server
// server does not exist in the list (i.e. was removed by Serf during a // does not exist in the list (i.e. was removed by Serf during a
// PingConsulServer() call. Newly added servers are appended to the list and // PingConsulServer() call. Newly added servers are appended to the list and
// other missing servers are removed from the list. // other missing servers are removed from the list.
func (m *Manager) reconcileServerList(l *serverList) bool { func (m *Manager) reconcileServerList(l *serverList) bool {
@ -346,7 +345,7 @@ func (m *Manager) reconcileServerList(l *serverList) bool {
newServerCfg := m.getServerList() newServerCfg := m.getServerList()
// If Serf has removed all nodes, or there is no selected server // If Serf has removed all nodes, or there is no selected server
// (zero nodes in l), abort early. // (zero nodes in serverList), abort early.
if len(newServerCfg.servers) == 0 || len(l.servers) == 0 { if len(newServerCfg.servers) == 0 || len(l.servers) == 0 {
return false return false
} }
@ -423,12 +422,12 @@ func (m *Manager) RemoveServer(s *agent.Server) {
// refreshServerRebalanceTimer is only called once m.rebalanceTimer expires. // refreshServerRebalanceTimer is only called once m.rebalanceTimer expires.
func (m *Manager) refreshServerRebalanceTimer() time.Duration { func (m *Manager) refreshServerRebalanceTimer() time.Duration {
l := m.getServerList() l := m.getServerList()
numConsulServers := len(l.servers) numServers := len(l.servers)
// Limit this connection's life based on the size (and health) of the // Limit this connection's life based on the size (and health) of the
// cluster. Never rebalance a connection more frequently than // cluster. Never rebalance a connection more frequently than
// connReuseLowWatermarkDuration, and make sure we never exceed // connReuseLowWatermarkDuration, and make sure we never exceed
// clusterWideRebalanceConnsPerSec operations/s across numLANMembers. // clusterWideRebalanceConnsPerSec operations/s across numLANMembers.
clusterWideRebalanceConnsPerSec := float64(numConsulServers * newRebalanceConnsPerSecPerServer) clusterWideRebalanceConnsPerSec := float64(numServers * newRebalanceConnsPerSecPerServer)
connReuseLowWatermarkDuration := clientRPCMinReuseDuration + lib.RandomStagger(clientRPCMinReuseDuration/clientRPCJitterFraction) connReuseLowWatermarkDuration := clientRPCMinReuseDuration + lib.RandomStagger(clientRPCMinReuseDuration/clientRPCJitterFraction)
numLANMembers := m.clusterInfo.NumNodes() numLANMembers := m.clusterInfo.NumNodes()
connRebalanceTimeout := lib.RateScaledInterval(clusterWideRebalanceConnsPerSec, connReuseLowWatermarkDuration, numLANMembers) connRebalanceTimeout := lib.RateScaledInterval(clusterWideRebalanceConnsPerSec, connReuseLowWatermarkDuration, numLANMembers)
@ -437,8 +436,8 @@ func (m *Manager) refreshServerRebalanceTimer() time.Duration {
return connRebalanceTimeout return connRebalanceTimeout
} }
// ResetRebalanceTimer resets the rebalance timer. This method primarily // ResetRebalanceTimer resets the rebalance timer. This method exists for
// exists for testing and should not be used directly. // testing and should not be used directly.
func (m *Manager) ResetRebalanceTimer() { func (m *Manager) ResetRebalanceTimer() {
m.listLock.Lock() m.listLock.Lock()
defer m.listLock.Unlock() defer m.listLock.Unlock()
@ -446,11 +445,11 @@ func (m *Manager) ResetRebalanceTimer() {
} }
// Start is used to start and manage the task of automatically shuffling and // Start is used to start and manage the task of automatically shuffling and
// rebalancing the list of consul servers. This maintenance only happens // rebalancing the list of Consul servers. This maintenance only happens
// periodically based on the expiration of the timer. Failed servers are // periodically based on the expiration of the timer. Failed servers are
// automatically cycled to the end of the list. New servers are appended to // automatically cycled to the end of the list. New servers are appended to
// the list. The order of the server list must be shuffled periodically to // the list. The order of the server list must be shuffled periodically to
// distribute load across all known and available consul servers. // distribute load across all known and available Consul servers.
func (m *Manager) Start() { func (m *Manager) Start() {
for { for {
select { select {

2
testutil/README.md
View File

@ -26,7 +26,7 @@ import (
) )
func TestMain(t *testing.T) { func TestMain(t *testing.T) {
// Create a server // Create a test Consul server
srv1 := testutil.NewTestServer(t) srv1 := testutil.NewTestServer(t)
defer srv1.Stop() defer srv1.Stop()