1 files changed, 249 insertions, 0 deletions
diff --git a/vendor/src/github.com/coreos/go-systemd/dbus/subscription.go b/vendor/src/github.com/coreos/go-systemd/dbus/subscription.go
new file mode 100644
index 0000000000..3d896d896f
--- /dev/null
+++ b/vendor/src/github.com/coreos/go-systemd/dbus/subscription.go
@@ -0,0 +1,249 @@
+/*
+Copyright 2013 CoreOS Inc.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package dbus
+
+import (
+	"errors"
+	"time"
+
+	"github.com/godbus/dbus"
+)
+
+const (
+	cleanIgnoreInterval = int64(10 * time.Second)
+	ignoreInterval      = int64(30 * time.Millisecond)
+)
+
+// Subscribe sets up this connection to subscribe to all systemd dbus events.
+// This is required before calling SubscribeUnits. When the connection closes
+// systemd will automatically stop sending signals so there is no need to
+// explicitly call Unsubscribe().
+func (c *Conn) Subscribe() error {
+	c.sysconn.BusObject().Call("org.freedesktop.DBus.AddMatch", 0,
+		"type='signal',interface='org.freedesktop.systemd1.Manager',member='UnitNew'")
+	c.sysconn.BusObject().Call("org.freedesktop.DBus.AddMatch", 0,
+		"type='signal',interface='org.freedesktop.DBus.Properties',member='PropertiesChanged'")
+
+	err := c.sysobj.Call("org.freedesktop.systemd1.Manager.Subscribe", 0).Store()
+	if err != nil {
+		c.sysconn.Close()
+		return err
+	}
+
+	return nil
+}
+
+// Unsubscribe this connection from systemd dbus events.
+func (c *Conn) Unsubscribe() error {
+	err := c.sysobj.Call("org.freedesktop.systemd1.Manager.Unsubscribe", 0).Store()
+	if err != nil {
+		c.sysconn.Close()
+		return err
+	}
+
+	return nil
+}
+
+func (c *Conn) initSubscription() {
+	c.subscriber.ignore = make(map[dbus.ObjectPath]int64)
+}
+
+func (c *Conn) initDispatch() {
+	ch := make(chan *dbus.Signal, signalBuffer)
+
+	c.sysconn.Signal(ch)
+
+	go func() {
+		for {
+			signal := <-ch
+			switch signal.Name {
+			case "org.freedesktop.systemd1.Manager.JobRemoved":
+				c.jobComplete(signal)
+
+				unitName := signal.Body[2].(string)
+				var unitPath dbus.ObjectPath
+				c.sysobj.Call("org.freedesktop.systemd1.Manager.GetUnit", 0, unitName).Store(&unitPath)
+				if unitPath != dbus.ObjectPath("") {
+					c.sendSubStateUpdate(unitPath)
+				}
+			case "org.freedesktop.systemd1.Manager.UnitNew":
+				c.sendSubStateUpdate(signal.Body[1].(dbus.ObjectPath))
+			case "org.freedesktop.DBus.Properties.PropertiesChanged":
+				if signal.Body[0].(string) == "org.freedesktop.systemd1.Unit" {
+					// we only care about SubState updates, which are a Unit property
+					c.sendSubStateUpdate(signal.Path)
+				}
+			}
+		}
+	}()
+}
+
+// Returns two unbuffered channels which will receive all changed units every
+// interval.  Deleted units are sent as nil.
+func (c *Conn) SubscribeUnits(interval time.Duration) (<-chan map[string]*UnitStatus, <-chan error) {
+	return c.SubscribeUnitsCustom(interval, 0, func(u1, u2 *UnitStatus) bool { return *u1 != *u2 }, nil)
+}
+
+// SubscribeUnitsCustom is like SubscribeUnits but lets you specify the buffer
+// size of the channels, the comparison function for detecting changes and a filter
+// function for cutting down on the noise that your channel receives.
+func (c *Conn) SubscribeUnitsCustom(interval time.Duration, buffer int, isChanged func(*UnitStatus, *UnitStatus) bool, filterUnit func (string) bool) (<-chan map[string]*UnitStatus, <-chan error) {
+	old := make(map[string]*UnitStatus)
+	statusChan := make(chan map[string]*UnitStatus, buffer)
+	errChan := make(chan error, buffer)
+
+	go func() {
+		for {
+			timerChan := time.After(interval)
+
+			units, err := c.ListUnits()
+			if err == nil {
+				cur := make(map[string]*UnitStatus)
+				for i := range units {
+					if filterUnit != nil && filterUnit(units[i].Name) {
+						continue
+					}
+					cur[units[i].Name] = &units[i]
+				}
+
+				// add all new or changed units
+				changed := make(map[string]*UnitStatus)
+				for n, u := range cur {
+					if oldU, ok := old[n]; !ok || isChanged(oldU, u) {
+						changed[n] = u
+					}
+					delete(old, n)
+				}
+
+				// add all deleted units
+				for oldN := range old {
+					changed[oldN] = nil
+				}
+
+				old = cur
+
+				if len(changed) != 0 {
+					statusChan <- changed
+				}
+			} else {
+				errChan <- err
+			}
+
+			<-timerChan
+		}
+	}()
+
+	return statusChan, errChan
+}
+
+type SubStateUpdate struct {
+	UnitName string
+	SubState string
+}
+
+// SetSubStateSubscriber writes to updateCh when any unit's substate changes.
+// Although this writes to updateCh on every state change, the reported state
+// may be more recent than the change that generated it (due to an unavoidable
+// race in the systemd dbus interface).  That is, this method provides a good
+// way to keep a current view of all units' states, but is not guaranteed to
+// show every state transition they go through.  Furthermore, state changes
+// will only be written to the channel with non-blocking writes.  If updateCh
+// is full, it attempts to write an error to errCh; if errCh is full, the error
+// passes silently.
+func (c *Conn) SetSubStateSubscriber(updateCh chan<- *SubStateUpdate, errCh chan<- error) {
+	c.subscriber.Lock()
+	defer c.subscriber.Unlock()
+	c.subscriber.updateCh = updateCh
+	c.subscriber.errCh = errCh
+}
+
+func (c *Conn) sendSubStateUpdate(path dbus.ObjectPath) {
+	c.subscriber.Lock()
+	defer c.subscriber.Unlock()
+	if c.subscriber.updateCh == nil {
+		return
+	}
+
+	if c.shouldIgnore(path) {
+		return
+	}
+
+	info, err := c.GetUnitProperties(string(path))
+	if err != nil {
+		select {
+		case c.subscriber.errCh <- err:
+		default:
+		}
+	}
+
+	name := info["Id"].(string)
+	substate := info["SubState"].(string)
+
+	update := &SubStateUpdate{name, substate}
+	select {
+	case c.subscriber.updateCh <- update:
+	default:
+		select {
+		case c.subscriber.errCh <- errors.New("update channel full!"):
+		default:
+		}
+	}
+
+	c.updateIgnore(path, info)
+}
+
+// The ignore functions work around a wart in the systemd dbus interface.
+// Requesting the properties of an unloaded unit will cause systemd to send a
+// pair of UnitNew/UnitRemoved signals.  Because we need to get a unit's
+// properties on UnitNew (as that's the only indication of a new unit coming up
+// for the first time), we would enter an infinite loop if we did not attempt
+// to detect and ignore these spurious signals.  The signal themselves are
+// indistinguishable from relevant ones, so we (somewhat hackishly) ignore an
+// unloaded unit's signals for a short time after requesting its properties.
+// This means that we will miss e.g. a transient unit being restarted
+// *immediately* upon failure and also a transient unit being started
+// immediately after requesting its status (with systemctl status, for example,
+// because this causes a UnitNew signal to be sent which then causes us to fetch
+// the properties).
+
+func (c *Conn) shouldIgnore(path dbus.ObjectPath) bool {
+	t, ok := c.subscriber.ignore[path]
+	return ok && t >= time.Now().UnixNano()
+}
+
+func (c *Conn) updateIgnore(path dbus.ObjectPath, info map[string]interface{}) {
+	c.cleanIgnore()
+
+	// unit is unloaded - it will trigger bad systemd dbus behavior
+	if info["LoadState"].(string) == "not-found" {
+		c.subscriber.ignore[path] = time.Now().UnixNano() + ignoreInterval
+	}
+}
+
+// without this, ignore would grow unboundedly over time
+func (c *Conn) cleanIgnore() {
+	now := time.Now().UnixNano()
+	if c.subscriber.cleanIgnore < now {
+		c.subscriber.cleanIgnore = now + cleanIgnoreInterval
+
+		for p, t := range c.subscriber.ignore {
+			if t < now {
+				delete(c.subscriber.ignore, p)
+			}
+		}
+	}
+}