gotosocial/vendor/github.com/godbus/dbus/v5/default_handler.go
Daniele Sluijters acc333c40b
[feature] Inherit resource limits from cgroups (#1336)
When GTS is running in a container runtime which has configured CPU or
memory limits or under an init system that uses cgroups to impose CPU
and memory limits the values the Go runtime sees for GOMAXPROCS and
GOMEMLIMIT are still based on the host resources, not the cgroup.

At least for the throttling middlewares which use GOMAXPROCS to
configure their queue size, this can result in GTS running with values
too big compared to the resources that will actuall be available to it.

This introduces 2 dependencies which can pick up resource contraints
from the current cgroup and tune the Go runtime accordingly. This should
result in the different queues being appropriately sized and in general
more predictable performance. These dependencies are a no-op on
non-Linux systems or if running in a cgroup that doesn't set a limit on
CPU or memory.

The automatic tuning of GOMEMLIMIT can be disabled by either explicitly
setting GOMEMLIMIT yourself or by setting AUTOMEMLIMIT=off. The
automatic tuning of GOMAXPROCS can similarly be counteracted by setting
GOMAXPROCS yourself.
2023-01-17 20:59:04 +00:00

342 lines
7.5 KiB
Go

package dbus
import (
"bytes"
"reflect"
"strings"
"sync"
)
func newIntrospectIntf(h *defaultHandler) *exportedIntf {
methods := make(map[string]Method)
methods["Introspect"] = exportedMethod{
reflect.ValueOf(func(msg Message) (string, *Error) {
path := msg.Headers[FieldPath].value.(ObjectPath)
return h.introspectPath(path), nil
}),
}
return newExportedIntf(methods, true)
}
//NewDefaultHandler returns an instance of the default
//call handler. This is useful if you want to implement only
//one of the two handlers but not both.
//
// Deprecated: this is the default value, don't use it, it will be unexported.
func NewDefaultHandler() *defaultHandler {
h := &defaultHandler{
objects: make(map[ObjectPath]*exportedObj),
defaultIntf: make(map[string]*exportedIntf),
}
h.defaultIntf["org.freedesktop.DBus.Introspectable"] = newIntrospectIntf(h)
return h
}
type defaultHandler struct {
sync.RWMutex
objects map[ObjectPath]*exportedObj
defaultIntf map[string]*exportedIntf
}
func (h *defaultHandler) PathExists(path ObjectPath) bool {
_, ok := h.objects[path]
return ok
}
func (h *defaultHandler) introspectPath(path ObjectPath) string {
subpath := make(map[string]struct{})
var xml bytes.Buffer
xml.WriteString("<node>")
for obj := range h.objects {
p := string(path)
if p != "/" {
p += "/"
}
if strings.HasPrefix(string(obj), p) {
node_name := strings.Split(string(obj[len(p):]), "/")[0]
subpath[node_name] = struct{}{}
}
}
for s := range subpath {
xml.WriteString("\n\t<node name=\"" + s + "\"/>")
}
xml.WriteString("\n</node>")
return xml.String()
}
func (h *defaultHandler) LookupObject(path ObjectPath) (ServerObject, bool) {
h.RLock()
defer h.RUnlock()
object, ok := h.objects[path]
if ok {
return object, ok
}
// If an object wasn't found for this exact path,
// look for a matching subtree registration
subtreeObject := newExportedObject()
path = path[:strings.LastIndex(string(path), "/")]
for len(path) > 0 {
object, ok = h.objects[path]
if ok {
for name, iface := range object.interfaces {
// Only include this handler if it registered for the subtree
if iface.isFallbackInterface() {
subtreeObject.interfaces[name] = iface
}
}
break
}
path = path[:strings.LastIndex(string(path), "/")]
}
for name, intf := range h.defaultIntf {
if _, exists := subtreeObject.interfaces[name]; exists {
continue
}
subtreeObject.interfaces[name] = intf
}
return subtreeObject, true
}
func (h *defaultHandler) AddObject(path ObjectPath, object *exportedObj) {
h.Lock()
h.objects[path] = object
h.Unlock()
}
func (h *defaultHandler) DeleteObject(path ObjectPath) {
h.Lock()
delete(h.objects, path)
h.Unlock()
}
type exportedMethod struct {
reflect.Value
}
func (m exportedMethod) Call(args ...interface{}) ([]interface{}, error) {
t := m.Type()
params := make([]reflect.Value, len(args))
for i := 0; i < len(args); i++ {
params[i] = reflect.ValueOf(args[i]).Elem()
}
ret := m.Value.Call(params)
var err error
nilErr := false // The reflection will find almost-nils, let's only pass back clean ones!
if t.NumOut() > 0 {
if e, ok := ret[t.NumOut()-1].Interface().(*Error); ok { // godbus *Error
nilErr = ret[t.NumOut()-1].IsNil()
ret = ret[:t.NumOut()-1]
err = e
} else if ret[t.NumOut()-1].Type().Implements(errType) { // Go error
i := ret[t.NumOut()-1].Interface()
if i == nil {
nilErr = ret[t.NumOut()-1].IsNil()
} else {
err = i.(error)
}
ret = ret[:t.NumOut()-1]
}
}
out := make([]interface{}, len(ret))
for i, val := range ret {
out[i] = val.Interface()
}
if nilErr || err == nil {
//concrete type to interface nil is a special case
return out, nil
}
return out, err
}
func (m exportedMethod) NumArguments() int {
return m.Value.Type().NumIn()
}
func (m exportedMethod) ArgumentValue(i int) interface{} {
return reflect.Zero(m.Type().In(i)).Interface()
}
func (m exportedMethod) NumReturns() int {
return m.Value.Type().NumOut()
}
func (m exportedMethod) ReturnValue(i int) interface{} {
return reflect.Zero(m.Type().Out(i)).Interface()
}
func newExportedObject() *exportedObj {
return &exportedObj{
interfaces: make(map[string]*exportedIntf),
}
}
type exportedObj struct {
mu sync.RWMutex
interfaces map[string]*exportedIntf
}
func (obj *exportedObj) LookupInterface(name string) (Interface, bool) {
if name == "" {
return obj, true
}
obj.mu.RLock()
defer obj.mu.RUnlock()
intf, exists := obj.interfaces[name]
return intf, exists
}
func (obj *exportedObj) AddInterface(name string, iface *exportedIntf) {
obj.mu.Lock()
defer obj.mu.Unlock()
obj.interfaces[name] = iface
}
func (obj *exportedObj) DeleteInterface(name string) {
obj.mu.Lock()
defer obj.mu.Unlock()
delete(obj.interfaces, name)
}
func (obj *exportedObj) LookupMethod(name string) (Method, bool) {
obj.mu.RLock()
defer obj.mu.RUnlock()
for _, intf := range obj.interfaces {
method, exists := intf.LookupMethod(name)
if exists {
return method, exists
}
}
return nil, false
}
func (obj *exportedObj) isFallbackInterface() bool {
return false
}
func newExportedIntf(methods map[string]Method, includeSubtree bool) *exportedIntf {
return &exportedIntf{
methods: methods,
includeSubtree: includeSubtree,
}
}
type exportedIntf struct {
methods map[string]Method
// Whether or not this export is for the entire subtree
includeSubtree bool
}
func (obj *exportedIntf) LookupMethod(name string) (Method, bool) {
out, exists := obj.methods[name]
return out, exists
}
func (obj *exportedIntf) isFallbackInterface() bool {
return obj.includeSubtree
}
//NewDefaultSignalHandler returns an instance of the default
//signal handler. This is useful if you want to implement only
//one of the two handlers but not both.
//
// Deprecated: this is the default value, don't use it, it will be unexported.
func NewDefaultSignalHandler() *defaultSignalHandler {
return &defaultSignalHandler{}
}
type defaultSignalHandler struct {
mu sync.RWMutex
closed bool
signals []*signalChannelData
}
func (sh *defaultSignalHandler) DeliverSignal(intf, name string, signal *Signal) {
sh.mu.RLock()
defer sh.mu.RUnlock()
if sh.closed {
return
}
for _, scd := range sh.signals {
scd.deliver(signal)
}
}
func (sh *defaultSignalHandler) Terminate() {
sh.mu.Lock()
defer sh.mu.Unlock()
if sh.closed {
return
}
for _, scd := range sh.signals {
scd.close()
close(scd.ch)
}
sh.closed = true
sh.signals = nil
}
func (sh *defaultSignalHandler) AddSignal(ch chan<- *Signal) {
sh.mu.Lock()
defer sh.mu.Unlock()
if sh.closed {
return
}
sh.signals = append(sh.signals, &signalChannelData{
ch: ch,
done: make(chan struct{}),
})
}
func (sh *defaultSignalHandler) RemoveSignal(ch chan<- *Signal) {
sh.mu.Lock()
defer sh.mu.Unlock()
if sh.closed {
return
}
for i := len(sh.signals) - 1; i >= 0; i-- {
if ch == sh.signals[i].ch {
sh.signals[i].close()
copy(sh.signals[i:], sh.signals[i+1:])
sh.signals[len(sh.signals)-1] = nil
sh.signals = sh.signals[:len(sh.signals)-1]
}
}
}
type signalChannelData struct {
wg sync.WaitGroup
ch chan<- *Signal
done chan struct{}
}
func (scd *signalChannelData) deliver(signal *Signal) {
select {
case scd.ch <- signal:
case <-scd.done:
return
default:
scd.wg.Add(1)
go scd.deferredDeliver(signal)
}
}
func (scd *signalChannelData) deferredDeliver(signal *Signal) {
select {
case scd.ch <- signal:
case <-scd.done:
}
scd.wg.Done()
}
func (scd *signalChannelData) close() {
close(scd.done)
scd.wg.Wait() // wait until all spawned goroutines return
}