gotosocial/vendor/github.com/godbus/dbus/v5/variant.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

150 lines
3.6 KiB
Go

package dbus
import (
"bytes"
"fmt"
"reflect"
"sort"
"strconv"
)
// Variant represents the D-Bus variant type.
type Variant struct {
sig Signature
value interface{}
}
// MakeVariant converts the given value to a Variant. It panics if v cannot be
// represented as a D-Bus type.
func MakeVariant(v interface{}) Variant {
return MakeVariantWithSignature(v, SignatureOf(v))
}
// MakeVariantWithSignature converts the given value to a Variant.
func MakeVariantWithSignature(v interface{}, s Signature) Variant {
return Variant{s, v}
}
// ParseVariant parses the given string as a variant as described at
// https://developer.gnome.org/glib/stable/gvariant-text.html. If sig is not
// empty, it is taken to be the expected signature for the variant.
func ParseVariant(s string, sig Signature) (Variant, error) {
tokens := varLex(s)
p := &varParser{tokens: tokens}
n, err := varMakeNode(p)
if err != nil {
return Variant{}, err
}
if sig.str == "" {
sig, err = varInfer(n)
if err != nil {
return Variant{}, err
}
}
v, err := n.Value(sig)
if err != nil {
return Variant{}, err
}
return MakeVariant(v), nil
}
// format returns a formatted version of v and whether this string can be parsed
// unambigously.
func (v Variant) format() (string, bool) {
switch v.sig.str[0] {
case 'b', 'i':
return fmt.Sprint(v.value), true
case 'n', 'q', 'u', 'x', 't', 'd', 'h':
return fmt.Sprint(v.value), false
case 's':
return strconv.Quote(v.value.(string)), true
case 'o':
return strconv.Quote(string(v.value.(ObjectPath))), false
case 'g':
return strconv.Quote(v.value.(Signature).str), false
case 'v':
s, unamb := v.value.(Variant).format()
if !unamb {
return "<@" + v.value.(Variant).sig.str + " " + s + ">", true
}
return "<" + s + ">", true
case 'y':
return fmt.Sprintf("%#x", v.value.(byte)), false
}
rv := reflect.ValueOf(v.value)
switch rv.Kind() {
case reflect.Slice:
if rv.Len() == 0 {
return "[]", false
}
unamb := true
buf := bytes.NewBuffer([]byte("["))
for i := 0; i < rv.Len(); i++ {
// TODO: slooow
s, b := MakeVariant(rv.Index(i).Interface()).format()
unamb = unamb && b
buf.WriteString(s)
if i != rv.Len()-1 {
buf.WriteString(", ")
}
}
buf.WriteByte(']')
return buf.String(), unamb
case reflect.Map:
if rv.Len() == 0 {
return "{}", false
}
unamb := true
var buf bytes.Buffer
kvs := make([]string, rv.Len())
for i, k := range rv.MapKeys() {
s, b := MakeVariant(k.Interface()).format()
unamb = unamb && b
buf.Reset()
buf.WriteString(s)
buf.WriteString(": ")
s, b = MakeVariant(rv.MapIndex(k).Interface()).format()
unamb = unamb && b
buf.WriteString(s)
kvs[i] = buf.String()
}
buf.Reset()
buf.WriteByte('{')
sort.Strings(kvs)
for i, kv := range kvs {
if i > 0 {
buf.WriteString(", ")
}
buf.WriteString(kv)
}
buf.WriteByte('}')
return buf.String(), unamb
}
return `"INVALID"`, true
}
// Signature returns the D-Bus signature of the underlying value of v.
func (v Variant) Signature() Signature {
return v.sig
}
// String returns the string representation of the underlying value of v as
// described at https://developer.gnome.org/glib/stable/gvariant-text.html.
func (v Variant) String() string {
s, unamb := v.format()
if !unamb {
return "@" + v.sig.str + " " + s
}
return s
}
// Value returns the underlying value of v.
func (v Variant) Value() interface{} {
return v.value
}
// Store converts the variant into a native go type using the same
// mechanism as the "Store" function.
func (v Variant) Store(value interface{}) error {
return storeInterfaces(v.value, value)
}