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namespace_api.go
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namespace_api.go
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// Copyright (c) 2018 Cisco and/or its affiliates.
//
// 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 linuxcalls
import (
"os"
"runtime"
"github.com/ligato/cn-infra/logging"
"github.com/vishvananda/netns"
)
var enableNsCtxCheck = os.Getenv("NSPLUGIN_CHECK_NS_CTX") != ""
// NamedNetNsAPI defines methods related to management of named network namespaces.
type NamedNetNsAPI interface {
// CreateNamedNetNs creates a new named Linux network namespace.
// It does exactly the same thing as the command "ip netns add NAMESPACE".
CreateNamedNetNs(ctx NamespaceMgmtCtx, nsName string) (netns.NsHandle, error)
// DeleteNamedNetNs deletes an existing named Linux network namespace.
// It does exactly the same thing as the command "ip netns del NAMESPACE".
DeleteNamedNetNs(nsName string) error
// NamedNetNsExists checks whether named namespace exists.
NamedNetNsExists(nsName string) (bool, error)
}
// NamespaceMgmtCtx represents context of an ongoing management of Linux namespaces.
// The same context should not be used concurrently.
type NamespaceMgmtCtx interface {
// LockOSThread wires the calling goroutine to its current operating system thread.
// The method should implement re-entrant lock always called from a single go routine.
LockOSThread()
// UnlockOSThread unwires the calling goroutine from its fixed operating system thread.
// The method should implement re-entrant lock always called from a single go routine.
UnlockOSThread()
}
// namespaceMgmtCtx implements NamespaceMgmtCtx.
type namespaceMgmtCtx struct {
lockOsThreadCnt int
}
// LockOSThread wires the calling goroutine to its current operating system thread.
func (ctx *namespaceMgmtCtx) LockOSThread() {
if ctx.lockOsThreadCnt == 0 {
runtime.LockOSThread()
}
ctx.lockOsThreadCnt++
}
// UnlockOSThread unwires the calling goroutine from its fixed operating system thread.
func (ctx *namespaceMgmtCtx) UnlockOSThread() {
ctx.lockOsThreadCnt--
if ctx.lockOsThreadCnt == 0 {
runtime.UnlockOSThread()
}
}
// NewNamespaceMgmtCtx creates and returns a new context for management of Linux
// namespaces.
func NewNamespaceMgmtCtx() NamespaceMgmtCtx {
nsCtx := &namespaceMgmtCtx{}
if enableNsCtxCheck {
bt := make([]byte, 1<<16)
runtime.Stack(bt, false)
runtime.SetFinalizer(nsCtx, func(ctx *namespaceMgmtCtx) {
if ctx.lockOsThreadCnt != 0 {
panic("locked ns ctx to be GCed - created at: " + string(bt))
}
})
}
return nsCtx
}
// namedNetNsHandler implements NamedNetNsAPI using provided system handler.
type namedNetNsHandler struct {
log logging.Logger
sysHandler SystemAPI
}
// NewNamedNetNsHandler creates new instance of namespace handler
func NewNamedNetNsHandler(sysHandler SystemAPI, log logging.Logger) NamedNetNsAPI {
return &namedNetNsHandler{
log: log,
sysHandler: sysHandler,
}
}