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// Copyright (c) 2017 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.
// +build !windows,!darwin,!novpp
package vppapiclient
/*
#cgo CFLAGS: -DPNG_DEBUG=1
#cgo LDFLAGS: -lvppapiclient
#include "vppapiclient_wrapper.h"
*/
import "C"
import (
"fmt"
"os"
"path/filepath"
"reflect"
"time"
"unsafe"
"github.com/fsnotify/fsnotify"
"git.fd.io/govpp.git/adapter"
)
var (
// MaxWaitReady defines maximum duration before waiting for shared memory
// segment times out
MaxWaitReady = time.Second * 10
)
const (
// shmDir is a directory where shared memory is supposed to be created.
shmDir = "/dev/shm/"
// vppShmFile is a default name of the file in the shmDir.
vppShmFile = "vpe-api"
)
// global VPP binary API client, library vppapiclient only supports
// single connection at a time
var globalVppClient *vppClient
// stubVppClient is the default implementation of the VppAPI.
type vppClient struct {
shmPrefix string
msgCallback adapter.MsgCallback
inputQueueSize uint16
}
// NewVppClient returns a new VPP binary API client.
func NewVppClient(shmPrefix string) adapter.VppAPI {
return NewVppClientWithInputQueueSize(shmPrefix, 32)
}
// NewVppClientWithInputQueueSize returns a new VPP binary API client with a custom input queue size.
func NewVppClientWithInputQueueSize(shmPrefix string, inputQueueSize uint16) adapter.VppAPI {
return &vppClient{
shmPrefix: shmPrefix,
inputQueueSize: inputQueueSize,
}
}
// Connect connects the process to VPP.
func (a *vppClient) Connect() error {
if globalVppClient != nil {
return fmt.Errorf("already connected to binary API, disconnect first")
}
rxQlen := C.int(a.inputQueueSize)
var rc C.int
if a.shmPrefix == "" {
rc = C.govpp_connect(nil, rxQlen)
} else {
shm := C.CString(a.shmPrefix)
rc = C.govpp_connect(shm, rxQlen)
}
if rc != 0 {
return fmt.Errorf("connecting to VPP binary API failed (rc=%v)", rc)
}
globalVppClient = a
return nil
}
// Disconnect disconnects the process from VPP.
func (a *vppClient) Disconnect() error {
globalVppClient = nil
rc := C.govpp_disconnect()
if rc != 0 {
return fmt.Errorf("disconnecting from VPP binary API failed (rc=%v)", rc)
}
return nil
}
// GetMsgID returns a runtime message ID for the given message name and CRC.
func (a *vppClient) GetMsgID(msgName string, msgCrc string) (uint16, error) {
nameAndCrc := C.CString(msgName + "_" + msgCrc)
defer C.free(unsafe.Pointer(nameAndCrc))
msgID := uint16(C.govpp_get_msg_index(nameAndCrc))
if msgID == ^uint16(0) {
// VPP does not know this message
return msgID, fmt.Errorf("unknown message: %v (crc: %v)", msgName, msgCrc)
}
return msgID, nil
}
// SendMsg sends a binary-encoded message to VPP.
func (a *vppClient) SendMsg(context uint32, data []byte) error {
rc := C.govpp_send(C.uint32_t(context), unsafe.Pointer(&data[0]), C.size_t(len(data)))
if rc != 0 {
return fmt.Errorf("unable to send the message (rc=%v)", rc)
}
return nil
}
// SetMsgCallback sets a callback function that will be called by the adapter
// whenever a message comes from VPP.
func (a *vppClient) SetMsgCallback(cb adapter.MsgCallback) {
a.msgCallback = cb
}
// WaitReady blocks until shared memory for sending
// binary api calls is present on the file system.
func (a *vppClient) WaitReady() error {
// join the path to the shared memory segment
var path string
if a.shmPrefix == "" {
path = filepath.Join(shmDir, vppShmFile)
} else {
path = filepath.Join(shmDir, a.shmPrefix+"-"+vppShmFile)
}
// check if file already exists
if _, err := os.Stat(path); err == nil {
return nil // file exists, we are ready
} else if !os.IsNotExist(err) {
return err // some other error occurred
}
// file does not exist, start watching folder
watcher, err := fsnotify.NewWatcher()
if err != nil {
return err
}
defer watcher.Close()
// start watching directory
if err := watcher.Add(shmDir); err != nil {
return err
}
timeout := time.NewTimer(MaxWaitReady)
for {
select {
case <-timeout.C:
return fmt.Errorf("timeout waiting (%s) for shm file: %s", MaxWaitReady, path)
case e := <-watcher.Errors:
return e
case ev := <-watcher.Events:
if ev.Name == path && (ev.Op&fsnotify.Create) == fsnotify.Create {
// file created, we are ready
return nil
}
}
}
}
//export go_msg_callback
func go_msg_callback(msgID C.uint16_t, data unsafe.Pointer, size C.size_t) {
// convert unsafe.Pointer to byte slice
sliceHeader := &reflect.SliceHeader{Data: uintptr(data), Len: int(size), Cap: int(size)}
byteSlice := *(*[]byte)(unsafe.Pointer(sliceHeader))
globalVppClient.msgCallback(uint16(msgID), byteSlice)
}
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