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// SPDX-License-Identifier: GPL-3.0-or-later
package functions
import (
"bufio"
"context"
"encoding/json"
"fmt"
"io"
"log/slog"
"os"
"strconv"
"strings"
"sync"
"time"
"github.com/netdata/netdata/go/go.d.plugin/agent/netdataapi"
"github.com/netdata/netdata/go/go.d.plugin/agent/safewriter"
"github.com/netdata/netdata/go/go.d.plugin/logger"
"github.com/mattn/go-isatty"
"github.com/muesli/cancelreader"
)
var isTerminal = isatty.IsTerminal(os.Stdout.Fd()) || isatty.IsTerminal(os.Stdin.Fd())
func NewManager() *Manager {
return &Manager{
Logger: logger.New().With(
slog.String("component", "functions manager"),
),
Input: os.Stdin,
api: netdataapi.New(safewriter.Stdout),
mux: &sync.Mutex{},
FunctionRegistry: make(map[string]func(Function)),
}
}
type Manager struct {
*logger.Logger
Input io.Reader
api *netdataapi.API
mux *sync.Mutex
FunctionRegistry map[string]func(Function)
}
func (m *Manager) Run(ctx context.Context) {
m.Info("instance is started")
defer func() { m.Info("instance is stopped") }()
if !isTerminal {
r, err := cancelreader.NewReader(m.Input)
if err != nil {
m.Errorf("fail to create cancel reader: %v", err)
return
}
go func() { <-ctx.Done(); r.Cancel() }()
var wg sync.WaitGroup
wg.Add(1)
go func() { defer wg.Done(); m.run(r) }()
wg.Wait()
_ = r.Close()
}
<-ctx.Done()
}
func (m *Manager) run(r io.Reader) {
sc := bufio.NewScanner(r)
for sc.Scan() {
text := sc.Text()
var fn *Function
var err error
// FIXME: if we are waiting for FUNCTION_PAYLOAD_END and a new FUNCTION* appears,
// we need to discard the current one and switch to the new one
switch {
case strings.HasPrefix(text, "FUNCTION "):
fn, err = parseFunction(text)
case strings.HasPrefix(text, "FUNCTION_PAYLOAD "):
fn, err = parseFunctionWithPayload(text, sc)
case text == "":
continue
default:
m.Warningf("unexpected line: '%s'", text)
continue
}
if err != nil {
m.Warningf("parse function: %v ('%s')", err, text)
continue
}
function, ok := m.lookupFunction(fn.Name)
if !ok {
m.Infof("skipping execution of '%s': unregistered function", fn.Name)
m.respf(fn, 501, "unregistered function: %s", fn.Name)
continue
}
if function == nil {
m.Warningf("skipping execution of '%s': nil function registered", fn.Name)
m.respf(fn, 501, "nil function: %s", fn.Name)
continue
}
function(*fn)
}
}
func (m *Manager) lookupFunction(name string) (func(Function), bool) {
m.mux.Lock()
defer m.mux.Unlock()
f, ok := m.FunctionRegistry[name]
return f, ok
}
func (m *Manager) respf(fn *Function, code int, msgf string, a ...any) {
bs, _ := json.Marshal(struct {
Status int `json:"status"`
Message string `json:"message"`
}{
Status: code,
Message: fmt.Sprintf(msgf, a...),
})
ts := strconv.FormatInt(time.Now().Unix(), 10)
m.api.FUNCRESULT(fn.UID, "application/json", string(bs), strconv.Itoa(code), ts)
}
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