99 lines
2.2 KiB
Go
99 lines
2.2 KiB
Go
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package rtt
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import (
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"context"
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"sync"
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"time"
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errors "github.com/pkg/errors"
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tcp "github.com/status-im/tcp-shaker"
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)
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type Result struct {
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Addr string
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RTTMs int
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Err error
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}
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// timeoutError indicates an error due to TCP connection timeout.
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// tcp-shaker returns an error implementing this interface in such a case.
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type timeoutError interface {
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Timeout() bool
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}
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func runCheck(c *tcp.Checker, address string, timeout time.Duration) Result {
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// mesaure RTT
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start := time.Now()
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// TCP Ping
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err := c.CheckAddr(address, timeout)
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// measure RTT
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elapsed := time.Since(start)
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latency := int(elapsed.Nanoseconds() / 1e6)
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if err != nil { // don't confuse users with valid latency values on error
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latency = -1
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switch err.(type) {
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case timeoutError:
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err = errors.Wrap(err, "tcp check timeout")
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case tcp.ErrConnect:
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err = errors.Wrap(err, "unable to connect")
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}
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}
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return Result{
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Addr: address,
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RTTMs: latency,
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Err: err,
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}
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}
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func waitForResults(errCh <-chan error, resCh <-chan Result) (results []Result, err error) {
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for {
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select {
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case err = <-errCh:
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return nil, err
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case res, ok := <-resCh:
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if !ok {
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return
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}
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results = append(results, res)
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}
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}
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}
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func CheckHosts(addresses []string, timeout time.Duration) ([]Result, error) {
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c := tcp.NewChecker()
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// channel for receiving possible checking loop failure
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errCh := make(chan error, 1)
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// stop the checking loop when function exists
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ctx, stopChecker := context.WithCancel(context.Background())
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defer stopChecker()
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// loop that queries Epoll and pipes events to CheckAddr() calls
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go func() {
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errCh <- c.CheckingLoop(ctx)
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}()
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// wait for CheckingLoop to prepare the epoll/kqueue
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<-c.WaitReady()
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// channel for returning results from concurrent checks
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resCh := make(chan Result, len(addresses))
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var wg sync.WaitGroup
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for i := 0; i < len(addresses); i++ {
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wg.Add(1)
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go func(address string, resCh chan<- Result) {
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defer wg.Done()
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resCh <- runCheck(c, address, timeout)
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}(addresses[i], resCh)
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}
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// wait for all the routines to finish before closing results channel
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wg.Wait()
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close(resCh)
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// wait for the results for all addresses or a checking loop error
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return waitForResults(errCh, resCh)
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}
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