Implement functionality to terminate ndt7 tests early given a client parameter

[cristinaleonr]

This PR implements functionality to terminate ndt7 download tests early when the client passes in an early_exit parameter in the request.

The changes were tested by running the server locally and making a request from ndt7-client-go.

$ go run main.go -service-url ws://localhost/ndt/v7/download?early_exit=250
download in progress with localhost
Avg. speed  : 16630.5 Mbit/s
download: complete
         Server: localhost
         Client: 172.17.0.1
        Latency:     0.0 ms
       Download: 16630.5
         Upload:     0.0
 Retransmission:    0.12 %

$ go run main.go -service-url ws://localhost/ndt/v7/download?early_exit=200
download failed: websocket: bad handshake

download: complete
         Server: localhost
         Client:
        Latency:     0.0
       Download:     0.0
         Upload:     0.0
 Retransmission:    0.00
exit status 1

This change is 

[stephen-soltesz]

Reviewed 2 of 7 files at r1.
Reviewable status: 0 of 1 approvals obtained (waiting on @cristinaleonr)

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ndt7/download/sender/sender.go line 21 at r1 (raw file):

// EarlyExitParams defines the parameters for the sender to end the
// test early.
type EarlyExitParams struct {

Please name this only spec.Params.

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ndt7/download/sender/sender.go line 101 at r1 (raw file):

			}
			// End the test once enough bytes have been acked.
			if params.IsEarlyExit && m.TCPInfo.BytesAcked >= params.MaxBytes {

I recommend additionally checking that TCPInfo is not nil.

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ndt7/handler/handler.go line 261 at r1 (raw file):

		}

		value := values[0]

What happens if early_exit= is given?

[cristinaleonr]

Reviewable status: 0 of 1 approvals obtained (waiting on @stephen-soltesz)

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ndt7/download/sender/sender.go line 21 at r1 (raw file):

Previously, stephen-soltesz (Stephen Soltesz) wrote…

Please name this only spec.Params.

Done.

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ndt7/download/sender/sender.go line 101 at r1 (raw file):

Previously, stephen-soltesz (Stephen Soltesz) wrote…

I recommend additionally checking that TCPInfo is not nil.

Done.

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ndt7/handler/handler.go line 261 at r1 (raw file):

Previously, stephen-soltesz (Stephen Soltesz) wrote…

What happens if early_exit= is given?

It takes the parameter value as "", the condition below becomes true, and it returns an error. I added a test case for this.

This is also the output from the client:

$ go run main.go -service-url ws://localhost/ndt/v7/download?early_exit=
download failed: websocket: bad handshake

download: complete
         Server: localhost
         Client:
        Latency:     0.0
       Download:     0.0
         Upload:     0.0
 Retransmission:    0.00
exit status 1

[stephen-soltesz]

I'm sorry - I put a typo in my comment about sender.Params.

With that change

Reviewed 2 of 5 files at r2.
Reviewable status: complete! 1 of 1 approvals obtained (waiting on @cristinaleonr)

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ndt7/download/sender/sender.go line 21 at r1 (raw file):

Previously, cristinaleonr (Cristina Leon) wrote…

Done.

I'm so sorry - I wrote spec but meant to leave it in the sender package. I just wanted the shorter type name. /shamecube me

Would you please return the type definition to this package with the short name?

[cristinaleonr]

Reviewable status: complete! 1 of 1 approvals obtained (waiting on @stephen-soltesz)

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ndt7/download/sender/sender.go line 21 at r1 (raw file):

Previously, stephen-soltesz (Stephen Soltesz) wrote…

I'm so sorry - I wrote spec but meant to leave it in the sender package. I just wanted the shorter type name. /shamecube me

Would you please return the type definition to this package with the short name?

Yes, done.