Write data into socket without rewriting obj

[webknjaz]

• What kind of change does this PR introduce?

  • bug fix
  • feature
  • docs update
  • tests/coverage improvement
  • refactoring
  • other

• What is the related issue number (starting with #)

Fix #133

• What is the current behavior? (You can also link to an open issue here)

slow down because of data var rewriting

• What is the new behavior (if this is a feature change)?

N/A

• Other information:

• Checklist:

  • I think the code is well written
  • I wrote good commit messages
  • I have squashed related commits together after the changes have been approved
  • Unit tests for the changes exist
  • Integration tests for the changes exist (if applicable)
  • I used the same coding conventions as the rest of the project
  • The new code doesn't generate linter offenses
  • Documentation reflects the changes
  • The PR relates to only one subject with a clear title
    and description in grammatically correct, complete sentences

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This change is 

[nav-agarwal]

This fix still won't help in improving performance as strings are immutable and they are "passed by value" and hence it will still lead to copy of string. Check below sample code to see performance impact of copying whole buffer.

import time

data = "a" * 1024 * 1024 * 200
packet_sz = 16 * 1024
bytes_sent = 0


def dummy_send(data):
    time.sleep(0.0001)  # for write to socket
    return


while data:
    dummy_send(data[bytes_sent:])
    bytes_sent += packet_sz

[webknjaz]

@nav-agarwal GitHub is behaving inconsistently today. Could you please verify that you saw my memoryview commit?

[webknjaz]

@nav-agarwal memoryview/buffer should fix this now.

[nav-agarwal]

I am not getting enought time to test it. But using memoryview might land us into trouble because of pyopenssl limitation. Read more here urllib3/urllib3#717

[webknjaz]

@nav-agarwal that's a curious find.. we could do .to_bytes() there as well, if needed.

[webknjaz]

Oh, and we could probably use smaller chunks as urllib3 does...

[nav-agarwal]

yes... something like data[total_sent:total_sent + SSL_WRITE_BLOCKSIZE]

[webknjaz]

@nav-agarwal #137 should do