⚡️ Speed up method Tunnel.start_tunnel by 17%

[codeflash-ai]

📄 17% (0.17x) speedup for Tunnel.start_tunnel in gradio/tunneling.py

⏱️ Runtime : 18.6 milliseconds → 15.9 milliseconds (best of 47 runs)

📝 Explanation and details

The optimized code achieves a 17% speedup through several targeted optimizations that reduce function call overhead and improve I/O efficiency:

Key Optimizations:

1. Path existence check improvement: Replaced Path(BINARY_PATH).exists() with os.path.exists(BINARY_PATH). This eliminates the overhead of creating a Path object on every call, showing a 4.5x speedup in the download_binary function (281,928ns → 63,127ns in line profiler).

2. Directory creation optimization: Changed Path(BINARY_FOLDER).mkdir(parents=True, exist_ok=True) to os.makedirs(BINARY_FOLDER, exist_ok=True). This removes Path object creation overhead and uses the more direct os module function.

3. Chunked file writing: Replaced file.write(resp.content) with a chunked approach using resp.iter_bytes(CHUNK_SIZE * 64). This reduces memory pressure by streaming the download instead of loading the entire binary into memory at once, which is particularly beneficial for larger binary files.

4. Checksum loop simplification: Rewrote the checksum calculation from iter(lambda: f.read(...), b"") to a simple while True loop with explicit break. This eliminates lambda function call overhead on each iteration.

Performance Impact:
The optimizations are most effective when:

• The binary doesn't exist and needs to be downloaded (chunked writing helps with large files)
• The function is called repeatedly (reduced Path object creation overhead accumulates)
• System memory is constrained (streaming download vs loading entire file)

Based on the test results, the optimizations show consistent improvements across different scenarios, with edge cases like login failures seeing up to 27.4% speedup due to the reduced overhead in the setup phase before the actual tunnel operation begins.

The main bottleneck remains the _read_url_from_tunnel_stream() call (94.8% of execution time), but these optimizations effectively reduce the setup overhead, making tunnel initialization more efficient.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 147 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	66.7%

🌀 Generated Regression Tests and Runtime

import atexit
import hashlib
import os
import platform
import re
import stat
import subprocess
import sys
import time
from pathlib import Path

import httpx
# imports
import pytest  # used for our unit tests
from gradio.tunneling import Tunnel

CURRENT_TUNNELS: list["Tunnel"] = []

# ----------- UNIT TESTS ------------

# Basic Test Cases

def test_start_tunnel_returns_url_basic():
    """Basic: Tunnel returns correct URL when output contains success string."""
    t = Tunnel(
        remote_host="localhost",
        remote_port=8080,
        local_host="127.0.0.1",
        local_port=7860,
        share_token="token",
        share_server_tls_certificate=None,
    )
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_start_tunnel_tls_certificate():
    """Basic: Tunnel handles TLS certificate argument."""
    t = Tunnel(
        remote_host="localhost",
        remote_port=8080,
        local_host="127.0.0.1",
        local_port=7860,
        share_token="token",
        share_server_tls_certificate="dummy_cert.pem",
    )
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_start_tunnel_multiple_calls():
    """Basic: Multiple tunnels can be started independently."""
    t1 = Tunnel("localhost", 8080, "127.0.0.1", 7860, "token1", None)
    t2 = Tunnel("localhost", 8081, "127.0.0.1", 7861, "token2", None)
    codeflash_output = t1.start_tunnel(); url1 = codeflash_output
    codeflash_output = t2.start_tunnel(); url2 = codeflash_output

# Edge Test Cases


def test_start_tunnel_login_failed_string():
    """Edge: Tunnel raises ValueError if login to server failed."""
    class TunnelLoginFail(Tunnel):
        def _start_tunnel(self, binary: str) -> str:
            class DummyProc:
                def __init__(self):
                    self.stdout = self
                    self.idx = 0
                def readline(self):
                    self.idx += 1
                    if self.idx == 1:
                        return b"login to server failed\n"
                    return b""
                def terminate(self):
                    pass
            self.proc = DummyProc()
            atexit.register(self.kill)
            return self._read_url_from_tunnel_stream()
    t = TunnelLoginFail("localhost", 8080, "127.0.0.1", 7860, "token", None)
    with pytest.raises(ValueError) as excinfo:
        t.start_tunnel()

def test_start_tunnel_malformed_success_line():
    """Edge: Tunnel raises ValueError if success line is malformed."""
    class TunnelMalformedSuccess(Tunnel):
        def _start_tunnel(self, binary: str) -> str:
            class DummyProc:
                def __init__(self):
                    self.stdout = self
                    self.idx = 0
                def readline(self):
                    self.idx += 1
                    if self.idx == 1:
                        return b"start proxy success: \n"
                    return b""
                def terminate(self):
                    pass
            self.proc = DummyProc()
            atexit.register(self.kill)
            return self._read_url_from_tunnel_stream()
    t = TunnelMalformedSuccess("localhost", 8080, "127.0.0.1", 7860, "token", None)
    with pytest.raises(ValueError) as excinfo:
        t.start_tunnel()



def test_download_binary_oserror():
    """Edge: Tunnel raises OSError if download fails due to platform."""
    class TunnelOSError(Tunnel):
        @staticmethod
        def download_binary():
            raise OSError("Cannot set up a share link as this platform is incompatible.")
    t = TunnelOSError("localhost", 8080, "127.0.0.1", 7860, "token", None)
    with pytest.raises(OSError):
        t.start_tunnel() # 1.70μs -> 1.62μs (4.31% faster)

def test_kill_proc_none():
    """Edge: kill() does nothing if proc is None."""
    t = Tunnel("localhost", 8080, "127.0.0.1", 7860, "token", None)
    t.proc = None
    t.kill()

def test_kill_proc_terminates():
    """Edge: kill() terminates process if proc is not None."""
    class DummyProc:
        def __init__(self):
            self.terminated = False
        def terminate(self):
            self.terminated = True
    t = Tunnel("localhost", 8080, "127.0.0.1", 7860, "token", None)
    dummy = DummyProc()
    t.proc = dummy
    t.kill()

# Large Scale Test Cases

def test_start_tunnel_many_tunnels():
    """Large Scale: Start many tunnels and check all return correct URL."""
    tunnels = []
    for i in range(100):
        t = Tunnel(
            remote_host="localhost",
            remote_port=8000 + i,
            local_host="127.0.0.1",
            local_port=7860 + i,
            share_token=f"token{i}",
            share_server_tls_certificate=None,
        )
        tunnels.append(t)
    urls = [t.start_tunnel() for t in tunnels]

def test_start_tunnel_long_token_and_host():
    """Large Scale: Test with long token and host strings."""
    long_token = "t" * 512
    long_host = "host" * 64
    t = Tunnel(
        remote_host=long_host,
        remote_port=8080,
        local_host=long_host,
        local_port=7860,
        share_token=long_token,
        share_server_tls_certificate=None,
    )
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_start_tunnel_port_edge_values():
    """Large Scale: Test with port numbers at edge of valid range."""
    for port in [1, 65535]:
        t = Tunnel(
            remote_host="localhost",
            remote_port=port,
            local_host="127.0.0.1",
            local_port=port,
            share_token="token",
            share_server_tls_certificate=None,
        )
        codeflash_output = t.start_tunnel(); url = codeflash_output

def test_start_tunnel_with_tls_many():
    """Large Scale: Test many tunnels with TLS certificate."""
    for i in range(50):
        t = Tunnel(
            remote_host="localhost",
            remote_port=9000 + i,
            local_host="127.0.0.1",
            local_port=8000 + i,
            share_token=f"token{i}",
            share_server_tls_certificate="dummy_cert.pem",
        )
        codeflash_output = t.start_tunnel(); url = codeflash_output
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
import atexit
import hashlib
import os
import platform
import re
import stat
import subprocess
import sys
import time
from pathlib import Path

import httpx
# imports
import pytest
from gradio.tunneling import Tunnel


# -- Minimal stubs for missing imports and constants --
class ChecksumMismatchError(Exception):
    pass
TUNNEL_ERROR_MESSAGE = (
    "Could not create share URL. "
    "Please check the appended log from frpc for more information:"
)

# -- Pytest unit tests --

# 1. Basic Test Cases
def test_basic_success_url():
    """Test basic tunnel creation returns correct URL."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "basic_success"
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_basic_success_with_tls():
    """Test tunnel creation with TLS certificate."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", "/path/to/cert")
    t.test_case = "basic_success"
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_basic_success_port_and_host_variations():
    """Test tunnel with different ports and hosts."""
    t = Tunnel("remotehost", 9999, "127.0.0.1", 80, "token", None)
    t.test_case = "basic_success"
    codeflash_output = t.start_tunnel(); url = codeflash_output

# 2. Edge Test Cases
def test_malformed_success_line():
    """Test tunnel error on malformed success line (no URL)."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "malformed_success"
    with pytest.raises(ValueError) as excinfo:
        t.start_tunnel() # 6.07ms -> 5.40ms (12.3% faster)

def test_login_failed_line():
    """Test tunnel error on login failed line."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "login_failed"
    with pytest.raises(ValueError) as excinfo:
        t.start_tunnel() # 6.82ms -> 5.35ms (27.4% faster)

def test_timeout_on_empty_lines():
    """Test tunnel error on only empty lines (timeout)."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "empty_lines"
    with pytest.raises(ValueError) as excinfo:
        t.start_tunnel() # 5.73ms -> 5.14ms (11.5% faster)

def test_success_after_delay():
    """Test tunnel returns correct URL after several empty lines."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "delayed_success"
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_checksum_mismatch():
    """Test checksum mismatch raises ChecksumMismatchError."""
    # Patch Tunnel.download_binary to simulate checksum error
    orig_download_binary = Tunnel.download_binary
    def bad_download_binary():
        raise ChecksumMismatchError()
    Tunnel.download_binary = staticmethod(bad_download_binary)
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "basic_success"
    with pytest.raises(ChecksumMismatchError):
        t.start_tunnel() # 1.64μs -> 1.73μs (5.14% slower)
    Tunnel.download_binary = orig_download_binary  # restore

# 3. Large Scale Test Cases
def test_large_token_url():
    """Test tunnel handles very large share token, returns large URL."""
    token = "t"*900
    t = Tunnel("remote", 1234, "localhost", 8080, token, None)
    t.test_case = "large_token"
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_many_empty_then_success():
    """Test tunnel handles many empty lines before success."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "many_empty_then_success"
    codeflash_output = t.start_tunnel(); url = codeflash_output

def test_multiple_tunnels_scalability():
    """Test starting many tunnels in sequence (scalability)."""
    urls = []
    for i in range(10):  # reasonable number for unit test
        t = Tunnel("remote", 1234+i, "localhost", 8000+i, f"token{i}", None)
        t.test_case = "basic_success"
        codeflash_output = t.start_tunnel(); url = codeflash_output
        urls.append(url)

def test_tunnel_kill_clears_proc():
    """Test that kill() sets proc to None."""
    t = Tunnel("remote", 1234, "localhost", 8080, "token", None)
    t.test_case = "basic_success"
    t.start_tunnel()
    t.kill()
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-Tunnel.start_tunnel-mhlbqv7w and push.