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Move windows specific code to its own file
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,101 @@ | ||
| import subprocess | ||
| import sys | ||
| import os | ||
| from test import support | ||
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| # Max size of asynchronous reads | ||
| BUFSIZE = 8192 | ||
| # Exponential damping factor (see below) | ||
| LOAD_FACTOR_1 = 0.9200444146293232478931553241 | ||
| # Seconds per measurement | ||
| SAMPLING_INTERVAL = 5 | ||
| COUNTER_NAME = r'\System\Processor Queue Length' | ||
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| class WindowsLoadTracker(): | ||
| """ | ||
| This class asynchronously interacts with the `typeperf` command to read | ||
| the system load on Windows. Mulitprocessing and threads can't be used | ||
| here because they interfere with the test suite's cases for those | ||
| modules. | ||
| """ | ||
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| def __init__(self): | ||
| self.load = 0.0 | ||
| self.start() | ||
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| def start(self): | ||
| import _winapi | ||
| import msvcrt | ||
| import uuid | ||
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| # Create a named pipe which allows for asynchronous IO in Windows | ||
| pipe_name = r'\\.\pipe\typeperf_output_' + str(uuid.uuid4()) | ||
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| open_mode = _winapi.PIPE_ACCESS_INBOUND | ||
| open_mode |= _winapi.FILE_FLAG_FIRST_PIPE_INSTANCE | ||
| open_mode |= _winapi.FILE_FLAG_OVERLAPPED | ||
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| # This is the read end of the pipe, where we will be grabbing output | ||
| self.pipe = _winapi.CreateNamedPipe( | ||
| pipe_name, open_mode, _winapi.PIPE_WAIT, | ||
| 1, BUFSIZE, BUFSIZE, _winapi.NMPWAIT_WAIT_FOREVER, _winapi.NULL | ||
| ) | ||
| # The write end of the pipe which is passed to the created process | ||
| pipe_write_end = _winapi.CreateFile( | ||
| pipe_name, _winapi.GENERIC_WRITE, 0, _winapi.NULL, | ||
| _winapi.OPEN_EXISTING, 0, _winapi.NULL | ||
| ) | ||
| # Open up the handle as a python file object so we can pass it to | ||
| # subprocess | ||
| command_stdout = msvcrt.open_osfhandle(pipe_write_end, 0) | ||
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| # Connect to the read end of the pipe in overlap/async mode | ||
| overlap = _winapi.ConnectNamedPipe(self.pipe, overlapped=True) | ||
| overlap.GetOverlappedResult(True) | ||
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| # Spawn off the load monitor | ||
| command = ['typeperf', COUNTER_NAME, '-si', str(SAMPLING_INTERVAL)] | ||
| self.p = subprocess.Popen(command, stdout=command_stdout, cwd=support.SAVEDCWD) | ||
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| # Close our copy of the write end of the pipe | ||
| os.close(command_stdout) | ||
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| def __del__(self): | ||
| self.p.kill() | ||
| self.p.wait() | ||
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| def read_output(self): | ||
| import _winapi | ||
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| overlapped, _ = _winapi.ReadFile(self.pipe, BUFSIZE, True) | ||
| bytes_read, res = overlapped.GetOverlappedResult(False) | ||
| if res != 0: | ||
| return | ||
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| return overlapped.getbuffer().decode() | ||
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| def getloadavg(self): | ||
| typeperf_output = self.read_output() | ||
| # Nothing to update, just return the current load | ||
| if not typeperf_output: | ||
| return self.load | ||
|
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| # Process the backlog of load values | ||
| for line in typeperf_output.splitlines(): | ||
| # typeperf outputs in a CSV format like this: | ||
| # "07/19/2018 01:32:26.605","3.000000" | ||
| toks = line.split(',') | ||
| # Ignore blank lines and the initial header | ||
| if line.strip() == '' or (COUNTER_NAME in line) or len(toks) != 2: | ||
| continue | ||
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| load = float(toks[1].replace('"', '')) | ||
| # We use an exponentially weighted moving average, imitating the | ||
| # load calculation on Unix systems. | ||
| # https://en.wikipedia.org/wiki/Load_(computing)#Unix-style_load_calculation | ||
| new_load = self.load * LOAD_FACTOR_1 + load * (1.0 - LOAD_FACTOR_1) | ||
| self.load = new_load | ||
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| return self.load |