#!/usr/bin/env python3
"""Collect system resource information on processes running in Evergreen on a given interval."""

from datetime import datetime
import optparse
import os
import sys
import time

from bson.json_util import dumps
import requests

# Get relative imports to work when the package is not installed on the PYTHONPATH.
if __name__ == "__main__" and __package__ is None:
    sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from buildscripts.resmokelib import utils  # pylint: disable=wrong-import-position


def main():
    """Collect system resources."""
    usage = "usage: %prog [options]"
    parser = optparse.OptionParser(description=__doc__, usage=usage)
    parser.add_option(
        "-i", "--interval", dest="interval", default=5, type="int",
        help="Collect system resource information every <interval> seconds. "
        "Default is every 5 seconds.")
    parser.add_option(
        "-o", "--output-file", dest="outfile", default="-",
        help="If '-', then the file is written to stdout."
        " Any other value is treated as the output file name. By default,"
        " output is written to stdout.")

    (options, _) = parser.parse_args()

    with utils.open_or_use_stdout(options.outfile) as fp:
        while True:
            try:
                # Requires the Evergreen agent to be running on port 2285.
                response = requests.get("http://localhost:2285/status")
                if response.status_code != requests.codes.ok:
                    print(
                        "Received a {} HTTP response: {}".format(response.status_code,
                                                                 response.text), file=sys.stderr)
                    time.sleep(options.interval)
                    continue

                timestamp = datetime.now()
                try:
                    res_json = response.json()
                except ValueError:
                    print("Invalid JSON object returned with response: {}".format(response.text),
                          file=sys.stderr)
                    time.sleep(options.interval)
                    continue

                sys_res_dict = {}
                sys_res_dict["timestamp"] = timestamp
                sys_info = res_json["sys_info"]
                sys_res_dict["num_cpus"] = sys_info["num_cpus"]
                sys_res_dict["mem_total"] = sys_info["vmstat"]["total"]
                sys_res_dict["mem_avail"] = sys_info["vmstat"]["available"]
                ps_info = res_json["ps_info"]
                for process in ps_info:
                    try:
                        sys_res_dict["pid"] = process["pid"]
                        sys_res_dict["ppid"] = process["parentPid"]
                        sys_res_dict["num_threads"] = process["numThreads"]
                        sys_res_dict["command"] = process.get("command", "")
                        sys_res_dict["cpu_user"] = process["cpu"]["user"]
                        sys_res_dict["cpu_sys"] = process["cpu"]["system"]
                        sys_res_dict["io_wait"] = process["cpu"]["iowait"]
                        sys_res_dict["io_write"] = process["io"]["writeBytes"]
                        sys_res_dict["io_read"] = process["io"]["readBytes"]
                        sys_res_dict["mem_used"] = process["mem"]["rss"]
                    except KeyError:
                        # KeyError may occur as a result of file missing from /proc, likely due to
                        # process exiting.
                        continue

                    print(dumps(sys_res_dict, sort_keys=True), file=fp)

                    if fp.fileno() != sys.stdout.fileno():
                        # Flush internal buffers associated with file to disk.
                        fp.flush()
                        os.fsync(fp.fileno())
                time.sleep(options.interval)
            except requests.ConnectionError as error:
                print(error, file=sys.stderr)


if __name__ == "__main__":
    main()