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1#!/usr/bin/env python3
2#
3# Copyright © 2020 Google LLC
4#
5# Permission is hereby granted, free of charge, to any person obtaining a
6# copy of this software and associated documentation files (the "Software"),
7# to deal in the Software without restriction, including without limitation
8# the rights to use, copy, modify, merge, publish, distribute, sublicense,
9# and/or sell copies of the Software, and to permit persons to whom the
10# Software is furnished to do so, subject to the following conditions:
11#
12# The above copyright notice and this permission notice (including the next
13# paragraph) shall be included in all copies or substantial portions of the
14# Software.
15#
16# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
19# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22# IN THE SOFTWARE.
23
24import argparse
25from datetime import datetime, timezone
26import queue
27import serial
28import threading
29import time
30
31
32class SerialBuffer:
33    def __init__(self, dev, filename, prefix):
34        self.filename = filename
35        self.dev = dev
36
37        if dev:
38            self.f = open(filename, "wb+")
39            self.serial = serial.Serial(dev, 115200, timeout=10)
40        else:
41            self.f = open(filename, "rb")
42
43        self.byte_queue = queue.Queue()
44        self.line_queue = queue.Queue()
45        self.prefix = prefix
46        self.sentinel = object()
47
48        if self.dev:
49            self.read_thread = threading.Thread(
50                target=self.serial_read_thread_loop, daemon=True)
51        else:
52            self.read_thread = threading.Thread(
53                target=self.serial_file_read_thread_loop, daemon=True)
54        self.read_thread.start()
55
56        self.lines_thread = threading.Thread(
57            target=self.serial_lines_thread_loop, daemon=True)
58        self.lines_thread.start()
59
60    # Thread that just reads the bytes from the serial device to try to keep from
61    # buffer overflowing it.
62    def serial_read_thread_loop(self):
63        greet = "Serial thread reading from %s\n" % self.dev
64        self.byte_queue.put(greet.encode())
65
66        while True:
67            try:
68                self.byte_queue.put(self.serial.read())
69            except Exception as err:
70                print(self.prefix + str(err))
71                self.byte_queue.put(self.sentinel)
72                break
73
74    # Thread that just reads the bytes from the file of serial output that some
75    # other process is appending to.
76    def serial_file_read_thread_loop(self):
77        greet = "Serial thread reading from %s\n" % self.filename
78        self.byte_queue.put(greet.encode())
79
80        while True:
81            line = self.f.readline()
82            if line:
83                self.byte_queue.put(line)
84            else:
85                time.sleep(0.1)
86
87    # Thread that processes the stream of bytes to 1) log to stdout, 2) log to
88    # file, 3) add to the queue of lines to be read by program logic
89
90    def serial_lines_thread_loop(self):
91        line = bytearray()
92        while True:
93            bytes = self.byte_queue.get(block=True)
94
95            if bytes == self.sentinel:
96                self.read_thread.join()
97                self.line_queue.put(self.sentinel)
98                break
99
100            # Write our data to the output file if we're the ones reading from
101            # the serial device
102            if self.dev:
103                self.f.write(bytes)
104                self.f.flush()
105
106            for b in bytes:
107                line.append(b)
108                if b == b'\n'[0]:
109                    line = line.decode(errors="replace")
110
111                    time = datetime.now().strftime('%y-%m-%d %H:%M:%S')
112                    print("{endc}{time} {prefix}{line}".format(
113                        time=time, prefix=self.prefix, line=line, endc='\033[0m'), flush=True, end='')
114
115                    self.line_queue.put(line)
116                    line = bytearray()
117
118    def get_line(self):
119        line = self.line_queue.get()
120        if line == self.sentinel:
121            self.lines_thread.join()
122        return line
123
124    def lines(self):
125        return iter(self.get_line, self.sentinel)
126
127
128def main():
129    parser = argparse.ArgumentParser()
130
131    parser.add_argument('--dev', type=str, help='Serial device')
132    parser.add_argument('--file', type=str,
133                        help='Filename for serial output', required=True)
134    parser.add_argument('--prefix', type=str,
135                        help='Prefix for logging serial to stdout', nargs='?')
136
137    args = parser.parse_args()
138
139    ser = SerialBuffer(args.dev, args.file, args.prefix or "")
140    for line in ser.lines():
141        # We're just using this as a logger, so eat the produced lines and drop
142        # them
143        pass
144
145
146if __name__ == '__main__':
147    main()
148