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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, timeout = None):
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=timeout if timeout else 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.timeout = timeout
47        self.sentinel = object()
48
49        if self.dev:
50            self.read_thread = threading.Thread(
51                target=self.serial_read_thread_loop, daemon=True)
52        else:
53            self.read_thread = threading.Thread(
54                target=self.serial_file_read_thread_loop, daemon=True)
55        self.read_thread.start()
56
57        self.lines_thread = threading.Thread(
58            target=self.serial_lines_thread_loop, daemon=True)
59        self.lines_thread.start()
60
61    # Thread that just reads the bytes from the serial device to try to keep from
62    # buffer overflowing it. If nothing is received in 1 minute, it finalizes.
63    def serial_read_thread_loop(self):
64        greet = "Serial thread reading from %s\n" % self.dev
65        self.byte_queue.put(greet.encode())
66
67        while True:
68            try:
69                b = self.serial.read()
70                if len(b) > 0:
71                    self.byte_queue.put(b)
72                elif self.timeout:
73                    self.byte_queue.put(self.sentinel)
74                    break
75            except Exception as err:
76                print(self.prefix + str(err))
77                self.byte_queue.put(self.sentinel)
78                break
79
80    # Thread that just reads the bytes from the file of serial output that some
81    # other process is appending to.
82    def serial_file_read_thread_loop(self):
83        greet = "Serial thread reading from %s\n" % self.filename
84        self.byte_queue.put(greet.encode())
85
86        while True:
87            line = self.f.readline()
88            if line:
89                self.byte_queue.put(line)
90            else:
91                time.sleep(0.1)
92
93    # Thread that processes the stream of bytes to 1) log to stdout, 2) log to
94    # file, 3) add to the queue of lines to be read by program logic
95
96    def serial_lines_thread_loop(self):
97        line = bytearray()
98        while True:
99            bytes = self.byte_queue.get(block=True)
100
101            if bytes == self.sentinel:
102                self.read_thread.join()
103                self.line_queue.put(self.sentinel)
104                break
105
106            # Write our data to the output file if we're the ones reading from
107            # the serial device
108            if self.dev:
109                self.f.write(bytes)
110                self.f.flush()
111
112            for b in bytes:
113                line.append(b)
114                if b == b'\n'[0]:
115                    line = line.decode(errors="replace")
116
117                    time = datetime.now().strftime('%y-%m-%d %H:%M:%S')
118                    print("{endc}{time} {prefix}{line}".format(
119                        time=time, prefix=self.prefix, line=line, endc='\033[0m'), flush=True, end='')
120
121                    self.line_queue.put(line)
122                    line = bytearray()
123
124    def get_line(self):
125        line = self.line_queue.get()
126        if line == self.sentinel:
127            self.lines_thread.join()
128        return line
129
130    def lines(self):
131        return iter(self.get_line, self.sentinel)
132
133
134def main():
135    parser = argparse.ArgumentParser()
136
137    parser.add_argument('--dev', type=str, help='Serial device')
138    parser.add_argument('--file', type=str,
139                        help='Filename for serial output', required=True)
140    parser.add_argument('--prefix', type=str,
141                        help='Prefix for logging serial to stdout', nargs='?')
142
143    args = parser.parse_args()
144
145    ser = SerialBuffer(args.dev, args.file, args.prefix or "")
146    for line in ser.lines():
147        # We're just using this as a logger, so eat the produced lines and drop
148        # them
149        pass
150
151
152if __name__ == '__main__':
153    main()
154