openrvdas.logger.readers.reader

Abstract base class for data Readers.

 1#!/usr/bin/env python3
 2"""
 3Abstract base class for data Readers.
 4"""
 5
 6
 7from logger.utils.base_module import BaseModule   # noqa: E402
 8
 9
10################################################################################
11class Reader(BaseModule):
12    """
13    Base class Reader about which we know nothing else.
14
15    Passes arguments quiet, encoding and encoding_errors up to BaseModule
16    """
17    ############################
18    def __init__(self, **kwargs):
19        super().__init__(**kwargs)
20
21    ############################
22    def read(self):
23        """
24        read() should return None when there are no more records.
25        """
26        raise NotImplementedError('Class %s (subclass of Reader) is missing '
27                                  'implementation of read() method.'
28                                  % self.__class__.__name__)
29
30################################################################################
31
32
33class StorageReader(Reader):
34    """
35    A StorageReader is something like a file, where we can, in theory,
36    seek and rewind, or retrieve a range of records.
37    """
38
39    ############################
40    def __init__(self, **kwargs):
41        super().__init__(**kwargs)
42
43    ############################
44    # Behavior is intended to mimic file seek() behavior but with
45    # respect to records: 'offset' means number of records, and origin
46    # is either 'start', 'current' or 'end'.
47    def seek(self, offset=0, origin='current'):
48        raise NotImplementedError('Class %s (subclass of StorageReader) is missing '
49                                  'implementation of seek() method.'
50                                  % self.__class__.__name__)
51
52    ############################
53    def read_range(self, start=None, stop=None):
54        """
55        Read a range of records beginning with record number start, and ending
56        *before* record number stop.
57        """
58        raise NotImplementedError('Class %s (subclass of StorageReader) is missing '
59                                  'implementation of read_range() method.'
60                                  % self.__class__.__name__)
61
62
63################################################################################
64class TimestampedReader(StorageReader):
65    """
66    A TimestampedReader is a special case of a StorageReader where we
67    can seek and retrieve a range specified by timestamps.
68    """
69
70    ############################
71    def __init__(self, **kwargs):
72        super().__init__(**kwargs)
73
74    ############################
75    # Behavior is intended to mimic file seek() behavior but with
76    # respect to timestamps: 'offset' means number of milliseconds, and
77    # origin is either 'start', 'current' or 'end'.
78    def seek_time(self, offset=0, origin='current'):
79        raise NotImplementedError('Class %s (subclass of TimestampedReader) is missing '
80                                  'implementation of seek_time() method.'
81                                  % self.__class__.__name__)
82
83    ############################
84    # Read a range of records beginning with timestamp start
85    # milliseconds, and ending *before* timestamp stop milliseconds.
86    def read_time_range(self, start=None, stop=None):
87        raise NotImplementedError('Class %s (subclass of TimestampedReader) is missing '
88                                  'implementation of read_range() method.'
89                                  % self.__class__.__name__)
class Reader(logger.utils.base_module.BaseModule): 
12class Reader(BaseModule):
13    """
14    Base class Reader about which we know nothing else.
15
16    Passes arguments quiet, encoding and encoding_errors up to BaseModule
17    """
18    ############################
19    def __init__(self, **kwargs):
20        super().__init__(**kwargs)
21
22    ############################
23    def read(self):
24        """
25        read() should return None when there are no more records.
26        """
27        raise NotImplementedError('Class %s (subclass of Reader) is missing '
28                                  'implementation of read() method.'
29                                  % self.__class__.__name__)

Base class Reader about which we know nothing else.

Passes arguments quiet, encoding and encoding_errors up to BaseModule

Reader(**kwargs) 
19    def __init__(self, **kwargs):
20        super().__init__(**kwargs)

quiet - if type checking should log type errors or operate silently.

Two additional arguments govern how records will be encoded/decoded
from bytes, if desired by the Writer subclass when it calls
_encode_str() or _decode_bytes:

encoding - 'utf-8' by default. If empty or None, do not attempt any
        decoding and return raw bytes. Other possible encodings are
        listed in online documentation here:
        https://docs.python.org/3/library/codecs.html#standard-encodings

encoding_errors - 'ignore' by default. Other error strategies are
        'strict', 'replace', and 'backslashreplace', described here:
        https://docs.python.org/3/howto/unicode.html#encodings

mirror_to - Optional Writer to which all records read or transformed
        by this module (if it is a Reader or Transform) will be
        "mirrored" (copied). Mirroring happens asynchronously via
        a queue and background thread to minimize impact on the
        primary data flow. Writers cannot be mirrored.
def read(self): 
23    def read(self):
24        """
25        read() should return None when there are no more records.
26        """
27        raise NotImplementedError('Class %s (subclass of Reader) is missing '
28                                  'implementation of read() method.'
29                                  % self.__class__.__name__)

read() should return None when there are no more records.

class StorageReader(Reader): 
34class StorageReader(Reader):
35    """
36    A StorageReader is something like a file, where we can, in theory,
37    seek and rewind, or retrieve a range of records.
38    """
39
40    ############################
41    def __init__(self, **kwargs):
42        super().__init__(**kwargs)
43
44    ############################
45    # Behavior is intended to mimic file seek() behavior but with
46    # respect to records: 'offset' means number of records, and origin
47    # is either 'start', 'current' or 'end'.
48    def seek(self, offset=0, origin='current'):
49        raise NotImplementedError('Class %s (subclass of StorageReader) is missing '
50                                  'implementation of seek() method.'
51                                  % self.__class__.__name__)
52
53    ############################
54    def read_range(self, start=None, stop=None):
55        """
56        Read a range of records beginning with record number start, and ending
57        *before* record number stop.
58        """
59        raise NotImplementedError('Class %s (subclass of StorageReader) is missing '
60                                  'implementation of read_range() method.'
61                                  % self.__class__.__name__)

A StorageReader is something like a file, where we can, in theory, seek and rewind, or retrieve a range of records.

StorageReader(**kwargs) 
41    def __init__(self, **kwargs):
42        super().__init__(**kwargs)

quiet - if type checking should log type errors or operate silently.

Two additional arguments govern how records will be encoded/decoded
from bytes, if desired by the Writer subclass when it calls
_encode_str() or _decode_bytes:

encoding - 'utf-8' by default. If empty or None, do not attempt any
        decoding and return raw bytes. Other possible encodings are
        listed in online documentation here:
        https://docs.python.org/3/library/codecs.html#standard-encodings

encoding_errors - 'ignore' by default. Other error strategies are
        'strict', 'replace', and 'backslashreplace', described here:
        https://docs.python.org/3/howto/unicode.html#encodings

mirror_to - Optional Writer to which all records read or transformed
        by this module (if it is a Reader or Transform) will be
        "mirrored" (copied). Mirroring happens asynchronously via
        a queue and background thread to minimize impact on the
        primary data flow. Writers cannot be mirrored.
def seek(self, offset=0, origin='current'): 
48    def seek(self, offset=0, origin='current'):
49        raise NotImplementedError('Class %s (subclass of StorageReader) is missing '
50                                  'implementation of seek() method.'
51                                  % self.__class__.__name__)
def read_range(self, start=None, stop=None): 
54    def read_range(self, start=None, stop=None):
55        """
56        Read a range of records beginning with record number start, and ending
57        *before* record number stop.
58        """
59        raise NotImplementedError('Class %s (subclass of StorageReader) is missing '
60                                  'implementation of read_range() method.'
61                                  % self.__class__.__name__)

Read a range of records beginning with record number start, and ending before record number stop.

Inherited Members
Reader
read
class TimestampedReader(StorageReader): 
65class TimestampedReader(StorageReader):
66    """
67    A TimestampedReader is a special case of a StorageReader where we
68    can seek and retrieve a range specified by timestamps.
69    """
70
71    ############################
72    def __init__(self, **kwargs):
73        super().__init__(**kwargs)
74
75    ############################
76    # Behavior is intended to mimic file seek() behavior but with
77    # respect to timestamps: 'offset' means number of milliseconds, and
78    # origin is either 'start', 'current' or 'end'.
79    def seek_time(self, offset=0, origin='current'):
80        raise NotImplementedError('Class %s (subclass of TimestampedReader) is missing '
81                                  'implementation of seek_time() method.'
82                                  % self.__class__.__name__)
83
84    ############################
85    # Read a range of records beginning with timestamp start
86    # milliseconds, and ending *before* timestamp stop milliseconds.
87    def read_time_range(self, start=None, stop=None):
88        raise NotImplementedError('Class %s (subclass of TimestampedReader) is missing '
89                                  'implementation of read_range() method.'
90                                  % self.__class__.__name__)

A TimestampedReader is a special case of a StorageReader where we can seek and retrieve a range specified by timestamps.

TimestampedReader(**kwargs) 
72    def __init__(self, **kwargs):
73        super().__init__(**kwargs)

quiet - if type checking should log type errors or operate silently.

Two additional arguments govern how records will be encoded/decoded
from bytes, if desired by the Writer subclass when it calls
_encode_str() or _decode_bytes:

encoding - 'utf-8' by default. If empty or None, do not attempt any
        decoding and return raw bytes. Other possible encodings are
        listed in online documentation here:
        https://docs.python.org/3/library/codecs.html#standard-encodings

encoding_errors - 'ignore' by default. Other error strategies are
        'strict', 'replace', and 'backslashreplace', described here:
        https://docs.python.org/3/howto/unicode.html#encodings

mirror_to - Optional Writer to which all records read or transformed
        by this module (if it is a Reader or Transform) will be
        "mirrored" (copied). Mirroring happens asynchronously via
        a queue and background thread to minimize impact on the
        primary data flow. Writers cannot be mirrored.
def seek_time(self, offset=0, origin='current'): 
79    def seek_time(self, offset=0, origin='current'):
80        raise NotImplementedError('Class %s (subclass of TimestampedReader) is missing '
81                                  'implementation of seek_time() method.'
82                                  % self.__class__.__name__)
def read_time_range(self, start=None, stop=None): 
87    def read_time_range(self, start=None, stop=None):
88        raise NotImplementedError('Class %s (subclass of TimestampedReader) is missing '
89                                  'implementation of read_range() method.'
90                                  % self.__class__.__name__)
Inherited Members
StorageReader
seek
read_range
Reader
read