FastWARC

Resiliparse FastWARC API documentation.

WARC

class fastwarc.warc.WarcRecordType(value)

An enumeration.

Enum indicating a WARC record’s type as given by its WARC-Type header. Multiple types can be combined with boolean operators for filtering records.

unknown = 512: Special type: unknown record type (filter only)

any_type = 65535: Special type: any record type (filter only)

no_type = 0: Special type: no record type (filter only)

warcinfo = 2

response = 4

resource = 8

request = 16

metadata = 32

revisit = 64

conversion = 128

continuation = 256

class fastwarc.warc.ArchiveIterator(self, stream, record_types=any_type, parse_http=True, min_content_length=-1, max_content_length=-1, func_filter=None, verify_digests=False, strict_mode=True, auto_decode='none')

Bases: object

WARC record stream iterator.

Parameters:

stream – input stream (preferably an IOStream, but any file-like Python object is fine)
parse_http (bool) – whether to parse HTTP records automatically (disable for better performance if not needed)
record_types (int) – bitmask of WarcRecordType record types to return (others will be skipped)
min_content_length (int) – skip records with Content-Length less than this
max_content_length (int) – skip records with Content-Length large than this
func_filter (Callable) – Python callable taking a WarcRecord and returning a bool for further record filtering
verify_digests (bool) – skip records which have no or an invalid block digest
strict_mode (bool) – enforce strict spec compliance (setting this to False will enable quirks such as LF instead of CRLF for headers)
auto_decode (str) – automatically decode record body if Content-Encoding or Transfer-Encoding headers are set (accepted values: 'none' [default], 'content', 'transfer', 'all', has no effect if parse_http is False)

__iter__(self)

Iterate all WarcRecord items in the current WARC stream.

Return type:: t.Iterable[WarcRecord]

__next__(self)

Implements an iterator that can be used with next().

Return type:: WarcRecord

class fastwarc.warc.WarcHeaderMap(self, encoding='utf-8')

Bases: object

Dict-like type representing a WARC or HTTP header block.

Parameters:: encoding (str) – header source encoding

__iter__(self)

Iterate all header map items.

Return type:: t.Iterable[(str, str)]

append(self, key, value)

Append header (use if header name is not unique).

Parameters:

key (str) – header key
value (str) – header value

asdict(self)

Headers as Python dict.

If multiple headers have the same key, only the last occurrence will be returned.

Return type:: t.Dict[str, str]

astuples(self)

Headers as a series of tuples, including multiple headers with the same key. Use this over asdict() if header keys are not necessarily unique.

Return type:: ((str, str),)

clear(self): Clear all headers.

get(self, key, default=None)

Get header value or default.

If multiple headers have the same key, only the last occurrence will be returned.

Parameters:

key (str) – header key
default (str) – default value if key not found

Return type:

str

items(self)

Item view of keys and values.

If multiple headers have the same key, only the last occurrence will be returned.

Return type:: t.Iterable[(str, str)]

keys(self)

Iterable of header keys.

If multiple headers have the same key, only the last occurrence will be returned.

Return type:: t.Iterable[str]

values(self)

Iterable of header values.

If multiple headers have the same key, only the last occurrence will be returned.

Return type:: t.Iterable[str]

write(): Write header block into stream.

reason_phrase

HTTP reason phrase (unset if header block is not an HTTP header block).

Type:: str or None

status_code

HTTP status code (unset if header block is not an HTTP header block).

Type:: int or None

status_line

Header status line.

Type:: str

class fastwarc.warc.WarcRecord(self)

Bases: object

A WARC record.

WARC records are picklable, but pickling will freeze() the WARC record.

freeze(self)

“Freeze” a record by baking in the remaining payload stream contents.

Freezing a record makes the WarcRecord instance copyable and reusable by decoupling it from the underlying raw WARC stream. Instead of reading directly from the raw stream, a frozen record maintains an internal buffer the size of the remaining payload stream contents at the time of calling freeze().

Freezing a record will advance the underlying raw stream.

init_headers(self, content_length=0, record_type=no_type, record_urn=None)

Initialize mandatory headers in a fresh WarcRecord instance.

Parameters:

content_length (int) – WARC record body length in bytes
record_type (WarcRecordType) – WARC-Type
record_urn (bytes) – WARC-Record-ID as URN without '<', '>' (if unset, a random URN will be generated)

parse_http(self, strict_mode=True, auto_decode='none')

Parse HTTP headers and advance content reader.

It is safe to call this method multiple times, even if the record is not an HTTP record.

Parameters:

strict_mode – enforce CRLF line endings, setting this to False will allow plain LF also
auto_decode (str) – automatically decode record body if Content-Encoding or Transfer-Encoding headers are set (accepted values: 'none' [default], 'content', 'transfer', 'all')

Type:

strict_mode: bool

set_bytes_content(self, b)

Set WARC body.

Parameters:: b (bytes) – body as bytes

verify_block_digest(self, consume=False)

Verify whether record block digest is valid.

Parameters:: consume (bool) – do not create an in-memory copy of the record stream (will fully consume the rest of the record)
Returns:: True if digest exists and is valid
Return type:: bool

verify_payload_digest(self, consume=False)

Verify whether record payload digest is valid.

Parameters:: consume (bool) – do not create an in-memory copy of the record stream (will fully consume the rest of the record)
Returns:: True if record is HTTP record and digest exists and is valid
Return type:: bool

write(self, stream, checksum_data=False, chunk_size=16384)

Write WARC record onto a stream.

Parameters:

stream – output stream
checksum_data (bool) – add block and payload digest headers
payload_digest (bytes) – optional SHA-1 payload digest as bytes
chunk_size (int) – write block size

Returns:

number of bytes written

Return type:

int

content_length

Remaining WARC record length in bytes (not necessarily the same as the Content-Length header).

Type:: int

headers

WARC record headers.

Type:: WarcHeaderMap

http_charset

HTTP charset/encoding as returned by the server or None if no valid charset is set. A returned string is guaranteed to be a valid Python encoding name.

Type:: str or None

http_content_type

Plain HTTP Content-Type without additional fields such as charset=.

Type:: str or None

http_date

Parsed HTTP Date header or None if server did not return a valid HTTP date.

Type:: datetime.datetime | None

http_headers

HTTP headers if record is an HTTP record and HTTP headers have been parsed yet.

Type:: WarcHeaderMap or None

http_last_modified

Parsed HTTP Last-Modified header or None if server did not return a valid HTTP modification date.

Type:: datetime.datetime | None

is_http

Whether record is an HTTP record.

Modifying this property will also affect the Content-Type of this record.

Type:: bool

is_http_parsed

Whether HTTP headers have been parsed.

Type:: bool

reader

Reader for the remaining WARC record content.

Type:: BufferedReader

record_date

WARC Date.

Type:: datetime.datetime | None

record_id

Record ID (same as headers['WARC-Record-ID']).

Type:: str

record_type

Record type (same as headers['WARC-Type'].

Type:: WarcRecordType

stream_pos

WARC record start offset in the original (uncompressed) stream.

Type:: int

fastwarc.warc.has_block_digest(record)

Filter predicate for checking if record has a block digest.

Parameters:: record (WarcRecord) – WARC record
Return type:: bool

fastwarc.warc.has_payload_digest(record)

Filter predicate for checking if record has a payload digest.

Parameters:: record (WarcRecord) – WARC record
Return type:: bool

fastwarc.warc.is_concurrent(record)

Filter predicate for checking if record is concurrent to another record.

Parameters:: record (WarcRecord) – WARC record
Return type:: bool

fastwarc.warc.is_http(record)

Filter predicate for checking if record is an HTTP record.

Parameters:: record (WarcRecord) – WARC record
Return type:: bool

fastwarc.warc.is_warc_10(record)

Filter predicate for checking if record is a WARC/1.0 record.

Parameters:: record (WarcRecord) – WARC record
Return type:: bool

fastwarc.warc.is_warc_11(record)

Filter predicate for checking if record is a WARC/1.1 record.

Parameters:: record (WarcRecord) – WARC record
Return type:: bool

StreamIO

exception fastwarc.stream_io.FastWARCError

Bases: Exception

Generic FastWARC exception.

exception fastwarc.stream_io.ReaderStaleError

Bases: FastWARCError

FastWARC reader stale error.

exception fastwarc.stream_io.StreamError

Bases: FastWARCError

FastWARC stream error.

class fastwarc.stream_io.BrotliStream(self, raw_stream, quality=11, lgwin=22, lgblock=0)

Bases: CompressingStream

Brotli IOStream implementation.

Implementation relies on Google’s brotli Python package, will be ported to native C version in a later version.

Parameters:

raw_stream – raw data stream
quality (int) – compression quality (higher quality means better compression, but less speed)
lgwin (int) – Base 2 logarithm of the sliding window size in the range 16 to 24
lgblock (int) – Base 2 logarithm of the maximum input block size in the range 16 to 24 (will be set based on quality of value is 0)

begin_member()

Begin compression member / frame (if not already started).

Returns:: bytes written
Return type:: int

close(self): Close the stream.

end_member()

End compression member / frame (if one has been started).

Returns:: bytes written
Return type:: int

flush(self): Flush stream buffer.

seek(self, offset)

Seek to specified offset.

Parameters:: offset (int) – seek offset

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

class fastwarc.stream_io.BufferedReader(self, stream, buf_size=16384, negotiate_stream=True)

Bases: object

Buffered reader operating on an IOStream instance.

Parameters:

stream (IOStream) – stream to operate on
buf_size (int) – internal buffer size
negotiate_stream (bool) – whether to auto-negotiate stream type

close(self): Close stream.

consume(self, size=-1)

Consume up to size bytes from the input stream without allocating a buffer for it.

Parameters:: size (int) – number of bytes to read (default means read remaining stream)
Returns:: number of bytes consumed
Return type:: int

read(self, size=-1)

Read up to size bytes from the input stream.

Parameters:: size (int) – number of bytes to read (default means read remaining stream)
Returns:: consumed buffer contents as bytes (or empty string if EOF)
Return type:: bytes

readline(self, crlf=True, max_line_len=8192)

Read a single line from the input stream.

Parameters:

crlf (bool) – whether lines are separated by CRLF or LF
max_line_len (int) – maximum line length (longer lines will still be consumed, but the return value will not be larger than this)

Returns:

line contents (or empty string if EOF)

Return type:

bytes

tell(self)

Offset on the input stream.

Returns:: offset
Return type:: int

class fastwarc.stream_io.BytesIOStream(self, initial_data=None)

Bases: IOStream

IOStream that uses an in-memory buffer.

Parameters:: initial_data (bytes) – fill internal buffer with this initial data

close(self): Close the stream.

getvalue(self)

Get buffer value.

Returns:: buffer value
Return type:: bytes

seek(self, offset)

Seek to specified offset.

Parameters:: offset (int) – seek offset

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

class fastwarc.stream_io.CompressingStream

Bases: IOStream

Base class for compressed IOStream types.

begin_member()

Begin compression member / frame (if not already started).

Returns:: bytes written
Return type:: int

end_member()

End compression member / frame (if one has been started).

Returns:: bytes written
Return type:: int

class fastwarc.stream_io.FileStream(self, filename=None, mode='rb')

Bases: IOStream

Fast alternative to Python file objects for local files.

Parameters:

filename (str) – input filename
mode (str) – file open mode

close(self): Close the stream.

flush(self): Flush stream buffer.

seek(self, offset)

Seek to specified offset.

Parameters:: offset (int) – seek offset

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

class fastwarc.stream_io.GZipStream(self, raw_stream, compression_level=9, zlib=False)

Bases: CompressingStream

GZip IOStream implementation.

Parameters:

raw_stream – raw data stream
compression_level (int) – GZip compression level (for compression only)
zlib (bool) – use raw deflate / zlib format instead of gzip

begin_member()

Begin compression member / frame (if not already started).

Returns:: bytes written
Return type:: int

close(self): Close the stream.

end_member()

End compression member / frame (if one has been started).

Returns:: bytes written
Return type:: int

flush(self): Flush stream buffer.

prepopulate(self, initial_data)

Fill internal working buffer with initial data. Use if some initial data of the stream have already been consumed (e.g., for stream content negotiation). Has to be called before the first read().

Parameters:

deflate (int) – True if data is uncompressed, False if data is compressed GZip data.
initial_data (bytes) – data to pre-populate

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

class fastwarc.stream_io.IOStream

Bases: object

IOStream base class.

close(self): Close the stream.

flush(self): Flush stream buffer.

read(self, size)

Read size bytes from stream.

Parameters:: size (int) – bytes to read
Returns:: read bytes
Return type:: bytearray

seek(self, offset)

Seek to specified offset.

Parameters:: offset (int) – seek offset

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

write(self, data)

Write bytes to stream.

Parameters:: data (bytes) – data to write
Returns:: number of bytes written
Return type:: int

class fastwarc.stream_io.LZ4Stream(self, raw_stream, compression_level=12, favor_dec_speed=True)

Bases: CompressingStream

LZ4 IOStream implementation.

Parameters:

raw_stream – raw data stream
compression_level (int) – LZ4 compression level (for compression only)
favor_dec_speed (bool) – favour decompression speed over compression speed and size

begin_member()

Begin compression member / frame (if not already started).

Returns:: bytes written
Return type:: int

close(self): Close the stream.

end_member()

End compression member / frame (if one has been started).

Returns:: bytes written
Return type:: int

flush(self): Flush stream buffer.

prepopulate(self, initial_data)

Fill internal working buffer with initial data. Use if some initial data of the stream have already been consumed (e.g., for stream content negotiation). Has to be called before the first read().

Parameters:: initial_data (bytes) – data to pre-populate

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

class fastwarc.stream_io.PythonIOStreamAdapter(self, py_stream)

Bases: IOStream

IOStream adapter for file-like Python objects.

Parameters:: py_stream – input Python stream object

close(self): Close the stream.

flush(self): Flush stream buffer.

seek(self, offset)

Seek to specified offset.

Parameters:: offset (int) – seek offset

tell(self)

Return current stream offset.

Returns:: stream offset
Return type:: int

fastwarc.stream_io.wrap_stream(raw_stream)

Wrap raw_stream into a PythonIOStreamAdapter if it is a Python object or return raw_stream unmodified if it is a IOStream already.

Parameters:: raw_stream – stream to wrap
Returns:: wrapped stream
Return type:: IOStream