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recordbuilder.py
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recordbuilder.py
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import datetime
import six
import tempfile
from io import BytesIO
from warcio.recordloader import ArcWarcRecord, ArcWarcRecordLoader
from warcio.statusandheaders import StatusAndHeadersParser, StatusAndHeaders
from warcio.timeutils import datetime_to_iso_date
from warcio.utils import to_native_str, BUFF_SIZE, Digester
#=================================================================
class RecordBuilder(object):
REVISIT_PROFILE = 'http://netpreserve.org/warc/1.0/revisit/identical-payload-digest'
WARC_1_0 = 'WARC/1.0'
WARC_1_1 = 'WARC/1.1'
# default warc version
WARC_VERSION = WARC_1_0
WARC_RECORDS = {'warcinfo': 'application/warc-fields',
'response': 'application/http; msgtype=response',
'revisit': 'application/http; msgtype=response',
'request': 'application/http; msgtype=request',
'metadata': 'application/warc-fields',
}
NO_PAYLOAD_DIGEST_TYPES = ('warcinfo', 'revisit')
NO_BLOCK_DIGEST_TYPES = ('warcinfo')
def __init__(self, warc_version=None):
self.warc_version = self._parse_warc_version(warc_version)
def create_warcinfo_record(self, filename, info):
warc_headers = StatusAndHeaders(self.warc_version, [])
warc_headers.add_header('WARC-Type', 'warcinfo')
warc_headers.add_header('WARC-Record-ID', self._make_warc_id())
if filename:
warc_headers.add_header('WARC-Filename', filename)
warc_headers.add_header('WARC-Date', self.curr_warc_date())
warcinfo = BytesIO()
for name, value in six.iteritems(info):
if not value:
continue
line = name + ': ' + str(value) + '\r\n'
warcinfo.write(line.encode('utf-8'))
length = warcinfo.tell()
warcinfo.seek(0)
return self.create_warc_record('', 'warcinfo',
warc_headers=warc_headers,
payload=warcinfo,
length=length)
def create_revisit_record(self, uri, digest, refers_to_uri, refers_to_date,
http_headers=None, warc_headers_dict=None):
assert digest, 'Digest can not be empty'
if warc_headers_dict is None:
warc_headers_dict = dict()
record = self.create_warc_record(uri, 'revisit', http_headers=http_headers,
warc_headers_dict=warc_headers_dict)
record.rec_headers.add_header('WARC-Profile', self.REVISIT_PROFILE)
record.rec_headers.add_header('WARC-Refers-To-Target-URI', refers_to_uri)
record.rec_headers.add_header('WARC-Refers-To-Date', refers_to_date)
record.rec_headers.add_header('WARC-Payload-Digest', digest)
return record
def create_warc_record(self, uri, record_type,
payload=None,
length=None,
warc_content_type='',
warc_headers_dict=None,
warc_headers=None,
http_headers=None):
if warc_headers_dict is None:
warc_headers_dict = dict()
if payload and not http_headers:
loader = ArcWarcRecordLoader()
http_headers = loader.load_http_headers(record_type, uri, payload, length)
if http_headers and length is not None:
length -= payload.tell()
if not payload:
payload = BytesIO()
length = 0
if not warc_headers:
warc_headers = self._init_warc_headers(uri, record_type, warc_headers_dict)
# compute Content-Type
if not warc_content_type:
warc_content_type = warc_headers.get_header('Content-Type')
if not warc_content_type:
warc_content_type = self.WARC_RECORDS.get(record_type,
'application/warc-record')
record = ArcWarcRecord('warc', record_type, warc_headers, payload,
http_headers, warc_content_type, length)
record.payload_length = length
self.ensure_digest(record, block=False, payload=True)
return record
def _init_warc_headers(self, uri, record_type, warc_headers_dict):
warc_headers = StatusAndHeaders(self.warc_version, list(warc_headers_dict.items()))
warc_headers.replace_header('WARC-Type', record_type)
if not warc_headers.get_header('WARC-Record-ID'):
warc_headers.add_header('WARC-Record-ID', self._make_warc_id())
if uri:
warc_headers.replace_header('WARC-Target-URI', uri)
if not warc_headers.get_header('WARC-Date'):
warc_headers.add_header('WARC-Date', self.curr_warc_date())
return warc_headers
def curr_warc_date(self):
use_micros = (self.warc_version >= self.WARC_1_1)
return self._make_warc_date(use_micros=use_micros)
def _parse_warc_version(self, version):
if not version:
return self.WARC_VERSION
version = str(version)
if version.startswith('WARC/'):
return version
return 'WARC/' + version
@classmethod
def _make_warc_id(cls):
return StatusAndHeadersParser.make_warc_id()
@classmethod
def _make_warc_date(cls, use_micros=False):
return datetime_to_iso_date(datetime.datetime.utcnow(), use_micros=use_micros)
@classmethod
def ensure_digest(cls, record, block=True, payload=True):
if block:
if (record.rec_headers.get_header('WARC-Block-Digest') or
(record.rec_type in cls.NO_BLOCK_DIGEST_TYPES)):
block = False
if payload:
if (record.rec_headers.get_header('WARC-Payload-Digest') or
(record.rec_type in cls.NO_PAYLOAD_DIGEST_TYPES)):
payload = False
block_digester = cls._create_digester() if block else None
payload_digester = cls._create_digester() if payload else None
has_length = (record.length is not None)
if not block_digester and not payload_digester and has_length:
return
temp_file = None
try:
# force buffering if no length is set
assert(has_length)
pos = record.raw_stream.tell()
record.raw_stream.seek(pos)
except:
pos = 0
temp_file = cls._create_temp_file()
if block_digester and record.http_headers:
if not record.http_headers.headers_buff:
record.http_headers.compute_headers_buffer(self.header_filter)
block_digester.update(record.http_headers.headers_buff)
for buf in cls._iter_stream(record.raw_stream):
if block_digester:
block_digester.update(buf)
if payload_digester:
payload_digester.update(buf)
if temp_file:
temp_file.write(buf)
if temp_file:
record.payload_length = temp_file.tell()
temp_file.seek(0)
record._orig_stream = record.raw_stream
record.raw_stream = temp_file
else:
record.raw_stream.seek(pos)
if payload_digester:
record.rec_headers.add_header('WARC-Payload-Digest', str(payload_digester))
if block_digester:
record.rec_headers.add_header('WARC-Block-Digest', str(block_digester))
@staticmethod
def _iter_stream(stream):
while True:
buf = stream.read(BUFF_SIZE)
if not buf:
return
yield buf
@staticmethod
def _create_digester():
return Digester('sha1')
@staticmethod
def _create_temp_file():
return tempfile.SpooledTemporaryFile(max_size=512*1024)