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2960 lines (2643 loc) · 82 KB
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##
# .driver.pq3 - interface to PostgreSQL using PQ v3.0.
##
"""
PG-API interface for PostgreSQL using PQ version 3.0.
"""
import os
import weakref
import socket
from traceback import format_exception
from itertools import repeat, chain, count
from functools import partial
from abc import abstractmethod
from codecs import lookup as lookup_codecs
from operator import itemgetter
get0 = itemgetter(0)
get1 = itemgetter(1)
from .. import lib as pg_lib
from .. import versionstring as pg_version
from .. import iri as pg_iri
from .. import exceptions as pg_exc
from .. import string as pg_str
from .. import api as pg_api
from .. import message as pg_msg
from ..encodings.aliases import get_python_name
from ..string import quote_ident
from ..python.itertools import interlace, chunk
from ..python.socket import SocketFactory
from ..python.functools import process_tuple, process_chunk
from ..python.functools import Composition as compose
from ..protocol import xact3 as xact
from ..protocol import element3 as element
from ..protocol import client3 as client
from ..protocol.message_types import message_types
from ..notifyman import NotificationManager
from .. import types as pg_types
from ..types import io as pg_types_io
from ..types.io import lib as io_lib
# Map element3.Notice field identifiers
# to names used by message.Message.
notice_field_to_name = {
message_types[b'S'[0]] : 'severity',
message_types[b'C'[0]] : 'code',
message_types[b'M'[0]] : 'message',
message_types[b'D'[0]] : 'detail',
message_types[b'H'[0]] : 'hint',
message_types[b'W'[0]] : 'context',
message_types[b'P'[0]] : 'position',
message_types[b'p'[0]] : 'internal_position',
message_types[b'q'[0]] : 'internal_query',
message_types[b'F'[0]] : 'file',
message_types[b'L'[0]] : 'line',
message_types[b'R'[0]] : 'function',
}
del message_types
notice_field_from_name = dict(
(v, k) for (k, v) in notice_field_to_name.items()
)
could_not_connect = element.ClientError((
(b'S', 'FATAL'),
(b'C', '08001'),
(b'M', "could not establish connection to server"),
))
# generate an id for a client statement or cursor
def ID(s, title = None, IDNS = 'py:'):
return IDNS + hex(id(s))
def declare_statement_string(
cursor_id,
statement_string,
insensitive = True,
scroll = True,
hold = True
):
s = 'DECLARE ' + cursor_id
if insensitive is True:
s += ' INSENSITIVE'
if scroll is True:
s += ' SCROLL'
s += ' CURSOR'
if hold is True:
s += ' WITH HOLD'
else:
s += ' WITHOUT HOLD'
return s + ' FOR ' + statement_string
def direction_str_to_bool(str):
s = str.upper()
if s == 'FORWARD':
return True
elif s == 'BACKWARD':
return False
else:
raise ValueError("invalid direction " + repr(str))
def direction_to_bool(v):
if isinstance(v, str):
return direction_str_to_bool(v)
elif v is not True and v is not False:
raise TypeError("invalid direction " + repr(v))
else:
return v
class TypeIO(pg_api.TypeIO):
"""
A class that manages I/O for a given configuration. Normally, a connection
would create an instance, and configure it based upon the version and
configuration of PostgreSQL that it is connected to.
"""
_e_factors = ('database',)
strio = (None, None, str)
def __init__(self, database):
self.database = database
self.encoding = None
strio = self.strio
self._cache = {
# Encoded character strings
pg_types.ACLITEMOID : strio, # No binary functions.
pg_types.NAMEOID : strio,
pg_types.BPCHAROID : strio,
pg_types.VARCHAROID : strio,
pg_types.CSTRINGOID : strio,
pg_types.TEXTOID : strio,
pg_types.REGTYPEOID : strio,
pg_types.REGPROCOID : strio,
pg_types.REGPROCEDUREOID : strio,
pg_types.REGOPEROID : strio,
pg_types.REGOPERATOROID : strio,
pg_types.REGCLASSOID : strio,
}
self.typinfo = {}
super().__init__()
def lookup_type_info(self, typid):
return self.database.sys.lookup_type(typid)
def lookup_composite_type_info(self, typid):
return self.database.sys.lookup_composite(typid)
def set_encoding(self, value):
"""
Set a new client encoding.
"""
self.encoding = value.lower().strip()
enc = get_python_name(self.encoding)
ci = lookup_codecs(enc or self.encoding)
self._encode, self._decode, *_ = ci
def encode(self, string_data):
return self._encode(string_data)[0]
def decode(self, bytes_data):
return self._decode(bytes_data)[0]
def encodes(self, iter, get0 = get0):
"""
Encode the items in the iterable in the configured encoding.
"""
return map(compose((self._encode, get0)), iter)
def decodes(self, iter, get0 = get0):
"""
Decode the items in the iterable from the configured encoding.
"""
return map(compose((self._decode, get0)), iter)
def resolve_pack(self, typid):
return self.resolve(typid)[0] or self.encode
def resolve_unpack(self, typid):
return self.resolve(typid)[1] or self.decode
def attribute_map(self, pq_descriptor):
return zip(self.decodes(pq_descriptor.keys()), count())
def sql_type_from_oid(self, oid, qi = quote_ident):
if oid in pg_types.oid_to_sql_name:
return pg_types.oid_to_sql_name[oid]
if oid in self.typinfo:
nsp, name, *_ = self.typinfo[oid]
return qi(nsp) + '.' + qi(name)
return 'pg_catalog.' + pg_types.oid_to_name.get(oid)
def type_from_oid(self, oid):
if oid in self._cache:
typ = self._cache[oid][2]
return typ
def resolve_descriptor(self, desc, index):
'create a sequence of I/O routines from a pq descriptor'
return [
(self.resolve(x[3]) or (None, None))[index] for x in desc
]
# lookup a type's IO routines from a given typid
def resolve(self,
typid : "The Oid of the type to resolve pack and unpack routines for.",
from_resolution_of : \
"Sequence of typid's used to identify infinite recursion" = (),
builtins : "types.io.resolve" = pg_types_io.resolve,
quote_ident = quote_ident
):
if from_resolution_of and typid in from_resolution_of:
raise TypeError(
"type, %d, is already being looked up: %r" %(
typid, from_resolution_of
)
)
typid = int(typid)
typio = None
if typid in self._cache:
typio = self._cache[typid]
else:
typio = builtins(typid)
if typio is not None:
if typio.__class__ is not tuple:
typio = typio(typid, self)
self._cache[typid] = typio
if typio is None:
# Lookup the type information for the typid as it's not cached.
##
ti = self.lookup_type_info(typid)
if ti is not None:
typnamespace, typname, typtype, typlen, typelem, typrelid, \
ae_typid, ae_hasbin_input, ae_hasbin_output = ti
self.typinfo[typid] = (
typnamespace, typname, typrelid, int(typelem) if ae_typid else None
)
if typrelid:
# Row type
#
# The attribute name map,
# column I/O,
# column type Oids
# are needed to build the packing pair.
attmap = {}
cio = []
typids = []
attnames = []
i = 0
for x in self.lookup_composite_type_info(typrelid):
attmap[x[1]] = i
attnames.append(x[1])
typids.append(x[0])
pack, unpack, typ = self.resolve(
x[0], list(from_resolution_of) + [typid]
)
cio.append((pack or self.encode, unpack or self.decode))
i += 1
self._cache[typid] = typio = self.record_io_factory(
cio, typids, attmap, list(
map(self.sql_type_from_oid, typids)
), attnames,
quote_ident(typnamespace) + '.' + \
quote_ident(typname),
)
elif ae_typid is not None:
# resolve the element type and I/O pair
te = self.resolve(
int(typelem),
from_resolution_of = list(from_resolution_of) + [typid]
) or (None, None)
typio = self.array_io_factory(
te[0] or self.encode,
te[1] or self.decode,
typelem,
ae_hasbin_input,
ae_hasbin_output
)
self._cache[typid] = typio
else:
self._cache[typid] = typio = self.strio
else:
# Throw warning about type without entry in pg_type?
typio = self.strio
return typio
def identify(self, **identity_mappings):
"""
Explicitly designate the I/O handler for the specified type.
Primarily used in cases involving UDTs.
"""
# get them ordered; we process separately, then recombine.
id = list(identity_mappings.items())
ios = [pg_types_io.resolve(x[0]) for x in id]
oids = list(self.database.sys.regtypes([x[1] for x in id]))
self._cache.update([
(oid, io if io.__class__ is tuple else io(oid, self))
for oid, io in zip(oids, ios)
])
def array_parts(self, array, ArrayType = pg_types.Array):
if array.__class__ is not ArrayType:
# Assume the data is a nested list.
array = ArrayType(array)
return (
array.elements(),
array.dimensions,
array.lowerbounds
)
def array_from_parts(self, parts, ArrayType = pg_types.Array):
elements, dimensions, lowerbounds = parts
return ArrayType.from_elements(
elements,
lowerbounds = lowerbounds,
upperbounds = [x + lb - 1 for x, lb in zip(dimensions, lowerbounds)]
)
##
# array_io_factory - build I/O pair for ARRAYs
##
def array_io_factory(
self,
pack_element, unpack_element,
typoid, # array element id
hasbin_input, hasbin_output,
array_pack = io_lib.array_pack,
array_unpack = io_lib.array_unpack,
):
packed_typoid = io_lib.ulong_pack(typoid)
if hasbin_input:
def pack_an_array(data, get_parts = self.array_parts):
elements, dimensions, lowerbounds = get_parts(data)
return array_pack((
0, # unused flags
typoid, dimensions, lowerbounds,
(x if x is None else pack_element(x) for x in elements),
))
else:
# signals string formatting
pack_an_array = None
if hasbin_output:
def unpack_an_array(data, array_from_parts = self.array_from_parts):
flags, typoid, dims, lbs, elements = array_unpack(data)
return array_from_parts((map(unpack_element, elements), dims, lbs))
else:
# signals string formatting
unpack_an_array = None
return (pack_an_array, unpack_an_array, pg_types.Array)
def RowTypeFactory(self, attribute_map = {}, _Row = pg_types.Row.from_sequence):
return partial(_Row, attribute_map)
##
# record_io_factory - Build an I/O pair for RECORDs
##
def record_io_factory(self,
column_io : "sequence (pack,unpack) tuples corresponding to the columns",
typids : "sequence of type Oids; index must correspond to the composite's",
attmap : "mapping of column name to index number",
typnames : "sequence of sql type names in order",
attnames : "sequence of attribute names in order",
composite_name : "the name of the composite type",
get0 = get0,
get1 = get1,
fmt_errmsg = "failed to {0} attribute {1}, {2}::{3}, of composite {4} from wire data".format
):
fpack = tuple(map(get0, column_io))
funpack = tuple(map(get1, column_io))
row_constructor = self.RowTypeFactory(attribute_map = attmap)
def raise_pack_tuple_error(procs, tup, itemnum):
data = repr(tup[itemnum])
if len(data) > 80:
# Be sure not to fill screen with noise.
data = data[:75] + ' ...'
self.raise_client_error(element.ClientError((
(b'C', '--cIO',),
(b'S', 'ERROR',),
(b'M', fmt_errmsg('pack', itemnum, attnames[itemnum], typnames[itemnum], composite_name),),
(b'W', data,),
(b'P', str(itemnum),)
)))
def raise_unpack_tuple_error(procs, tup, itemnum):
data = repr(tup[itemnum])
if len(data) > 80:
# Be sure not to fill screen with noise.
data = data[:75] + ' ...'
self.raise_client_error(element.ClientError((
(b'C', '--cIO',),
(b'S', 'ERROR',),
(b'M', fmt_errmsg('unpack', itemnum, attnames[itemnum], typnames[itemnum], composite_name),),
(b'W', data,),
(b'P', str(itemnum),),
)))
def unpack_a_record(data,
unpack = io_lib.record_unpack,
process_tuple = process_tuple,
row_constructor = row_constructor
):
data = tuple([x[1] for x in unpack(data)])
return row_constructor(process_tuple(funpack, data, raise_unpack_tuple_error))
sorted_atts = sorted(attmap.items(), key = get1)
def pack_a_record(data,
pack = io_lib.record_pack,
process_tuple = process_tuple,
):
if isinstance(data, dict):
data = [data.get(k) for k,_ in sorted_atts]
return pack(
tuple(zip(
typids,
process_tuple(fpack, tuple(data), raise_pack_tuple_error)
))
)
return (pack_a_record, unpack_a_record, tuple)
def raise_client_error(self, error_message, cause = None, creator = None):
m = {
notice_field_to_name[k] : v
for k, v in error_message.items()
# don't include unknown messages in this list.
if k in notice_field_to_name
}
c = m.pop('code')
ms = m.pop('message')
client_error = self.lookup_exception(c)
client_error = client_error(ms, code = c, details = m, source = 'CLIENT', creator = creator or self.database)
client_error.database = self.database
if cause is not None:
raise client_error from cause
else:
raise client_error
def lookup_exception(self, code, errorlookup = pg_exc.ErrorLookup,):
return errorlookup(code)
def lookup_warning(self, code, warninglookup = pg_exc.WarningLookup,):
return warninglookup(code)
def raise_server_error(self, error_message, cause = None, creator = None):
m = dict(self.decode_notice(error_message))
c = m.pop('code')
ms = m.pop('message')
server_error = self.lookup_exception(c)
server_error = server_error(ms, code = c, details = m, source = 'SERVER', creator = creator or self.database)
server_error.database = self.database
if cause is not None:
raise server_error from cause
else:
raise server_error
def raise_error(self, error_message, ClientError = element.ClientError, **kw):
if 'creator' not in kw:
kw['creator'] = getattr(self.database, '_controller', self.database) or self.database
if error_message.__class__ is ClientError:
self.raise_client_error(error_message, **kw)
else:
self.raise_server_error(error_message, **kw)
##
# Used by decode_notice()
def _decode_failsafe(self, data):
decode = self._decode
i = iter(data)
for x in i:
try:
# prematurely optimized for your viewing displeasure.
v = x[1]
yield (x[0], decode(v)[0])
for x in i:
v = x[1]
yield (x[0], decode(v)[0])
except UnicodeDecodeError:
# Fallback to the bytes representation.
# This should be sufficiently informative in most cases,
# and in the cases where it isn't, an element traceback should
# ultimately yield the pertinent information
yield (x[0], repr(data[1])[2:-1])
def decode_notice(self, notice):
notice = self._decode_failsafe(notice.items())
return {
notice_field_to_name[k] : v
for k, v in notice
# don't include unknown messages in this list.
if k in notice_field_to_name
}
def emit_server_message(self, message, creator = None,
MessageType = pg_msg.Message
):
fields = self.decode_notice(message)
m = fields.pop('message')
c = fields.pop('code')
if fields['severity'].upper() == 'WARNING':
MessageType = self.lookup_warning(c)
message = MessageType(m, code = c, details = fields,
creator = creator, source = 'SERVER')
message.database = self.database
message.emit()
return message
def emit_client_message(self, message, creator = None,
MessageType = pg_msg.Message
):
fields = {
notice_field_to_name[k] : v
for k, v in message.items()
# don't include unknown messages in this list.
if k in notice_field_to_name
}
m = fields.pop('message')
c = fields.pop('code')
if fields['severity'].upper() == 'WARNING':
MessageType = self.lookup_warning(c)
message = MessageType(m, code = c, details = fields,
creator = creator, source = 'CLIENT')
message.database = self.database
message.emit()
return message
def emit_message(self, message, ClientNotice = element.ClientNotice, **kw):
if message.__class__ is ClientNotice:
return self.emit_client_message(message, **kw)
else:
return self.emit_server_message(message, **kw)
##
# This class manages all the functionality used to get
# rows from a PostgreSQL portal/cursor.
class Output(object):
_output = None
_output_io = None
_output_formats = None
_output_attmap = None
closed = False
cursor_id = None
statement = None
parameters = None
_complete_message = None
@abstractmethod
def _init(self):
"""
Bind a cursor based on the configured parameters.
"""
# The local initialization for the specific cursor.
def __init__(self, cursor_id, wref = weakref.ref, ID = ID):
self.cursor_id = cursor_id
if self.statement is not None:
stmt = self.statement
self._output = stmt._output
self._output_io = stmt._output_io
self._row_constructor = stmt._row_constructor
self._output_formats = stmt._output_formats or ()
self._output_attmap = stmt._output_attmap
self._pq_cursor_id = self.database.typio.encode(cursor_id)
# If the cursor's id was generated, it should be garbage collected.
if cursor_id == ID(self):
garbage = self.database.pq.garbage_cursors.append
cid = self._pq_cursor_id
# Callback for closing the cursor on remote end.
self._del = wref(self, lambda x: garbage(cid))
self._quoted_cursor_id = '"' + cursor_id.replace('"', '""') + '"'
self._init()
def __iter__(self):
return self
def close(self):
if self.closed is False:
self.database.pq.garbage_cursors.append(self._pq_cursor_id)
self.closed = True
# Don't need the weakref anymore.
if hasattr(self, '_del'):
del self._del
def _ins(self, *args):
return xact.Instruction(*args, asynchook = self.database._receive_async)
def _pq_xp_describe(self):
return (element.DescribePortal(self._pq_cursor_id),)
def _pq_xp_bind(self):
return (
element.Bind(
self._pq_cursor_id,
self.statement._pq_statement_id,
self.statement._input_formats,
self.statement._pq_parameters(self.parameters),
self._output_formats,
),
)
def _pq_xp_fetchall(self):
return (
element.Bind(
b'',
self.statement._pq_statement_id,
self.statement._input_formats,
self.statement._pq_parameters(self.parameters),
self._output_formats,
),
element.Execute(b'', 0xFFFFFFFF),
)
def _pq_xp_declare(self):
return (
element.Parse(b'', self.database.typio.encode(
declare_statement_string(
str(self._quoted_cursor_id),
str(self.statement.string)
)
), ()
),
element.Bind(
b'', b'', self.statement._input_formats,
self.statement._pq_parameters(self.parameters), ()
),
element.Execute(b'', 1),
)
def _pq_xp_execute(self, quantity):
return (
element.Execute(self._pq_cursor_id, quantity),
)
def _pq_xp_fetch(self, direction, quantity):
##
# It's an SQL declared cursor, manually construct the fetch commands.
qstr = "FETCH " + ("FORWARD " if direction else "BACKWARD ")
if quantity is None:
qstr = qstr + "ALL IN " + self._quoted_cursor_id
else:
qstr = qstr \
+ str(quantity) + " IN " + self._quoted_cursor_id
return (
element.Parse(b'', self.database.typio.encode(qstr), ()),
element.Bind(b'', b'', (), (), self._output_formats),
# The "limit" is defined in the fetch query.
element.Execute(b'', 0xFFFFFFFF),
)
def _pq_xp_move(self, position, whence):
return (
element.Parse(b'',
b'MOVE ' + whence + b' ' + position + b' IN ' + \
self.database.typio.encode(self._quoted_cursor_id),
()
),
element.Bind(b'', b'', (), (), ()),
element.Execute(b'', 1),
)
def _process_copy_chunk(self, x):
if x:
if x[0].__class__ is not bytes or x[-1].__class__ is not bytes:
return [
y for y in x if y.__class__ is bytes
]
return x
# Process the element.Tuple message in x for column()
def _process_tuple_chunk_Column(self, x, range = range):
unpack = self._output_io[0]
# get the raw data for the first column
l = [y[0] for y in x]
# iterate over the range to keep track
# of which item we're processing.
r = range(len(l))
try:
return [unpack(l[i]) for i in r]
except:
try:
i = next(r)
except StopIteration:
i = len(l)
self._raise_column_tuple_error(self._output_io, (l[i],), 0)
# Process the element.Tuple message in x for rows()
def _process_tuple_chunk_Row(self, x,
proc = process_chunk,
):
rc = self._row_constructor
return [
rc(y)
for y in proc(self._output_io, x, self._raise_column_tuple_error)
]
# Process the elemnt.Tuple messages in `x` for chunks()
def _process_tuple_chunk(self, x, proc = process_chunk):
return proc(self._output_io, x, self._raise_column_tuple_error)
def _raise_column_tuple_error(self, procs, tup, itemnum):
'for column processing'
# The element traceback will include the full list of parameters.
data = repr(tup[itemnum])
if len(data) > 80:
# Be sure not to fill screen with noise.
data = data[:75] + ' ...'
em = element.ClientError((
(b'S', 'ERROR'),
(b'C', "--CIO"),
(b'M', "failed to unpack column %r, %s::%s, from wire data" %(
itemnum,
self.column_names[itemnum],
self.database.typio.sql_type_from_oid(
self.statement.pg_column_types[itemnum]
) or '<unknown>',
)
),
(b'D', data),
(b'H', "Try casting the column to 'text'."),
(b'P', str(itemnum)),
))
self.database.typio.raise_client_error(em, creator = self)
@property
def state(self):
if self.closed:
return 'closed'
else:
return 'open'
@property
def column_names(self):
if self._output is not None:
return list(self.database.typio.decodes(self._output.keys()))
# `None` if _output does not exist; not row data
@property
def column_types(self):
if self._output is not None:
return [self.database.typio.type_from_oid(x[3]) for x in self._output]
# `None` if _output does not exist; not row data
@property
def pg_column_types(self):
if self._output is not None:
return [x[3] for x in self._output]
# `None` if _output does not exist; not row data
@property
def sql_column_types(self):
return [
self.database.typio.sql_type_from_oid(x)
for x in self.pg_column_types
]
def command(self):
"The completion message's command identifier"
if self._complete_message is not None:
return self._complete_message.extract_command().decode('ascii')
def count(self):
"The completion message's count number"
if self._complete_message is not None:
return self._complete_message.extract_count()
class Chunks(Output, pg_api.Chunks):
pass
##
# FetchAll - A Chunks cursor that gets *all* the records in the cursor.
#
# It has added complexity over other variants as in order to stream results,
# chunks have to be removed from the protocol transaction's received messages.
# If this wasn't done, the entire result set would be fully buffered prior
# to processing.
class FetchAll(Chunks):
_e_factors = ('statement', 'parameters',)
def _e_metas(self):
yield ('type', type(self).__name__)
def __init__(self, statement, parameters):
self.statement = statement
self.parameters = parameters
self.database = statement.database
Output.__init__(self, '')
def _init(self,
null = element.Null.type,
complete = element.Complete.type,
bindcomplete = element.BindComplete.type,
parsecomplete = element.ParseComplete.type,
):
expect = self._expect
self._xact = self._ins(
self._pq_xp_fetchall() + (element.SynchronizeMessage,)
)
self.database._pq_push(self._xact, self)
# Get more messages until the first Tuple is seen.
STEP = self.database._pq_step
while self._xact.state != xact.Complete:
STEP()
for x in self._xact.messages_received():
if x.__class__ is tuple or expect == x.type:
# No need to step anymore once this is seen.
return
elif x.type == null:
# The protocol transaction is going to be complete..
self.database._pq_complete()
self._xact = None
return
elif x.type == complete:
self._complete_message = x
self.database._pq_complete()
# If this was a select/copy cursor,
# the data messages would have caused an earlier
# return. It's empty.
self._xact = None
return
elif x.type in (bindcomplete, parsecomplete):
# Noise.
pass
else:
# This should have been caught by the protocol transaction.
# "Can't happen".
self.database._pq_complete()
if self._xact.fatal is None:
self._xact.fatal = False
self._xact.error_message = element.ClientError((
(b'S', 'ERROR'),
(b'C', "--000"),
(b'M', "unexpected message type " + repr(x.type))
))
self.database.typio.raise_client_error(self._xact.error_message, creator = self)
return
def __next__(self,
data_types = (tuple,bytes),
complete = element.Complete.type,
):
x = self._xact
# self._xact = None; means that the cursor has been exhausted.
if x is None:
raise StopIteration
# Finish the protocol transaction.
STEP = self.database._pq_step
while x.state is not xact.Complete and not x.completed:
STEP()
# fatal is None == no error
# fatal is True == dead connection
# fatal is False == dead transaction
if x.fatal is not None:
self.database.typio.raise_error(x.error_message, creator = getattr(self, '_controller', self) or self)
# no messages to process?
if not x.completed:
# Transaction has been cleaned out of completed? iterator is done.
self._xact = None
self.close()
raise StopIteration
# Get the chunk to be processed.
chunk = [
y for y in x.completed[0][1]
if y.__class__ in data_types
]
r = self._process_chunk(chunk)
# Scan for _complete_message.
# Arguably, this can fail, but it would be a case
# where multiple sync messages were issued. Something that's
# not naturally occurring.
for y in x.completed[0][1][-3:]:
if getattr(y, 'type', None) == complete:
self._complete_message = y
# Remove it, it's been processed.
del x.completed[0]
return r
class SingleXactCopy(FetchAll):
_expect = element.CopyToBegin.type
_process_chunk = FetchAll._process_copy_chunk
class SingleXactFetch(FetchAll):
_expect = element.Tuple.type
class MultiXactStream(Chunks):
chunksize = 1024 * 4
# only tuple streams
_process_chunk = Output._process_tuple_chunk
def _e_metas(self):
yield ('chunksize', self.chunksize)
yield ('type', self.__class__.__name__)
def __init__(self, statement, parameters, cursor_id):
self.statement = statement
self.parameters = parameters
self.database = statement.database
Output.__init__(self, cursor_id or ID(self))
@abstractmethod
def _bind(self):
"""
Generate the commands needed to bind the cursor.
"""
@abstractmethod
def _fetch(self):
"""
Generate the commands needed to bind the cursor.
"""
def _init(self):
self._command = self._fetch()
self._xact = self._ins(self._bind() + self._command)
self.database._pq_push(self._xact, self)
def __next__(self, tuple_type = tuple):
x = self._xact
if x is None:
raise StopIteration
if self.database.pq.xact is x:
self.database._pq_complete()
# get all the element.Tuple messages
chunk = [
y for y in x.messages_received() if y.__class__ is tuple_type
]
if len(chunk) == self.chunksize:
# there may be more, dispatch the request for the next chunk
self._xact = self._ins(self._command)
self.database._pq_push(self._xact, self)
else:
# it's done.
self._xact = None
self.close()
if not chunk:
# chunk is empty, it's done *right* now.
raise StopIteration
chunk = self._process_chunk(chunk)
return chunk
##
# The cursor is streamed to the client on demand *inside*
# a single SQL transaction block.
class MultiXactInsideBlock(MultiXactStream):
_bind = MultiXactStream._pq_xp_bind
def _fetch(self):
##
# Use the extended protocol's execute to fetch more.
return self._pq_xp_execute(self.chunksize) + \
(element.SynchronizeMessage,)
##
# The cursor is streamed to the client on demand *outside* of
# a single SQL transaction block. [DECLARE ... WITH HOLD]
class MultiXactOutsideBlock(MultiXactStream):
_bind = MultiXactStream._pq_xp_declare
def _fetch(self):
##
# Use the extended protocol's execute to fetch more *against*
# an SQL FETCH statement yielding the data in the proper format.
#
# MultiXactOutsideBlock uses DECLARE to create the cursor WITH HOLD.
# When this is done, the cursor is configured to use StringFormat with
# all columns. It's necessary to use FETCH to adjust the formatting.
return self._pq_xp_fetch(True, self.chunksize) + \
(element.SynchronizeMessage,)
##
# Cursor is used to manage scrollable cursors.
class Cursor(Output, pg_api.Cursor):
_process_tuple = Output._process_tuple_chunk_Row
def _e_metas(self):
yield ('direction', 'FORWARD' if self.direction else 'BACKWORD')
yield ('type', 'Cursor')
def clone(self):