/usr/share/pyshared/gluon/contrib/pg8000/interface.py is in python-gluon 1.99.7-1.
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#
# Copyright (c) 2007-2009, Mathieu Fenniak
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# * The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
__author__ = "Mathieu Fenniak"
import socket
import protocol
import threading
from errors import *
def conninfo_parse(conninfo):
"Conninfo parser routine based on libpq conninfo_parse"
options = {}
buf = conninfo + " "
tmp = pname = ""
quoted_string = False
cp = 0
while cp < len(buf):
# Skip blanks before the parameter name
c = buf[cp]
if c.isspace() and tmp and not quoted_string and pname:
options[pname] = tmp
tmp = pname = ""
elif c == "'":
quoted_string = not quoted_string
elif c == '\\':
cp += 1
tmp += buf[cp]
elif c == "=":
if not tmp:
raise RuntimeError("missing parameter name (conninfo:%s)" % cp)
pname = tmp
tmp = ""
elif not c.isspace() or quoted_string:
tmp += c
cp += 1
if quoted_string:
raise RuntimeError("unterminated quoted string (conninfo:%s)" % cp)
return options
class DataIterator(object):
def __init__(self, obj, func):
self.obj = obj
self.func = func
def __iter__(self):
return self
def next(self):
retval = self.func(self.obj)
if retval == None:
raise StopIteration()
return retval
statement_number_lock = threading.Lock()
statement_number = 0
##
# This class represents a prepared statement. A prepared statement is
# pre-parsed on the server, which reduces the need to parse the query every
# time it is run. The statement can have parameters in the form of $1, $2, $3,
# etc. When parameters are used, the types of the parameters need to be
# specified when creating the prepared statement.
# <p>
# As of v1.01, instances of this class are thread-safe. This means that a
# single PreparedStatement can be accessed by multiple threads without the
# internal consistency of the statement being altered. However, the
# responsibility is on the client application to ensure that one thread reading
# from a statement isn't affected by another thread starting a new query with
# the same statement.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
#
# @param connection An instance of {@link Connection Connection}.
#
# @param statement The SQL statement to be represented, often containing
# parameters in the form of $1, $2, $3, etc.
#
# @param types Python type objects for each parameter in the SQL
# statement. For example, int, float, str.
class PreparedStatement(object):
##
# Determines the number of rows to read from the database server at once.
# Reading more rows increases performance at the cost of memory. The
# default value is 100 rows. The affect of this parameter is transparent.
# That is, the library reads more rows when the cache is empty
# automatically.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx. It is
# possible that implementation changes in the future could cause this
# parameter to be ignored.
row_cache_size = 100
def __init__(self, connection, statement, *types, **kwargs):
global statement_number
if connection == None or connection.c == None:
raise InterfaceError("connection not provided")
try:
statement_number_lock.acquire()
self._statement_number = statement_number
statement_number += 1
finally:
statement_number_lock.release()
self.c = connection.c
self._portal_name = None
self._statement_name = kwargs.get("statement_name", "pg8000_statement_%s" % self._statement_number)
self._row_desc = None
self._cached_rows = []
self._ongoing_row_count = 0
self._command_complete = True
self._parse_row_desc = self.c.parse(self._statement_name, statement, types)
self._lock = threading.RLock()
def close(self):
if self._statement_name != "": # don't close unnamed statement
self.c.close_statement(self._statement_name)
if self._portal_name != None:
self.c.close_portal(self._portal_name)
self._portal_name = None
row_description = property(lambda self: self._getRowDescription())
def _getRowDescription(self):
if self._row_desc == None:
return None
return self._row_desc.fields
##
# Run the SQL prepared statement with the given parameters.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def execute(self, *args, **kwargs):
self._lock.acquire()
try:
if not self._command_complete:
# cleanup last execute
self._cached_rows = []
self._ongoing_row_count = 0
if self._portal_name != None:
self.c.close_portal(self._portal_name)
self._command_complete = False
self._portal_name = "pg8000_portal_%s" % self._statement_number
self._row_desc, cmd = self.c.bind(self._portal_name, self._statement_name, args, self._parse_row_desc, kwargs.get("stream"))
if self._row_desc:
# We execute our cursor right away to fill up our cache. This
# prevents the cursor from being destroyed, apparently, by a rogue
# Sync between Bind and Execute. Since it is quite likely that
# data will be read from us right away anyways, this seems a safe
# move for now.
self._fill_cache()
else:
self._command_complete = True
self._ongoing_row_count = -1
if cmd != None and cmd.rows != None:
self._ongoing_row_count = cmd.rows
finally:
self._lock.release()
def _fill_cache(self):
self._lock.acquire()
try:
if self._cached_rows:
raise InternalError("attempt to fill cache that isn't empty")
end_of_data, rows = self.c.fetch_rows(self._portal_name, self.row_cache_size, self._row_desc)
self._cached_rows = rows
if end_of_data:
self._command_complete = True
finally:
self._lock.release()
def _fetch(self):
if not self._row_desc:
raise ProgrammingError("no result set")
self._lock.acquire()
try:
if not self._cached_rows:
if self._command_complete:
return None
self._fill_cache()
if self._command_complete and not self._cached_rows:
# fill cache tells us the command is complete, but yet we have
# no rows after filling our cache. This is a special case when
# a query returns no rows.
return None
row = self._cached_rows.pop(0)
self._ongoing_row_count += 1
return tuple(row)
finally:
self._lock.release()
##
# Return a count of the number of rows relevant to the executed statement.
# For a SELECT, this is the number of rows returned. For UPDATE or DELETE,
# this the number of rows affected. For INSERT, the number of rows
# inserted. This property may have a value of -1 to indicate that there
# was no row count.
# <p>
# During a result-set query (eg. SELECT, or INSERT ... RETURNING ...),
# accessing this property requires reading the entire result-set into
# memory, as reading the data to completion is the only way to determine
# the total number of rows. Avoid using this property in with
# result-set queries, as it may cause unexpected memory usage.
# <p>
# Stability: Added in v1.03, stability guaranteed for v1.xx.
row_count = property(lambda self: self._get_row_count())
def _get_row_count(self):
self._lock.acquire()
try:
if not self._command_complete:
end_of_data, rows = self.c.fetch_rows(self._portal_name, 0, self._row_desc)
self._cached_rows += rows
if end_of_data:
self._command_complete = True
else:
raise InternalError("fetch_rows(0) did not hit end of data")
return self._ongoing_row_count + len(self._cached_rows)
finally:
self._lock.release()
##
# Read a row from the database server, and return it in a dictionary
# indexed by column name/alias. This method will raise an error if two
# columns have the same name. Returns None after the last row.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def read_dict(self):
row = self._fetch()
if row == None:
return row
retval = {}
for i in range(len(self._row_desc.fields)):
col_name = self._row_desc.fields[i]['name']
if retval.has_key(col_name):
raise InterfaceError("cannot return dict of row when two columns have the same name (%r)" % (col_name,))
retval[col_name] = row[i]
return retval
##
# Read a row from the database server, and return it as a tuple of values.
# Returns None after the last row.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def read_tuple(self):
return self._fetch()
##
# Return an iterator for the output of this statement. The iterator will
# return a tuple for each row, in the same manner as {@link
# #PreparedStatement.read_tuple read_tuple}.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def iterate_tuple(self):
return DataIterator(self, PreparedStatement.read_tuple)
##
# Return an iterator for the output of this statement. The iterator will
# return a dict for each row, in the same manner as {@link
# #PreparedStatement.read_dict read_dict}.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def iterate_dict(self):
return DataIterator(self, PreparedStatement.read_dict)
class SimpleStatement(PreparedStatement):
"Internal wrapper to Simple Query protocol emulating a PreparedStatement"
# This should be used internally only for trivial queries
# (not a true Prepared Statement, in fact it can have multiple statements)
# See Simple Query Protocol limitations and trade-offs (send_simple_query)
row_cache_size = None
def __init__(self, connection, statement):
if connection == None or connection.c == None:
raise InterfaceError("connection not provided")
self.c = connection.c
self._row_desc = None
self._cached_rows = []
self._ongoing_row_count = -1
self._command_complete = True
self.statement = statement
self._lock = threading.RLock()
def close(self):
# simple query doesn't have portals
pass
def execute(self, *args, **kwargs):
"Run the SQL simple query stataments"
self._lock.acquire()
try:
self._row_desc, cmd_complete, self._cached_rows = \
self.c.send_simple_query(self.statement, kwargs.get("stream"))
self._command_complete = True
self._ongoing_row_count = -1
if cmd_complete is not None and cmd_complete.rows is not None:
self._ongoing_row_count = cmd_complete.rows
finally:
self._lock.release()
def _fill_cache(self):
# data rows are already fetched in _cached_rows
pass
def _fetch(self):
if not self._row_desc:
raise ProgrammingError("no result set")
self._lock.acquire()
try:
if not self._cached_rows:
return None
row = self._cached_rows.pop(0)
return tuple(row)
finally:
self._lock.release()
def _get_row_count(self):
return self._ongoing_row_count
##
# The Cursor class allows multiple queries to be performed concurrently with a
# single PostgreSQL connection. The Cursor object is implemented internally by
# using a {@link PreparedStatement PreparedStatement} object, so if you plan to
# use a statement multiple times, you might as well create a PreparedStatement
# and save a small amount of reparsing time.
# <p>
# As of v1.01, instances of this class are thread-safe. See {@link
# PreparedStatement PreparedStatement} for more information.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
#
# @param connection An instance of {@link Connection Connection}.
class Cursor(object):
def __init__(self, connection):
self.connection = connection
self._stmt = None
def require_stmt(func):
def retval(self, *args, **kwargs):
if self._stmt == None:
raise ProgrammingError("attempting to use unexecuted cursor")
return func(self, *args, **kwargs)
return retval
row_description = property(lambda self: self._getRowDescription())
def _getRowDescription(self):
if self._stmt == None:
return None
return self._stmt.row_description
##
# Run an SQL statement using this cursor. The SQL statement can have
# parameters in the form of $1, $2, $3, etc., which will be filled in by
# the additional arguments passed to this function.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
# @param query The SQL statement to execute.
def execute(self, query, *args, **kwargs):
if self.connection.is_closed:
raise ConnectionClosedError()
self.connection._unnamed_prepared_statement_lock.acquire()
try:
if kwargs.get("simple_query"):
# no arguments and no statement name,
# use PostgreSQL Simple Query Protocol
## print "SimpleQuery:", query
self._stmt = SimpleStatement(self.connection, query)
else:
# use PostgreSQL Extended Query Protocol
self._stmt = PreparedStatement(self.connection, query, statement_name="", *[{"type": type(x), "value": x} for x in args])
self._stmt.execute(*args, **kwargs)
finally:
self.connection._unnamed_prepared_statement_lock.release()
##
# Return a count of the number of rows currently being read. If possible,
# please avoid using this function. It requires reading the entire result
# set from the database to determine the number of rows being returned.
# <p>
# Stability: Added in v1.03, stability guaranteed for v1.xx.
# Implementation currently requires caching entire result set into memory,
# avoid using this property.
row_count = property(lambda self: self._get_row_count())
@require_stmt
def _get_row_count(self):
return self._stmt.row_count
##
# Read a row from the database server, and return it in a dictionary
# indexed by column name/alias. This method will raise an error if two
# columns have the same name. Returns None after the last row.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
@require_stmt
def read_dict(self):
return self._stmt.read_dict()
##
# Read a row from the database server, and return it as a tuple of values.
# Returns None after the last row.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
@require_stmt
def read_tuple(self):
return self._stmt.read_tuple()
##
# Return an iterator for the output of this statement. The iterator will
# return a tuple for each row, in the same manner as {@link
# #PreparedStatement.read_tuple read_tuple}.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
@require_stmt
def iterate_tuple(self):
return self._stmt.iterate_tuple()
##
# Return an iterator for the output of this statement. The iterator will
# return a dict for each row, in the same manner as {@link
# #PreparedStatement.read_dict read_dict}.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
@require_stmt
def iterate_dict(self):
return self._stmt.iterate_dict()
def close(self):
if self._stmt != None:
self._stmt.close()
self._stmt = None
##
# Return the fileno of the underlying socket for this cursor's connection.
# <p>
# Stability: Added in v1.07, stability guaranteed for v1.xx.
def fileno(self):
return self.connection.fileno()
##
# Poll the underlying socket for this cursor and sync if there is data waiting
# to be read. This has the effect of flushing asynchronous messages from the
# backend. Returns True if messages were read, False otherwise.
# <p>
# Stability: Added in v1.07, stability guaranteed for v1.xx.
def isready(self):
return self.connection.isready()
##
# This class represents a connection to a PostgreSQL database.
# <p>
# The database connection is derived from the {@link #Cursor Cursor} class,
# which provides a default cursor for running queries. It also provides
# transaction control via the 'begin', 'commit', and 'rollback' methods.
# Without beginning a transaction explicitly, all statements will autocommit to
# the database.
# <p>
# As of v1.01, instances of this class are thread-safe. See {@link
# PreparedStatement PreparedStatement} for more information.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
#
# @param user The username to connect to the PostgreSQL server with. This
# parameter is required.
#
# @keyparam host The hostname of the PostgreSQL server to connect with.
# Providing this parameter is necessary for TCP/IP connections. One of either
# host, or unix_sock, must be provided.
#
# @keyparam unix_sock The path to the UNIX socket to access the database
# through, for example, '/tmp/.s.PGSQL.5432'. One of either unix_sock or host
# must be provided. The port parameter will have no affect if unix_sock is
# provided.
#
# @keyparam port The TCP/IP port of the PostgreSQL server instance. This
# parameter defaults to 5432, the registered and common port of PostgreSQL
# TCP/IP servers.
#
# @keyparam database The name of the database instance to connect with. This
# parameter is optional, if omitted the PostgreSQL server will assume the
# database name is the same as the username.
#
# @keyparam password The user password to connect to the server with. This
# parameter is optional. If omitted, and the database server requests password
# based authentication, the connection will fail. On the other hand, if this
# parameter is provided and the database does not request password
# authentication, then the password will not be used.
#
# @keyparam socket_timeout Socket connect timeout measured in seconds.
# Defaults to 60 seconds.
#
# @keyparam ssl Use SSL encryption for TCP/IP socket. Defaults to False.
class Connection(Cursor):
def __init__(self, dsn="", user=None, host=None, unix_sock=None, port=5432, database=None, password=None, socket_timeout=60, ssl=False):
self._row_desc = None
if dsn:
# update connection parameters parsed of the conninfo dsn
opts = conninfo_parse(dsn)
database = opts.get("dbname", database)
user = opts.get("user", user)
password = opts.get("password", user)
host = opts.get("host", host)
port = int(opts.get("port", port))
ssl = opts.get("sslmode", 'disable') != 'disable'
try:
self.c = protocol.Connection(unix_sock=unix_sock, host=host, port=port, socket_timeout=socket_timeout, ssl=ssl)
self.c.authenticate(user, password=password, database=database)
except socket.error, e:
raise InterfaceError("communication error", e)
Cursor.__init__(self, self)
self._begin = PreparedStatement(self, "BEGIN TRANSACTION")
self._commit = PreparedStatement(self, "COMMIT TRANSACTION")
self._rollback = PreparedStatement(self, "ROLLBACK TRANSACTION")
self._unnamed_prepared_statement_lock = threading.RLock()
self.in_transaction = False
self.autocommit = False
##
# An event handler that is fired when NOTIFY occurs for a notification that
# has been LISTEN'd for. The value of this property is a
# util.MulticastDelegate. A callback can be added by using
# connection.NotificationReceived += SomeMethod. The method will be called
# with a single argument, an object that has properties: backend_pid,
# condition, and additional_info. Callbacks can be removed with the -=
# operator.
# <p>
# Stability: Added in v1.03, stability guaranteed for v1.xx.
NotificationReceived = property(
lambda self: getattr(self.c, "NotificationReceived"),
lambda self, value: setattr(self.c, "NotificationReceived", value)
)
##
# An event handler that is fired when the database server issues a notice.
# The value of this property is a util.MulticastDelegate. A callback can
# be added by using connection.NotificationReceived += SomeMethod. The
# method will be called with a single argument, an object that has
# properties: severity, code, msg, and possibly others (detail, hint,
# position, where, file, line, and routine). Callbacks can be removed with
# the -= operator.
# <p>
# Stability: Added in v1.03, stability guaranteed for v1.xx.
NoticeReceived = property(
lambda self: getattr(self.c, "NoticeReceived"),
lambda self, value: setattr(self.c, "NoticeReceived", value)
)
##
# An event handler that is fired when a runtime configuration option is
# changed on the server. The value of this property is a
# util.MulticastDelegate. A callback can be added by using
# connection.NotificationReceived += SomeMethod. Callbacks can be removed
# with the -= operator. The method will be called with a single argument,
# an object that has properties "key" and "value".
# <p>
# Stability: Added in v1.03, stability guaranteed for v1.xx.
ParameterStatusReceived = property(
lambda self: getattr(self.c, "ParameterStatusReceived"),
lambda self, value: setattr(self.c, "ParameterStatusReceived", value)
)
##
# Begins a new transaction.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def begin(self):
if self.is_closed:
raise ConnectionClosedError()
if self.autocommit:
return
self._begin.execute()
self.in_transaction = True
##
# Commits the running transaction.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def commit(self):
if self.is_closed:
raise ConnectionClosedError()
self._commit.execute()
self.in_transaction = False
##
# Rolls back the running transaction.
# <p>
# Stability: Added in v1.00, stability guaranteed for v1.xx.
def rollback(self):
if self.is_closed:
raise ConnectionClosedError()
self._rollback.execute()
self.in_transaction = False
##
# Closes an open connection.
def close(self):
if self.is_closed:
raise ConnectionClosedError()
self.c.close()
self.c = None
is_closed = property(lambda self: self.c == None)
##
# Return the fileno of the underlying socket for this connection.
# <p>
# Stability: Added in v1.07, stability guaranteed for v1.xx.
def fileno(self):
return self.c.fileno()
##
# Poll the underlying socket for this connection and sync if there is data
# waiting to be read. This has the effect of flushing asynchronous
# messages from the backend. Returns True if messages were read, False
# otherwise.
# <p>
# Stability: Added in v1.07, stability guaranteed for v1.xx.
def isready(self):
return self.c.isready()
##
# Return the server_version as reported from the connected server.
# Raises InterfaceError if no version has been reported from the server.
def server_version(self):
return self.c.server_version()
def encoding(self, encoding=None):
"Returns the client_encoding as reported from the connected server"
return self.c.encoding()
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