/usr/lib/python3/dist-packages/amqp/channel.py is in python3-amqp 2.2.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 | """AMQP Channels."""
# Copyright (C) 2007-2008 Barry Pederson <bp@barryp.org>
from __future__ import absolute_import, unicode_literals
import logging
import socket
from collections import defaultdict
from warnings import warn
from vine import ensure_promise
from . import spec
from .abstract_channel import AbstractChannel
from .exceptions import (
ChannelError, ConsumerCancelled,
RecoverableChannelError, RecoverableConnectionError, error_for_code,
)
from .five import Queue
from .protocol import queue_declare_ok_t
__all__ = ['Channel']
AMQP_LOGGER = logging.getLogger('amqp')
EXCHANGE_AUTODELETE_DEPRECATED = """\
The auto_delete flag for exchanges has been deprecated and will be removed
from py-amqp v1.5.0.\
"""
REJECTED_MESSAGE_WITHOUT_CALLBACK = """\
Rejecting message with delivery tag %r for reason of having no callbacks.
consumer_tag=%r exchange=%r routing_key=%r.\
"""
class VDeprecationWarning(DeprecationWarning):
pass
class Channel(AbstractChannel):
"""AMQP Channel.
The channel class provides methods for a client to establish a
virtual connection - a channel - to a server and for both peers to
operate the virtual connection thereafter.
GRAMMAR::
channel = open-channel *use-channel close-channel
open-channel = C:OPEN S:OPEN-OK
use-channel = C:FLOW S:FLOW-OK
/ S:FLOW C:FLOW-OK
/ functional-class
close-channel = C:CLOSE S:CLOSE-OK
/ S:CLOSE C:CLOSE-OK
Create a channel bound to a connection and using the specified
numeric channel_id, and open on the server.
The 'auto_decode' parameter (defaults to True), indicates
whether the library should attempt to decode the body
of Messages to a Unicode string if there's a 'content_encoding'
property for the message. If there's no 'content_encoding'
property, or the decode raises an Exception, the message body
is left as plain bytes.
"""
_METHODS = {
spec.method(spec.Channel.Close, 'BsBB'),
spec.method(spec.Channel.CloseOk),
spec.method(spec.Channel.Flow, 'b'),
spec.method(spec.Channel.FlowOk, 'b'),
spec.method(spec.Channel.OpenOk),
spec.method(spec.Exchange.DeclareOk),
spec.method(spec.Exchange.DeleteOk),
spec.method(spec.Exchange.BindOk),
spec.method(spec.Exchange.UnbindOk),
spec.method(spec.Queue.BindOk),
spec.method(spec.Queue.UnbindOk),
spec.method(spec.Queue.DeclareOk, 'sll'),
spec.method(spec.Queue.DeleteOk, 'l'),
spec.method(spec.Queue.PurgeOk, 'l'),
spec.method(spec.Basic.Cancel, 's'),
spec.method(spec.Basic.CancelOk, 's'),
spec.method(spec.Basic.ConsumeOk, 's'),
spec.method(spec.Basic.Deliver, 'sLbss', content=True),
spec.method(spec.Basic.GetEmpty, 's'),
spec.method(spec.Basic.GetOk, 'Lbssl', content=True),
spec.method(spec.Basic.QosOk),
spec.method(spec.Basic.RecoverOk),
spec.method(spec.Basic.Return, 'Bsss', content=True),
spec.method(spec.Tx.CommitOk),
spec.method(spec.Tx.RollbackOk),
spec.method(spec.Tx.SelectOk),
spec.method(spec.Confirm.SelectOk),
spec.method(spec.Basic.Ack, 'Lb'),
}
_METHODS = {m.method_sig: m for m in _METHODS}
def __init__(self, connection,
channel_id=None, auto_decode=True, on_open=None):
if channel_id:
connection._claim_channel_id(channel_id)
else:
channel_id = connection._get_free_channel_id()
AMQP_LOGGER.debug('using channel_id: %s', channel_id)
super(Channel, self).__init__(connection, channel_id)
self.is_open = False
self.active = True # Flow control
self.returned_messages = Queue()
self.callbacks = {}
self.cancel_callbacks = {}
self.auto_decode = auto_decode
self.events = defaultdict(set)
self.no_ack_consumers = set()
self.on_open = ensure_promise(on_open)
# set first time basic_publish_confirm is called
# and publisher confirms are enabled for this channel.
self._confirm_selected = False
if self.connection.confirm_publish:
self.basic_publish = self.basic_publish_confirm
def then(self, on_success, on_error=None):
return self.on_open.then(on_success, on_error)
def _setup_listeners(self):
self._callbacks.update({
spec.Channel.Close: self._on_close,
spec.Channel.CloseOk: self._on_close_ok,
spec.Channel.Flow: self._on_flow,
spec.Channel.OpenOk: self._on_open_ok,
spec.Basic.Cancel: self._on_basic_cancel,
spec.Basic.CancelOk: self._on_basic_cancel_ok,
spec.Basic.Deliver: self._on_basic_deliver,
spec.Basic.Return: self._on_basic_return,
spec.Basic.Ack: self._on_basic_ack,
})
def collect(self):
"""Tear down this object.
Best called after we've agreed to close with the server.
"""
AMQP_LOGGER.debug('Closed channel #%s', self.channel_id)
self.is_open = False
channel_id, self.channel_id = self.channel_id, None
connection, self.connection = self.connection, None
if connection:
connection.channels.pop(channel_id, None)
connection._avail_channel_ids.append(channel_id)
self.callbacks.clear()
self.cancel_callbacks.clear()
self.events.clear()
self.no_ack_consumers.clear()
def _do_revive(self):
self.is_open = False
self.open()
def close(self, reply_code=0, reply_text='', method_sig=(0, 0),
argsig='BsBB'):
"""Request a channel close.
This method indicates that the sender wants to close the
channel. This may be due to internal conditions (e.g. a forced
shut-down) or due to an error handling a specific method, i.e.
an exception. When a close is due to an exception, the sender
provides the class and method id of the method which caused
the exception.
RULE:
After sending this method any received method except
Channel.Close-OK MUST be discarded.
RULE:
The peer sending this method MAY use a counter or timeout
to detect failure of the other peer to respond correctly
with Channel.Close-OK..
PARAMETERS:
reply_code: short
The reply code. The AMQ reply codes are defined in AMQ
RFC 011.
reply_text: shortstr
The localised reply text. This text can be logged as an
aid to resolving issues.
class_id: short
failing method class
When the close is provoked by a method exception, this
is the class of the method.
method_id: short
failing method ID
When the close is provoked by a method exception, this
is the ID of the method.
"""
try:
is_closed = (
not self.is_open or
self.connection is None or
self.connection.channels is None
)
if is_closed:
return
return self.send_method(
spec.Channel.Close, argsig,
(reply_code, reply_text, method_sig[0], method_sig[1]),
wait=spec.Channel.CloseOk,
)
finally:
self.connection = None
def _on_close(self, reply_code, reply_text, class_id, method_id):
"""Request a channel close.
This method indicates that the sender wants to close the
channel. This may be due to internal conditions (e.g. a forced
shut-down) or due to an error handling a specific method, i.e.
an exception. When a close is due to an exception, the sender
provides the class and method id of the method which caused
the exception.
RULE:
After sending this method any received method except
Channel.Close-OK MUST be discarded.
RULE:
The peer sending this method MAY use a counter or timeout
to detect failure of the other peer to respond correctly
with Channel.Close-OK..
PARAMETERS:
reply_code: short
The reply code. The AMQ reply codes are defined in AMQ
RFC 011.
reply_text: shortstr
The localised reply text. This text can be logged as an
aid to resolving issues.
class_id: short
failing method class
When the close is provoked by a method exception, this
is the class of the method.
method_id: short
failing method ID
When the close is provoked by a method exception, this
is the ID of the method.
"""
self.send_method(spec.Channel.CloseOk)
self._do_revive()
raise error_for_code(
reply_code, reply_text, (class_id, method_id), ChannelError,
)
def _on_close_ok(self):
"""Confirm a channel close.
This method confirms a Channel.Close method and tells the
recipient that it is safe to release resources for the channel
and close the socket.
RULE:
A peer that detects a socket closure without having
received a Channel.Close-Ok handshake method SHOULD log
the error.
"""
self.collect()
def flow(self, active):
"""Enable/disable flow from peer.
This method asks the peer to pause or restart the flow of
content data. This is a simple flow-control mechanism that a
peer can use to avoid oveflowing its queues or otherwise
finding itself receiving more messages than it can process.
Note that this method is not intended for window control. The
peer that receives a request to stop sending content should
finish sending the current content, if any, and then wait
until it receives a Flow restart method.
RULE:
When a new channel is opened, it is active. Some
applications assume that channels are inactive until
started. To emulate this behaviour a client MAY open the
channel, then pause it.
RULE:
When sending content data in multiple frames, a peer
SHOULD monitor the channel for incoming methods and
respond to a Channel.Flow as rapidly as possible.
RULE:
A peer MAY use the Channel.Flow method to throttle
incoming content data for internal reasons, for example,
when exchangeing data over a slower connection.
RULE:
The peer that requests a Channel.Flow method MAY
disconnect and/or ban a peer that does not respect the
request.
PARAMETERS:
active: boolean
start/stop content frames
If True, the peer starts sending content frames. If
False, the peer stops sending content frames.
"""
return self.send_method(
spec.Channel.Flow, 'b', (active,), wait=spec.Channel.FlowOk,
)
def _on_flow(self, active):
"""Enable/disable flow from peer.
This method asks the peer to pause or restart the flow of
content data. This is a simple flow-control mechanism that a
peer can use to avoid oveflowing its queues or otherwise
finding itself receiving more messages than it can process.
Note that this method is not intended for window control. The
peer that receives a request to stop sending content should
finish sending the current content, if any, and then wait
until it receives a Flow restart method.
RULE:
When a new channel is opened, it is active. Some
applications assume that channels are inactive until
started. To emulate this behaviour a client MAY open the
channel, then pause it.
RULE:
When sending content data in multiple frames, a peer
SHOULD monitor the channel for incoming methods and
respond to a Channel.Flow as rapidly as possible.
RULE:
A peer MAY use the Channel.Flow method to throttle
incoming content data for internal reasons, for example,
when exchangeing data over a slower connection.
RULE:
The peer that requests a Channel.Flow method MAY
disconnect and/or ban a peer that does not respect the
request.
PARAMETERS:
active: boolean
start/stop content frames
If True, the peer starts sending content frames. If
False, the peer stops sending content frames.
"""
self.active = active
self._x_flow_ok(self.active)
def _x_flow_ok(self, active):
"""Confirm a flow method.
Confirms to the peer that a flow command was received and
processed.
PARAMETERS:
active: boolean
current flow setting
Confirms the setting of the processed flow method:
True means the peer will start sending or continue
to send content frames; False means it will not.
"""
return self.send_method(spec.Channel.FlowOk, 'b', (active,))
def open(self):
"""Open a channel for use.
This method opens a virtual connection (a channel).
RULE:
This method MUST NOT be called when the channel is already
open.
PARAMETERS:
out_of_band: shortstr (DEPRECATED)
out-of-band settings
Configures out-of-band transfers on this channel. The
syntax and meaning of this field will be formally
defined at a later date.
"""
if self.is_open:
return
return self.send_method(
spec.Channel.Open, 's', ('',), wait=spec.Channel.OpenOk,
)
def _on_open_ok(self):
"""Signal that the channel is ready.
This method signals to the client that the channel is ready
for use.
"""
self.is_open = True
self.on_open(self)
AMQP_LOGGER.debug('Channel open')
#############
#
# Exchange
#
#
# work with exchanges
#
# Exchanges match and distribute messages across queues.
# Exchanges can be configured in the server or created at runtime.
#
# GRAMMAR::
#
# exchange = C:DECLARE S:DECLARE-OK
# / C:DELETE S:DELETE-OK
#
# RULE:
#
# The server MUST implement the direct and fanout exchange
# types, and predeclare the corresponding exchanges named
# amq.direct and amq.fanout in each virtual host. The server
# MUST also predeclare a direct exchange to act as the default
# exchange for content Publish methods and for default queue
# bindings.
#
# RULE:
#
# The server SHOULD implement the topic exchange type, and
# predeclare the corresponding exchange named amq.topic in
# each virtual host.
#
# RULE:
#
# The server MAY implement the system exchange type, and
# predeclare the corresponding exchanges named amq.system in
# each virtual host. If the client attempts to bind a queue to
# the system exchange, the server MUST raise a connection
# exception with reply code 507 (not allowed).
#
def exchange_declare(self, exchange, type, passive=False, durable=False,
auto_delete=True, nowait=False, arguments=None,
argsig='BssbbbbbF'):
"""Declare exchange, create if needed.
This method creates an exchange if it does not already exist,
and if the exchange exists, verifies that it is of the correct
and expected class.
RULE:
The server SHOULD support a minimum of 16 exchanges per
virtual host and ideally, impose no limit except as
defined by available resources.
PARAMETERS:
exchange: shortstr
RULE:
Exchange names starting with "amq." are reserved
for predeclared and standardised exchanges. If
the client attempts to create an exchange starting
with "amq.", the server MUST raise a channel
exception with reply code 403 (access refused).
type: shortstr
exchange type
Each exchange belongs to one of a set of exchange
types implemented by the server. The exchange types
define the functionality of the exchange - i.e. how
messages are routed through it. It is not valid or
meaningful to attempt to change the type of an
existing exchange.
RULE:
If the exchange already exists with a different
type, the server MUST raise a connection exception
with a reply code 507 (not allowed).
RULE:
If the server does not support the requested
exchange type it MUST raise a connection exception
with a reply code 503 (command invalid).
passive: boolean
do not create exchange
If set, the server will not create the exchange. The
client can use this to check whether an exchange
exists without modifying the server state.
RULE:
If set, and the exchange does not already exist,
the server MUST raise a channel exception with
reply code 404 (not found).
durable: boolean
request a durable exchange
If set when creating a new exchange, the exchange will
be marked as durable. Durable exchanges remain active
when a server restarts. Non-durable exchanges
(transient exchanges) are purged if/when a server
restarts.
RULE:
The server MUST support both durable and transient
exchanges.
RULE:
The server MUST ignore the durable field if the
exchange already exists.
auto_delete: boolean
auto-delete when unused
If set, the exchange is deleted when all queues have
finished using it.
RULE:
The server SHOULD allow for a reasonable delay
between the point when it determines that an
exchange is not being used (or no longer used),
and the point when it deletes the exchange. At
the least it must allow a client to create an
exchange and then bind a queue to it, with a small
but non-zero delay between these two actions.
RULE:
The server MUST ignore the auto-delete field if
the exchange already exists.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
arguments: table
arguments for declaration
A set of arguments for the declaration. The syntax and
semantics of these arguments depends on the server
implementation. This field is ignored if passive is
True.
"""
if auto_delete:
warn(VDeprecationWarning(EXCHANGE_AUTODELETE_DEPRECATED))
self.send_method(
spec.Exchange.Declare, argsig,
(0, exchange, type, passive, durable, auto_delete,
False, nowait, arguments),
wait=None if nowait else spec.Exchange.DeclareOk,
)
def exchange_delete(self, exchange, if_unused=False, nowait=False,
argsig='Bsbb'):
"""Delete an exchange.
This method deletes an exchange. When an exchange is deleted
all queue bindings on the exchange are cancelled.
PARAMETERS:
exchange: shortstr
RULE:
The exchange MUST exist. Attempting to delete a
non-existing exchange causes a channel exception.
if_unused: boolean
delete only if unused
If set, the server will only delete the exchange if it
has no queue bindings. If the exchange has queue
bindings the server does not delete it but raises a
channel exception instead.
RULE:
If set, the server SHOULD delete the exchange but
only if it has no queue bindings.
RULE:
If set, the server SHOULD raise a channel
exception if the exchange is in use.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
"""
return self.send_method(
spec.Exchange.Delete, argsig, (0, exchange, if_unused, nowait),
wait=None if nowait else spec.Exchange.DeleteOk,
)
def exchange_bind(self, destination, source='', routing_key='',
nowait=False, arguments=None, argsig='BsssbF'):
"""Bind an exchange to an exchange.
RULE:
A server MUST allow and ignore duplicate bindings - that
is, two or more bind methods for a specific exchanges,
with identical arguments - without treating these as an
error.
RULE:
A server MUST allow cycles of exchange bindings to be
created including allowing an exchange to be bound to
itself.
RULE:
A server MUST not deliver the same message more than once
to a destination exchange, even if the topology of
exchanges and bindings results in multiple (even infinite)
routes to that exchange.
PARAMETERS:
reserved-1: short
destination: shortstr
Specifies the name of the destination exchange to
bind.
RULE:
A client MUST NOT be allowed to bind a non-
existent destination exchange.
RULE:
The server MUST accept a blank exchange name to
mean the default exchange.
source: shortstr
Specifies the name of the source exchange to bind.
RULE:
A client MUST NOT be allowed to bind a non-
existent source exchange.
RULE:
The server MUST accept a blank exchange name to
mean the default exchange.
routing-key: shortstr
Specifies the routing key for the binding. The routing
key is used for routing messages depending on the
exchange configuration. Not all exchanges use a
routing key - refer to the specific exchange
documentation.
no-wait: bit
arguments: table
A set of arguments for the binding. The syntax and
semantics of these arguments depends on the exchange
class.
"""
return self.send_method(
spec.Exchange.Bind, argsig,
(0, destination, source, routing_key, nowait, arguments),
wait=None if nowait else spec.Exchange.BindOk,
)
def exchange_unbind(self, destination, source='', routing_key='',
nowait=False, arguments=None, argsig='BsssbF'):
"""Unbind an exchange from an exchange.
RULE:
If a unbind fails, the server MUST raise a connection
exception.
PARAMETERS:
reserved-1: short
destination: shortstr
Specifies the name of the destination exchange to
unbind.
RULE:
The client MUST NOT attempt to unbind an exchange
that does not exist from an exchange.
RULE:
The server MUST accept a blank exchange name to
mean the default exchange.
source: shortstr
Specifies the name of the source exchange to unbind.
RULE:
The client MUST NOT attempt to unbind an exchange
from an exchange that does not exist.
RULE:
The server MUST accept a blank exchange name to
mean the default exchange.
routing-key: shortstr
Specifies the routing key of the binding to unbind.
no-wait: bit
arguments: table
Specifies the arguments of the binding to unbind.
"""
return self.send_method(
spec.Exchange.Unbind, argsig,
(0, destination, source, routing_key, nowait, arguments),
wait=None if nowait else spec.Exchange.UnbindOk,
)
#############
#
# Queue
#
#
# work with queues
#
# Queues store and forward messages. Queues can be configured in
# the server or created at runtime. Queues must be attached to at
# least one exchange in order to receive messages from publishers.
#
# GRAMMAR::
#
# queue = C:DECLARE S:DECLARE-OK
# / C:BIND S:BIND-OK
# / C:PURGE S:PURGE-OK
# / C:DELETE S:DELETE-OK
#
# RULE:
#
# A server MUST allow any content class to be sent to any
# queue, in any mix, and queue and delivery these content
# classes independently. Note that all methods that fetch
# content off queues are specific to a given content class.
#
def queue_bind(self, queue, exchange='', routing_key='',
nowait=False, arguments=None, argsig='BsssbF'):
"""Bind queue to an exchange.
This method binds a queue to an exchange. Until a queue is
bound it will not receive any messages. In a classic
messaging model, store-and-forward queues are bound to a dest
exchange and subscription queues are bound to a dest_wild
exchange.
RULE:
A server MUST allow ignore duplicate bindings - that is,
two or more bind methods for a specific queue, with
identical arguments - without treating these as an error.
RULE:
If a bind fails, the server MUST raise a connection
exception.
RULE:
The server MUST NOT allow a durable queue to bind to a
transient exchange. If the client attempts this the server
MUST raise a channel exception.
RULE:
Bindings for durable queues are automatically durable and
the server SHOULD restore such bindings after a server
restart.
RULE:
The server SHOULD support at least 4 bindings per queue,
and ideally, impose no limit except as defined by
available resources.
PARAMETERS:
queue: shortstr
Specifies the name of the queue to bind. If the queue
name is empty, refers to the current queue for the
channel, which is the last declared queue.
RULE:
If the client did not previously declare a queue,
and the queue name in this method is empty, the
server MUST raise a connection exception with
reply code 530 (not allowed).
RULE:
If the queue does not exist the server MUST raise
a channel exception with reply code 404 (not
found).
exchange: shortstr
The name of the exchange to bind to.
RULE:
If the exchange does not exist the server MUST
raise a channel exception with reply code 404 (not
found).
routing_key: shortstr
message routing key
Specifies the routing key for the binding. The
routing key is used for routing messages depending on
the exchange configuration. Not all exchanges use a
routing key - refer to the specific exchange
documentation. If the routing key is empty and the
queue name is empty, the routing key will be the
current queue for the channel, which is the last
declared queue.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
arguments: table
arguments for binding
A set of arguments for the binding. The syntax and
semantics of these arguments depends on the exchange
class.
"""
return self.send_method(
spec.Queue.Bind, argsig,
(0, queue, exchange, routing_key, nowait, arguments),
wait=None if nowait else spec.Queue.BindOk,
)
def queue_unbind(self, queue, exchange, routing_key='',
nowait=False, arguments=None, argsig='BsssF'):
"""Unbind a queue from an exchange.
This method unbinds a queue from an exchange.
RULE:
If a unbind fails, the server MUST raise a connection exception.
PARAMETERS:
queue: shortstr
Specifies the name of the queue to unbind.
RULE:
The client MUST either specify a queue name or have
previously declared a queue on the same channel
RULE:
The client MUST NOT attempt to unbind a queue that
does not exist.
exchange: shortstr
The name of the exchange to unbind from.
RULE:
The client MUST NOT attempt to unbind a queue from an
exchange that does not exist.
RULE:
The server MUST accept a blank exchange name to mean
the default exchange.
routing_key: shortstr
routing key of binding
Specifies the routing key of the binding to unbind.
arguments: table
arguments of binding
Specifies the arguments of the binding to unbind.
"""
return self.send_method(
spec.Queue.Unbind, argsig,
(0, queue, exchange, routing_key, arguments),
wait=None if nowait else spec.Queue.UnbindOk,
)
def queue_declare(self, queue='', passive=False, durable=False,
exclusive=False, auto_delete=True, nowait=False,
arguments=None, argsig='BsbbbbbF'):
"""Declare queue, create if needed.
This method creates or checks a queue. When creating a new
queue the client can specify various properties that control
the durability of the queue and its contents, and the level of
sharing for the queue.
RULE:
The server MUST create a default binding for a newly-
created queue to the default exchange, which is an
exchange of type 'direct'.
RULE:
The server SHOULD support a minimum of 256 queues per
virtual host and ideally, impose no limit except as
defined by available resources.
PARAMETERS:
queue: shortstr
RULE:
The queue name MAY be empty, in which case the
server MUST create a new queue with a unique
generated name and return this to the client in
the Declare-Ok method.
RULE:
Queue names starting with "amq." are reserved for
predeclared and standardised server queues. If
the queue name starts with "amq." and the passive
option is False, the server MUST raise a connection
exception with reply code 403 (access refused).
passive: boolean
do not create queue
If set, the server will not create the queue. The
client can use this to check whether a queue exists
without modifying the server state.
RULE:
If set, and the queue does not already exist, the
server MUST respond with a reply code 404 (not
found) and raise a channel exception.
durable: boolean
request a durable queue
If set when creating a new queue, the queue will be
marked as durable. Durable queues remain active when
a server restarts. Non-durable queues (transient
queues) are purged if/when a server restarts. Note
that durable queues do not necessarily hold persistent
messages, although it does not make sense to send
persistent messages to a transient queue.
RULE:
The server MUST recreate the durable queue after a
restart.
RULE:
The server MUST support both durable and transient
queues.
RULE:
The server MUST ignore the durable field if the
queue already exists.
exclusive: boolean
request an exclusive queue
Exclusive queues may only be consumed from by the
current connection. Setting the 'exclusive' flag
always implies 'auto-delete'.
RULE:
The server MUST support both exclusive (private)
and non-exclusive (shared) queues.
RULE:
The server MUST raise a channel exception if
'exclusive' is specified and the queue already
exists and is owned by a different connection.
auto_delete: boolean
auto-delete queue when unused
If set, the queue is deleted when all consumers have
finished using it. Last consumer can be cancelled
either explicitly or because its channel is closed. If
there was no consumer ever on the queue, it won't be
deleted.
RULE:
The server SHOULD allow for a reasonable delay
between the point when it determines that a queue
is not being used (or no longer used), and the
point when it deletes the queue. At the least it
must allow a client to create a queue and then
create a consumer to read from it, with a small
but non-zero delay between these two actions. The
server should equally allow for clients that may
be disconnected prematurely, and wish to re-
consume from the same queue without losing
messages. We would recommend a configurable
timeout, with a suitable default value being one
minute.
RULE:
The server MUST ignore the auto-delete field if
the queue already exists.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
arguments: table
arguments for declaration
A set of arguments for the declaration. The syntax and
semantics of these arguments depends on the server
implementation. This field is ignored if passive is
True.
Returns a tuple containing 3 items:
the name of the queue (essential for automatically-named queues)
message count
consumer count
"""
self.send_method(
spec.Queue.Declare, argsig,
(0, queue, passive, durable, exclusive, auto_delete,
nowait, arguments),
)
if not nowait:
return queue_declare_ok_t(*self.wait(
spec.Queue.DeclareOk, returns_tuple=True,
))
def queue_delete(self, queue='',
if_unused=False, if_empty=False, nowait=False,
argsig='Bsbbb'):
"""Delete a queue.
This method deletes a queue. When a queue is deleted any
pending messages are sent to a dead-letter queue if this is
defined in the server configuration, and all consumers on the
queue are cancelled.
RULE:
The server SHOULD use a dead-letter queue to hold messages
that were pending on a deleted queue, and MAY provide
facilities for a system administrator to move these
messages back to an active queue.
PARAMETERS:
queue: shortstr
Specifies the name of the queue to delete. If the
queue name is empty, refers to the current queue for
the channel, which is the last declared queue.
RULE:
If the client did not previously declare a queue,
and the queue name in this method is empty, the
server MUST raise a connection exception with
reply code 530 (not allowed).
RULE:
The queue must exist. Attempting to delete a non-
existing queue causes a channel exception.
if_unused: boolean
delete only if unused
If set, the server will only delete the queue if it
has no consumers. If the queue has consumers the
server does does not delete it but raises a channel
exception instead.
RULE:
The server MUST respect the if-unused flag when
deleting a queue.
if_empty: boolean
delete only if empty
If set, the server will only delete the queue if it
has no messages. If the queue is not empty the server
raises a channel exception.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
"""
return self.send_method(
spec.Queue.Delete, argsig,
(0, queue, if_unused, if_empty, nowait),
wait=None if nowait else spec.Queue.DeleteOk,
)
def queue_purge(self, queue='', nowait=False, argsig='Bsb'):
"""Purge a queue.
This method removes all messages from a queue. It does not
cancel consumers. Purged messages are deleted without any
formal "undo" mechanism.
RULE:
A call to purge MUST result in an empty queue.
RULE:
On transacted channels the server MUST not purge messages
that have already been sent to a client but not yet
acknowledged.
RULE:
The server MAY implement a purge queue or log that allows
system administrators to recover accidentally-purged
messages. The server SHOULD NOT keep purged messages in
the same storage spaces as the live messages since the
volumes of purged messages may get very large.
PARAMETERS:
queue: shortstr
Specifies the name of the queue to purge. If the
queue name is empty, refers to the current queue for
the channel, which is the last declared queue.
RULE:
If the client did not previously declare a queue,
and the queue name in this method is empty, the
server MUST raise a connection exception with
reply code 530 (not allowed).
RULE:
The queue must exist. Attempting to purge a non-
existing queue causes a channel exception.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
if nowait is False, returns a message_count
"""
return self.send_method(
spec.Queue.Purge, argsig, (0, queue, nowait),
wait=None if nowait else spec.Queue.PurgeOk,
)
#############
#
# Basic
#
#
# work with basic content
#
# The Basic class provides methods that support an industry-
# standard messaging model.
#
# GRAMMAR::
#
# basic = C:QOS S:QOS-OK
# / C:CONSUME S:CONSUME-OK
# / C:CANCEL S:CANCEL-OK
# / C:PUBLISH content
# / S:RETURN content
# / S:DELIVER content
# / C:GET ( S:GET-OK content / S:GET-EMPTY )
# / C:ACK
# / C:REJECT
#
# RULE:
#
# The server SHOULD respect the persistent property of basic
# messages and SHOULD make a best-effort to hold persistent
# basic messages on a reliable storage mechanism.
#
# RULE:
#
# The server MUST NOT discard a persistent basic message in
# case of a queue overflow. The server MAY use the
# Channel.Flow method to slow or stop a basic message
# publisher when necessary.
#
# RULE:
#
# The server MAY overflow non-persistent basic messages to
# persistent storage and MAY discard or dead-letter non-
# persistent basic messages on a priority basis if the queue
# size exceeds some configured limit.
#
# RULE:
#
# The server MUST implement at least 2 priority levels for
# basic messages, where priorities 0-4 and 5-9 are treated as
# two distinct levels. The server MAY implement up to 10
# priority levels.
#
# RULE:
#
# The server MUST deliver messages of the same priority in
# order irrespective of their individual persistence.
#
# RULE:
#
# The server MUST support both automatic and explicit
# acknowledgments on Basic content.
#
def basic_ack(self, delivery_tag, multiple=False, argsig='Lb'):
"""Acknowledge one or more messages.
This method acknowledges one or more messages delivered via
the Deliver or Get-Ok methods. The client can ask to confirm
a single message or a set of messages up to and including a
specific message.
PARAMETERS:
delivery_tag: longlong
server-assigned delivery tag
The server-assigned and channel-specific delivery tag
RULE:
The delivery tag is valid only within the channel
from which the message was received. I.e. a client
MUST NOT receive a message on one channel and then
acknowledge it on another.
RULE:
The server MUST NOT use a zero value for delivery
tags. Zero is reserved for client use, meaning "all
messages so far received".
multiple: boolean
acknowledge multiple messages
If set to True, the delivery tag is treated as "up to
and including", so that the client can acknowledge
multiple messages with a single method. If set to
False, the delivery tag refers to a single message.
If the multiple field is True, and the delivery tag
is zero, tells the server to acknowledge all
outstanding mesages.
RULE:
The server MUST validate that a non-zero delivery-
tag refers to an delivered message, and raise a
channel exception if this is not the case.
"""
return self.send_method(
spec.Basic.Ack, argsig, (delivery_tag, multiple),
)
def basic_cancel(self, consumer_tag, nowait=False, argsig='sb'):
"""End a queue consumer.
This method cancels a consumer. This does not affect already
delivered messages, but it does mean the server will not send
any more messages for that consumer. The client may receive
an abitrary number of messages in between sending the cancel
method and receiving the cancel-ok reply.
RULE:
If the queue no longer exists when the client sends a
cancel command, or the consumer has been cancelled for
other reasons, this command has no effect.
PARAMETERS:
consumer_tag: shortstr
consumer tag
Identifier for the consumer, valid within the current
connection.
RULE:
The consumer tag is valid only within the channel
from which the consumer was created. I.e. a client
MUST NOT create a consumer in one channel and then
use it in another.
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
"""
if self.connection is not None:
self.no_ack_consumers.discard(consumer_tag)
return self.send_method(
spec.Basic.Cancel, argsig, (consumer_tag, nowait),
wait=None if nowait else spec.Basic.CancelOk,
)
def _on_basic_cancel(self, consumer_tag):
"""Consumer cancelled by server.
Most likely the queue was deleted.
"""
callback = self._remove_tag(consumer_tag)
if callback:
callback(consumer_tag)
else:
raise ConsumerCancelled(consumer_tag, spec.Basic.Cancel)
def _on_basic_cancel_ok(self, consumer_tag):
self._remove_tag(consumer_tag)
def _remove_tag(self, consumer_tag):
self.callbacks.pop(consumer_tag, None)
return self.cancel_callbacks.pop(consumer_tag, None)
def basic_consume(self, queue='', consumer_tag='', no_local=False,
no_ack=False, exclusive=False, nowait=False,
callback=None, arguments=None, on_cancel=None,
argsig='BssbbbbF'):
"""Start a queue consumer.
This method asks the server to start a "consumer", which is a
transient request for messages from a specific queue.
Consumers last as long as the channel they were created on, or
until the client cancels them.
RULE:
The server SHOULD support at least 16 consumers per queue,
unless the queue was declared as private, and ideally,
impose no limit except as defined by available resources.
PARAMETERS:
queue: shortstr
Specifies the name of the queue to consume from. If
the queue name is null, refers to the current queue
for the channel, which is the last declared queue.
RULE:
If the client did not previously declare a queue,
and the queue name in this method is empty, the
server MUST raise a connection exception with
reply code 530 (not allowed).
consumer_tag: shortstr
Specifies the identifier for the consumer. The
consumer tag is local to a connection, so two clients
can use the same consumer tags. If this field is empty
the server will generate a unique tag.
RULE:
The tag MUST NOT refer to an existing consumer. If
the client attempts to create two consumers with
the same non-empty tag the server MUST raise a
connection exception with reply code 530 (not
allowed).
no_local: boolean
do not deliver own messages
If the no-local field is set the server will not send
messages to the client that published them.
no_ack: boolean
no acknowledgment needed
If this field is set the server does not expect
acknowledgments for messages. That is, when a message
is delivered to the client the server automatically and
silently acknowledges it on behalf of the client. This
functionality increases performance but at the cost of
reliability. Messages can get lost if a client dies
before it can deliver them to the application.
exclusive: boolean
request exclusive access
Request exclusive consumer access, meaning only this
consumer can access the queue.
RULE:
If the server cannot grant exclusive access to the
queue when asked, - because there are other
consumers active - it MUST raise a channel
exception with return code 403 (access refused).
nowait: boolean
do not send a reply method
If set, the server will not respond to the method. The
client should not wait for a reply method. If the
server could not complete the method it will raise a
channel or connection exception.
callback: Python callable
function/method called with each delivered message
For each message delivered by the broker, the
callable will be called with a Message object
as the single argument. If no callable is specified,
messages are quietly discarded, no_ack should probably
be set to True in that case.
"""
p = self.send_method(
spec.Basic.Consume, argsig,
(0, queue, consumer_tag, no_local, no_ack, exclusive,
nowait, arguments),
wait=None if nowait else spec.Basic.ConsumeOk,
)
# XXX Fix this hack
if not nowait and not consumer_tag:
consumer_tag = p
self.callbacks[consumer_tag] = callback
if on_cancel:
self.cancel_callbacks[consumer_tag] = on_cancel
if no_ack:
self.no_ack_consumers.add(consumer_tag)
return p
def _on_basic_deliver(self, consumer_tag, delivery_tag, redelivered,
exchange, routing_key, msg):
msg.channel = self
msg.delivery_info = {
'consumer_tag': consumer_tag,
'delivery_tag': delivery_tag,
'redelivered': redelivered,
'exchange': exchange,
'routing_key': routing_key,
}
try:
fun = self.callbacks[consumer_tag]
except KeyError:
AMQP_LOGGER.warning(
REJECTED_MESSAGE_WITHOUT_CALLBACK,
delivery_tag, consumer_tag, exchange, routing_key,
)
self.basic_reject(delivery_tag, requeue=True)
else:
fun(msg)
def basic_get(self, queue='', no_ack=False, argsig='Bsb'):
"""Direct access to a queue.
This method provides a direct access to the messages in a
queue using a synchronous dialogue that is designed for
specific types of application where synchronous functionality
is more important than performance.
PARAMETERS:
queue: shortstr
Specifies the name of the queue to consume from. If
the queue name is null, refers to the current queue
for the channel, which is the last declared queue.
RULE:
If the client did not previously declare a queue,
and the queue name in this method is empty, the
server MUST raise a connection exception with
reply code 530 (not allowed).
no_ack: boolean
no acknowledgment needed
If this field is set the server does not expect
acknowledgments for messages. That is, when a message
is delivered to the client the server automatically and
silently acknowledges it on behalf of the client. This
functionality increases performance but at the cost of
reliability. Messages can get lost if a client dies
before it can deliver them to the application.
Non-blocking, returns a message object, or None.
"""
ret = self.send_method(
spec.Basic.Get, argsig, (0, queue, no_ack),
wait=[spec.Basic.GetOk, spec.Basic.GetEmpty], returns_tuple=True,
)
if not ret or len(ret) < 2:
return self._on_get_empty(*ret)
return self._on_get_ok(*ret)
def _on_get_empty(self, cluster_id=None):
pass
def _on_get_ok(self, delivery_tag, redelivered, exchange, routing_key,
message_count, msg):
msg.channel = self
msg.delivery_info = {
'delivery_tag': delivery_tag,
'redelivered': redelivered,
'exchange': exchange,
'routing_key': routing_key,
'message_count': message_count
}
return msg
def _basic_publish(self, msg, exchange='', routing_key='',
mandatory=False, immediate=False, timeout=None,
argsig='Bssbb'):
"""Publish a message.
This method publishes a message to a specific exchange. The
message will be routed to queues as defined by the exchange
configuration and distributed to any active consumers when the
transaction, if any, is committed.
PARAMETERS:
exchange: shortstr
Specifies the name of the exchange to publish to. The
exchange name can be empty, meaning the default
exchange. If the exchange name is specified, and that
exchange does not exist, the server will raise a
channel exception.
RULE:
The server MUST accept a blank exchange name to
mean the default exchange.
RULE:
The exchange MAY refuse basic content in which
case it MUST raise a channel exception with reply
code 540 (not implemented).
routing_key: shortstr
Message routing key
Specifies the routing key for the message. The
routing key is used for routing messages depending on
the exchange configuration.
mandatory: boolean
indicate mandatory routing
This flag tells the server how to react if the message
cannot be routed to a queue. If this flag is True, the
server will return an unroutable message with a Return
method. If this flag is False, the server silently
drops the message.
RULE:
The server SHOULD implement the mandatory flag.
immediate: boolean
request immediate delivery
This flag tells the server how to react if the message
cannot be routed to a queue consumer immediately. If
this flag is set, the server will return an
undeliverable message with a Return method. If this
flag is zero, the server will queue the message, but
with no guarantee that it will ever be consumed.
RULE:
The server SHOULD implement the immediate flag.
"""
if not self.connection:
raise RecoverableConnectionError(
'basic_publish: connection closed')
try:
with self.connection.transport.having_timeout(timeout):
return self.send_method(
spec.Basic.Publish, argsig,
(0, exchange, routing_key, mandatory, immediate), msg
)
except socket.timeout:
raise RecoverableChannelError('basic_publish: timed out')
basic_publish = _basic_publish
def basic_publish_confirm(self, *args, **kwargs):
if not self._confirm_selected:
self._confirm_selected = True
self.confirm_select()
ret = self._basic_publish(*args, **kwargs)
self.wait(spec.Basic.Ack)
return ret
def basic_qos(self, prefetch_size, prefetch_count, a_global,
argsig='lBb'):
"""Specify quality of service.
This method requests a specific quality of service. The QoS
can be specified for the current channel or for all channels
on the connection. The particular properties and semantics of
a qos method always depend on the content class semantics.
Though the qos method could in principle apply to both peers,
it is currently meaningful only for the server.
PARAMETERS:
prefetch_size: long
prefetch window in octets
The client can request that messages be sent in
advance so that when the client finishes processing a
message, the following message is already held
locally, rather than needing to be sent down the
channel. Prefetching gives a performance improvement.
This field specifies the prefetch window size in
octets. The server will send a message in advance if
it is equal to or smaller in size than the available
prefetch size (and also falls into other prefetch
limits). May be set to zero, meaning "no specific
limit", although other prefetch limits may still
apply. The prefetch-size is ignored if the no-ack
option is set.
RULE:
The server MUST ignore this setting when the
client is not processing any messages - i.e. the
prefetch size does not limit the transfer of
single messages to a client, only the sending in
advance of more messages while the client still
has one or more unacknowledged messages.
prefetch_count: short
prefetch window in messages
Specifies a prefetch window in terms of whole
messages. This field may be used in combination with
the prefetch-size field; a message will only be sent
in advance if both prefetch windows (and those at the
channel and connection level) allow it. The prefetch-
count is ignored if the no-ack option is set.
RULE:
The server MAY send less data in advance than
allowed by the client's specified prefetch windows
but it MUST NOT send more.
a_global: boolean
apply to entire connection
By default the QoS settings apply to the current
channel only. If this field is set, they are applied
to the entire connection.
"""
return self.send_method(
spec.Basic.Qos, argsig, (prefetch_size, prefetch_count, a_global),
wait=spec.Basic.QosOk,
)
def basic_recover(self, requeue=False):
"""Redeliver unacknowledged messages.
This method asks the broker to redeliver all unacknowledged
messages on a specified channel. Zero or more messages may be
redelivered. This method is only allowed on non-transacted
channels.
RULE:
The server MUST set the redelivered flag on all messages
that are resent.
RULE:
The server MUST raise a channel exception if this is
called on a transacted channel.
PARAMETERS:
requeue: boolean
requeue the message
If this field is False, the message will be redelivered
to the original recipient. If this field is True, the
server will attempt to requeue the message,
potentially then delivering it to an alternative
subscriber.
"""
return self.send_method(spec.Basic.Recover, 'b', (requeue,))
def basic_recover_async(self, requeue=False):
return self.send_method(spec.Basic.RecoverAsync, 'b', (requeue,))
def basic_reject(self, delivery_tag, requeue, argsig='Lb'):
"""Reject an incoming message.
This method allows a client to reject a message. It can be
used to interrupt and cancel large incoming messages, or
return untreatable messages to their original queue.
RULE:
The server SHOULD be capable of accepting and process the
Reject method while sending message content with a Deliver
or Get-Ok method. I.e. the server should read and process
incoming methods while sending output frames. To cancel a
partially-send content, the server sends a content body
frame of size 1 (i.e. with no data except the frame-end
octet).
RULE:
The server SHOULD interpret this method as meaning that
the client is unable to process the message at this time.
RULE:
A client MUST NOT use this method as a means of selecting
messages to process. A rejected message MAY be discarded
or dead-lettered, not necessarily passed to another
client.
PARAMETERS:
delivery_tag: longlong
server-assigned delivery tag
The server-assigned and channel-specific delivery tag
RULE:
The delivery tag is valid only within the channel
from which the message was received. I.e. a client
MUST NOT receive a message on one channel and then
acknowledge it on another.
RULE:
The server MUST NOT use a zero value for delivery
tags. Zero is reserved for client use, meaning "all
messages so far received".
requeue: boolean
requeue the message
If this field is False, the message will be discarded.
If this field is True, the server will attempt to
requeue the message.
RULE:
The server MUST NOT deliver the message to the
same client within the context of the current
channel. The recommended strategy is to attempt
to deliver the message to an alternative consumer,
and if that is not possible, to move the message
to a dead-letter queue. The server MAY use more
sophisticated tracking to hold the message on the
queue and redeliver it to the same client at a
later stage.
"""
return self.send_method(
spec.Basic.Reject, argsig, (delivery_tag, requeue),
)
def _on_basic_return(self, reply_code, reply_text,
exchange, routing_key, message):
"""Return a failed message.
This method returns an undeliverable message that was
published with the "immediate" flag set, or an unroutable
message published with the "mandatory" flag set. The reply
code and text provide information about the reason that the
message was undeliverable.
PARAMETERS:
reply_code: short
The reply code. The AMQ reply codes are defined in AMQ
RFC 011.
reply_text: shortstr
The localised reply text. This text can be logged as an
aid to resolving issues.
exchange: shortstr
Specifies the name of the exchange that the message
was originally published to.
routing_key: shortstr
Message routing key
Specifies the routing key name specified when the
message was published.
"""
exc = error_for_code(
reply_code, reply_text, spec.Basic.Return, ChannelError,
)
handlers = self.events.get('basic_return')
if not handlers:
raise exc
for callback in handlers:
callback(exc, exchange, routing_key, message)
#############
#
# Tx
#
#
# work with standard transactions
#
# Standard transactions provide so-called "1.5 phase commit". We
# can ensure that work is never lost, but there is a chance of
# confirmations being lost, so that messages may be resent.
# Applications that use standard transactions must be able to
# detect and ignore duplicate messages.
#
# GRAMMAR::
#
# tx = C:SELECT S:SELECT-OK
# / C:COMMIT S:COMMIT-OK
# / C:ROLLBACK S:ROLLBACK-OK
#
# RULE:
#
# An client using standard transactions SHOULD be able to
# track all messages received within a reasonable period, and
# thus detect and reject duplicates of the same message. It
# SHOULD NOT pass these to the application layer.
#
#
def tx_commit(self):
"""Commit the current transaction.
This method commits all messages published and acknowledged in
the current transaction. A new transaction starts immediately
after a commit.
"""
return self.send_method(spec.Tx.Commit, wait=spec.Tx.CommitOk)
def tx_rollback(self):
"""Abandon the current transaction.
This method abandons all messages published and acknowledged
in the current transaction. A new transaction starts
immediately after a rollback.
"""
return self.send_method(spec.Tx.Rollback, wait=spec.Tx.RollbackOk)
def tx_select(self):
"""Select standard transaction mode.
This method sets the channel to use standard transactions.
The client must use this method at least once on a channel
before using the Commit or Rollback methods.
"""
return self.send_method(spec.Tx.Select, wait=spec.Tx.SelectOk)
def confirm_select(self, nowait=False):
"""Enable publisher confirms for this channel.
Note: This is an RabbitMQ extension.
Can now be used if the channel is in transactional mode.
:param nowait:
If set, the server will not respond to the method.
The client should not wait for a reply method. If the
server could not complete the method it will raise a channel
or connection exception.
"""
return self.send_method(
spec.Confirm.Select, 'b', (nowait,),
wait=None if nowait else spec.Confirm.SelectOk,
)
def _on_basic_ack(self, delivery_tag, multiple):
for callback in self.events['basic_ack']:
callback(delivery_tag, multiple)
|