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"""Table handler.
Per-table decision how to create trigger, copy data and apply events.
"""
"""
-- redirect & create table
partition by batch_time
partition by date field
-- sql handling:
cube1 - I/U/D -> partition, insert
cube2 - I/U/D -> partition, del/insert
field remap
name remap
bublin filter
- replay: filter events
- copy: additional where
- add: add trigger args
multimaster
- replay: conflict handling, add fncall to sql queue?
- add: add 'backup' arg to trigger
plain londiste:
- replay: add to sql queue
"""
import sys, skytools
__all__ = ['RowCache', 'BaseHandler', 'parse_handler', 'build_handler', 'load_handlers']
class RowCache:
def __init__(self, table_name):
self.table_name = table_name
self.keys = {}
self.rows = []
def add_row(self, d):
row = [None] * len(self.keys)
for k, v in d.items():
try:
row[self.keys[k]] = v
except KeyError:
i = len(row)
self.keys[k] = i
row.append(v)
row = tuple(row)
self.rows.append(row)
def get_fields(self):
row = [None] * len(self.keys)
for k, i in self.keys.keys():
row[i] = k
return tuple(row)
def apply_rows(self, curs):
fields = self.get_fields()
skytools.magic_insert(curs, self.table_name, self.rows, fields)
class BaseHandler:
handler_name = 'fwd'
def __init__(self, table_name, next, args, log):
self.table_name = table_name
self.next = next
self.args = args
self.log = log
def add(self, trigger_arg_list):
"""Called when table is added.
Can modify trigger args.
"""
if self.next:
self.next.add(trigger_arg_list)
def reset(self):
"""Called before starting to process a batch.
Should clean any pending data.
"""
if self.next:
self.next.reset()
def prepare_batch(self, batch_info, dst_curs):
"""Called on first event for this table in current batch."""
if self.next:
self.next.prepare_batch(batch_info, dst_curs)
def process_event(self, ev, sql_queue_func, arg):
"""Process a event.
Event should be added to sql_queue or executed directly.
"""
if self.next:
self.next.process_event(ev, sql_queue_func, arg)
def finish_batch(self, batch_info, dst_curs):
"""Called when batch finishes."""
if self.next:
self.next.finish_batch(batch_info, dst_curs)
def prepare_copy(self, expr_list, dst_curs):
"""Can change COPY behaviour.
Returns new expr.
"""
if self.next:
self.next.prepare_copy(expr_list, dst_curs)
class TableHandler(BaseHandler):
handler_name = 'londiste'
sql_command = {
'I': "insert into %s %s;",
'U': "update only %s set %s;",
'D': "delete from only %s where %s;",
}
def process_event(self, ev, sql_queue_func, arg):
if len(ev.type) == 1:
# sql event
fqname = skytools.quote_fqident(ev.extra1)
fmt = self.sql_command[ev.type]
sql = fmt % (fqname, ev.data)
else:
# urlenc event
pklist = ev.type[2:].split(',')
row = skytools.db_urldecode(ev.data)
op = ev.type[0]
tbl = ev.extra1
if op == 'I':
sql = skytools.mk_insert_sql(row, tbl, pklist)
elif op == 'U':
sql = skytools.mk_update_sql(row, tbl, pklist)
elif op == 'D':
sql = skytools.mk_delete_sql(row, tbl, pklist)
sql_queue_func(sql, arg)
_handler_map = {
'londiste': TableHandler,
}
def register_handler_module(modname):
"""Import and module and register handlers."""
__import__(modname)
m = sys.modules[modname]
for h in m.__londiste_handlers__:
_handler_map[h.handler_name] = h
def build_handler(tblname, hlist, log):
"""Execute array of handler initializers."""
klist = []
for h in hlist:
if not h:
continue
pos = h.find('(')
if pos >= 0:
if h[-1] != ')':
raise Exception("handler fmt error")
name = h[:pos].strip()
args = h[pos+1 : -1].split(',')
args = [a.strip() for a in args]
else:
name = h
args = []
klass = _handler_map[name]
klist.append( (klass, args) )
# always append default handler
klist.append( (TableHandler, []) )
# link them together
p = None
klist.reverse()
for klass, args in klist:
p = klass(tblname, p, args, log)
return p
def parse_handler(tblname, hstr, log):
"""Parse and execute string of colon-separated handler initializers."""
hlist = hstr.split(':')
return build_handler(tblname, hlist, log)
def load_handlers(cf):
"""Load and register modules from config."""
lst = cf.getlist('handler_modules', [])
for m in lst:
register_handler_module(m)
|
