"""Useful functions and classes for database scripts. """ from __future__ import division, absolute_import, print_function import errno import logging import logging.config import logging.handlers import optparse import os import select import signal import sys import time import skytools import skytools.skylog try: import skytools.installer_config default_skylog = skytools.installer_config.skylog except ImportError: default_skylog = 0 __pychecker__ = 'no-badexcept' __all__ = ['BaseScript', 'UsageError', 'daemonize', 'DBScript'] class UsageError(Exception): """User induced error.""" # # daemon mode # def daemonize(): """Turn the process into daemon. Goes background and disables all i/o. """ # launch new process, kill parent pid = os.fork() if pid != 0: os._exit(0) # start new session os.setsid() # stop i/o fd = os.open("/dev/null", os.O_RDWR) os.dup2(fd, 0) os.dup2(fd, 1) os.dup2(fd, 2) if fd > 2: os.close(fd) # # Pidfile locking+cleanup & daemonization combined # def run_single_process(runnable, daemon, pidfile): """Run runnable class, possibly daemonized, locked on pidfile.""" # check if another process is running if pidfile and os.path.isfile(pidfile): if skytools.signal_pidfile(pidfile, 0): print("Pidfile exists, another process running?") sys.exit(1) else: print("Ignoring stale pidfile") # daemonize if needed if daemon: daemonize() # clean only own pidfile own_pidfile = False try: if pidfile: data = str(os.getpid()) skytools.write_atomic(pidfile, data) own_pidfile = True runnable.run() finally: if own_pidfile: try: os.remove(pidfile) except: pass # # logging setup # _log_config_done = 0 _log_init_done = {} def _load_log_config(fn, defs): """Fixed fileConfig.""" # Work around fileConfig default behaviour to disable # not only old handlers on load (which slightly makes sense) # but also old logger objects (which does not make sense). if sys.hexversion >= 0x2060000: logging.config.fileConfig(fn, defs, False) else: logging.config.fileConfig(fn, defs) root = logging.getLogger() for lg in root.manager.loggerDict.values(): lg.disabled = 0 def _init_log(job_name, service_name, cf, log_level, is_daemon): """Logging setup happens here.""" global _log_config_done got_skylog = 0 use_skylog = cf.getint("use_skylog", default_skylog) # if non-daemon, avoid skylog if script is running on console. # set use_skylog=2 to disable. if not is_daemon and use_skylog == 1: # pylint gets spooked by it's own stdout wrapper and refuses to shut down # about it. 'noqa' tells prospector to ignore all warnings here. if sys.stdout.isatty(): # noqa use_skylog = 0 # load logging config if needed if use_skylog and not _log_config_done: # python logging.config braindamage: # cannot specify external classess without such hack logging.skylog = skytools.skylog skytools.skylog.set_service_name(service_name, job_name) # load general config flist = cf.getlist('skylog_locations', ['skylog.ini', '~/.skylog.ini', '/etc/skylog.ini']) for fn in flist: fn = os.path.expanduser(fn) if os.path.isfile(fn): defs = {'job_name': job_name, 'service_name': service_name} _load_log_config(fn, defs) got_skylog = 1 break _log_config_done = 1 if not got_skylog: sys.stderr.write("skylog.ini not found!\n") sys.exit(1) # avoid duplicate logging init for job_name log = logging.getLogger(job_name) if job_name in _log_init_done: return log _log_init_done[job_name] = 1 # tune level on root logger root = logging.getLogger() root.setLevel(log_level) # compatibility: specify ini file in script config def_fmt = '%(asctime)s %(process)s %(levelname)s %(message)s' def_datefmt = '' # None logfile = cf.getfile("logfile", "") if logfile: fstr = cf.get('logfmt_file', def_fmt) fstr_date = cf.get('logdatefmt_file', def_datefmt) if log_level < logging.INFO: fstr = cf.get('logfmt_file_verbose', fstr) fstr_date = cf.get('logdatefmt_file_verbose', fstr_date) fmt = logging.Formatter(fstr, fstr_date) size = cf.getint('log_size', 10*1024*1024) num = cf.getint('log_count', 3) file_hdlr = logging.handlers.RotatingFileHandler( logfile, 'a', size, num) file_hdlr.setFormatter(fmt) root.addHandler(file_hdlr) # if skylog.ini is disabled or not available, log at least to stderr if not got_skylog: fstr = cf.get('logfmt_console', def_fmt) fstr_date = cf.get('logdatefmt_console', def_datefmt) if log_level < logging.INFO: fstr = cf.get('logfmt_console_verbose', fstr) fstr_date = cf.get('logdatefmt_console_verbose', fstr_date) stream_hdlr = logging.StreamHandler() fmt = logging.Formatter(fstr, fstr_date) stream_hdlr.setFormatter(fmt) root.addHandler(stream_hdlr) return log class BaseScript(object): """Base class for service scripts. Handles logging, daemonizing, config, errors. Config template:: ## Parameters for skytools.BaseScript ## # how many seconds to sleep between work loops # if missing or 0, then instead sleeping, the script will exit loop_delay = 1.0 # where to log logfile = ~/log/%(job_name)s.log # where to write pidfile pidfile = ~/pid/%(job_name)s.pid # per-process name to use in logging #job_name = %(config_name)s # whether centralized logging should be used # search-path [ ./skylog.ini, ~/.skylog.ini, /etc/skylog.ini ] # 0 - disabled # 1 - enabled, unless non-daemon on console (os.isatty()) # 2 - always enabled #use_skylog = 0 # where to find skylog.ini #skylog_locations = skylog.ini, ~/.skylog.ini, /etc/skylog.ini # how many seconds to sleep after catching a exception #exception_sleep = 20 """ service_name = None job_name = None cf = None cf_defaults = {} pidfile = None # >0 - sleep time if work() requests sleep # 0 - exit if work requests sleep # <0 - run work() once [same as looping=0] loop_delay = 1.0 # 0 - run work() once # 1 - run work() repeatedly looping = 1 # result from last work() call: # 1 - there is probably more work, don't sleep # 0 - no work, sleep before calling again # -1 - exception was thrown work_state = 1 # setup logger here, this allows override by subclass log = logging.getLogger('skytools.BaseScript') # start time started = 0 def __init__(self, service_name, args): """Script setup. User class should override work() and optionally __init__(), startup(), reload(), reset(), shutdown() and init_optparse(). NB: In case of daemon, __init__() and startup()/work()/shutdown() will be run in different processes. So nothing fancy should be done in __init__(). @param service_name: unique name for script. It will be also default job_name, if not specified in config. @param args: cmdline args (sys.argv[1:]), but can be overridden """ self.service_name = service_name self.go_daemon = 0 self.need_reload = 0 self.exception_count = 0 self.stat_dict = {} self.log_level = logging.INFO # parse command line parser = self.init_optparse() self.options, self.args = parser.parse_args(args) # check args if self.options.version: self.print_version() sys.exit(0) if self.options.daemon: self.go_daemon = 1 if self.options.quiet: self.log_level = logging.WARNING if self.options.verbose: if self.options.verbose > 1: self.log_level = skytools.skylog.TRACE else: self.log_level = logging.DEBUG self.cf_override = {} if self.options.set: for a in self.options.set: k, v = a.split('=', 1) self.cf_override[k.strip()] = v.strip() if self.options.ini: self.print_ini() sys.exit(0) # read config file self.reload() # init logging _init_log(self.job_name, self.service_name, self.cf, self.log_level, self.go_daemon) # send signal, if needed if self.options.cmd == "kill": self.send_signal(signal.SIGTERM) elif self.options.cmd == "stop": self.send_signal(signal.SIGINT) elif self.options.cmd == "reload": self.send_signal(signal.SIGHUP) def print_version(self): service = self.service_name ver = getattr(self, '__version__', None) if ver: service += ' version %s' % ver print('%s, Skytools version %s' % (service, getattr(skytools, '__version__'))) def print_ini(self): """Prints out ini file from doc string of the script of default for dbscript Used by --ini option on command line. """ # current service name print("[%s]\n" % self.service_name) # walk class hierarchy bases = [self.__class__] while len(bases) > 0: parents = [] for c in bases: for p in c.__bases__: if p not in parents: parents.append(p) doc = c.__doc__ if doc: self._print_ini_frag(doc) bases = parents def _print_ini_frag(self, doc): # use last '::' block as config template pos = doc and doc.rfind('::\n') or -1 if pos < 0: return doc = doc[pos+2 : ].rstrip() doc = skytools.dedent(doc) # merge overrided options into output for ln in doc.splitlines(): vals = ln.split('=', 1) if len(vals) != 2: print(ln) continue k = vals[0].strip() v = vals[1].strip() if k and k[0] == '#': print(ln) k = k[1:] if k in self.cf_override: print('%s = %s' % (k, self.cf_override[k])) elif k in self.cf_override: if v: print('#' + ln) print('%s = %s' % (k, self.cf_override[k])) else: print(ln) print('') def load_config(self): """Loads and returns skytools.Config instance. By default it uses first command-line argument as config file name. Can be overridden. """ if len(self.args) < 1: print("need config file, use --help for help.") sys.exit(1) conf_file = self.args[0] return skytools.Config(self.service_name, conf_file, user_defs=self.cf_defaults, override=self.cf_override) def init_optparse(self, parser=None): """Initialize a OptionParser() instance that will be used to parse command line arguments. Note that it can be overridden both directions - either DBScript will initialize an instance and pass it to user code or user can initialize and then pass to DBScript.init_optparse(). @param parser: optional OptionParser() instance, where DBScript should attach its own arguments. @return: initialized OptionParser() instance. """ if parser: p = parser else: p = optparse.OptionParser() p.set_usage("%prog [options] INI") # generic options p.add_option("-q", "--quiet", action="store_true", help="log only errors and warnings") p.add_option("-v", "--verbose", action="count", help="log verbosely") p.add_option("-d", "--daemon", action="store_true", help="go background") p.add_option("-V", "--version", action="store_true", help="print version info and exit") p.add_option("", "--ini", action="store_true", help="display sample ini file") p.add_option("", "--set", action="append", help="override config setting (--set 'PARAM=VAL')") # control options g = optparse.OptionGroup(p, 'control running process') g.add_option("-r", "--reload", action="store_const", const="reload", dest="cmd", help="reload config (send SIGHUP)") g.add_option("-s", "--stop", action="store_const", const="stop", dest="cmd", help="stop program safely (send SIGINT)") g.add_option("-k", "--kill", action="store_const", const="kill", dest="cmd", help="kill program immediately (send SIGTERM)") p.add_option_group(g) return p def send_signal(self, sig): if not self.pidfile: self.log.warning("No pidfile in config, nothing to do") elif os.path.isfile(self.pidfile): alive = skytools.signal_pidfile(self.pidfile, sig) if not alive: self.log.warning("pidfile exists, but process not running") else: self.log.warning("No pidfile, process not running") sys.exit(0) def set_single_loop(self, do_single_loop): """Changes whether the script will loop or not.""" if do_single_loop: self.looping = 0 else: self.looping = 1 def _boot_daemon(self): run_single_process(self, self.go_daemon, self.pidfile) def start(self): """This will launch main processing thread.""" if self.go_daemon: if not self.pidfile: self.log.error("Daemon needs pidfile") sys.exit(1) self.run_func_safely(self._boot_daemon) def stop(self): """Safely stops processing loop.""" self.looping = 0 def reload(self): "Reload config." # avoid double loading on startup if not self.cf: self.cf = self.load_config() else: self.cf.reload() self.log.info("Config reloaded") self.job_name = self.cf.get("job_name") self.pidfile = self.cf.getfile("pidfile", '') self.loop_delay = self.cf.getfloat("loop_delay", self.loop_delay) self.exception_sleep = self.cf.getfloat("exception_sleep", 20) self.exception_quiet = self.cf.getlist("exception_quiet", []) self.exception_grace = self.cf.getfloat("exception_grace", 5*60) self.exception_reset = self.cf.getfloat("exception_reset", 15*60) def hook_sighup(self, sig, frame): "Internal SIGHUP handler. Minimal code here." self.need_reload = 1 last_sigint = 0 def hook_sigint(self, sig, frame): "Internal SIGINT handler. Minimal code here." self.stop() t = time.time() if t - self.last_sigint < 1: self.log.warning("Double ^C, fast exit") sys.exit(1) self.last_sigint = t def stat_get(self, key): """Reads a stat value.""" try: value = self.stat_dict[key] except KeyError: value = None return value def stat_put(self, key, value): """Sets a stat value.""" self.stat_dict[key] = value def stat_increase(self, key, increase=1): """Increases a stat value.""" try: self.stat_dict[key] += increase except KeyError: self.stat_dict[key] = increase def send_stats(self): "Send statistics to log." res = [] for k, v in self.stat_dict.items(): res.append("%s: %s" % (k, v)) if len(res) == 0: return logmsg = "{%s}" % ", ".join(res) self.log.info(logmsg) self.stat_dict = {} def reset(self): "Something bad happened, reset all state." pass def run(self): "Thread main loop." # run startup, safely self.run_func_safely(self.startup) while 1: # reload config, if needed if self.need_reload: self.reload() self.need_reload = 0 # do some work work = self.run_once() if not self.looping or self.loop_delay < 0: break # remember work state self.work_state = work # should sleep? if not work: if self.loop_delay > 0: self.sleep(self.loop_delay) if not self.looping: break else: break # run shutdown, safely? self.shutdown() def run_once(self): state = self.run_func_safely(self.work, True) # send stats that was added self.send_stats() return state last_func_fail = None def run_func_safely(self, func, prefer_looping=False): "Run users work function, safely." try: r = func() if self.last_func_fail and time.time() > self.last_func_fail + self.exception_reset: self.last_func_fail = None # set exception count to 0 after success self.exception_count = 0 return r except UsageError as d: self.log.error(str(d)) sys.exit(1) except MemoryError as d: try: # complex logging may not succeed self.log.exception("Job %s out of memory, exiting", self.job_name) except MemoryError: self.log.fatal("Out of memory") sys.exit(1) except SystemExit as d: self.send_stats() if prefer_looping and self.looping and self.loop_delay > 0: self.log.info("got SystemExit(%s), exiting", str(d)) self.reset() raise d except KeyboardInterrupt as d: self.send_stats() if prefer_looping and self.looping and self.loop_delay > 0: self.log.info("got KeyboardInterrupt, exiting") self.reset() sys.exit(1) except Exception as d: try: # this may fail too self.send_stats() except: pass if self.last_func_fail is None: self.last_func_fail = time.time() emsg = str(d).rstrip() self.reset() self.exception_hook(d, emsg) # reset and sleep self.reset() if prefer_looping and self.looping and self.loop_delay > 0: # increase exception count & sleep self.exception_count += 1 self.sleep_on_exception() return -1 sys.exit(1) def sleep(self, secs): """Make script sleep for some amount of time.""" try: time.sleep(secs) except IOError as ex: if ex.errno != errno.EINTR: raise def sleep_on_exception(self): """Make script sleep for some amount of time when an exception occurs. To implement more advance exception sleeping like exponential backoff you can override this method. Also note that you can use self.exception_count to track the number of consecutive exceptions. """ self.sleep(self.exception_sleep) def _is_quiet_exception(self, ex): return ((self.exception_quiet == ["ALL"] or ex.__class__.__name__ in self.exception_quiet) and self.last_func_fail and time.time() < self.last_func_fail + self.exception_grace) def exception_hook(self, det, emsg): """Called on after exception processing. Can do additional logging. @param det: exception details @param emsg: exception msg """ lm = "Job %s crashed: %s" % (self.job_name, emsg) if self._is_quiet_exception(det): self.log.warning(lm) else: self.log.exception(lm) def work(self): """Here should user's processing happen. Return value is taken as boolean - if true, the next loop starts immediately. If false, DBScript sleeps for a loop_delay. """ raise Exception("Nothing implemented?") def startup(self): """Will be called just before entering main loop. In case of daemon, if will be called in same process as work(), unlike __init__(). """ self.started = time.time() # set signals if hasattr(signal, 'SIGHUP'): signal.signal(signal.SIGHUP, self.hook_sighup) if hasattr(signal, 'SIGINT'): signal.signal(signal.SIGINT, self.hook_sigint) def shutdown(self): """Will be called just after exiting main loop. In case of daemon, if will be called in same process as work(), unlike __init__(). """ pass # define some aliases (short-cuts / backward compatibility cruft) stat_add = stat_put # Old, deprecated function. stat_inc = stat_increase ## ## DBScript ## #: how old connections need to be closed DEF_CONN_AGE = 20*60 # 20 min class DBScript(BaseScript): """Base class for database scripts. Handles database connection state. Config template:: ## Parameters for skytools.DBScript ## # default lifetime for database connections (in seconds) #connection_lifetime = 1200 """ def __init__(self, service_name, args): """Script setup. User class should override work() and optionally __init__(), startup(), reload(), reset() and init_optparse(). NB: in case of daemon, the __init__() and startup()/work() will be run in different processes. So nothing fancy should be done in __init__(). @param service_name: unique name for script. It will be also default job_name, if not specified in config. @param args: cmdline args (sys.argv[1:]), but can be overridden """ self.db_cache = {} self._db_defaults = {} self._listen_map = {} # dbname: channel_list super(DBScript, self).__init__(service_name, args) def connection_hook(self, dbname, conn): pass def set_database_defaults(self, dbname, **kwargs): self._db_defaults[dbname] = kwargs def add_connect_string_profile(self, connstr, profile): """Add extra profile info to connect string. """ if profile: extra = self.cf.get("%s_extra_connstr" % profile, '') if extra: connstr += ' ' + extra return connstr def get_database(self, dbname, autocommit=0, isolation_level=-1, cache=None, connstr=None, profile=None): """Load cached database connection. User must not store it permanently somewhere, as all connections will be invalidated on reset. """ max_age = self.cf.getint('connection_lifetime', DEF_CONN_AGE) if not cache: cache = dbname params = {} defs = self._db_defaults.get(cache, {}) params.update(defs) if isolation_level >= 0: params['isolation_level'] = isolation_level elif autocommit: params['isolation_level'] = 0 elif params.get('autocommit', 0): params['isolation_level'] = 0 elif 'isolation_level' not in params: params['isolation_level'] = skytools.I_READ_COMMITTED if 'max_age' not in params: params['max_age'] = max_age if cache in self.db_cache: dbc = self.db_cache[cache] if connstr is None: connstr = self.cf.get(dbname, '') if connstr: connstr = self.add_connect_string_profile(connstr, profile) dbc.check_connstr(connstr) else: if not connstr: connstr = self.cf.get(dbname) connstr = self.add_connect_string_profile(connstr, profile) # connstr might contain password, it is not a good idea to log it filtered_connstr = connstr pos = connstr.lower().find('password') if pos >= 0: filtered_connstr = connstr[:pos] + ' [...]' self.log.debug("Connect '%s' to '%s'", cache, filtered_connstr) dbc = DBCachedConn(cache, connstr, params['max_age'], setup_func=self.connection_hook) self.db_cache[cache] = dbc clist = [] if cache in self._listen_map: clist = self._listen_map[cache] return dbc.get_connection(params['isolation_level'], clist) def close_database(self, dbname): """Explicitly close a cached connection. Next call to get_database() will reconnect. """ if dbname in self.db_cache: dbc = self.db_cache[dbname] dbc.reset() del self.db_cache[dbname] def reset(self): "Something bad happened, reset all connections." for dbc in self.db_cache.values(): dbc.reset() self.db_cache = {} super(DBScript, self).reset() def run_once(self): state = super(DBScript, self).run_once() # reconnect if needed for dbc in self.db_cache.values(): dbc.refresh() return state def exception_hook(self, d, emsg): """Log database and query details from exception.""" curs = getattr(d, 'cursor', None) conn = getattr(curs, 'connection', None) cname = getattr(conn, 'my_name', None) if cname: # Properly named connection cname = d.cursor.connection.my_name sql = getattr(curs, 'query', None) or '?' if len(sql) > 200: # avoid logging londiste huge batched queries sql = sql[:60] + " ..." lm = "Job %s got error on connection '%s': %s. Query: %s" % ( self.job_name, cname, emsg, sql) if self._is_quiet_exception(d): self.log.warning(lm) else: self.log.exception(lm) else: super(DBScript, self).exception_hook(d, emsg) def sleep(self, secs): """Make script sleep for some amount of time.""" fdlist = [] for dbname in self._listen_map: if dbname not in self.db_cache: continue fd = self.db_cache[dbname].fileno() if fd is None: continue fdlist.append(fd) if not fdlist: return super(DBScript, self).sleep(secs) try: if hasattr(select, 'poll'): p = select.poll() for fd in fdlist: p.register(fd, select.POLLIN) p.poll(int(secs * 1000)) else: select.select(fdlist, [], [], secs) except select.error: self.log.info('wait canceled') def _exec_cmd(self, curs, sql, args, quiet=False, prefix=None): """Internal tool: Run SQL on cursor.""" if self.options.verbose: self.log.debug("exec_cmd: %s", skytools.quote_statement(sql, args)) _pfx = "" if prefix: _pfx = "[%s] " % prefix curs.execute(sql, args) ok = True rows = curs.fetchall() for row in rows: try: code = row['ret_code'] msg = row['ret_note'] except KeyError: self.log.error("Query does not conform to exec_cmd API:") self.log.error("SQL: %s", skytools.quote_statement(sql, args)) self.log.error("Row: %s", repr(row.copy())) sys.exit(1) level = code // 100 if level == 1: self.log.debug("%s%d %s", _pfx, code, msg) elif level == 2: if quiet: self.log.debug("%s%d %s", _pfx, code, msg) else: self.log.info("%s%s", _pfx, msg) elif level == 3: self.log.warning("%s%s", _pfx, msg) else: self.log.error("%s%s", _pfx, msg) self.log.debug("Query was: %s", skytools.quote_statement(sql, args)) ok = False return (ok, rows) def _exec_cmd_many(self, curs, sql, baseargs, extra_list, quiet=False, prefix=None): """Internal tool: Run SQL on cursor multiple times.""" ok = True rows = [] for a in extra_list: (tmp_ok, tmp_rows) = self._exec_cmd(curs, sql, baseargs + [a], quiet, prefix) if not tmp_ok: ok = False rows += tmp_rows return (ok, rows) def exec_cmd(self, db_or_curs, q, args, commit=True, quiet=False, prefix=None): """Run SQL on db with code/value error handling.""" if hasattr(db_or_curs, 'cursor'): db = db_or_curs curs = db.cursor() else: db = None curs = db_or_curs (ok, rows) = self._exec_cmd(curs, q, args, quiet, prefix) if ok: if commit and db: db.commit() return rows else: if db: db.rollback() if self.options.verbose: raise Exception("db error") # error is already logged sys.exit(1) def exec_cmd_many(self, db_or_curs, sql, baseargs, extra_list, commit=True, quiet=False, prefix=None): """Run SQL on db multiple times.""" if hasattr(db_or_curs, 'cursor'): db = db_or_curs curs = db.cursor() else: db = None curs = db_or_curs (ok, rows) = self._exec_cmd_many(curs, sql, baseargs, extra_list, quiet, prefix) if ok: if commit and db: db.commit() return rows else: if db: db.rollback() if self.options.verbose: raise Exception("db error") # error is already logged sys.exit(1) def execute_with_retry(self, dbname, stmt, args, exceptions=None): """ Execute SQL and retry if it fails. Return number of retries and current valid cursor, or raise an exception. """ sql_retry = self.cf.getbool("sql_retry", False) sql_retry_max_count = self.cf.getint("sql_retry_max_count", 10) sql_retry_max_time = self.cf.getint("sql_retry_max_time", 300) sql_retry_formula_a = self.cf.getint("sql_retry_formula_a", 1) sql_retry_formula_b = self.cf.getint("sql_retry_formula_b", 5) sql_retry_formula_cap = self.cf.getint("sql_retry_formula_cap", 60) elist = exceptions or tuple() stime = time.time() tried = 0 dbc = None while True: try: if dbc is None: if dbname not in self.db_cache: self.get_database(dbname, autocommit=1) dbc = self.db_cache[dbname] if dbc.isolation_level != skytools.I_AUTOCOMMIT: raise skytools.UsageError("execute_with_retry: autocommit required") else: dbc.reset() curs = dbc.get_connection(dbc.isolation_level).cursor() curs.execute(stmt, args) break except elist as e: if not sql_retry or tried >= sql_retry_max_count or time.time() - stime >= sql_retry_max_time: raise self.log.info("Job %s got error on connection %s: %s", self.job_name, dbname, e) except: raise # y = a + bx , apply cap y = sql_retry_formula_a + sql_retry_formula_b * tried if sql_retry_formula_cap is not None and y > sql_retry_formula_cap: y = sql_retry_formula_cap tried += 1 self.log.info("Retry #%i in %i seconds ...", tried, y) self.sleep(y) return tried, curs def listen(self, dbname, channel): """Make connection listen for specific event channel. Listening will be activated on next .get_database() call. Basically this means that DBScript.sleep() will poll for events on that db connection, so when event appears, script will be woken up. """ if dbname not in self._listen_map: self._listen_map[dbname] = [] clist = self._listen_map[dbname] if channel not in clist: clist.append(channel) def unlisten(self, dbname, channel='*'): """Stop connection for listening on specific event channel. Listening will stop on next .get_database() call. """ if dbname not in self._listen_map: return if channel == '*': del self._listen_map[dbname] return clist = self._listen_map[dbname] try: clist.remove(channel) except ValueError: pass class DBCachedConn(object): """Cache a db connection.""" def __init__(self, name, loc, max_age=DEF_CONN_AGE, verbose=False, setup_func=None, channels=()): self.name = name self.loc = loc self.conn = None self.conn_time = 0 self.max_age = max_age self.isolation_level = -1 self.verbose = verbose self.setup_func = setup_func self.listen_channel_list = [] def fileno(self): if not self.conn: return None return self.conn.cursor().fileno() def get_connection(self, isolation_level=-1, listen_channel_list=()): # default isolation_level is READ COMMITTED if isolation_level < 0: isolation_level = skytools.I_READ_COMMITTED # new conn? if not self.conn: self.isolation_level = isolation_level self.conn = skytools.connect_database(self.loc) self.conn.my_name = self.name self.conn.set_isolation_level(isolation_level) self.conn_time = time.time() if self.setup_func: self.setup_func(self.name, self.conn) else: if self.isolation_level != isolation_level: raise Exception("Conflict in isolation_level") self._sync_listen(listen_channel_list) # done return self.conn def _sync_listen(self, new_clist): if not new_clist and not self.listen_channel_list: return curs = self.conn.cursor() for ch in self.listen_channel_list: if ch not in new_clist: curs.execute("UNLISTEN %s" % skytools.quote_ident(ch)) for ch in new_clist: if ch not in self.listen_channel_list: curs.execute("LISTEN %s" % skytools.quote_ident(ch)) if self.isolation_level != skytools.I_AUTOCOMMIT: self.conn.commit() self.listen_channel_list = new_clist[:] def refresh(self): if not self.conn: return #for row in self.conn.notifies(): # if row[0].lower() == "reload": # self.reset() # return if not self.max_age: return if time.time() - self.conn_time >= self.max_age: self.reset() def reset(self): if not self.conn: return # drop reference conn = self.conn self.conn = None self.listen_channel_list = [] # close try: conn.close() except: pass def check_connstr(self, connstr): """Drop connection if connect string has changed. """ if self.loc != connstr: self.reset()