tdaemon: prevent races by opening with O_EXCL - electrum - Electrum Bitcoin wallet
HTML git clone https://git.parazyd.org/electrum
DIR Log
DIR Files
DIR Refs
DIR Submodules
---
DIR commit e6020975a51f8f0d9e739d860454b2ade5b80e1f
DIR parent 69da96feb4843ebb2ca9f84b128eb9af829b5a43
HTML Author: Neil Booth <kyuupichan@gmail.com>
Date: Sun, 31 Jan 2016 14:40:22 +0900
daemon: prevent races by opening with O_EXCL
Rework the way the daemon and server are created. If we might
want to create a daemon, try to grab the lockfile with O_EXCL.
If we got it, create a server and daemon, otherwise try and
connect to the server. If connecting to the server fails (including
after sleeping a little in case the server was recently created),
remove the lockfile and start over.
Other fix: shut down network gracefully on daemon exit.
Fixes #1638
Diffstat:
M lib/daemon.py | 157 ++++++++++++++++++++++---------
1 file changed, 110 insertions(+), 47 deletions(-)
---
DIR diff --git a/lib/daemon.py b/lib/daemon.py
t@@ -19,6 +19,7 @@
import ast
import os
import sys
+import time
import jsonrpclib
from jsonrpclib.SimpleJSONRPCServer import SimpleJSONRPCServer, SimpleJSONRPCRequestHandler
t@@ -49,7 +50,6 @@ def get_daemon(config):
except:
pass
-
class RequestHandler(SimpleJSONRPCRequestHandler):
def do_OPTIONS(self):
t@@ -66,7 +66,7 @@ class RequestHandler(SimpleJSONRPCRequestHandler):
class Daemon(DaemonThread):
- def __init__(self, config):
+ def __init__(self, config, server):
DaemonThread.__init__(self)
self.config = config
if config.get('offline'):
t@@ -78,18 +78,15 @@ class Daemon(DaemonThread):
self.wallets = {}
self.wallet = None
self.cmd_runner = Commands(self.config, self.wallet, self.network)
- host = config.get('rpchost', 'localhost')
- port = config.get('rpcport', 0)
- self.server = SimpleJSONRPCServer((host, port), requestHandler=RequestHandler, logRequests=False)
- with open(lockfile(config), 'w') as f:
- f.write(repr(self.server.socket.getsockname()))
- self.server.timeout = 0.1
+ self.server = server
+ # Setup server
+ server.timeout = 0.1
for cmdname in known_commands:
- self.server.register_function(getattr(self.cmd_runner, cmdname), cmdname)
- self.server.register_function(self.run_cmdline, 'run_cmdline')
- self.server.register_function(self.ping, 'ping')
- self.server.register_function(self.run_daemon, 'daemon')
- self.server.register_function(self.run_gui, 'gui')
+ server.register_function(getattr(self.cmd_runner, cmdname), cmdname)
+ server.register_function(self.run_cmdline, 'run_cmdline')
+ server.register_function(self.ping, 'ping')
+ server.register_function(self.run_daemon, 'daemon')
+ server.register_function(self.run_gui, 'gui')
def ping(self):
return True
t@@ -178,11 +175,16 @@ class Daemon(DaemonThread):
def run(self):
while self.is_running():
self.server.handle_request()
- os.unlink(lockfile(self.config))
-
- def stop(self):
for k, wallet in self.wallets.items():
wallet.stop_threads()
+ if self.network:
+ self.print_error("shutting down network")
+ self.network.stop()
+ self.network.join()
+
+ def stop(self):
+ self.print_error("stopping, removing lockfile")
+ Daemon.remove_lockfile(Daemon.lockfile(self.config))
DaemonThread.stop(self)
def init_gui(self, config, plugins):
t@@ -194,19 +196,78 @@ class Daemon(DaemonThread):
self.gui.main()
@staticmethod
- def gui_command(config, config_options, plugins):
- server = get_daemon(config)
- if server is not None:
- return server.gui(config_options)
+ def lockfile(config):
+ return os.path.join(config.path, 'daemon')
- daemon = Daemon(config)
+ @staticmethod
+ def remove_lockfile(lockfile):
+ os.unlink(lockfile)
+
+ @staticmethod
+ def get_fd_or_server(lockfile):
+ '''If create is True, tries to create the lockfile, using O_EXCL to
+ prevent races. If it succeeds it returns the FD.
+
+ Otherwise try and connect to the server specified in the lockfile.
+ If this succeeds, the server is returned. Otherwise remove the
+ lockfile and try again.'''
+ while True:
+ try:
+ return os.open(lockfile, os.O_CREAT | os.O_EXCL | os.O_WRONLY)
+ except OSError:
+ pass
+ server = Daemon.get_server(lockfile)
+ if server is not None:
+ return server
+ # Couldn't connect; remove lockfile and try again.
+ Daemon.remove_lockfile(lockfile)
+
+ @staticmethod
+ def get_server(lockfile):
+ while True:
+ create_time = None
+ try:
+ with open(lockfile) as f:
+ (host, port), create_time = ast.literal_eval(f.read())
+ server = jsonrpclib.Server('http://%s:%d' % (host, port))
+ # Test daemon is running
+ server.ping()
+ return server
+ except:
+ pass
+ if not create_time or create_time < time.time() - 1.0:
+ return None
+ # Sleep a bit and try again; it might have just been started
+ time.sleep(1.0)
+
+ @staticmethod
+ def create_daemon(config, fd):
+ '''Create a daemon and server when they don't exist.'''
+ host = config.get('rpchost', 'localhost')
+ port = config.get('rpcport', 0)
+ server = SimpleJSONRPCServer((host, port), logRequests=False,
+ requestHandler=RequestHandler)
+ os.write(fd, repr((server.socket.getsockname(), time.time())))
+ os.close(fd)
+
+ daemon = Daemon(config, server)
daemon.start()
- daemon.init_gui(config, plugins)
- sys.exit(0)
+ return daemon
+
+ @staticmethod
+ def gui_command(config, config_options, plugins):
+ lockfile = Daemon.lockfile(config)
+ fd = Daemon.get_fd_or_server(lockfile)
+ if isinstance(fd, int):
+ daemon = Daemon.create_daemon(config, fd)
+ daemon.init_gui(config, plugins)
+ sys.exit(0)
+ server = fd
+ return server.gui(config_options)
@staticmethod
def cmdline_command(config, config_options):
- server = get_daemon(config)
+ server = get_server(Daemon.lockfile(config))
if server is not None:
return False, server.run_cmdline(config_options)
t@@ -214,29 +275,31 @@ class Daemon(DaemonThread):
@staticmethod
def daemon_command(config, config_options):
- server = get_daemon(config)
- if server is not None:
- return server.daemon(config_options)
-
- subcommand = config.get('subcommand')
- if subcommand in ['status', 'stop']:
- print_msg("Daemon not running")
- sys.exit(1)
- elif subcommand == 'start':
+ lockfile = Daemon.lockfile(config)
+ fd = Daemon.get_fd_or_server(lockfile)
+ if isinstance(fd, int):
+ subcommand = config.get('subcommand')
+ if subcommand != 'start':
+ if subcommand in ['status', 'stop']:
+ print_msg("Daemon not running")
+ else:
+ print_msg("syntax: electrum daemon <start|status|stop>")
+ os.close(fd)
+ Daemon.remove_lockfile(lockfile)
+ sys.exit(1)
pid = os.fork()
- if pid == 0:
- daemon = Daemon(config)
- if config.get('websocket_server'):
- from electrum import websockets
- websockets.WebSocketServer(config, daemon.network).start()
- if config.get('requests_dir'):
- check_www_dir(config.get('requests_dir'))
- daemon.start()
- daemon.join()
- sys.exit(0)
- else:
+ if pid:
print_stderr("starting daemon (PID %d)" % pid)
sys.exit(0)
- else:
- print_msg("syntax: electrum daemon <start|status|stop>")
- sys.exit(1)
+ daemon = Daemon.create_daemon(config, fd)
+ if config.get('websocket_server'):
+ from electrum import websockets
+ websockets.WebSocketServer(config, daemon.network).start()
+ if config.get('requests_dir'):
+ check_www_dir(config.get('requests_dir'))
+ daemon.join()
+ sys.exit(0)
+
+ server = fd
+ if server is not None:
+ return server.daemon(config_options)