branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
#!/usr/bin/env python3
import os
import signal
import sys
import time
if os.name == 'nt':
import ctypes
_BOOL = ctypes.c_long
_DWORD = ctypes.c_ulong
_UINT = ctypes.c_uint
_HANDLE = ctypes.c_void_p
ctypes.windll.kernel32.CloseHandle.argtypes = [_HANDLE]
ctypes.windll.kernel32.CloseHandle.restype = _BOOL
ctypes.windll.kernel32.GetLastError.argtypes = []
ctypes.windll.kernel32.GetLastError.restype = _DWORD
ctypes.windll.kernel32.OpenProcess.argtypes = [_DWORD, _BOOL, _DWORD]
ctypes.windll.kernel32.OpenProcess.restype = _HANDLE
ctypes.windll.kernel32.TerminateProcess.argtypes = [_HANDLE, _UINT]
ctypes.windll.kernel32.TerminateProcess.restype = _BOOL
ctypes.windll.kernel32.WaitForSingleObject.argtypes = [_HANDLE, _DWORD]
ctypes.windll.kernel32.WaitForSingleObject.restype = _DWORD
def _check(ret, expectederr=None):
if ret == 0:
winerrno = ctypes.GetLastError()
if winerrno == expectederr:
return True
raise ctypes.WinError(winerrno)
def kill(pid, logfn, tryhard=True):
logfn('# Killing daemon process %d' % pid)
PROCESS_TERMINATE = 1
PROCESS_QUERY_INFORMATION = 0x400
SYNCHRONIZE = 0x00100000
WAIT_OBJECT_0 = 0
WAIT_TIMEOUT = 258
WAIT_FAILED = _DWORD(0xFFFFFFFF).value
handle = ctypes.windll.kernel32.OpenProcess(
PROCESS_TERMINATE | SYNCHRONIZE | PROCESS_QUERY_INFORMATION,
False,
pid,
)
if handle is None:
_check(0, 87) # err 87 when process not found
return # process not found, already finished
try:
r = ctypes.windll.kernel32.WaitForSingleObject(handle, 100)
if r == WAIT_OBJECT_0:
pass # terminated, but process handle still available
elif r == WAIT_TIMEOUT:
_check(ctypes.windll.kernel32.TerminateProcess(handle, -1))
elif r == WAIT_FAILED:
_check(0) # err stored in GetLastError()
# TODO?: forcefully kill when timeout
# and ?shorter waiting time? when tryhard==True
r = ctypes.windll.kernel32.WaitForSingleObject(handle, 100)
# timeout = 100 ms
if r == WAIT_OBJECT_0:
pass # process is terminated
elif r == WAIT_TIMEOUT:
logfn('# Daemon process %d is stuck')
elif r == WAIT_FAILED:
_check(0) # err stored in GetLastError()
except: # re-raises
ctypes.windll.kernel32.CloseHandle(handle) # no _check, keep error
raise
_check(ctypes.windll.kernel32.CloseHandle(handle))
else:
def kill(pid, logfn, tryhard=True):
try:
os.kill(pid, 0)
logfn('# Killing daemon process %d' % pid)
os.kill(pid, signal.SIGTERM)
if tryhard:
for i in range(10):
time.sleep(0.05)
os.kill(pid, 0)
else:
time.sleep(0.1)
os.kill(pid, 0)
logfn('# Daemon process %d is stuck - really killing it' % pid)
os.kill(pid, signal.SIGKILL)
except ProcessLookupError:
pass
def killdaemons(pidfile, tryhard=True, remove=False, logfn=None):
if not logfn:
logfn = lambda s: s
# Kill off any leftover daemon processes
try:
pids = []
with open(pidfile) as fp:
for line in fp:
try:
pid = int(line)
if pid <= 0:
raise ValueError
except ValueError:
logfn(
'# Not killing daemon process %s - invalid pid'
% line.rstrip()
)
continue
pids.append(pid)
for pid in pids:
kill(pid, logfn, tryhard)
if remove:
os.unlink(pidfile)
except IOError:
pass
if __name__ == '__main__':
if len(sys.argv) > 1:
(path,) = sys.argv[1:]
else:
path = os.environ["DAEMON_PIDS"]
killdaemons(path, remove=True)