Mercurial > hg
view mercurial/win32.py @ 26623:5a95fe44121d
clonebundles: support for seeding clones from pre-generated bundles
Cloning can be an expensive operation for servers because the server
generates a bundle from existing repository data at request time. For
a large repository like mozilla-central, this consumes 4+ minutes
of CPU time on the server. It also results in significant network
utilization. Multiplied by hundreds or even thousands of clients and
the ensuing load can result in difficulties scaling the Mercurial server.
Despite generation of bundles being deterministic until the next
changeset is added, the generation of bundles to service a clone request
is not cached. Each clone thus performs redundant work. This is
wasteful.
This patch introduces the "clonebundles" extension and related
client-side functionality to help alleviate this deficiency. The
client-side feature is behind an experimental flag and is not enabled by
default.
It works as follows:
1) Server operator generates a bundle and makes it available on a
server (likely HTTP).
2) Server operator defines the URL of a bundle file in a
.hg/clonebundles.manifest file.
3) Client `hg clone`ing sees the server is advertising bundle URLs.
4) Client fetches and applies the advertised bundle.
5) Client performs equivalent of `hg pull` to fetch changes made since
the bundle was created.
Essentially, the server performs the expensive work of generating a
bundle once and all subsequent clones fetch a static file from
somewhere. Scaling static file serving is a much more manageable
problem than scaling a Python application like Mercurial. Assuming your
repository grows less than 1% per day, the end result is 99+% of CPU
and network load from clones is eliminated, allowing Mercurial servers
to scale more easily. Serving static files also means data can be
transferred to clients as fast as they can consume it, rather than as
fast as servers can generate it. This makes clones faster.
Mozilla has implemented similar functionality of this patch on
hg.mozilla.org using a custom extension. We are hosting bundle files in
Amazon S3 and CloudFront (a CDN) and have successfully offloaded
>1 TB/day in data transfer from hg.mozilla.org, freeing up significant
bandwidth and CPU resources. The positive impact has been stellar and
I believe it has proved its value to be included in Mercurial core. I
feel it is important for the client-side support to be enabled in core
by default because it means that clients will get faster, more reliable
clones and will enable server operators to reduce load without
requiring any client-side configuration changes (assuming clients are
up to date, of course).
The scope of this feature is narrowly and specifically tailored to
cloning, despite "serve pulls from pre-generated bundles" being a valid
and useful feature. I would eventually like for Mercurial servers to
support transferring *all* repository data via statically hosted files.
You could imagine a server that siphons all pushed data to bundle files
and instructs clients to apply a stream of bundles to reconstruct all
repository data. This feature, while useful and powerful, is
significantly more work to implement because it requires the server
component have awareness of discovery and a mapping of which changesets
are in which files. Full, clone bundles, by contrast, are much simpler.
The wire protocol command is named "clonebundles" instead of something
more generic like "staticbundles" to leave the door open for a new, more
powerful and more generic server-side component with minimal backwards
compatibility implications. The name "bundleclone" is used by Mozilla's
extension and would cause problems since there are subtle differences
in Mozilla's extension.
Mozilla's experience with this idea has taught us that some form of
"content negotiation" is required. Not all clients will support all
bundle formats or even URLs (advanced TLS requirements, etc). To ensure
the highest uptake possible, a server needs to advertise multiple
versions of bundles and clients need to be able to choose the most
appropriate from that list one. The "attributes" in each
server-advertised entry facilitate this filtering and sorting. Their
use will become apparent in subsequent patches.
Initial inspiration and credit for the idea of cloning from static files
belongs to Augie Fackler and his "lookaside clone" extension proof of
concept.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 09 Oct 2015 11:22:01 -0700 |
parents | d6beeb618700 |
children | 392633d7860e |
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# win32.py - utility functions that use win32 API # # Copyright 2005-2009 Matt Mackall <mpm@selenic.com> and others # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import ctypes import errno import msvcrt import os import random import subprocess _kernel32 = ctypes.windll.kernel32 _advapi32 = ctypes.windll.advapi32 _user32 = ctypes.windll.user32 _BOOL = ctypes.c_long _WORD = ctypes.c_ushort _DWORD = ctypes.c_ulong _UINT = ctypes.c_uint _LONG = ctypes.c_long _LPCSTR = _LPSTR = ctypes.c_char_p _HANDLE = ctypes.c_void_p _HWND = _HANDLE _INVALID_HANDLE_VALUE = _HANDLE(-1).value # GetLastError _ERROR_SUCCESS = 0 _ERROR_NO_MORE_FILES = 18 _ERROR_INVALID_PARAMETER = 87 _ERROR_BROKEN_PIPE = 109 _ERROR_INSUFFICIENT_BUFFER = 122 # WPARAM is defined as UINT_PTR (unsigned type) # LPARAM is defined as LONG_PTR (signed type) if ctypes.sizeof(ctypes.c_long) == ctypes.sizeof(ctypes.c_void_p): _WPARAM = ctypes.c_ulong _LPARAM = ctypes.c_long elif ctypes.sizeof(ctypes.c_longlong) == ctypes.sizeof(ctypes.c_void_p): _WPARAM = ctypes.c_ulonglong _LPARAM = ctypes.c_longlong class _FILETIME(ctypes.Structure): _fields_ = [('dwLowDateTime', _DWORD), ('dwHighDateTime', _DWORD)] class _BY_HANDLE_FILE_INFORMATION(ctypes.Structure): _fields_ = [('dwFileAttributes', _DWORD), ('ftCreationTime', _FILETIME), ('ftLastAccessTime', _FILETIME), ('ftLastWriteTime', _FILETIME), ('dwVolumeSerialNumber', _DWORD), ('nFileSizeHigh', _DWORD), ('nFileSizeLow', _DWORD), ('nNumberOfLinks', _DWORD), ('nFileIndexHigh', _DWORD), ('nFileIndexLow', _DWORD)] # CreateFile _FILE_SHARE_READ = 0x00000001 _FILE_SHARE_WRITE = 0x00000002 _FILE_SHARE_DELETE = 0x00000004 _OPEN_EXISTING = 3 _FILE_FLAG_BACKUP_SEMANTICS = 0x02000000 # SetFileAttributes _FILE_ATTRIBUTE_NORMAL = 0x80 _FILE_ATTRIBUTE_NOT_CONTENT_INDEXED = 0x2000 # Process Security and Access Rights _PROCESS_QUERY_INFORMATION = 0x0400 # GetExitCodeProcess _STILL_ACTIVE = 259 class _STARTUPINFO(ctypes.Structure): _fields_ = [('cb', _DWORD), ('lpReserved', _LPSTR), ('lpDesktop', _LPSTR), ('lpTitle', _LPSTR), ('dwX', _DWORD), ('dwY', _DWORD), ('dwXSize', _DWORD), ('dwYSize', _DWORD), ('dwXCountChars', _DWORD), ('dwYCountChars', _DWORD), ('dwFillAttribute', _DWORD), ('dwFlags', _DWORD), ('wShowWindow', _WORD), ('cbReserved2', _WORD), ('lpReserved2', ctypes.c_char_p), ('hStdInput', _HANDLE), ('hStdOutput', _HANDLE), ('hStdError', _HANDLE)] class _PROCESS_INFORMATION(ctypes.Structure): _fields_ = [('hProcess', _HANDLE), ('hThread', _HANDLE), ('dwProcessId', _DWORD), ('dwThreadId', _DWORD)] _CREATE_NO_WINDOW = 0x08000000 _SW_HIDE = 0 class _COORD(ctypes.Structure): _fields_ = [('X', ctypes.c_short), ('Y', ctypes.c_short)] class _SMALL_RECT(ctypes.Structure): _fields_ = [('Left', ctypes.c_short), ('Top', ctypes.c_short), ('Right', ctypes.c_short), ('Bottom', ctypes.c_short)] class _CONSOLE_SCREEN_BUFFER_INFO(ctypes.Structure): _fields_ = [('dwSize', _COORD), ('dwCursorPosition', _COORD), ('wAttributes', _WORD), ('srWindow', _SMALL_RECT), ('dwMaximumWindowSize', _COORD)] _STD_ERROR_HANDLE = _DWORD(-12).value # CreateToolhelp32Snapshot, Process32First, Process32Next _TH32CS_SNAPPROCESS = 0x00000002 _MAX_PATH = 260 class _tagPROCESSENTRY32(ctypes.Structure): _fields_ = [('dwsize', _DWORD), ('cntUsage', _DWORD), ('th32ProcessID', _DWORD), ('th32DefaultHeapID', ctypes.c_void_p), ('th32ModuleID', _DWORD), ('cntThreads', _DWORD), ('th32ParentProcessID', _DWORD), ('pcPriClassBase', _LONG), ('dwFlags', _DWORD), ('szExeFile', ctypes.c_char * _MAX_PATH)] def __init__(self): super(_tagPROCESSENTRY32, self).__init__() self.dwsize = ctypes.sizeof(self) # types of parameters of C functions used (required by pypy) _kernel32.CreateFileA.argtypes = [_LPCSTR, _DWORD, _DWORD, ctypes.c_void_p, _DWORD, _DWORD, _HANDLE] _kernel32.CreateFileA.restype = _HANDLE _kernel32.GetFileInformationByHandle.argtypes = [_HANDLE, ctypes.c_void_p] _kernel32.GetFileInformationByHandle.restype = _BOOL _kernel32.CloseHandle.argtypes = [_HANDLE] _kernel32.CloseHandle.restype = _BOOL try: _kernel32.CreateHardLinkA.argtypes = [_LPCSTR, _LPCSTR, ctypes.c_void_p] _kernel32.CreateHardLinkA.restype = _BOOL except AttributeError: pass _kernel32.SetFileAttributesA.argtypes = [_LPCSTR, _DWORD] _kernel32.SetFileAttributesA.restype = _BOOL _kernel32.OpenProcess.argtypes = [_DWORD, _BOOL, _DWORD] _kernel32.OpenProcess.restype = _HANDLE _kernel32.GetExitCodeProcess.argtypes = [_HANDLE, ctypes.c_void_p] _kernel32.GetExitCodeProcess.restype = _BOOL _kernel32.GetLastError.argtypes = [] _kernel32.GetLastError.restype = _DWORD _kernel32.GetModuleFileNameA.argtypes = [_HANDLE, ctypes.c_void_p, _DWORD] _kernel32.GetModuleFileNameA.restype = _DWORD _kernel32.CreateProcessA.argtypes = [_LPCSTR, _LPCSTR, ctypes.c_void_p, ctypes.c_void_p, _BOOL, _DWORD, ctypes.c_void_p, _LPCSTR, ctypes.c_void_p, ctypes.c_void_p] _kernel32.CreateProcessA.restype = _BOOL _kernel32.ExitProcess.argtypes = [_UINT] _kernel32.ExitProcess.restype = None _kernel32.GetCurrentProcessId.argtypes = [] _kernel32.GetCurrentProcessId.restype = _DWORD _SIGNAL_HANDLER = ctypes.WINFUNCTYPE(_BOOL, _DWORD) _kernel32.SetConsoleCtrlHandler.argtypes = [_SIGNAL_HANDLER, _BOOL] _kernel32.SetConsoleCtrlHandler.restype = _BOOL _kernel32.GetStdHandle.argtypes = [_DWORD] _kernel32.GetStdHandle.restype = _HANDLE _kernel32.GetConsoleScreenBufferInfo.argtypes = [_HANDLE, ctypes.c_void_p] _kernel32.GetConsoleScreenBufferInfo.restype = _BOOL _advapi32.GetUserNameA.argtypes = [ctypes.c_void_p, ctypes.c_void_p] _advapi32.GetUserNameA.restype = _BOOL _user32.GetWindowThreadProcessId.argtypes = [_HANDLE, ctypes.c_void_p] _user32.GetWindowThreadProcessId.restype = _DWORD _user32.ShowWindow.argtypes = [_HANDLE, ctypes.c_int] _user32.ShowWindow.restype = _BOOL _WNDENUMPROC = ctypes.WINFUNCTYPE(_BOOL, _HWND, _LPARAM) _user32.EnumWindows.argtypes = [_WNDENUMPROC, _LPARAM] _user32.EnumWindows.restype = _BOOL _kernel32.CreateToolhelp32Snapshot.argtypes = [_DWORD, _DWORD] _kernel32.CreateToolhelp32Snapshot.restype = _BOOL _kernel32.PeekNamedPipe.argtypes = [_HANDLE, ctypes.c_void_p, _DWORD, ctypes.c_void_p, ctypes.c_void_p, ctypes.c_void_p] _kernel32.PeekNamedPipe.restype = _BOOL _kernel32.Process32First.argtypes = [_HANDLE, ctypes.c_void_p] _kernel32.Process32First.restype = _BOOL _kernel32.Process32Next.argtypes = [_HANDLE, ctypes.c_void_p] _kernel32.Process32Next.restype = _BOOL def _raiseoserror(name): err = ctypes.WinError() raise OSError(err.errno, '%s: %s' % (name, err.strerror)) def _getfileinfo(name): fh = _kernel32.CreateFileA(name, 0, _FILE_SHARE_READ | _FILE_SHARE_WRITE | _FILE_SHARE_DELETE, None, _OPEN_EXISTING, _FILE_FLAG_BACKUP_SEMANTICS, None) if fh == _INVALID_HANDLE_VALUE: _raiseoserror(name) try: fi = _BY_HANDLE_FILE_INFORMATION() if not _kernel32.GetFileInformationByHandle(fh, ctypes.byref(fi)): _raiseoserror(name) return fi finally: _kernel32.CloseHandle(fh) def oslink(src, dst): try: if not _kernel32.CreateHardLinkA(dst, src, None): _raiseoserror(src) except AttributeError: # Wine doesn't support this function _raiseoserror(src) def nlinks(name): '''return number of hardlinks for the given file''' return _getfileinfo(name).nNumberOfLinks def samefile(path1, path2): '''Returns whether path1 and path2 refer to the same file or directory.''' res1 = _getfileinfo(path1) res2 = _getfileinfo(path2) return (res1.dwVolumeSerialNumber == res2.dwVolumeSerialNumber and res1.nFileIndexHigh == res2.nFileIndexHigh and res1.nFileIndexLow == res2.nFileIndexLow) def samedevice(path1, path2): '''Returns whether path1 and path2 are on the same device.''' res1 = _getfileinfo(path1) res2 = _getfileinfo(path2) return res1.dwVolumeSerialNumber == res2.dwVolumeSerialNumber def peekpipe(pipe): handle = msvcrt.get_osfhandle(pipe.fileno()) avail = _DWORD() if not _kernel32.PeekNamedPipe(handle, None, 0, None, ctypes.byref(avail), None): err = _kernel32.GetLastError() if err == _ERROR_BROKEN_PIPE: return 0 raise ctypes.WinError(err) return avail.value def testpid(pid): '''return True if pid is still running or unable to determine, False otherwise''' h = _kernel32.OpenProcess(_PROCESS_QUERY_INFORMATION, False, pid) if h: try: status = _DWORD() if _kernel32.GetExitCodeProcess(h, ctypes.byref(status)): return status.value == _STILL_ACTIVE finally: _kernel32.CloseHandle(h) return _kernel32.GetLastError() != _ERROR_INVALID_PARAMETER def executablepath(): '''return full path of hg.exe''' size = 600 buf = ctypes.create_string_buffer(size + 1) len = _kernel32.GetModuleFileNameA(None, ctypes.byref(buf), size) if len == 0: raise ctypes.WinError() # Note: WinError is a function elif len == size: raise ctypes.WinError(_ERROR_INSUFFICIENT_BUFFER) return buf.value def getuser(): '''return name of current user''' size = _DWORD(300) buf = ctypes.create_string_buffer(size.value + 1) if not _advapi32.GetUserNameA(ctypes.byref(buf), ctypes.byref(size)): raise ctypes.WinError() return buf.value _signalhandler = [] def setsignalhandler(): '''Register a termination handler for console events including CTRL+C. python signal handlers do not work well with socket operations. ''' def handler(event): _kernel32.ExitProcess(1) if _signalhandler: return # already registered h = _SIGNAL_HANDLER(handler) _signalhandler.append(h) # needed to prevent garbage collection if not _kernel32.SetConsoleCtrlHandler(h, True): raise ctypes.WinError() def hidewindow(): def callback(hwnd, pid): wpid = _DWORD() _user32.GetWindowThreadProcessId(hwnd, ctypes.byref(wpid)) if pid == wpid.value: _user32.ShowWindow(hwnd, _SW_HIDE) return False # stop enumerating windows return True pid = _kernel32.GetCurrentProcessId() _user32.EnumWindows(_WNDENUMPROC(callback), pid) def termwidth(): # cmd.exe does not handle CR like a unix console, the CR is # counted in the line length. On 80 columns consoles, if 80 # characters are written, the following CR won't apply on the # current line but on the new one. Keep room for it. width = 79 # Query stderr to avoid problems with redirections screenbuf = _kernel32.GetStdHandle( _STD_ERROR_HANDLE) # don't close the handle returned if screenbuf is None or screenbuf == _INVALID_HANDLE_VALUE: return width csbi = _CONSOLE_SCREEN_BUFFER_INFO() if not _kernel32.GetConsoleScreenBufferInfo( screenbuf, ctypes.byref(csbi)): return width width = csbi.srWindow.Right - csbi.srWindow.Left return width def _1stchild(pid): '''return the 1st found child of the given pid None is returned when no child is found''' pe = _tagPROCESSENTRY32() # create handle to list all processes ph = _kernel32.CreateToolhelp32Snapshot(_TH32CS_SNAPPROCESS, 0) if ph == _INVALID_HANDLE_VALUE: raise ctypes.WinError() try: r = _kernel32.Process32First(ph, ctypes.byref(pe)) # loop over all processes while r: if pe.th32ParentProcessID == pid: # return first child found return pe.th32ProcessID r = _kernel32.Process32Next(ph, ctypes.byref(pe)) finally: _kernel32.CloseHandle(ph) if _kernel32.GetLastError() != _ERROR_NO_MORE_FILES: raise ctypes.WinError() return None # no child found class _tochildpid(int): # pid is _DWORD, which always matches in an int '''helper for spawndetached, returns the child pid on conversion to string Does not resolve the child pid immediately because the child may not yet be started. ''' def childpid(self): '''returns the child pid of the first found child of the process with this pid''' return _1stchild(self) def __str__(self): # run when the pid is written to the file ppid = self.childpid() if ppid is None: # race, child has exited since check # fall back to this pid. Its process will also have disappeared, # raising the same error type later as when the child pid would # be returned. return " %d" % self return str(ppid) def spawndetached(args): # No standard library function really spawns a fully detached # process under win32 because they allocate pipes or other objects # to handle standard streams communications. Passing these objects # to the child process requires handle inheritance to be enabled # which makes really detached processes impossible. si = _STARTUPINFO() si.cb = ctypes.sizeof(_STARTUPINFO) pi = _PROCESS_INFORMATION() env = '' for k in os.environ: env += "%s=%s\0" % (k, os.environ[k]) if not env: env = '\0' env += '\0' args = subprocess.list2cmdline(args) # Not running the command in shell mode makes Python 2.6 hang when # writing to hgweb output socket. comspec = os.environ.get("COMSPEC", "cmd.exe") args = comspec + " /c " + args res = _kernel32.CreateProcessA( None, args, None, None, False, _CREATE_NO_WINDOW, env, os.getcwd(), ctypes.byref(si), ctypes.byref(pi)) if not res: raise ctypes.WinError() # _tochildpid because the process is the child of COMSPEC return _tochildpid(pi.dwProcessId) def unlink(f): '''try to implement POSIX' unlink semantics on Windows''' if os.path.isdir(f): # use EPERM because it is POSIX prescribed value, even though # unlink(2) on directories returns EISDIR on Linux raise IOError(errno.EPERM, "Unlinking directory not permitted: '%s'" % f) # POSIX allows to unlink and rename open files. Windows has serious # problems with doing that: # - Calling os.unlink (or os.rename) on a file f fails if f or any # hardlinked copy of f has been opened with Python's open(). There is no # way such a file can be deleted or renamed on Windows (other than # scheduling the delete or rename for the next reboot). # - Calling os.unlink on a file that has been opened with Mercurial's # posixfile (or comparable methods) will delay the actual deletion of # the file for as long as the file is held open. The filename is blocked # during that time and cannot be used for recreating a new file under # that same name ("zombie file"). Directories containing such zombie files # cannot be removed or moved. # A file that has been opened with posixfile can be renamed, so we rename # f to a random temporary name before calling os.unlink on it. This allows # callers to recreate f immediately while having other readers do their # implicit zombie filename blocking on a temporary name. for tries in xrange(10): temp = '%s-%08x' % (f, random.randint(0, 0xffffffff)) try: os.rename(f, temp) # raises OSError EEXIST if temp exists break except OSError as e: if e.errno != errno.EEXIST: raise else: raise IOError(errno.EEXIST, "No usable temporary filename found") try: os.unlink(temp) except OSError: # The unlink might have failed because the READONLY attribute may heave # been set on the original file. Rename works fine with READONLY set, # but not os.unlink. Reset all attributes and try again. _kernel32.SetFileAttributesA(temp, _FILE_ATTRIBUTE_NORMAL) try: os.unlink(temp) except OSError: # The unlink might have failed due to some very rude AV-Scanners. # Leaking a tempfile is the lesser evil than aborting here and # leaving some potentially serious inconsistencies. pass def makedir(path, notindexed): os.mkdir(path) if notindexed: _kernel32.SetFileAttributesA(path, _FILE_ATTRIBUTE_NOT_CONTENT_INDEXED)