apenwarr-redo/state.py
Avery Pennarun bb80118298 Cyclic dependency checker: don't give up token in common case.
The way the code was written, we'd give up our token, detect a cyclic
dependency, and then try to get our token back before exiting.  Even
with -j1, the temporary token release allowed any parent up the tree to
continue running jobs, so it would take an arbitrary amount of time
before we could exit (and report an error code to the parent).

There was no visible symptom of this except that, with -j1, t/355-deps-cyclic
would not finish until some of the later tests finished, which was
surprising.

To fix it, let's just check for a cyclic dependency first, then release
the token only once we're sure things are sane.
2018-11-13 07:00:09 -05:00

379 lines
11 KiB
Python

import sys, os, errno, glob, stat, fcntl, sqlite3
import vars
from helpers import unlink, close_on_exec, join
from log import warn, err, debug2, debug3
# When the module is imported, change the process title.
# We do it here because this module is imported by all the scripts.
try:
from setproctitle import setproctitle
except ImportError:
pass
else:
cmdline = sys.argv[:]
cmdline[0] = os.path.splitext(os.path.basename(cmdline[0]))[0]
setproctitle(" ".join(cmdline))
SCHEMA_VER=1
TIMEOUT=60
ALWAYS='//ALWAYS' # an invalid filename that is always marked as dirty
STAMP_DIR='dir' # the stamp of a directory; mtime is unhelpful
STAMP_MISSING='0' # the stamp of a nonexistent file
class CyclicDependencyError(Exception): pass
def _connect(dbfile):
_db = sqlite3.connect(dbfile, timeout=TIMEOUT)
_db.execute("pragma synchronous = off")
_db.execute("pragma journal_mode = WAL")
_db.text_factory = str
return _db
_db = None
def db():
global _db
if _db:
return _db
dbdir = '%s/.redo' % vars.BASE
dbfile = '%s/db.sqlite3' % dbdir
try:
os.mkdir(dbdir)
except OSError, e:
if e.errno == errno.EEXIST:
pass # if it exists, that's okay
else:
raise
must_create = not os.path.exists(dbfile)
if not must_create:
_db = _connect(dbfile)
try:
row = _db.cursor().execute("select version from Schema").fetchone()
except sqlite3.OperationalError:
row = None
ver = row and row[0] or None
if ver != SCHEMA_VER:
err("state database: discarding v%s (wanted v%s)\n"
% (ver, SCHEMA_VER))
must_create = True
_db = None
if must_create:
unlink(dbfile)
_db = _connect(dbfile)
_db.execute("create table Schema "
" (version int)")
_db.execute("create table Runid "
" (id integer primary key autoincrement)")
_db.execute("create table Files "
" (name not null primary key, "
" is_generated int, "
" is_override int, "
" checked_runid int, "
" changed_runid int, "
" failed_runid int, "
" stamp, "
" csum)")
_db.execute("create table Deps "
" (target int, "
" source int, "
" mode not null, "
" delete_me int, "
" primary key (target,source))")
_db.execute("insert into Schema (version) values (?)", [SCHEMA_VER])
# eat the '0' runid and File id
_db.execute("insert into Runid values "
" ((select max(id)+1 from Runid))")
_db.execute("insert into Files (name) values (?)", [ALWAYS])
if not vars.RUNID:
_db.execute("insert into Runid values "
" ((select max(id)+1 from Runid))")
vars.RUNID = _db.execute("select last_insert_rowid()").fetchone()[0]
os.environ['REDO_RUNID'] = str(vars.RUNID)
_db.commit()
return _db
def init():
db()
_wrote = 0
def _write(q, l):
if _insane:
return
global _wrote
_wrote += 1
db().execute(q, l)
def commit():
if _insane:
return
global _wrote
if _wrote:
db().commit()
_wrote = 0
def rollback():
if _insane:
return
global _wrote
if _wrote:
db().rollback()
_wrote = 0
def is_flushed():
return not _wrote
_insane = None
def check_sane():
global _insane, _writable
if not _insane:
_insane = not os.path.exists('%s/.redo' % vars.BASE)
return not _insane
_cwd = None
def relpath(t, base):
global _cwd
if not _cwd:
_cwd = os.getcwd()
t = os.path.normpath(os.path.join(_cwd, t))
base = os.path.normpath(base)
tparts = t.split('/')
bparts = base.split('/')
for tp,bp in zip(tparts,bparts):
if tp != bp:
break
tparts.pop(0)
bparts.pop(0)
while bparts:
tparts.insert(0, '..')
bparts.pop(0)
return join('/', tparts)
def warn_override(name):
warn('%s - you modified it; skipping\n' % name)
_file_cols = ['rowid', 'name', 'is_generated', 'is_override',
'checked_runid', 'changed_runid', 'failed_runid',
'stamp', 'csum']
class File(object):
# use this mostly to avoid accidentally assigning to typos
__slots__ = ['id'] + _file_cols[1:]
def _init_from_idname(self, id, name):
q = ('select %s from Files ' % join(', ', _file_cols))
if id != None:
q += 'where rowid=?'
l = [id]
elif name != None:
name = (name==ALWAYS) and ALWAYS or relpath(name, vars.BASE)
q += 'where name=?'
l = [name]
else:
raise Exception('name or id must be set')
d = db()
row = d.execute(q, l).fetchone()
if not row:
if not name:
raise Exception('No file with id=%r name=%r' % (id, name))
try:
_write('insert into Files (name) values (?)', [name])
except sqlite3.IntegrityError:
# some parallel redo probably added it at the same time; no
# big deal.
pass
row = d.execute(q, l).fetchone()
assert(row)
return self._init_from_cols(row)
def _init_from_cols(self, cols):
(self.id, self.name, self.is_generated, self.is_override,
self.checked_runid, self.changed_runid, self.failed_runid,
self.stamp, self.csum) = cols
if self.name == ALWAYS and self.changed_runid < vars.RUNID:
self.changed_runid = vars.RUNID
def __init__(self, id=None, name=None, cols=None):
if cols:
return self._init_from_cols(cols)
else:
return self._init_from_idname(id, name)
def __repr__(self):
return "File(%r)" % (self.nicename(),)
def refresh(self):
self._init_from_idname(self.id, None)
def save(self):
cols = join(', ', ['%s=?'%i for i in _file_cols[2:]])
_write('update Files set '
' %s '
' where rowid=?' % cols,
[self.is_generated, self.is_override,
self.checked_runid, self.changed_runid, self.failed_runid,
self.stamp, self.csum,
self.id])
def set_checked(self):
self.checked_runid = vars.RUNID
def set_checked_save(self):
self.set_checked()
self.save()
def set_changed(self):
debug2('BUILT: %r (%r)\n' % (self.name, self.stamp))
self.changed_runid = vars.RUNID
self.failed_runid = None
self.is_override = False
def set_failed(self):
debug2('FAILED: %r\n' % self.name)
self.update_stamp()
self.failed_runid = vars.RUNID
self.is_generated = True
def set_static(self):
self.update_stamp(must_exist=True)
self.is_override = False
self.is_generated = False
def set_override(self):
self.update_stamp()
self.is_override = True
def update_stamp(self, must_exist=False):
newstamp = self.read_stamp()
if must_exist and newstamp == STAMP_MISSING:
raise Exception("%r does not exist" % self.name)
if newstamp != self.stamp:
debug2("STAMP: %s: %r -> %r\n" % (self.name, self.stamp, newstamp))
self.stamp = newstamp
self.set_changed()
def is_checked(self):
return self.checked_runid and self.checked_runid >= vars.RUNID
def is_changed(self):
return self.changed_runid and self.changed_runid >= vars.RUNID
def is_failed(self):
return self.failed_runid and self.failed_runid >= vars.RUNID
def deps(self):
q = ('select Deps.mode, Deps.source, %s '
' from Files '
' join Deps on Files.rowid = Deps.source '
' where target=?' % join(', ', _file_cols[1:]))
for row in db().execute(q, [self.id]).fetchall():
mode = row[0]
cols = row[1:]
assert(mode in ('c', 'm'))
yield mode,File(cols=cols)
def zap_deps1(self):
debug2('zap-deps1: %r\n' % self.name)
_write('update Deps set delete_me=? where target=?', [True, self.id])
def zap_deps2(self):
debug2('zap-deps2: %r\n' % self.name)
_write('delete from Deps where target=? and delete_me=1', [self.id])
def add_dep(self, mode, dep):
src = File(name=dep)
debug3('add-dep: "%s" < %s "%s"\n' % (self.name, mode, src.name))
assert(self.id != src.id)
_write("insert or replace into Deps "
" (target, mode, source, delete_me) values (?,?,?,?)",
[self.id, mode, src.id, False])
def read_stamp(self):
try:
st = os.lstat(os.path.join(vars.BASE, self.name))
except OSError:
return STAMP_MISSING
if stat.S_ISDIR(st.st_mode):
return STAMP_DIR
else:
# a "unique identifier" stamp for a regular file
return str((st.st_mtime, st.st_size, st.st_ino,
st.st_mode, st.st_uid, st.st_gid))
def nicename(self):
return relpath(os.path.join(vars.BASE, self.name), vars.STARTDIR)
def files():
q = ('select %s from Files order by name' % join(', ', _file_cols))
for cols in db().execute(q).fetchall():
yield File(cols=cols)
# FIXME: I really want to use fcntl F_SETLK, F_SETLKW, etc here. But python
# doesn't do the lockdata structure in a portable way, so we have to use
# fcntl.lockf() instead. Usually this is just a wrapper for fcntl, so it's
# ok, but it doesn't have F_GETLK, so we can't report which pid owns the lock.
# The makes debugging a bit harder. When we someday port to C, we can do that.
_locks = {}
class Lock:
def __init__(self, fid):
self.owned = False
self.fid = fid
self.lockfile = None
self.lockfile = os.open(os.path.join(vars.BASE, '.redo/lock.%d' % fid),
os.O_RDWR | os.O_CREAT, 0666)
close_on_exec(self.lockfile, True)
assert(_locks.get(fid,0) == 0)
_locks[fid] = 1
def __del__(self):
_locks[self.fid] = 0
if self.owned:
self.unlock()
if self.lockfile is not None:
os.close(self.lockfile)
def check(self):
assert(not self.owned)
if str(self.fid) in vars.get_locks():
# Lock already held by parent: cyclic dependence
raise CyclicDependencyError()
def trylock(self):
self.check()
try:
fcntl.lockf(self.lockfile, fcntl.LOCK_EX|fcntl.LOCK_NB, 0, 0)
except IOError, e:
if e.errno in (errno.EAGAIN, errno.EACCES):
pass # someone else has it locked
else:
raise
else:
self.owned = True
def waitlock(self):
self.check()
fcntl.lockf(self.lockfile, fcntl.LOCK_EX, 0, 0)
self.owned = True
def unlock(self):
if not self.owned:
raise Exception("can't unlock %r - we don't own it"
% self.lockname)
fcntl.lockf(self.lockfile, fcntl.LOCK_UN, 0, 0)
self.owned = False