Mercurial > hg
view mercurial/transaction.py @ 7787:b8d750daadde
Introduce HG_PREPEND to solve pretxn races
- add writepending to flush delayed writes to separate file
- add support in hooks for lazy evaluation of callable parameters
- add HG_PENDING to pretxn hooks
- call writepending if hook is used
- pass repo root to hook environment
- if HG_PENDING = repo root, we're in pretxn hook
- read pending data to make pending changesets visible
- filter HG_PENDING in tests/printenv.py
author | Matt Mackall <mpm@selenic.com> |
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date | Mon, 16 Feb 2009 19:35:07 -0600 |
parents | 866d2715aff5 |
children | 9f14b66830a8 |
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# transaction.py - simple journalling scheme for mercurial # # This transaction scheme is intended to gracefully handle program # errors and interruptions. More serious failures like system crashes # can be recovered with an fsck-like tool. As the whole repository is # effectively log-structured, this should amount to simply truncating # anything that isn't referenced in the changelog. # # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms # of the GNU General Public License, incorporated herein by reference. from i18n import _ import os, errno class transaction(object): def __init__(self, report, opener, journal, after=None, createmode=None): self.journal = None self.count = 1 self.report = report self.opener = opener self.after = after self.entries = [] self.map = {} self.journal = journal self.file = open(self.journal, "w") if createmode is not None: os.chmod(self.journal, createmode & 0666) def __del__(self): if self.journal: if self.entries: self.abort() self.file.close() try: os.unlink(self.journal) except: pass def add(self, file, offset, data=None): if file in self.map: return self.entries.append((file, offset, data)) self.map[file] = len(self.entries) - 1 # add enough data to the journal to do the truncate self.file.write("%s\0%d\n" % (file, offset)) self.file.flush() def find(self, file): if file in self.map: return self.entries[self.map[file]] return None def replace(self, file, offset, data=None): if file not in self.map: raise KeyError(file) index = self.map[file] self.entries[index] = (file, offset, data) self.file.write("%s\0%d\n" % (file, offset)) self.file.flush() def nest(self): self.count += 1 return self def running(self): return self.count > 0 def close(self): self.count -= 1 if self.count != 0: return self.file.close() self.entries = [] if self.after: self.after() else: os.unlink(self.journal) self.journal = None def abort(self): if not self.entries: return self.report(_("transaction abort!\n")) for f, o, ignore in self.entries: try: self.opener(f, "a").truncate(o) except: self.report(_("failed to truncate %s\n") % f) self.entries = [] self.report(_("rollback completed\n")) def rollback(opener, file): files = {} for l in open(file).readlines(): f, o = l.split('\0') files[f] = int(o) for f in files: o = files[f] if o: opener(f, "a").truncate(int(o)) else: try: fn = opener(f).name os.unlink(fn) except OSError, inst: if inst.errno != errno.ENOENT: raise os.unlink(file)