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e4d910ab82
Commit would overwrite undo.dirstate unconditionally, so an undo after an aborted commit would restore the dirstate from the aborted commit and not the prior transaction. This copies dirstate to journal.dirstate and moves it after a successful transaction.
79 lines
2.2 KiB
Python
79 lines
2.2 KiB
Python
# transaction.py - simple journalling scheme for mercurial
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#
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# This transaction scheme is intended to gracefully handle program
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# errors and interruptions. More serious failures like system crashes
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# can be recovered with an fsck-like tool. As the whole repository is
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# effectively log-structured, this should amount to simply truncating
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# anything that isn't referenced in the changelog.
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#
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# Copyright 2005 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms
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# of the GNU General Public License, incorporated herein by reference.
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import os
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import util
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class transaction:
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def __init__(self, report, opener, journal, after = None):
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self.journal = None
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# abort here if the journal already exists
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if os.path.exists(journal):
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raise "journal already exists - run hg recover"
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self.report = report
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self.opener = opener
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self.after = after
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self.entries = []
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self.map = {}
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self.journal = journal
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self.file = open(self.journal, "w")
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def __del__(self):
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if self.journal:
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if self.entries: self.abort()
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self.file.close()
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try: os.unlink(self.journal)
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except: pass
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def add(self, file, offset):
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if file in self.map: return
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self.entries.append((file, offset))
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self.map[file] = 1
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# add enough data to the journal to do the truncate
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self.file.write("%s\0%d\n" % (file, offset))
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self.file.flush()
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def close(self):
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self.file.close()
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self.entries = []
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if self.after:
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self.after()
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else:
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os.unlink(self.journal)
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self.journal = None
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def abort(self):
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if not self.entries: return
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self.report("transaction abort!\n")
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for f, o in self.entries:
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try:
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self.opener(f, "a").truncate(o)
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except:
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self.report("failed to truncate %s\n" % f)
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self.entries = []
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self.report("rollback completed\n")
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def rollback(opener, file):
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for l in open(file).readlines():
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f, o = l.split('\0')
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opener(f, "a").truncate(int(o))
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os.unlink(file)
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