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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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# TODO: Up-front, stat all files in order and remove those which are deleted or
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# out-of-date. Don't actually re-read them until they're needed. That ought
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# to bring all the inodes into core so that future stats to them are fast, and
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# it preserves the nice property that any caller will always get up-to-date
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# data except in unavoidable cases.
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# TODO: Perhaps return more details on the file to avoid statting it
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# again: nonexistent, file type, size, etc
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# TODO: Perhaps use a Python pickle instead of a text file; might be faster.
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CACHE_HEADER = "### bzr hashcache v5\n"
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from bzrlib.osutils import sha_file, pathjoin, safe_unicode
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from bzrlib.trace import mutter, warning
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from bzrlib.atomicfile import AtomicFile
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from bzrlib.errors import BzrError
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CACHE_HEADER = "### bzr statcache v5\n"
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def _fingerprint(abspath):
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fs = os.lstat(abspath)
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number of misses (times files have been completely re-read)
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def __init__(self, root, cache_file_name, mode=None):
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"""Create a hash cache in base dir, and set the file mode to mode."""
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self.root = safe_unicode(root)
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def __init__(self, basedir):
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self.basedir = basedir
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self.hit_count = 0
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self.miss_count = 0
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self.stat_count = 0
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self.danger_count = 0
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self.removed_count = 0
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self.update_count = 0
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self._cache_file_name = safe_unicode(cache_file_name)
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def cache_file_name(self):
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return self._cache_file_name
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"""Discard all cached information.
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This does not reset the counters."""
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self.needs_write = True
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"""Scan all files and remove entries where the cache entry is obsolete.
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Obsolete entries are those where the file has been modified or deleted
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since the entry was inserted.
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# FIXME optimisation opportunity, on linux [and check other oses]:
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# rather than iteritems order, stat in inode order.
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prep = [(ce[1][3], path, ce) for (path, ce) in self._cache.iteritems()]
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for inum, path, cache_entry in prep:
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abspath = pathjoin(self.root, path)
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fp = _fingerprint(abspath)
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cache_fp = cache_entry[1]
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if (not fp) or (cache_fp != fp):
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# not here or not a regular file anymore
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self.removed_count += 1
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self.needs_write = True
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del self._cache[path]
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def get_sha1(self, path):
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"""Return the sha1 of a file.
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"""Return the hex SHA-1 of the contents of the file at path.
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XXX: If the file does not exist or is not a plain file???
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abspath = pathjoin(self.root, path)
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from bzrlib.osutils import sha_file
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abspath = os.path.join(self.basedir, path)
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fp = _fingerprint(abspath)
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c = self._cache.get(path)
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cache_sha1, cache_fp = c
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cache_sha1, cache_fp = None, None
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self.stat_count += 1
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file_fp = _fingerprint(abspath)
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# not a regular file or not existing
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if path in self._cache:
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self.removed_count += 1
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self.needs_write = True
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del self._cache[path]
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if path in self._cache:
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cache_sha1, cache_fp = self._cache[path]
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cache_sha1, cache_fp = None, None
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if cache_fp == file_fp:
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elif cache_fp and (cache_fp == fp):
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self.hit_count += 1
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return cache_sha1
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mode = file_fp[FP_MODE_COLUMN]
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if stat.S_ISREG(mode):
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digest = sha_file(file(abspath, 'rb', buffering=65000))
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elif stat.S_ISLNK(mode):
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digest = sha.new(os.readlink(abspath)).hexdigest()
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raise BzrError("file %r: unknown file stat mode: %o"%(abspath,mode))
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now = int(time.time())
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if file_fp[FP_MTIME_COLUMN] >= now or file_fp[FP_CTIME_COLUMN] >= now:
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# changed too recently; can't be cached. we can
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# return the result and it could possibly be cached
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# the point is that we only want to cache when we are sure that any
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# subsequent modifications of the file can be detected. If a
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# modification neither changes the inode, the device, the size, nor
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# the mode, then we can only distinguish it by time; therefore we
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# need to let sufficient time elapse before we may cache this entry
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# again. If we didn't do this, then, for example, a very quick 1
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# byte replacement in the file might go undetected.
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self.danger_count += 1
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self.removed_count += 1
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self.needs_write = True
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del self._cache[path]
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self.update_count += 1
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self.needs_write = True
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self._cache[path] = (digest, file_fp)
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digest = sha_file(file(abspath, 'rb'))
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now = int(time.time())
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if fp[1] >= now or fp[2] >= now:
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# changed too recently; can't be cached. we can
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# return the result and it could possibly be cached
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self.danger_count += 1
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del self._cache[path]
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self._cache[path] = (digest, fp)
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def write(self, cachefn):
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"""Write contents of cache to file."""
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outf = AtomicFile(self.cache_file_name(), 'wb', new_mode=self._mode)
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from atomicfile import AtomicFile
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outf = AtomicFile(cachefn, 'wb')
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print >>outf, CACHE_HEADER,
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print >>outf, "%d" % fld,
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self.needs_write = False
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mutter("write hash cache: %s hits=%d misses=%d stat=%d recent=%d updates=%d",
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self.cache_file_name(), self.hit_count, self.miss_count,
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self.danger_count, self.update_count)
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if not outf.closed:
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def read(self, cachefn):
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"""Reinstate cache from file.
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Overwrites existing cache.
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If the cache file has the wrong version marker, this just clears
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from bzrlib.trace import mutter, warning
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inf = file(cachefn, 'rb')
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fn = self.cache_file_name()
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inf = file(fn, 'rb', buffering=65000)
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mutter("failed to open %s: %s", fn, e)
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# better write it now so it is valid
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self.needs_write = True
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hdr = inf.readline()
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if hdr != CACHE_HEADER:
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mutter('cache header marker not found at top of %s;'
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' discarding cache', fn)
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self.needs_write = True
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mutter('cache header marker not found at top of %s; discarding cache'
added
removed
bzrlib/hashcache.py
