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# Copyright (C) 2008, 2009, 2010 Canonical Ltd
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# Copyright (C) 2008, 2009 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# If each line is 50 bytes, and you have 255 internal pages, with 255-way fan
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# out, it takes 3.1MB to cache the layer.
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_PAGE_CACHE_SIZE = 4*1024*1024
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# Per thread caches for 2 reasons:
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# - in the server we may be serving very different content, so we get less
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# - we avoid locking on every cache lookup.
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_thread_caches = threading.local()
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_thread_caches.page_cache = None
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"""Get the per-thread page cache.
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We need a function to do this because in a new thread the _thread_caches
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threading.local object does not have the cache initialized yet.
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page_cache = getattr(_thread_caches, 'page_cache', None)
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if page_cache is None:
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# We are caching bytes so len(value) is perfectly accurate
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page_cache = lru_cache.LRUSizeCache(_PAGE_CACHE_SIZE)
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_thread_caches.page_cache = page_cache
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# We are caching bytes so len(value) is perfectly accurate
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_page_cache = lru_cache.LRUSizeCache(_PAGE_CACHE_SIZE)
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# If a ChildNode falls below this many bytes, we check for a remap
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_INTERESTING_NEW_SIZE = 50
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# If a ChildNode shrinks by more than this amount, we check for a remap
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_INTERESTING_SHRINKAGE_LIMIT = 20
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# If we delete more than this many nodes applying a delta, we check for a remap
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_INTERESTING_DELETES_LIMIT = 5
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def _search_key_plain(key):
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into the map; if old_key is not None, then the old mapping
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of old_key is removed.
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# Check preconditions first.
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as_st = StaticTuple.from_sequence
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new_items = set([as_st(key) for (old, key, value) in delta
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for old, new, value in delta:
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if old is not None and old != new:
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self.unmap(old, check_remap=False)
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for old, new, value in delta:
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if new is not None:
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self.map(new, value)
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if delete_count > _INTERESTING_DELETES_LIMIT:
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trace.mutter("checking remap as %d deletions", delete_count)
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self._check_remap()
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return self._save()
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def _read_bytes(self, key):
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return _get_cache()[key]
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return _page_cache[key]
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stream = self._store.get_record_stream([key], 'unordered', True)
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bytes = stream.next().get_bytes_as('fulltext')
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_get_cache()[key] = bytes
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_page_cache[key] = bytes
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def _dump_tree(self, include_keys=False):
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"""Check if nodes can be collapsed."""
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self._ensure_root()
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if type(self._root_node) is InternalNode:
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self._root_node = self._root_node._check_remap(self._store)
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self._root_node._check_remap(self._store)
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"""Save the map completely.
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the key/value pairs.
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__slots__ = ('_common_serialised_prefix',)
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__slots__ = ('_common_serialised_prefix', '_serialise_key')
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def __init__(self, search_key_func=None):
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Node.__init__(self)
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# All of the keys in this leaf node share this common prefix
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self._common_serialised_prefix = None
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self._serialise_key = '\x00'.join
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if search_key_func is None:
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self._search_key_func = _search_key_plain
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raise AssertionError('%r must be known' % self._search_prefix)
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return self._search_prefix, [("", self)]
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_serialise_key = '\x00'.join
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def serialise(self, store):
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"""Serialise the LeafNode to store.
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bytes = ''.join(lines)
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if len(bytes) != self._current_size():
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raise AssertionError('Invalid _current_size')
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_get_cache().add(self._key, bytes)
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_page_cache.add(self._key, bytes)
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return [self._key]
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prefix, node_key_filter = keys[record.key]
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node_and_filters.append((node, node_key_filter))
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self._items[prefix] = node
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_get_cache().add(record.key, bytes)
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_page_cache.add(record.key, bytes)
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for info in node_and_filters:
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lines.append(serialised[prefix_len:])
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sha1, _, _ = store.add_lines((None,), (), lines)
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self._key = StaticTuple("sha1:" + sha1,).intern()
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_get_cache().add(self._key, ''.join(lines))
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_page_cache.add(self._key, ''.join(lines))
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yield self._key
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def _search_key(self, key):
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return self._search_prefix
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def unmap(self, store, key, check_remap=True):
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"""Remove key from this node and its children."""
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"""Remove key from this node and it's children."""
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if not len(self._items):
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raise AssertionError("can't unmap in an empty InternalNode.")
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children = [node for node, _
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self._state = None
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def _read_nodes_from_store(self, keys):
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# We chose not to use _get_cache(), because we think in
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# terms of records to be yielded. Also, we expect to touch each page
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# only 1 time during this code. (We may want to evaluate saving the
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# raw bytes into the page cache, which would allow a working tree
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# update after the fetch to not have to read the bytes again.)
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# We chose not to use _page_cache, because we think in terms of records
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# to be yielded. Also, we expect to touch each page only 1 time during
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# this code. (We may want to evaluate saving the raw bytes into the
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# page cache, which would allow a working tree update after the fetch
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# to not have to read the bytes again.)
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as_st = StaticTuple.from_sequence
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stream = self._store.get_record_stream(keys, 'unordered', True)
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for record in stream:
added
removed
bzrlib/chk_map.py
