mercurial/dirstatemap.py

stream-clone: stop getting the file size of all file in v3

The point of v3 is to do less work in the locked section. It was currently not
the case.


This significantly boost performance. The following number comes from a large
private repository using perf::stream-locked-section:

base-line:   35.03 seconds
this-change: 24.50 seconds (-30%)

# dirstatemap.py
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.


from .i18n import _

from . import (
    error,
    pathutil,
    policy,
    testing,
    txnutil,
    util,
)

from .dirstateutils import (
    docket as docketmod,
    v2,
)

parsers = policy.importmod('parsers')
rustmod = policy.importrust('dirstate')

propertycache = util.propertycache

if rustmod is None:
    DirstateItem = parsers.DirstateItem
else:
    DirstateItem = rustmod.DirstateItem

rangemask = 0x7FFFFFFF

WRITE_MODE_AUTO = 0
WRITE_MODE_FORCE_NEW = 1
WRITE_MODE_FORCE_APPEND = 2


V2_MAX_READ_ATTEMPTS = 5


class _dirstatemapcommon:
    """
    Methods that are identical for both implementations of the dirstatemap
    class, with and without Rust extensions enabled.
    """

    # please pytype

    _map = None
    copymap = None

    def __init__(self, ui, opener, root, nodeconstants, use_dirstate_v2):
        self._use_dirstate_v2 = use_dirstate_v2
        self._nodeconstants = nodeconstants
        self._ui = ui
        self._opener = opener
        self._root = root
        self._filename = b'dirstate'
        self._nodelen = 20  # Also update Rust code when changing this!
        self._parents = None
        self._dirtyparents = False
        self._docket = None
        write_mode = ui.config(b"devel", b"dirstate.v2.data_update_mode")
        if write_mode == b"auto":
            self._write_mode = WRITE_MODE_AUTO
        elif write_mode == b"force-append":
            self._write_mode = WRITE_MODE_FORCE_APPEND
        elif write_mode == b"force-new":
            self._write_mode = WRITE_MODE_FORCE_NEW
        else:
            # unknown value, fallback to default
            self._write_mode = WRITE_MODE_AUTO

        # for consistent view between _pl() and _read() invocations
        self._pendingmode = None

    def _set_identity(self):
        self.identity = self._get_current_identity()

    def _get_current_identity(self):
        try:
            return util.cachestat(self._opener.join(self._filename))
        except FileNotFoundError:
            return None

    def may_need_refresh(self):
        if 'identity' not in vars(self):
            # no existing identity, we need a refresh
            return True
        if self.identity is None:
            return True
        if not self.identity.cacheable():
            # We cannot trust the entry
            # XXX this is a problem on windows, NFS, or other inode less system
            return True
        current_identity = self._get_current_identity()
        if current_identity is None:
            return True
        if not current_identity.cacheable():
            # We cannot trust the entry
            # XXX this is a problem on windows, NFS, or other inode less system
            return True
        return current_identity != self.identity

    def preload(self):
        """Loads the underlying data, if it's not already loaded"""
        self._map

    def get(self, key, default=None):
        return self._map.get(key, default)

    def __len__(self):
        return len(self._map)

    def __iter__(self):
        return iter(self._map)

    def __contains__(self, key):
        return key in self._map

    def __getitem__(self, item):
        return self._map[item]

    ### disk interaction

    def _opendirstatefile(self):
        fp, mode = txnutil.trypending(self._root, self._opener, self._filename)
        if self._pendingmode is not None and self._pendingmode != mode:
            fp.close()
            raise error.Abort(
                _(b'working directory state may be changed parallelly')
            )
        self._pendingmode = mode
        return fp

    def _readdirstatefile(self, size=-1):
        try:
            with self._opendirstatefile() as fp:
                return fp.read(size)
        except FileNotFoundError:
            # File doesn't exist, so the current state is empty
            return b''

    @property
    def docket(self):
        if not self._docket:
            if not self._use_dirstate_v2:
                raise error.ProgrammingError(
                    b'dirstate only has a docket in v2 format'
                )
            self._set_identity()
            data = self._readdirstatefile()
            if data == b'' or data.startswith(docketmod.V2_FORMAT_MARKER):
                self._docket = docketmod.DirstateDocket.parse(
                    data, self._nodeconstants
                )
            else:
                raise error.CorruptedDirstate(b"dirstate is not in v2 format")
        return self._docket

    def _read_v2_data(self):
        data = None
        attempts = 0
        while attempts < V2_MAX_READ_ATTEMPTS:
            attempts += 1
            try:
                # TODO: use mmap when possible
                data = self._opener.read(self.docket.data_filename())
            except FileNotFoundError:
                # read race detected between docket and data file
                # reload the docket and retry
                self._docket = None
        if data is None:
            assert attempts >= V2_MAX_READ_ATTEMPTS
            msg = b"dirstate read race happened %d times in a row"
            msg %= attempts
            raise error.Abort(msg)
        return self._opener.read(self.docket.data_filename())

    def write_v2_no_append(self, tr, st, meta, packed):
        try:
            old_docket = self.docket
        except error.CorruptedDirstate:
            # This means we've identified a dirstate-v1 file on-disk when we
            # were expecting a dirstate-v2 docket. We've managed to recover
            # from that unexpected situation, and now we want to write back a
            # dirstate-v2 file to make the on-disk situation right again.
            #
            # This shouldn't be triggered since `self.docket` is cached and
            # we would have called parents() or read() first, but it's here
            # just in case.
            old_docket = None

        new_docket = docketmod.DirstateDocket.with_new_uuid(
            self.parents(), len(packed), meta
        )
        if old_docket is not None and old_docket.uuid == new_docket.uuid:
            raise error.ProgrammingError(b'dirstate docket name collision')
        data_filename = new_docket.data_filename()
        self._opener.write(data_filename, packed)
        # tell the transaction that we are adding a new file
        if tr is not None:
            tr.addbackup(data_filename, location=b'plain')
        # Write the new docket after the new data file has been
        # written. Because `st` was opened with `atomictemp=True`,
        # the actual `.hg/dirstate` file is only affected on close.
        st.write(new_docket.serialize())
        st.close()
        # Remove the old data file after the new docket pointing to
        # the new data file was written.
        if old_docket is not None and old_docket.uuid:
            data_filename = old_docket.data_filename()
            if tr is not None:
                tr.addbackup(data_filename, location=b'plain')
            unlink = lambda _tr=None: self._opener.unlink(data_filename)
            if tr:
                category = b"dirstate-v2-clean-" + old_docket.uuid
                tr.addpostclose(category, unlink)
            else:
                unlink()
        self._docket = new_docket

    ### reading/setting parents

    def parents(self):
        if not self._parents:
            if self._use_dirstate_v2:
                try:
                    self.docket
                except error.CorruptedDirstate as e:
                    # fall back to dirstate-v1 if we fail to read v2
                    self._v1_parents(e)
                else:
                    self._parents = self.docket.parents
            else:
                self._v1_parents()

        return self._parents

    def _v1_parents(self, from_v2_exception=None):
        read_len = self._nodelen * 2
        st = self._readdirstatefile(read_len)
        l = len(st)
        if l == read_len:
            self._parents = (
                st[: self._nodelen],
                st[self._nodelen : 2 * self._nodelen],
            )
        elif l == 0:
            self._parents = (
                self._nodeconstants.nullid,
                self._nodeconstants.nullid,
            )
        else:
            hint = None
            if from_v2_exception is not None:
                hint = _(b"falling back to dirstate-v1 from v2 also failed")
            raise error.Abort(
                _(b'working directory state appears damaged!'), hint
            )


class dirstatemap(_dirstatemapcommon):
    """Map encapsulating the dirstate's contents.

    The dirstate contains the following state:

    - `identity` is the identity of the dirstate file, which can be used to
      detect when changes have occurred to the dirstate file.

    - `parents` is a pair containing the parents of the working copy. The
      parents are updated by calling `setparents`.

    - the state map maps filenames to tuples of (state, mode, size, mtime),
      where state is a single character representing 'normal', 'added',
      'removed', or 'merged'. It is read by treating the dirstate as a
      dict.  File state is updated by calling various methods (see each
      documentation for details):

      - `reset_state`,
      - `set_tracked`
      - `set_untracked`
      - `set_clean`
      - `set_possibly_dirty`

    - `copymap` maps destination filenames to their source filename.

    The dirstate also provides the following views onto the state:

    - `filefoldmap` is a dict mapping normalized filenames to the denormalized
      form that they appear as in the dirstate.

    - `dirfoldmap` is a dict mapping normalized directory names to the
      denormalized form that they appear as in the dirstate.
    """

    ### Core data storage and access

    @propertycache
    def _map(self):
        self._map = {}
        self.read()
        return self._map

    @propertycache
    def copymap(self):
        self.copymap = {}
        self._map
        return self.copymap

    def clear(self):
        self._map.clear()
        self.copymap.clear()
        self.setparents(self._nodeconstants.nullid, self._nodeconstants.nullid)
        util.clearcachedproperty(self, b"_dirs")
        util.clearcachedproperty(self, b"_alldirs")
        util.clearcachedproperty(self, b"filefoldmap")
        util.clearcachedproperty(self, b"dirfoldmap")

    def items(self):
        return self._map.items()

    # forward for python2,3 compat
    iteritems = items

    def debug_iter(self, all):
        """
        Return an iterator of (filename, state, mode, size, mtime) tuples

        `all` is unused when Rust is not enabled
        """
        for (filename, item) in self.items():
            yield (filename, item.state, item.mode, item.size, item.mtime)

    def keys(self):
        return self._map.keys()

    ### reading/setting parents

    def setparents(self, p1, p2, fold_p2=False):
        self._parents = (p1, p2)
        self._dirtyparents = True
        copies = {}
        if fold_p2:
            for f, s in self._map.items():
                # Discard "merged" markers when moving away from a merge state
                if s.p2_info:
                    source = self.copymap.pop(f, None)
                    if source:
                        copies[f] = source
                    s.drop_merge_data()
        return copies

    ### disk interaction

    def read(self):
        testing.wait_on_cfg(self._ui, b'dirstate.pre-read-file')
        if self._use_dirstate_v2:
            try:
                self.docket
            except error.CorruptedDirstate:
                # fall back to dirstate-v1 if we fail to read v2
                self._set_identity()
                st = self._readdirstatefile()
            else:
                if not self.docket.uuid:
                    return
                testing.wait_on_cfg(self._ui, b'dirstate.post-docket-read-file')
                st = self._read_v2_data()
        else:
            self._set_identity()
            st = self._readdirstatefile()

        if not st:
            return

        # TODO: adjust this estimate for dirstate-v2
        if hasattr(parsers, 'dict_new_presized'):
            # Make an estimate of the number of files in the dirstate based on
            # its size. This trades wasting some memory for avoiding costly
            # resizes. Each entry have a prefix of 17 bytes followed by one or
            # two path names. Studies on various large-scale real-world repositories
            # found 54 bytes a reasonable upper limit for the average path names.
            # Copy entries are ignored for the sake of this estimate.
            self._map = parsers.dict_new_presized(len(st) // 71)

        # Python's garbage collector triggers a GC each time a certain number
        # of container objects (the number being defined by
        # gc.get_threshold()) are allocated. parse_dirstate creates a tuple
        # for each file in the dirstate. The C version then immediately marks
        # them as not to be tracked by the collector. However, this has no
        # effect on when GCs are triggered, only on what objects the GC looks
        # into. This means that O(number of files) GCs are unavoidable.
        # Depending on when in the process's lifetime the dirstate is parsed,
        # this can get very expensive. As a workaround, disable GC while
        # parsing the dirstate.
        #
        # (we cannot decorate the function directly since it is in a C module)
        if self._use_dirstate_v2:
            try:
                self.docket
            except error.CorruptedDirstate:
                # fall back to dirstate-v1 if we fail to parse v2
                parse_dirstate = util.nogc(parsers.parse_dirstate)
                p = parse_dirstate(self._map, self.copymap, st)
            else:
                p = self.docket.parents
                meta = self.docket.tree_metadata
                parse_dirstate = util.nogc(v2.parse_dirstate)
                parse_dirstate(self._map, self.copymap, st, meta)
        else:
            parse_dirstate = util.nogc(parsers.parse_dirstate)
            p = parse_dirstate(self._map, self.copymap, st)
        if not self._dirtyparents:
            self.setparents(*p)

        # Avoid excess attribute lookups by fast pathing certain checks
        self.__contains__ = self._map.__contains__
        self.__getitem__ = self._map.__getitem__
        self.get = self._map.get

    def write(self, tr, st):
        if self._use_dirstate_v2:
            packed, meta = v2.pack_dirstate(self._map, self.copymap)
            self.write_v2_no_append(tr, st, meta, packed)
        else:
            packed = parsers.pack_dirstate(
                self._map, self.copymap, self.parents()
            )
            st.write(packed)
            st.close()
        self._dirtyparents = False

    @propertycache
    def identity(self):
        self._map
        return self.identity

    ### code related to maintaining and accessing "extra" property
    # (e.g. "has_dir")

    def _dirs_incr(self, filename, old_entry=None):
        """increment the dirstate counter if applicable"""
        if (
            old_entry is None or old_entry.removed
        ) and "_dirs" in self.__dict__:
            self._dirs.addpath(filename)
        if old_entry is None and "_alldirs" in self.__dict__:
            self._alldirs.addpath(filename)

    def _dirs_decr(self, filename, old_entry=None, remove_variant=False):
        """decrement the dirstate counter if applicable"""
        if old_entry is not None:
            if "_dirs" in self.__dict__ and not old_entry.removed:
                self._dirs.delpath(filename)
            if "_alldirs" in self.__dict__ and not remove_variant:
                self._alldirs.delpath(filename)
        elif remove_variant and "_alldirs" in self.__dict__:
            self._alldirs.addpath(filename)
        if "filefoldmap" in self.__dict__:
            normed = util.normcase(filename)
            self.filefoldmap.pop(normed, None)

    @propertycache
    def filefoldmap(self):
        """Returns a dictionary mapping normalized case paths to their
        non-normalized versions.
        """
        try:
            makefilefoldmap = parsers.make_file_foldmap
        except AttributeError:
            pass
        else:
            return makefilefoldmap(
                self._map, util.normcasespec, util.normcasefallback
            )

        f = {}
        normcase = util.normcase
        for name, s in self._map.items():
            if not s.removed:
                f[normcase(name)] = name
        f[b'.'] = b'.'  # prevents useless util.fspath() invocation
        return f

    @propertycache
    def dirfoldmap(self):
        f = {}
        normcase = util.normcase
        for name in self._dirs:
            f[normcase(name)] = name
        return f

    def hastrackeddir(self, d):
        """
        Returns True if the dirstate contains a tracked (not removed) file
        in this directory.
        """
        return d in self._dirs

    def hasdir(self, d):
        """
        Returns True if the dirstate contains a file (tracked or removed)
        in this directory.
        """
        return d in self._alldirs

    @propertycache
    def _dirs(self):
        return pathutil.dirs(self._map, only_tracked=True)

    @propertycache
    def _alldirs(self):
        return pathutil.dirs(self._map)

    ### code related to manipulation of entries and copy-sources

    def reset_state(
        self,
        filename,
        wc_tracked=False,
        p1_tracked=False,
        p2_info=False,
        has_meaningful_mtime=True,
        parentfiledata=None,
    ):
        """Set a entry to a given state, diregarding all previous state

        This is to be used by the part of the dirstate API dedicated to
        adjusting the dirstate after a update/merge.

        note: calling this might result to no entry existing at all if the
        dirstate map does not see any point at having one for this file
        anymore.
        """
        # copy information are now outdated
        # (maybe new information should be in directly passed to this function)
        self.copymap.pop(filename, None)

        if not (p1_tracked or p2_info or wc_tracked):
            old_entry = self._map.get(filename)
            self._drop_entry(filename)
            self._dirs_decr(filename, old_entry=old_entry)
            return

        old_entry = self._map.get(filename)
        self._dirs_incr(filename, old_entry)
        entry = DirstateItem(
            wc_tracked=wc_tracked,
            p1_tracked=p1_tracked,
            p2_info=p2_info,
            has_meaningful_mtime=has_meaningful_mtime,
            parentfiledata=parentfiledata,
        )
        self._map[filename] = entry

    def set_tracked(self, filename):
        new = False
        entry = self.get(filename)
        if entry is None:
            self._dirs_incr(filename)
            entry = DirstateItem(
                wc_tracked=True,
            )

            self._map[filename] = entry
            new = True
        elif not entry.tracked:
            self._dirs_incr(filename, entry)
            entry.set_tracked()
            self._refresh_entry(filename, entry)
            new = True
        else:
            # XXX This is probably overkill for more case, but we need this to
            # fully replace the `normallookup` call with `set_tracked` one.
            # Consider smoothing this in the future.
            entry.set_possibly_dirty()
            self._refresh_entry(filename, entry)
        return new

    def set_untracked(self, f):
        """Mark a file as no longer tracked in the dirstate map"""
        entry = self.get(f)
        if entry is None:
            return False
        else:
            self._dirs_decr(f, old_entry=entry, remove_variant=not entry.added)
            if not entry.p2_info:
                self.copymap.pop(f, None)
            entry.set_untracked()
            self._refresh_entry(f, entry)
            return True

    def set_clean(self, filename, mode, size, mtime):
        """mark a file as back to a clean state"""
        entry = self[filename]
        size = size & rangemask
        entry.set_clean(mode, size, mtime)
        self._refresh_entry(filename, entry)
        self.copymap.pop(filename, None)

    def set_possibly_dirty(self, filename):
        """record that the current state of the file on disk is unknown"""
        entry = self[filename]
        entry.set_possibly_dirty()
        self._refresh_entry(filename, entry)

    def _refresh_entry(self, f, entry):
        """record updated state of an entry"""
        if not entry.any_tracked:
            self._map.pop(f, None)

    def _drop_entry(self, f):
        """remove any entry for file f

        This should also drop associated copy information

        The fact we actually need to drop it is the responsability of the caller"""
        self._map.pop(f, None)
        self.copymap.pop(f, None)


if rustmod is not None:

    class dirstatemap(_dirstatemapcommon):

        ### Core data storage and access

        @propertycache
        def _map(self):
            """
            Fills the Dirstatemap when called.
            """
            # ignore HG_PENDING because identity is used only for writing
            self._set_identity()

            testing.wait_on_cfg(self._ui, b'dirstate.pre-read-file')
            if self._use_dirstate_v2:
                try:
                    self.docket
                except error.CorruptedDirstate as e:
                    # fall back to dirstate-v1 if we fail to read v2
                    parents = self._v1_map(e)
                else:
                    parents = self.docket.parents
                    inode = (
                        self.identity.stat.st_ino
                        if self.identity is not None
                        and self.identity.stat is not None
                        else None
                    )
                    testing.wait_on_cfg(
                        self._ui, b'dirstate.post-docket-read-file'
                    )
                    if not self.docket.uuid:
                        data = b''
                        self._map = rustmod.DirstateMap.new_empty()
                    else:
                        data = self._read_v2_data()
                        self._map = rustmod.DirstateMap.new_v2(
                            data,
                            self.docket.data_size,
                            self.docket.tree_metadata,
                            self.docket.uuid,
                            inode,
                        )
                    parents = self.docket.parents
            else:
                parents = self._v1_map()

            if parents and not self._dirtyparents:
                self.setparents(*parents)

            self.__contains__ = self._map.__contains__
            self.__getitem__ = self._map.__getitem__
            self.get = self._map.get
            return self._map

        def _v1_map(self, from_v2_exception=None):
            self._set_identity()
            inode = (
                self.identity.stat.st_ino
                if self.identity is not None and self.identity.stat is not None
                else None
            )
            try:
                self._map, parents = rustmod.DirstateMap.new_v1(
                    self._readdirstatefile(), inode
                )
            except OSError as e:
                if from_v2_exception is not None:
                    raise e from from_v2_exception
                raise
            return parents

        @property
        def copymap(self):
            return self._map.copymap()

        def debug_iter(self, all):
            """
            Return an iterator of (filename, state, mode, size, mtime) tuples

            `all`: also include with `state == b' '` dirstate tree nodes that
            don't have an associated `DirstateItem`.

            """
            return self._map.debug_iter(all)

        def clear(self):
            self._map.clear()
            self.setparents(
                self._nodeconstants.nullid, self._nodeconstants.nullid
            )
            util.clearcachedproperty(self, b"_dirs")
            util.clearcachedproperty(self, b"_alldirs")
            util.clearcachedproperty(self, b"dirfoldmap")

        def items(self):
            return self._map.items()

        # forward for python2,3 compat
        iteritems = items

        def keys(self):
            return iter(self._map)

        ### reading/setting parents

        def setparents(self, p1, p2, fold_p2=False):
            self._parents = (p1, p2)
            self._dirtyparents = True
            copies = {}
            if fold_p2:
                copies = self._map.setparents_fixup()
            return copies

        ### disk interaction

        @propertycache
        def identity(self):
            self._map
            return self.identity

        def write(self, tr, st):
            if not self._use_dirstate_v2:
                p1, p2 = self.parents()
                packed = self._map.write_v1(p1, p2)
                st.write(packed)
                st.close()
                self._dirtyparents = False
                return

            write_mode = self._write_mode
            try:
                docket = self.docket
            except error.CorruptedDirstate:
                # fall back to dirstate-v1 if we fail to parse v2
                docket = None

            # We can only append to an existing data file if there is one
            if docket is None or docket.uuid is None:
                write_mode = WRITE_MODE_FORCE_NEW
            packed, meta, append = self._map.write_v2(write_mode)
            if append:
                docket = self.docket
                data_filename = docket.data_filename()
                # We mark it for backup to make sure a future `hg rollback` (or
                # `hg recover`?) call find the data it needs to restore a
                # working repository.
                #
                # The backup can use a hardlink because the format is resistant
                # to trailing "dead" data.
                if tr is not None:
                    tr.addbackup(data_filename, location=b'plain')
                with self._opener(data_filename, b'r+b') as fp:
                    fp.seek(docket.data_size)
                    assert fp.tell() == docket.data_size
                    written = fp.write(packed)
                    if written is not None:  # py2 may return None
                        assert written == len(packed), (written, len(packed))
                docket.data_size += len(packed)
                docket.parents = self.parents()
                docket.tree_metadata = meta
                st.write(docket.serialize())
                st.close()
            else:
                self.write_v2_no_append(tr, st, meta, packed)
            # Reload from the newly-written file
            util.clearcachedproperty(self, b"_map")
            self._dirtyparents = False

        ### code related to maintaining and accessing "extra" property
        # (e.g. "has_dir")

        @propertycache
        def filefoldmap(self):
            """Returns a dictionary mapping normalized case paths to their
            non-normalized versions.
            """
            return self._map.filefoldmapasdict()

        def hastrackeddir(self, d):
            return self._map.hastrackeddir(d)

        def hasdir(self, d):
            return self._map.hasdir(d)

        @propertycache
        def dirfoldmap(self):
            f = {}
            normcase = util.normcase
            for name in self._map.tracked_dirs():
                f[normcase(name)] = name
            return f

        ### code related to manipulation of entries and copy-sources

        def set_tracked(self, f):
            return self._map.set_tracked(f)

        def set_untracked(self, f):
            return self._map.set_untracked(f)

        def set_clean(self, filename, mode, size, mtime):
            self._map.set_clean(filename, mode, size, mtime)

        def set_possibly_dirty(self, f):
            self._map.set_possibly_dirty(f)

        def reset_state(
            self,
            filename,
            wc_tracked=False,
            p1_tracked=False,
            p2_info=False,
            has_meaningful_mtime=True,
            parentfiledata=None,
        ):
            return self._map.reset_state(
                filename,
                wc_tracked,
                p1_tracked,
                p2_info,
                has_meaningful_mtime,
                parentfiledata,
            )