# Code dedicated to the caching of "stable ranges"

#

# These stable ranges are use for obsolescence markers discovery

#

# Copyright 2017 Pierre-Yves David <pierre-yves.david@ens-lyon.org>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

import abc

import heapq

import random

import sqlite3

import time

import weakref

from mercurial import (

    error,

    localrepo,

    util,

)

from . import (

    exthelper,

    genericcaches,

    stablerange,

    utility,

)

from mercurial.i18n import _

eh = exthelper.exthelper()

class stablerangeondiskbase(stablerange.stablerangecached,

                            genericcaches.changelogsourcebase):

    """combine the generic stablerange cache usage with generic changelog one

    """

    def _updatefrom(self, repo, data):

        """compute the rev of one revision, assert previous revision has an hot cache

        """

        repo = repo.unfiltered()

        ui = repo.ui

        rangeheap = []

        for r in data:

            rangeheap.append((r, 0))

        total = len(data)

        heappop = heapq.heappop

        heappush = heapq.heappush

        heapify = heapq.heapify

        original = set(rangeheap)

        seen = 0

        # progress report is showing up in the profile for small and fast

        # repository so we only update it every so often

        progress_each = 100

        progress_last = time.time()

        heapify(rangeheap)

        while rangeheap:

            rangeid = heappop(rangeheap)

            if rangeid in original:

                if not seen % progress_each:

                    # if a lot of time passed, report more often

                    progress_new = time.time()

                    if (1 < progress_each) and (0.1 < progress_new - progress_last):

                        progress_each /= 10

                    ui.progress(_("filling stablerange cache"), seen,

                                total=total, unit=_("changesets"))

                    progress_last = progress_new

                seen += 1

                original.remove(rangeid) # might have been added from other source

            rangeid = rangeid

            if self._getsub(rangeid) is None:

                for sub in self.subranges(repo, rangeid):

                    if self._getsub(sub) is None:

                        heappush(rangeheap, sub)

        ui.progress(_("filling stablerange cache"), None, total=total)

    def clear(self, reset=False):

        super(stablerangeondiskbase, self).clear()

        self._subrangescache.clear()

#############################

### simple sqlite caching ###

#############################

_sqliteschema = [

    """CREATE TABLE meta(schemaversion INTEGER NOT NULL,

                         tiprev        INTEGER NOT NULL,

                         tipnode       BLOB    NOT NULL

                        );""",

    """CREATE TABLE range(rev INTEGER  NOT NULL,

                          idx INTEGER NOT NULL,

                          PRIMARY KEY(rev, idx));""",

    """CREATE TABLE subranges(listidx INTEGER NOT NULL,

                              suprev  INTEGER NOT NULL,

                              supidx  INTEGER NOT NULL,

                              subrev  INTEGER NOT NULL,

                              subidx  INTEGER NOT NULL,

                              PRIMARY KEY(listidx, suprev, supidx),

                              FOREIGN KEY (suprev, supidx) REFERENCES range(rev, idx),

                              FOREIGN KEY (subrev, subidx) REFERENCES range(rev, idx)

    );""",

    "CREATE INDEX subranges_index ON subranges (suprev, supidx);",

    "CREATE INDEX superranges_index ON subranges (subrev, subidx);",

    "CREATE INDEX range_index ON range (rev, idx);",

]

_newmeta = "INSERT INTO meta (schemaversion, tiprev, tipnode) VALUES (?,?,?);"

_updatemeta = "UPDATE meta SET tiprev = ?, tipnode = ?;"

_updaterange = "INSERT INTO range(rev, idx) VALUES (?,?);"

_updatesubranges = """INSERT

                       INTO subranges(listidx, suprev, supidx, subrev, subidx)

                       VALUES (?,?,?,?,?);"""

_queryexist = "SELECT name FROM sqlite_master WHERE type='table' AND name='meta';"

_querymeta = "SELECT schemaversion, tiprev, tipnode FROM meta;"

_queryrange = "SELECT * FROM range WHERE (rev = ? AND idx = ?);"

_querysubranges = """SELECT subrev, subidx

                     FROM subranges

                     WHERE (suprev = ? AND supidx = ?)

                     ORDER BY listidx;"""

_querysuperrangesmain = """SELECT DISTINCT suprev, supidx

                           FROM subranges

                           WHERE %s;"""

_querysuperrangesbody = '(subrev = %d and subidx = %d)'

def _make_querysuperranges(ranges):

    # building a tree of OR would allow for more ranges

    body = ' OR '.join(_querysuperrangesbody % r for r in ranges)

    return _querysuperrangesmain % body

class stablerangesqlbase(stablerange.stablerangecached):

    """class that can handle all the bits needed to store range into sql

    """

    __metaclass__ = abc.ABCMeta

    _schemaversion = None

    _cachefile = None

    def __init__(self, repo, **kwargs):

        super(stablerangesqlbase, self).__init__(**kwargs)

        self._vfs = repo.vfs

        self._path = repo.vfs.join(self._cachefile)

        self._cl = repo.unfiltered().changelog # (okay to keep an old one)

        self._ondisktiprev = None

        self._ondisktipnode = None

        self._unsavedsubranges = {}

    def contains(self, repo, revs):

        con = self._con

        assert con is not None

        new = set()

        known = set()

        depth = repo.depthcache.get

        for r in revs:

            new.add((r, depth(r) - 1))

            new.add((r, 0))

        while new:

            if len(new) < 300:

                sample = new

            else:

                sample = random.sample(new, 300)

            known.update(sample)

            query = _make_querysuperranges(sample)

            ranges = set(con.execute(query).fetchall())

            new.update(ranges)

            new -= known

        return sorted(known)

    def _getsub(self, rangeid):

        # 1) check the in memory cache

        # 2) check the sqlcaches (and warm in memory cache we want we find)

        cache = self._subrangescache

        if rangeid not in cache and rangeid[0] <= self._ondisktiprev and self._con is not None:

            value = None

            result = self._con.execute(_queryrange, rangeid).fetchone()

            if result is not None: # database know about this node (skip in the future?)

                value = self._con.execute(_querysubranges, rangeid).fetchall()

            # in memory caching of the value

            cache[rangeid] = value

        return cache.get(rangeid)

    def _setsub(self, rangeid, value):

        assert rangeid not in self._unsavedsubranges

        self._unsavedsubranges[rangeid] = value

        super(stablerangesqlbase, self)._setsub(rangeid, value)

    def _db(self):

        try:

            util.makedirs(self._vfs.dirname(self._path))

        except OSError:

            return None

        con = sqlite3.connect(self._path, timeout=30, isolation_level="IMMEDIATE")

        con.text_factory = str

        return con

    @util.propertycache

    def _con(self):

        con = self._db()

        if con is None:

            return None

        cur = con.execute(_queryexist)

        if cur.fetchone() is None:

            return None

        meta = con.execute(_querymeta).fetchone()

        if meta is None:

            return None

        if meta[0] != self._schemaversion:

            return None

        if len(self._cl) <= meta[1]:

            return None

        if self._cl.node(meta[1]) != meta[2]:

            return None

        self._ondisktiprev = meta[1]

        self._ondisktipnode = meta[2]

        if self._tiprev < self._ondisktiprev:

            self._tiprev = self._ondisktiprev

            self._tipnode = self._ondisktipnode

        return con

    def _save(self, repo):

        try:

            return self._trysave(repo)

        except (sqlite3.OperationalError, sqlite3.IntegrityError) as exc:

            # Catch error that may arise under stress

            #

            # operational error catch read-only and locked database

            # IntegrityError catch Unique constraint error that may arise

            if '_con' in vars(self):

                del self._con

            self._unsavedsubranges.clear()

            repo.ui.log('evoext-cache', 'error while saving new data: %s' % exc)

    def _trysave(self, repo):

        repo = repo.unfiltered()

        repo.depthcache.save(repo)

        repo.stablesort.save(repo)

        repo.firstmergecache.save(repo)

        if not self._unsavedsubranges:

            return # no new data

        if self._con is None:

            util.unlinkpath(self._path, ignoremissing=True)

            if '_con' in vars(self):

                del self._con

            con = self._db()

            if con is None:

                return

            con.execute('BEGIN IMMEDIATE;')

            with con:

                for req in _sqliteschema:

                    con.execute(req)

                meta = [self._schemaversion,

                        self._tiprev,

                        self._tipnode,

                ]

                con.execute(_newmeta, meta)

        else:

            con = self._con

            con.execute('BEGIN IMMEDIATE;')

            meta = con.execute(_querymeta).fetchone()

            if meta[2] != self._ondisktipnode or meta[1] != self._ondisktiprev:

                # drifting is currently an issue because this means another

                # process might have already added the cache line we are about

                # to add. This will confuse sqlite

                msg = _('stable-range cache: skipping write, '

                        'database drifted under my feet\n')

                repo.ui.warn(msg)

                repo.ui.warn(hint % data)

                con.execute('ROLLBACK;')

                return

            meta = [self._tiprev,

                    self._tipnode,

            ]

            con.execute(_updatemeta, meta)

        self._saverange(con, repo)

        con.commit()

        self._ondisktiprev = self._tiprev

        self._ondisktipnode = self._tipnode

        self._unsavedsubranges.clear()

    def _saverange(self, con, repo):

        repo = repo.unfiltered()

        data = []

        allranges = set()

        for key, value in self._unsavedsubranges.items():

            allranges.add(key)

            for idx, sub in enumerate(value):

                data.append((idx, key[0], key[1], sub[0], sub[1]))

        con.executemany(_updaterange, allranges)

        con.executemany(_updatesubranges, data)

class stablerangesql(stablerangesqlbase, stablerangeondiskbase):

    """base clase able to preserve data to disk as sql"""

    __metaclass__ = abc.ABCMeta

    # self._cachekey = (tiprev, tipnode)

    @property

    def _tiprev(self):

        return self._cachekey[0]

    @_tiprev.setter

    def _tiprev(self, value):

        self._cachekey = (value, self._cachekey[1])

    @property

    def _tipnode(self):

        return self._cachekey[1]

    @_tipnode.setter

    def _tipnode(self, value):

        self._cachekey = (self._cachekey[0], value)

    def clear(self, reset=False):

        super(stablerangesql, self).clear(reset=reset)

        if '_con' in vars(self):

            del self._con

        self._subrangescache.clear()

    def load(self, repo):

        """load data from disk"""

        assert repo.filtername is None

        self._cachekey = self.emptykey

        if self._con is not None:

            self._cachekey = (self._ondisktiprev, self._ondisktipnode)

        self._ondiskkey = self._cachekey

    def save(self, repo):

        if self._cachekey is None or self._cachekey == self._ondiskkey:

            return

        self._save(repo)

class mergepointsql(stablerangesql, stablerange.stablerange_mergepoint):

    _schemaversion = 2

    _cachefile = 'cache/evoext_stablerange_v2.sqlite'

    _cachename = 'evo-ext-stablerange-mergepoint'

class sqlstablerange(stablerangesqlbase, stablerange.stablerange):

    _schemaversion = 1

    _cachefile = 'cache/evoext_stablerange_v1.sqlite'

    def warmup(self, repo, upto=None):

        self._con # make sure the data base is loaded

        try:

            # samelessly lock the repo to ensure nobody will update the repo

            # concurently. This should not be too much of an issue if we warm

            # at the end of the transaction.

            #

            # XXX However, we lock even if we are up to date so we should check

            # before locking

            with repo.lock():

                super(sqlstablerange, self).warmup(repo, upto)

                self._save(repo)

        except error.LockError:

            # Exceptionnally we are noisy about it since performance impact is

            # large We should address that before using this more widely.

            repo.ui.warn('stable-range cache: unable to lock repo while warming\n')

            repo.ui.warn('(cache will not be saved)\n')

            super(sqlstablerange, self).warmup(repo, upto)

@eh.reposetup

def setupcache(ui, repo):

    class stablerangerepo(repo.__class__):