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"""

import codecs
import contextlib as cl
import errno
import functools as ft
import io
import json
import os
import os.path as op
import pickle
import pickletools
import sqlite3
import struct
import tempfile
import threading
import time
import warnings
import zlib


def full_name(func):
    """Return full name of `func` by adding the module and function name."""
    return func.__module__ + '.' + func.__qualname__


class Constant(tuple):
    """Pretty display of immutable constant."""

    def __new__(cls, name):
        return tuple.__new__(cls, (name,))

    def __repr__(self):
        return '%s' % self[0]


DBNAME = 'cache.db'
ENOVAL = Constant('ENOVAL')
UNKNOWN = Constant('UNKNOWN')

MODE_NONE = 0
MODE_RAW = 1
MODE_BINARY = 2
MODE_TEXT = 3
MODE_PICKLE = 4

DEFAULT_SETTINGS = {
    'statistics': 0,  # False
    'tag_index': 0,  # False
    'eviction_policy': 'least-recently-stored',
    'size_limit': 2**30,  # 1gb
    'cull_limit': 10,
    'sqlite_auto_vacuum': 1,  # FULL
    'sqlite_cache_size': 2**13,  # 8,192 pages
    'sqlite_journal_mode': 'wal',
    'sqlite_mmap_size': 2**26,  # 64mb
    'sqlite_synchronous': 1,  # NORMAL
    'disk_min_file_size': 2**15,  # 32kb
    'disk_pickle_protocol': pickle.HIGHEST_PROTOCOL,
}

METADATA = {
    'count': 0,
    'size': 0,
    'hits': 0,
    'misses': 0,
}

EVICTION_POLICY = {
    'none': {
        'init': None,
        'get': None,
        'cull': None,
    },
    'least-recently-stored': {
        'init': (
            'CREATE INDEX IF NOT EXISTS Cache_store_time ON'
            ' Cache (store_time)'
        ),
        'get': None,
        'cull': 'SELECT {fields} FROM Cache ORDER BY store_time LIMIT ?',
    },
    'least-recently-used': {
        'init': (
            'CREATE INDEX IF NOT EXISTS Cache_access_time ON'
            ' Cache (access_time)'
        ),
        'get': 'access_time = {now}',
        'cull': 'SELECT {fields} FROM Cache ORDER BY access_time LIMIT ?',
    },
    'least-frequently-used': {
        'init': (
            'CREATE INDEX IF NOT EXISTS Cache_access_count ON'
            ' Cache (access_count)'
        ),
        'get': 'access_count = access_count + 1',
        'cull': 'SELECT {fields} FROM Cache ORDER BY access_count LIMIT ?',
    },
}


class Disk:
    """Cache key and value serialization for SQLite database and files."""

    def __init__(self, directory, min_file_size=0, pickle_protocol=0):
        """Initialize disk instance.

        :param str directory: directory path
        :param int min_file_size: minimum size for file use
        :param int pickle_protocol: pickle protocol for serialization

        """
        self._directory = directory
        self.min_file_size = min_file_size
        self.pickle_protocol = pickle_protocol

    def hash(self, key):
        """Compute portable hash for `key`.

        :param key: key to hash
        :return: hash value

        """
        mask = 0xFFFFFFFF
        disk_key, _ = self.put(key)
        type_disk_key = type(disk_key)

        if type_disk_key is sqlite3.Binary:
            return zlib.adler32(disk_key) & mask
        elif type_disk_key is str:
            return zlib.adler32(disk_key.encode('utf-8')) & mask  # noqa
        elif type_disk_key is int:
            return disk_key % mask
        else:
            assert type_disk_key is float
            return zlib.adler32(struct.pack('!d', disk_key)) & mask

    def put(self, key):
        """Convert `key` to fields key and raw for Cache table.

        :param key: key to convert
        :return: (database key, raw boolean) pair

        """
        # pylint: disable=unidiomatic-typecheck
        type_key = type(key)

        if type_key is bytes:
            return sqlite3.Binary(key), True
        elif (
            (type_key is str)
            or (
                type_key is int
                and -9223372036854775808 <= key <= 9223372036854775807
            )
            or (type_key is float)
        ):