emmental/trackdb/__init__.py

# Copyright 2020 (c) Anna Schumaker.
from lib import data
from lib import idle
from lib import publisher
from . import library
from . import track
import pathlib
import threading

db_file = "trackdb.pickle"
need_save = False
idle_id = None
save_lock = threading.Lock()
library_paths = [ ]
LibraryAdded = publisher.Publisher()
LibraryRemoved = publisher.Publisher()

def add_path(path):
    if get_library(path) == None:
        lib = library.LibraryPath(path)
        library_paths.append(lib)
        LibraryAdded.publish(lib)
        return lib

def get_library(path):
    for lib in library_paths:
        if lib.path == pathlib.Path(path):
            return lib
    return None

def get_track(trackid):
    for lib in library_paths:
        if (track := lib[trackid]) != None:
            return track
    return None

def remove_path(path):
    lib = get_library(path)
    library_paths.remove(lib)
    LibraryRemoved.publish(lib)

def _do_save():
    global need_save
    global idle_id
    with save_lock:
        if need_save == False:
            idle_id = None
            return idle.REMOVE

        with data.DataFile(db_file, data.WRITE) as f:
            with library.IDLock:
                f.pickle([ library.NextID, library_paths ])
        need_save = False
        return idle.CONTINUE

def save(*args):
    global need_save
    global idle_id
    with save_lock:
        if need_save == False:
            need_save = True
            if idle_id == None:
                idle_id = idle.add(_do_save)

def __register_callbacks():
    LibraryAdded.register(save)
    LibraryRemoved.register(save)
    library.TrackAdded.register(save)
    library.TrackRemoved.register(save)
    track.TrackUpdated.register(save)
__register_callbacks()

def reset():
    global need_save
    global idle_id
    library_paths.clear()
    LibraryAdded.reset()
    LibraryRemoved.reset()
    library.reset()
    track.reset()

    data.DataFile(db_file, data.READ).remove()
    __register_callbacks()
    need_save = False
    idle_id = None