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refactor(playlistdb): Enforce constant entry index length

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To simplify the playlist handling, enforce that the indices are always
formatted to the same length (5, which allows for 100000 entries, that
should be enough).

Then make the position stored in the Playlist object be a simple integer
instead of a database key. This simplifies the code, and will make
implementing shuffle much easier.

Signed-off-by: Matthias Blankertz <matthias@blankertz.org>
This commit is contained in:
Matthias Blankertz
2025-09-07 17:45:27 +02:00
parent 7e532ec641
commit 7327549eea
4 changed files with 91 additions and 95 deletions
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6
DEVELOP.md
View File

@@ -18,10 +18,8 @@ pip install -U micropython-rp2-pico_w-stubs --target typings
The playlist data is stored in the btree database in a hierarchical schema. The hierarchy levels are
separated by the '/' character. Currently, the schema is as follows: The top level for a playlist
is the 'tag' id encoded as a hexadecimal string. Beneath this, the 'playlist' key contains the
elements in the playlist. The keys used for the playlist entries should be decimal integers,
prefixed with sufficient zeros such that they are in the correct order when sorted
lexicographically. All keys must have the same width. When writing a playlist using the playlistdb
module, the keys are 00000, 00001, etc. by default.
elements in the playlist. The keys used for the playlist entries must be decimal integers,
left-padded with zeros so their length is 5 (e.g. format `{:05}`).
#### Playlist modes

92
software/src/utils/playlistdb.py
View File

@@ -31,12 +31,13 @@ class BTreeDB(IPlaylistDB):
PERSIST_OFFSET = b'offset'
class Playlist(IPlaylist):
def __init__(self, parent, tag, pos, persist, shuffle):
def __init__(self, parent: "BTreeDB", tag: bytes, pos: int, persist, shuffle):
self.parent = parent
self.tag = tag
self.pos = pos
self.persist = persist
self.shuffle = shuffle
self.length = self.parent._getPlaylistLength(self.tag)
def getPaths(self):
"""
@@ -54,12 +55,14 @@ class BTreeDB(IPlaylistDB):
"""
Select next track and return path.
"""
try:
self.pos = self.parent._getNextTrack(self.tag, self.pos)
except StopIteration:
self.pos = self.parent._getFirstTrack(self.tag)
if self.pos + 1 >= self.length:
self.pos = 0
if self.persist != BTreeDB.PERSIST_NO:
self.parent._setPlaylistPos(self.tag, self.pos)
self.setPlaybackOffset(0)
return None
finally:
self.pos += 1
if self.persist != BTreeDB.PERSIST_NO:
self.parent._setPlaylistPos(self.tag, self.pos)
self.setPlaybackOffset(0)
@@ -122,27 +125,42 @@ class BTreeDB(IPlaylistDB):
if self.flush_func is not None:
self.flush_func()
def _getPlaylistValueIterator(self, tag):
def _getPlaylistValueIterator(self, tag: bytes):
start, end = self._keyPlaylistStartEnd(tag)
return self.db.values(start, end)
def _getPlaylistEntry(self, _, pos):
return self.db[pos]
def _getPlaylistEntry(self, tag: bytes, pos: int) -> bytes:
return self.db[self._keyPlaylistEntry(tag, pos)]
def _setPlaylistPos(self, tag, pos, flush=True):
assert pos.startswith(self._keyPlaylistStart(tag))
self.db[self._keyPlaylistPos(tag)] = pos[len(self._keyPlaylistStart(tag)):]
def _setPlaylistPos(self, tag: bytes, pos: int, flush=True):
self.db[self._keyPlaylistPos(tag)] = str(pos).encode()
if flush:
self._flush()
def _setPlaylistPosOffset(self, tag, offset, flush=True):
def _setPlaylistPosOffset(self, tag: bytes, offset: int, flush=True):
self.db[self._keyPlaylistPosOffset(tag)] = str(offset).encode()
if flush:
self._flush()
def _getPlaylistPosOffset(self, tag):
def _getPlaylistPosOffset(self, tag: bytes) -> int:
return int(self.db.get(self._keyPlaylistPosOffset(tag), b'0'))
def _getPlaylistLength(self, tag: bytes) -> int:
start, end = self._keyPlaylistStartEnd(tag)
for k in self.db.keys(end, start, btree.DESC):
# There is a bug in btreedb that causes an additional key after 'end' to be returned when iterating in
# descending order
# Check for this and skip it if needed
elements = k.split(b'/')
if len(elements) >= 2 and elements[1] == b'playlist':
last = k
break
print(last)
elements = last.split(b'/')
if len(elements) != 3:
raise RuntimeError("Malformed playlist key")
return int(elements[2])+1
def _savePlaylist(self, tag, entries, persist, shuffle, flush=True):
self._deletePlaylist(tag, False)
for idx, entry in enumerate(entries):
@@ -159,41 +177,32 @@ class BTreeDB(IPlaylistDB):
del self.db[k]
except KeyError:
pass
for k in (self._keyPlaylistPos(tag), self._keyPlaylistPosOffset(tag),
self._keyPlaylistPersist(tag), self._keyPlaylistShuffle(tag)):
try:
del self.db[self._keyPlaylistPos(tag)]
del self.db[k]
except KeyError:
pass
if flush:
self._flush()
def _getFirstTrack(self, tag: bytes):
start_key, end_key = self._keyPlaylistStartEnd(tag)
return next(self.db.keys(start_key, end_key))
def _getNextTrack(self, tag, pos):
_, end_key = self._keyPlaylistStartEnd(tag)
it = self.db.keys(pos, end_key)
next(it)
return next(it)
def getPlaylistForTag(self, tag: bytes):
"""
Lookup the playlist for 'tag' and return the Playlist object. Return None if no playlist exists for the given
tag.
"""
persist = self.db.get(self._keyPlaylistPersist(tag), self.PERSIST_TRACK)
if persist != self.PERSIST_NO:
pos = self.db.get(self._keyPlaylistPos(tag))
else:
pos = None
if pos is None:
pos = 0
if persist != self.PERSIST_NO and self._keyPlaylistPos(tag) in self.db:
try:
pos = self._getFirstTrack(tag)
except StopIteration:
# playist does not exist
pos = int(self.db[self._keyPlaylistPos(tag)])
except ValueError:
pass
if self._keyPlaylistEntry(tag, 0) not in self.db:
# Empty playlist
return None
else:
pos = self._keyPlaylistStart(tag) + pos
if self._keyPlaylistEntry(tag, pos) not in self.db:
pos = 0
shuffle = self.db.get(self._keyPlaylistShuffle(tag), self.SHUFFLE_NO)
return self.Playlist(self, tag, pos, persist, shuffle)
@@ -221,7 +230,6 @@ class BTreeDB(IPlaylistDB):
last_tag = None
last_pos = None
index_width = None
for k in self.db.keys():
fields = k.split(b'/')
if len(fields) <= 1:
@@ -240,13 +248,12 @@ class BTreeDB(IPlaylistDB):
except ValueError:
fail(f'Malformed playlist entry: {k!r}')
continue
if index_width is not None and len(fields[2]) != index_width:
fail(f'Inconsistent index width for {last_tag} at {idx}')
if len(fields[2]) != 5:
fail(f'Bad index width for {last_tag} at {idx}')
if (last_pos is not None and last_pos + 1 != idx) or \
(last_pos is None and idx != 0):
fail(f'Bad playlist entry sequence for {last_tag} at {idx}')
last_pos = idx
index_width = len(fields[2])
if dump:
print(f'\tTrack {idx}: {self.db[k]!r}')
elif fields[1] == b'playlistpos':
@@ -276,8 +283,11 @@ class BTreeDB(IPlaylistDB):
# Format TBD
pass
elif fields[1] == b'playlistposoffset':
# Format TBD
pass
val = self.db[k]
try:
_ = int(val)
except ValueError:
fail(f' Bad playlistposoffset value for {last_tag}: {val!r}')
else:
fail(f'Unknown key {k!r}')
return result

4
software/tests/mocks/btree.py
View File

@@ -19,3 +19,7 @@ class BTree:
def open(dbfile) -> BTree:
pass
DESC = 1
INCL = 2

74
software/tests/utils_test/test_btreedb.py
View File

@@ -1,6 +1,7 @@
# SPDX-License-Identifier: MIT
# Copyright (c) 2025 Matthias Blankertz <matthias@blankertz.org>
import btree
import pytest
from utils import BTreeDB
@@ -24,12 +25,18 @@ class FakeDB:
res.append(self.contents[key])
def keys(self, start_key=None, end_key=None, flags=None):
keys = []
if flags is not None and flags & btree.DESC != 0:
start_key, end_key = end_key, start_key
for key in sorted(self.contents):
if start_key is not None and start_key > key:
continue
if end_key is not None and end_key <= key:
break
yield key
keys.append(key)
if flags is not None and flags & btree.DESC != 0:
keys.reverse()
return iter(keys)
def get(self, key, default=None):
return self.contents.get(key, default)
@@ -43,11 +50,14 @@ class FakeDB:
def __delitem__(self, key):
del self.contents[key]
def __contains__(self, key):
return key in self.contents
def test_playlist_load():
contents = {b'foo/part': b'no',
b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlisttt': b'no'
}
uut = BTreeDB(FakeDB(contents))
@@ -58,8 +68,8 @@ def test_playlist_load():
def test_playlist_nextpath():
contents = FakeDB({b'foo/part': b'no',
b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlisttt': b'no'
})
uut = BTreeDB(contents)
@@ -69,8 +79,8 @@ def test_playlist_nextpath():
def test_playlist_nextpath_last():
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpos': b'1'
})
uut = BTreeDB(contents)
@@ -80,8 +90,8 @@ def test_playlist_nextpath_last():
def test_playlist_create():
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpos': b'1'
})
newplaylist = [b'never gonna give you up.mp3', b'durch den monsun.mp3']
@@ -93,43 +103,17 @@ def test_playlist_create():
def test_playlist_load_notexist():
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpos': b'1'
})
uut = BTreeDB(contents)
assert uut.getPlaylistForTag(b'notfound') is None
def test_playlist_remains_lexicographically_ordered_by_key():
contents = FakeDB({b'foo/playlist/3': b'track3',
b'foo/playlist/2': b'track2',
b'foo/playlist/1': b'track1',
b'foo/playlistpos': b'1'
})
uut = BTreeDB(contents)
pl = uut.getPlaylistForTag(b'foo')
assert pl.getCurrentPath() == b'track1'
assert pl.getNextPath() == b'track2'
assert pl.getNextPath() == b'track3'
def test_playlist_remains_lexicographically_ordered_with_non_numeric_keys():
contents = FakeDB({b'foo/playlist/k': b'trackk',
b'foo/playlist/l': b'trackl',
b'foo/playlist/i': b'tracki',
b'foo/playlistpos': b'k'
})
uut = BTreeDB(contents)
pl = uut.getPlaylistForTag(b'foo')
assert pl.getCurrentPath() == b'trackk'
assert pl.getNextPath() == b'trackl'
assert pl.getNextPath() is None
def test_playlist_starts_at_beginning_in_persist_no_mode():
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpersist': b'no',
})
uut = BTreeDB(contents)
@@ -143,8 +127,8 @@ def test_playlist_starts_at_beginning_in_persist_no_mode():
@pytest.mark.parametrize("mode", [b'no', b'track'])
def test_playlist_ignores_offset_in_other_modes(mode):
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpersist': mode,
})
uut = BTreeDB(contents)
@@ -156,8 +140,8 @@ def test_playlist_ignores_offset_in_other_modes(mode):
def test_playlist_stores_offset_in_offset_mode():
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpersist': b'offset',
})
uut = BTreeDB(contents)
@@ -169,8 +153,8 @@ def test_playlist_stores_offset_in_offset_mode():
def test_playlist_resets_offset_on_next_track():
contents = FakeDB({b'foo/playlist/0': b'track1',
b'foo/playlist/1': b'track2',
contents = FakeDB({b'foo/playlist/00000': b'track1',
b'foo/playlist/00001': b'track2',
b'foo/playlistpersist': b'offset',
})
uut = BTreeDB(contents)