core: add base cachew directory

my/bluemaestro/__init__.py

@@ -13,6 +13,7 @@ from typing import Iterable, NamedTuple, Sequence, Set
 from ..common import mcachew, LazyLogger, get_files
 
 
+from ..core.cachew import cache_dir
 from my.config import bluemaestro as config
 
 
@@ -28,7 +29,7 @@ class Measurement(NamedTuple):
     temp: float
 
 
-@mcachew(cache_path=config.cache_path)
+@mcachew(cache_path=cache_dir() / 'bluemaestro.cache')
 def measurements(dbs=inputs()) -> Iterable[Measurement]:
     emitted: Set[datetime] = set()
     for f in dbs:

my/core/cachew.py

@@ -1,5 +1,6 @@
 # TODO this probably belongs to cachew? or cachew.experimental
 from contextlib import contextmanager
+from pathlib import Path
 
 
 def disable_cachew():
@@ -25,3 +26,21 @@ def disabled_cachew():
         yield
     finally:
         cachew.cachew = old
+
+
+def cache_dir() -> Path:
+    '''
+    Base directory for cachew.
+    To override, add to your config file:
+    class config:
+        cache_dir = '/your/custom/cache/path'
+    '''
+    import my.config as C
+    common_config = getattr(C, 'common', object())
+    # TODO if attr is set _and_ it's none, disable cache?
+    cdir = getattr(common_config, 'cache_dir', None)
+    if cdir is None:
+        # TODO fallback to default cachew dir instead?
+        return Path('/var/tmp/cachew')
+    else:
+        return Path(cdir)

my/emfit/__init__.py

@@ -15,6 +15,7 @@ import pytz
 from more_itertools import bucket
 
 from ..common import get_files, LazyLogger, cproperty, mcachew
+from ..core.cachew import cache_dir
 
 from my.config import emfit as config
 
@@ -292,7 +293,7 @@ def dir_hash(path: Path):
 
 
 # TODO take __file__ into account somehow?
-@mcachew(cache_path=config.cache_path, hashf=dir_hash, logger=logger)
+@mcachew(cache_path=cache_dir() / 'emfit.cache', hashf=dir_hash, logger=logger)
 def iter_datas(path: Path=config.export_path) -> Iterator[Emfit]:
     for f in get_files(path, glob='*.json'):
         sid = f.stem

my/location/takeout.py

@@ -30,6 +30,7 @@ from ..kython import kompress
 logger = LazyLogger(__name__)
 
 
+# todo switch to use cachew.cache_dir
 def cache_path(*args, **kwargs):
     from my.config import location as config
     return config.cache_path