Added cache file

fieldlinetracer/cache.py

+import os
+import getpass
+import time
+import hashlib
+import numpy as np
+import warnings
+
+from .inputs import PredefinedField
+
+class Cache:
+	def __init__(self,
+		root = '\\\\share.ipp-hgw.mpg.de/mp',
+		dir = 'fieldline/{user}/fieldlinetracer/field_cache',
+		max_age = 7 * 24 * 60 * 60
+	):
+		self.user = getpass.getuser()
+		self.dir = dir.format(user = self.user)
+		self.root = root
+		
+		self.max_age = max_age;
+		
+		self.maintenance();	
+	
+	def maintenance(self):
+		root = self.cache_root();
+		
+		if not os.path.exists(root):
+			os.makedirs(root);
+		
+		for filename in os.listdir(root):
+			fullname = os.path.join(root, filename);
+			
+			age = time.time() - os.path.getmtime(fullname);
+			
+			if age > self.max_age:
+				os.remove(fullname);
+	
+	def cache_root(self):
+		return os.path.join(*(self.root.split('/')), *(self.dir.split('/')))
+	
+	def exists(self, id):
+		return os.path.exists(self.filename(id));
+	
+	def filename(self, id):
+		return os.path.join(self.cache_root(), id)
+	
+	def remote_reference(self, id):
+		return '/' + self.dir + '/' + id
+
+try:
+	cache = Cache()
+except Exception as e:
+	warnings.warn('Cache initialization failed for the following reason, faster field transfer will not be available')
+	print(e)
+	
+	cache = None
+
+def maybe_cache_config(config, cache = cache):
+	if not isinstance(config, PredefinedField):
+		return None
+	
+	if cache is None:
+		return None
+	
+	try:
+		cache.maintenance()
+		
+		flat_view = np.reshape(config.field, [3, -1])
+		id = hashlib.sha1(flat_view).hexdigest()
+		
+		if not cache.exists(id):
+			filename = cache.filename(id)
+			pre_filename = filename + '.tmp'
+			
+			#print('Writing temp file {} ...'.format(pre_filename))
+			
+			with open(pre_filename, 'w') as file:
+				for i in range(0, flat_view.shape[1]):
+					file.write('{bp} {br} {bz}\n'.format(
+						bp = flat_view[0, i],
+						br = flat_view[1, i],
+						bz = flat_view[2, i]
+					));
+						
+			os.rename(pre_filename, filename)
+			#print('Renamed temp file {} to {} ...'.format(pre_filename, filename))
+		
+		return cache.remote_reference(id)
+	except Exception as e:
+		warnings.warn('Failed to access the field cache for the following reason, falling back to slower direct transfer')
+		print(e)
+	
+	return None
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