mi@0: #!/usr/bin/env python
mi@0: # encoding: utf-8
mi@0: """
mi@0: ComputationCache.py
mi@0: 
mi@0: Created by George Fazekas on 2014-09-21.
mi@0: Copyright (c) 2014 . All rights reserved.
mi@0: 
mi@0: These methods can be used to decorate any function with a caching mechanism to avoid repeating long computations during experimentation.
mi@0: 
mi@0: Example:
mi@0: 
mi@0: m = Meta()
mi@0: m.cache = True
mi@0: m.cache_file_base = "filname-with-unique-parameters.txt"
mi@0: 
mi@0: @with_cache(meta)
mi@0: def some_heavy_function():
mi@0: 	... lots of computation here...
mi@0: 	return numpy_array
mi@0: 
mi@0: 
mi@0: Once decorated, some_heavy_function() will only execute once, then the results will be loaded from a file as long as the parametrs 
mi@0: encoded in cache_file_base don't change. The parameters and function name are appended to the cache file name so the decorator
mi@0: is safe to use for multiple computationally intense functions. 
mi@0: 
mi@0: The decorator assumes the heavy function returns a singke numpy array or matrix.
mi@0: 
mi@0: """
mi@0: 
mi@0: import cPickle
mi@0: import numpy as np
mi@0: from os.path import join, isdir, dirname
mi@0: 
mi@0: class Meta(object):
mi@0: 	__slots__ = ["cache","cache_file_base","cache_location"]
mi@0: 
mi@0: 	
mi@0: def makedir(output_folder) :
mi@0: 	'''Create a directory tree and set privileges to allow acces to multiple users.'''
mi@0: 	if output_folder and not isdir(output_folder) :
mi@0: 		try:
mi@0: 			from os import makedirs
mi@0: 			makedirs(output_folder,0o777)
mi@0: 		except :
mi@0: 			print "Failed to create directory: %s" %output_folder
mi@0: 			import sys
mi@0: 			sys.exit(-1)
mi@0: 	pass
mi@0: 
mi@0: 
mi@0: '''Generic decorator that caches function execution results.'''
mi@0: def with_cache(meta):
mi@0: 	def wrap(func):
mi@0: 		def file_cache(*args, **kwargs):
mi@0: 			if meta.cache :
mi@0: 				file = "Cache-" + meta.cache_file_base + "-f_%s.txt" %func.__name__
mi@0: 				file = join(getattr(meta,"cache_location",""),file)
mi@0: 				# print func, meta.cache, file			
mi@0: 				try :
mi@0: 					print "Loading data from file <%s>" %file
mi@0: 					return np.loadtxt(file)
mi@0: 				except :
mi@0: 					print "Loading from <%s> failed. Computing new results." %file
mi@0: 					makedir(dirname(file))
mi@0: 					result = func(*args, **kwargs)
mi@0: 					np.savetxt(file,result)
mi@0: 					return result
mi@0: 			else :
mi@0: 				return func(*args, **kwargs)
mi@0: 		return file_cache
mi@0: 	return wrap
mi@0: 
mi@0: def with_pickle_dump(meta):
mi@0: 	def wrap(func):
mi@0: 		def file_cache(*args, **kwargs):
mi@0: 			if meta.cache :
mi@0: 				file = "Cache-" + meta.cache_file_base + "-f_%s-pickle.txt" %func.__name__
mi@0: 				file = join(getattr(meta,"cache_location",""),file)
mi@0: 				file = file.replace(" ","-")
mi@0: 				# print func, meta.cache, file			
mi@0: 				try :
mi@0: 					print "Loading data from file <%s>" %file
mi@0: 					with open(file, 'r') as fh:
mi@0: 						return cPickle.load(fh)
mi@0: 				except :
mi@0: 					print "Loading from <%s> failed. Computing new results." %file
mi@0: 					makedir(dirname(file))
mi@0: 					result = func(*args, **kwargs)
mi@0: 					with open(file, 'w') as f:
mi@0: 						f.write(cPickle.dumps(result))
mi@0: 					return result
mi@0: 			else :
mi@0: 				return func(*args, **kwargs)
mi@0: 		return file_cache
mi@0: 	return wrap
mi@0: 
mi@0: