Purge cache on BufWrite

Instead of much simpler solution define an API that may be used for anybody
willing to add cache purging on events with a few keystrokes

powerline/bindings/vim/plugin/powerline.vim

@@ -67,6 +67,13 @@ function! s:UpdateWindows(use_last_current_window_id)
 	endfor
 endfunction
 
+function! PowerlineRegisterCachePurgerEvent(event)
+	exec s:powerline_pycmd 'from powerline.segments.vim import launchevent as powerline_launchevent'
+	augroup Powerline
+		exec 'autocmd!' a:event '*' s:powerline_pycmd.' powerline_launchevent("'.a:event.'")'
+	augroup END
+endfunction
+
 let s:last_current_window_id = ''
 augroup Powerline
 	autocmd!

powerline/lib/memoize.py

@@ -10,21 +10,26 @@ def default_cache_key(**kwargs):
 
 class memoize(object):
 	'''Memoization decorator with timeout.'''
-	def __init__(self, timeout, cache_key=default_cache_key):
+	def __init__(self, timeout, cache_key=default_cache_key, cache_reg_func=None):
 		self.timeout = timeout
 		self.cache_key = cache_key
-		self._cache = {}
+		self.cache = {}
+		self.cache_reg_func = cache_reg_func
 
 	def __call__(self, func):
 		@wraps(func)
 		def decorated_function(**kwargs):
+			if self.cache_reg_func:
+				self.cache_reg_func(self.cache)
+				self.cache_reg_func = None
+
 			key = self.cache_key(**kwargs)
 			try:
-				cached = self._cache.get(key, None)
+				cached = self.cache.get(key, None)
 			except TypeError:
 				return func(**kwargs)
 			if cached is None or time.time() - cached['time'] > self.timeout:
-				cached = self._cache[key] = {
+				cached = self.cache[key] = {
 					'result': func(**kwargs),
 					'time': time.time(),
 					}

powerline/segments/vim.py

@@ -12,10 +12,12 @@ from powerline.bindings.vim import vim_get_func, getbufvar
 from powerline.theme import requires_segment_info
 from powerline.lib import memoize, humanize_bytes
 from powerline.lib.vcs import guess
+from collections import defaultdict
 
 vim_funcs = {
 	'virtcol': vim_get_func('virtcol', rettype=int),
 	'fnamemodify': vim_get_func('fnamemodify'),
+	'expand': vim_get_func('expand'),
 	'getfsize': vim_get_func('getfsize', rettype=int),
 	'bufnr': vim_get_func('bufnr', rettype=int),
 }
@@ -47,6 +49,35 @@ mode_translations = {
 }
 
 
+eventcaches = defaultdict(lambda : [])
+bufeventcaches = defaultdict(lambda : [])
+def purgeonevents_reg(events, eventcaches=bufeventcaches):
+	def cache_reg_func(cache):
+		for event in events:
+			if event not in eventcaches:
+				vim.eval('PowerlineRegisterCachePurgerEvent("' + event + '")')
+			eventcaches[event].append(cache)
+
+	return cache_reg_func
+
+purgeall_on_shell = purgeonevents_reg(('ShellCmdPost', 'ShellFilterPost', 'FocusGained'), eventcaches=eventcaches)
+purgebuf_on_shell_and_write = purgeonevents_reg(('BufWritePost', 'ShellCmdPost', 'ShellFilterPost', 'FocusGained'))
+
+
+def launchevent(event):
+	global eventcaches
+	global bufeventcaches
+	for cache in eventcaches[event]:
+		cache.clear()
+	if bufeventcaches[event]:
+		buf = int(vim_funcs['expand']('<abuf>'))
+		for cache in bufeventcaches[event]:
+			try:
+				cache.pop(buf)
+			except KeyError:
+				pass
+
+
 def bufnr(segment_info, **kwargs):
 	'''Used for cache key, returns current buffer number'''
 	return segment_info['bufnr']
@@ -157,7 +188,7 @@ def file_name(segment_info, display_no_file=False, no_file_text='[No file]'):
 
 
 @requires_segment_info
-@memoize(2, cache_key=bufnr)
+@memoize(2, cache_key=bufnr, cache_reg_func=purgebuf_on_shell_and_write)
 def file_size(segment_info, suffix='B', binary_prefix=False):
 	'''Return file size.
 
@@ -254,7 +285,7 @@ def modified_buffers(text=u'+', join_str=','):
 
 
 @requires_segment_info
-@memoize(2, cache_key=bufnr)
+@memoize(2, cache_key=bufnr, cache_reg_func=purgeall_on_shell)
 def branch(segment_info):
 	'''Return the current working branch.'''
 	repo = guess(path=os.path.abspath(segment_info['buffer'].name or os.getcwd()))
@@ -263,9 +294,8 @@ def branch(segment_info):
 	return None
 
 
-# TODO Drop cache on BufWrite event
 @requires_segment_info
-@memoize(2, cache_key=bufnr)
+@memoize(2, cache_key=bufnr, cache_reg_func=purgebuf_on_shell_and_write)
 def file_vcs_status(segment_info):
 	'''Return the VCS status for this buffer.'''
 	name = segment_info['buffer'].name
@@ -287,7 +317,7 @@ def file_vcs_status(segment_info):
 
 
 @requires_segment_info
-@memoize(2, cache_key=bufnr)
+@memoize(2, cache_key=bufnr, cache_reg_func=purgeall_on_shell)
 def repository_status(segment_info):
 	'''Return the status for the current repo.'''
 	repo = guess(path=os.path.abspath(segment_info['buffer'].name or os.getcwd()))