Optimize stdout_spinner.update() methods so that they don't

waste cpu time by flushing output to the tty too frequently.
(trunk r8332)

svn path=/main/branches/2.1.2/; revision=8371

1 files changed, 22 insertions, 3 deletions

diff --git a/bin/emerge b/bin/emerge
index 1d0788f75..c75e3ef54 100755
--- a/bin/emerge
+++ b/bin/emerge
@@ -91,9 +91,25 @@ class stdout_spinner(object):
 		self.update = self.update_twirl
 		self.scroll_sequence = self.scroll_msgs[
 			int(time.time() * 100) % len(self.scroll_msgs)]
+		self.last_update = 0
+		self.min_display_latency = 0.05
+
+	def _return_early(self):
+		"""
+		Flushing ouput to the tty too frequently wastes cpu time. Therefore,
+		each update* method should return without doing any output when this
+		method returns True.
+		"""
+		cur_time = time.time()
+		if cur_time - self.last_update < self.min_display_latency:
+			return True
+		self.last_update = cur_time
+		return False
 
 	def update_basic(self):
 		self.spinpos = (self.spinpos + 1) % 500
+		if self._return_early():
+			return
 		if (self.spinpos % 100) == 0:
 			if self.spinpos == 0:
 				sys.stdout.write(". ")
@@ -102,6 +118,8 @@ class stdout_spinner(object):
 		sys.stdout.flush()
 
 	def update_scroll(self):
+		if self._return_early():
+			return
 		if(self.spinpos >= len(self.scroll_sequence)):
 			sys.stdout.write(darkgreen(" \b\b\b" + self.scroll_sequence[
 				len(self.scroll_sequence) - 1 - (self.spinpos % len(self.scroll_sequence))]))
@@ -112,6 +130,8 @@ class stdout_spinner(object):
 
 	def update_twirl(self):
 		self.spinpos = (self.spinpos + 1) % len(self.twirl_sequence)
+		if self._return_early():
+			return
 		sys.stdout.write("\b\b " + self.twirl_sequence[self.spinpos])
 		sys.stdout.flush()
 
@@ -1280,9 +1300,6 @@ class depgraph:
 					return 0
 				del e
 
-		if "--nodeps" not in self.myopts:
-			self.spinner.update()
-
 		reinstall_for_flags = None
 		merging=1
 		if mytype == "installed":
@@ -1439,6 +1456,8 @@ class depgraph:
 		elif "recurse" not in self.myparams:
 			return 1
 
+		self.spinner.update()
+
 		""" Check DEPEND/RDEPEND/PDEPEND/SLOT
 		Pull from bintree if it's binary package, porttree if it's ebuild.
 		Binpkg's can be either remote or local. """