ui: track label expansion when creating buffers
authorGregory Szorc <gregory.szorc@gmail.com>
Sun, 22 Nov 2015 14:10:48 -0800
changeset 27106 6ef17697b03d
parent 27101 61fbf5dc12b2
child 27107 c57ebef70f6f
ui: track label expansion when creating buffers As part of profiling `hg log` performance, I noticed a lot of time is spent in buffered writes to ui instances. This patch starts a series that refactors buffered writes with the eventual intent to improve performance. Currently, labels are expanded when buffers are popped. This means we have to preserve the original text and the label until we render the final output. This is avoidable overhead and adds complexity since we're retaining state. This patch adds functionality to ui.pushbuffer() to declare whether label expansion should be active for the buffer. Labels are still evaluated during buffer pop. This will change in a subsequent patch. Since we'll need to access the "expand labels" flag on future write() operations, we prematurely optimize how the current value is stored to optimize for rapid retrieval.
mercurial/ui.py
--- a/mercurial/ui.py	Tue Nov 24 21:41:12 2015 +0000
+++ b/mercurial/ui.py	Sun Nov 22 14:10:48 2015 -0800
@@ -94,9 +94,12 @@
     def __init__(self, src=None):
         # _buffers: used for temporary capture of output
         self._buffers = []
-        # _bufferstates:
-        #   should the temporary capture include stderr and subprocess output
+        # 3-tuple describing how each buffer in the stack behaves.
+        # Values are (capture stderr, capture subprocesses, apply labels).
         self._bufferstates = []
+        # When a buffer is active, defines whether we are expanding labels.
+        # This exists to prevent an extra list lookup.
+        self._bufferapplylabels = None
         self.quiet = self.verbose = self.debugflag = self.tracebackflag = False
         self._reportuntrusted = True
         self._ocfg = config.config() # overlay
@@ -572,15 +575,24 @@
     def paths(self):
         return paths(self)
 
-    def pushbuffer(self, error=False, subproc=False):
+    def pushbuffer(self, error=False, subproc=False, labeled=False):
         """install a buffer to capture standard output of the ui object
 
         If error is True, the error output will be captured too.
 
         If subproc is True, output from subprocesses (typically hooks) will be
-        captured too."""
+        captured too.
+
+        If labeled is True, any labels associated with buffered
+        output will be handled. By default, this has no effect
+        on the output returned, but extensions and GUI tools may
+        handle this argument and returned styled output. If output
+        is being buffered so it can be captured and parsed or
+        processed, labeled should not be set to True.
+        """
         self._buffers.append([])
-        self._bufferstates.append((error, subproc))
+        self._bufferstates.append((error, subproc, labeled))
+        self._bufferapplylabels = labeled
 
     def popbuffer(self, labeled=False):
         '''pop the last buffer and return the buffered output
@@ -593,6 +605,11 @@
         processed, labeled should not be set to True.
         '''
         self._bufferstates.pop()
+        if self._bufferstates:
+            self._bufferapplylabels = self._bufferstates[-1][2]
+        else:
+            self._bufferapplylabels = None
+
         return "".join(self._buffers.pop())
 
     def write(self, *args, **opts):