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Use std::vector::reserve to improve performance of adding properties

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The number of properties per node roughly corresponds to the number of members
of the class the node is representing and should be fairly low.

Use std::vector::reserve to prevent reallocation on insert for most node types,
there are exceptions like Region(~40 properties).

This seems worth it as part(maybe 1/10th of the total time) of saving a Session
is a combination of what occurs in "Create" and "Write" in this test.

Perf results before changes:

XMLTest::testPerfMediumXMLDocumentTiming
   Create : Count: 10 Min: 30610 Max: 42656 Total: 376672 Avg: 37667 (37 msecs)
   Write : Count: 10 Min: 42804 Max: 54277 Total: 460455 Avg: 46045 (46 msecs)
   Read : Count: 10 Min: 70364 Max: 85484 Total: 750909 Avg: 75090 (75 msecs)
XMLTest::testPerfLargeXMLDocumentTiming
   Create : Count: 10 Min: 164360 Max: 356995 Total: 3064482 Avg: 306448 (306 msecs)
   Write : Count: 10 Min: 308655 Max: 372953 Total: 3226707 Avg: 322670 (322 msecs)
   Read : Count: 10 Min: 517243 Max: 541839 Total: 5289950 Avg: 528995 (528 msecs)

Perf results after changes:

XMLTest::testPerfMediumXMLDocumentTiming
   Create : Count: 10 Min: 30375 Max: 48253 Total: 431727 Avg: 43172 (43 msecs)
   Write : Count: 10 Min: 42553 Max: 49163 Total: 453353 Avg: 45335 (45 msecs)
   Read : Count: 10 Min: 70307 Max: 75987 Total: 734923 Avg: 73492 (73 msecs)
XMLTest::testPerfLargeXMLDocumentTiming
   Create : Count: 10 Min: 154486 Max: 307856 Total: 2678989 Avg: 267898 (267 msecs)
   Write : Count: 10 Min: 304273 Max: 343274 Total: 3169158 Avg: 316915 (316 msecs)
   Read : Count: 10 Min: 496920 Max: 541394 Total: 5260410 Avg: 526041 (526 msecs)
This commit is contained in:
Tim Mayberry 2016-09-23 23:01:18 +10:00
parent e84fbfe6e5
commit 816f3bfb36
1 changed files with 5 additions and 0 deletions
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5
libs/pbd/xml++.cc
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@ -215,10 +215,13 @@ XMLTree::write_buffer() const
return retval;
}
static const int PROPERTY_RESERVE_COUNT = 16;
XMLNode::XMLNode(const string& n)
: _name(n)
, _is_content(false)
{
_proplist.reserve (PROPERTY_RESERVE_COUNT);
}
XMLNode::XMLNode(const string& n, const string& c)
@ -226,10 +229,12 @@ XMLNode::XMLNode(const string& n, const string& c)
, _is_content(true)
, _content(c)
{
_proplist.reserve (PROPERTY_RESERVE_COUNT);
}
XMLNode::XMLNode(const XMLNode& from)
{
_proplist.reserve (PROPERTY_RESERVE_COUNT);
*this = from;
}