From 86b47fa741408b061ab0bda784b8678bfd7dfa88 Mon Sep 17 00:00:00 2001 From: Akio Nakamura Date: Thu, 1 Feb 2018 19:34:50 +0900 Subject: speed up Unserialize_impl for prevector The unserializer for prevector uses resize() for reserve the area, but it's prefer to use reserve() because resize() have overhead to call its constructor many times. However, reserve() does not change the value of "_size" (a private member of prevector). This PR introduce resize_uninitialized() to prevector that similar to resize() but does not call constructor, and added elements are explicitly initialized in Unserialize_imple(). The changes are as follows: 1. prevector.h Add a public member function named 'resize_uninitialized'. This function processes like as resize() but does not call constructors. So added elemensts needs explicitly initialized after this returns. 2. serialize.h In the following two function: Unserialize_impl(Stream& is, prevector& v, const unsigned char&) Unserialize_impl(Stream& is, prevector& v, const V&) Calls resize_uninitialized() instead of resize() 3. test/prevector_tests.cpp Add a test for resize_uninitialized(). --- src/serialize.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src/serialize.h') diff --git a/src/serialize.h b/src/serialize.h index 2d0cfbbbf0..cb48dc174a 100644 --- a/src/serialize.h +++ b/src/serialize.h @@ -659,7 +659,7 @@ void Unserialize_impl(Stream& is, prevector& v, const unsigned char&) while (i < nSize) { unsigned int blk = std::min(nSize - i, (unsigned int)(1 + 4999999 / sizeof(T))); - v.resize(i + blk); + v.resize_uninitialized(i + blk); is.read((char*)&v[i], blk * sizeof(T)); i += blk; } @@ -677,8 +677,8 @@ void Unserialize_impl(Stream& is, prevector& v, const V&) nMid += 5000000 / sizeof(T); if (nMid > nSize) nMid = nSize; - v.resize(nMid); - for (; i < nMid; i++) + v.resize_uninitialized(nMid); + for (; i < nMid; ++i) Unserialize(is, v[i]); } } -- cgit v1.2.3