Skip to content

Optimized vector conversion to use memcpy if underlying types match #5

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
guruofquality merged 1 commit into from
Aug 21, 2019
Merged

Optimized vector conversion to use memcpy if underlying types match #5

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
74 changes: 72 additions & 2 deletions JavaConvert.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,11 +1,14 @@
// Copyright (c) 2013-2013 Josh Blum
// 2019 Nicholas Corgan
// SPDX-License-Identifier: BSL-1.0

#include <Pothos/Plugin.hpp>
#include "JavaProxy.hpp"
#include <Poco/Bugcheck.h>
#include <cstdint>
#include <cassert>
#include <cstring>
#include <type_traits>

/***********************************************************************
* Null
Expand Down Expand Up @@ -173,6 +176,73 @@ pothos_static_block(pothosRegisterJavaStringConversions)
/***********************************************************************
* Convert to Java Arrays
**********************************************************************/

// Utility functions

template <typename ctype>
using IsTypeBool = std::is_same<ctype, bool>;

template <typename ctype, typename jtype>
using DoTypesMatch = std::is_same<ctype, jtype>;

// If the C++ vector and the Java array are the same type under the hood,
// we can directly memcpy the values. This does not hold for bool, as
// std::vector<bool>'s specialization does not provide data().
template <typename ctype, typename jtype, typename retType>
using EnableForMemcpy = typename std::enable_if<DoTypesMatch<ctype, jtype>::value && !IsTypeBool<ctype>::value, retType>;

// If the C++ vector and the Java array are different types under the hood,
// or if the C++ type is a bool, we cannot use the memcpy optimization and must
// copy and cast each element individually.
template <typename ctype, typename jtype, typename retType>
using EnableForStaticCast = typename std::enable_if<!DoTypesMatch<ctype, jtype>::value || IsTypeBool<ctype>::value, retType>;

template <typename ctype, typename jtype>
static typename EnableForMemcpy<ctype, jtype, void>::type copyNumericVectorToJArray(
jtype* jElems,
const std::vector<ctype>& cppVec)
{
std::memcpy(
jElems,
const_cast<std::vector<ctype>&>(cppVec).data(),
(sizeof(ctype) * cppVec.size()));
}

template <typename ctype, typename jtype>
static typename EnableForStaticCast<ctype, jtype, void>::type copyNumericVectorToJArray(
jtype* jElems,
const std::vector<ctype>& cppVec)
{
for (size_t i = 0; i < cppVec.size(); i++)
{
jElems[i] = static_cast<jtype>(cppVec[i]);
}
}

template <typename ctype, typename jtype>
static typename EnableForMemcpy<ctype, jtype, void>::type copyJArrayToNumericVector(
std::vector<ctype>& cppVec,
const jtype* jElems)
{
std::memcpy(
cppVec.data(),
jElems,
(sizeof(ctype) * cppVec.size()));
}

template <typename ctype, typename jtype>
static typename EnableForStaticCast<ctype, jtype, void>::type copyJArrayToNumericVector(
std::vector<ctype>& cppVec,
const jtype* jElems)
{
for (size_t i = 0; i < cppVec.size(); i++)
{
cppVec[i] = static_cast<ctype>(jElems[i]);
}
}

// Functions used by Pothos for conversion

template <char sig, typename T>
Pothos::Proxy convertNumericVectorToJArray(Pothos::ProxyEnvironment::Sptr env, const std::vector<T> &vec)
{
Expand All @@ -183,7 +253,7 @@ Pothos::Proxy convertNumericVectorToJArray(Pothos::ProxyEnvironment::Sptr env, c
{ \
auto ar = jenv->env->New ## PrimitiveType ## Array(vec.size()); \
jtype *elems = jenv->env->Get ## PrimitiveType ## ArrayElements(ar, nullptr); \
for (size_t i = 0; i < vec.size(); i++) elems[i] = static_cast<jtype>(vec[i]); \
copyNumericVectorToJArray<T, jtype>(elems, vec); \
jenv->env->Release ## PrimitiveType ## ArrayElements(ar, elems, 0 /*mode*/); \
return jenv->makeHandle(ar); \
}
Expand All @@ -210,7 +280,7 @@ std::vector<T> convertJArrayToNumericVector(const Pothos::Proxy &proxy)
auto ar = (jtype ## Array) std::dynamic_pointer_cast<JavaProxyHandle>(proxy.getHandle())->value.l; \
std::vector<T> vec(jenv->env->GetArrayLength(ar)); \
jtype *elems = jenv->env->Get ## PrimitiveType ## ArrayElements(ar, nullptr); \
for (size_t i = 0; i < vec.size(); i++) vec[i] = static_cast<T>(elems[i]); \
copyJArrayToNumericVector<T, jtype>(vec, elems); \
jenv->env->Release ## PrimitiveType ## ArrayElements(ar, elems, JNI_ABORT); \
return vec; \
}
Expand Down