kdtree.cuh
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// right now the size of CUDA STACK is set to 50, increase it if you mean to make deeper tree
// data should be stored in row-major
// x1,x2,x3,x4,x5......
// y1,y2,y3,y4,y5......
// ....................
// ....................
#ifndef KDTREE_H
#define KDTREE_H
#define stack_size 50
#include "device_launch_parameters.h"
#include <cuda.h>
#include <cuda_runtime_api.h>
#include "cuda_runtime.h"
#include <vector>
#include <cstring>
#include <float.h>
#include <iostream>
#include <algorithm>
#include <stim/cuda/cudatools/error.h>
#include <stim/visualization/aabbn.h>
namespace stim {
namespace cpu_kdtree {
template<typename T, int D> // typename refers to float or double while D refers to dimension of points
struct point {
T dim[D]; // create a structure to store every one input point
};
template<typename T>
class cpu_kdnode {
public:
cpu_kdnode() { // constructor for initializing a kdnode
parent = NULL; // set every node's parent, left and right kdnode pointers to NULL
left = NULL;
right = NULL;
parent_idx = -1; // set parent node index to default -1
left_idx = -1;
right_idx = -1;
split_value = -1; // set split_value to default -1
}
int idx; // index of current node
int parent_idx, left_idx, right_idx; // index of parent, left and right nodes
cpu_kdnode *parent, *left, *right; // parent, left and right kdnodes
T split_value; // splitting value of current node
std::vector <size_t> indices; // it indicates the points' indices that current node has
size_t level; // tree level of current node
};
} // end of namespace cpu_kdtree
template <typename T>
struct cuda_kdnode {
int parent, left, right;
T split_value;
size_t num_index; // number of indices it has
int index; // the beginning index
size_t level;
};
template <typename T, int D>
__device__ T gpu_distance(cpu_kdtree::point<T, D> &a, cpu_kdtree::point<T, D> &b) {
T distance = 0;
for (size_t i = 0; i < D; i++) {
T d = a.dim[i] - b.dim[i];
distance += d*d;
}
return distance;
}
template <typename T, int D>
__device__ void search_at_node(cuda_kdnode<T> *nodes, size_t *indices, cpu_kdtree::point<T, D> *d_reference_points, int cur, cpu_kdtree::point<T, D> &d_query_point, size_t *d_index, T *d_distance, int *d_node) {
T best_distance = FLT_MAX;
size_t best_index = 0;
while (true) { // break until reach the bottom
int split_axis = nodes[cur].level % D;
if (nodes[cur].left == -1) { // check whether it has left node or not
*d_node = cur;
for (int i = 0; i < nodes[cur].num_index; i++) {
size_t idx = indices[nodes[cur].index + i];
T dist = gpu_distance<T, D>(d_query_point, d_reference_points[idx]);
if (dist < best_distance) {
best_distance = dist;
best_index = idx;
}
}
break;
}
else if (d_query_point.dim[split_axis] < nodes[cur].split_value) { // jump into specific son node
cur = nodes[cur].left;
}
else {
cur = nodes[cur].right;
}
}
*d_distance = best_distance;
*d_index = best_index;
}
template <typename T, int D>
__device__ void search_at_node_range(cuda_kdnode<T> *nodes, size_t *indices, cpu_kdtree::point<T, D> *d_reference_points, cpu_kdtree::point<T, D> &d_query_point, int cur, T range, size_t *d_index, T *d_distance, size_t id, int *next_nodes, int *next_search_nodes, int *Judge) {
T best_distance = FLT_MAX;
size_t best_index = 0;
int next_nodes_pos = 0; // initialize pop out order index
next_nodes[id * stack_size + next_nodes_pos] = cur; // find data that belongs to the very specific thread
next_nodes_pos++;
while (next_nodes_pos) {
int next_search_nodes_pos = 0; // record push back order index
while (next_nodes_pos) {
cur = next_nodes[id * stack_size + next_nodes_pos - 1]; // pop out the last push in one and keep poping out
next_nodes_pos--;
int split_axis = nodes[cur].level % D;
if (nodes[cur].left == -1) {
for (int i = 0; i < nodes[cur].num_index; i++) {
int idx = indices[nodes[cur].index + i]; // all indices are stored in one array, pick up from every node's beginning index
T d = gpu_distance<T>(d_query_point, d_reference_points[idx]);
if (d < best_distance) {
best_distance = d;
best_index = idx;
}
}
}
else {
T d = d_query_point.dim[split_axis] - nodes[cur].split_value;
if (fabs(d) > range) {
if (d < 0) {
next_search_nodes[id * stack_size + next_search_nodes_pos] = nodes[cur].left;
next_search_nodes_pos++;
}
else {
next_search_nodes[id * stack_size + next_search_nodes_pos] = nodes[cur].right;
next_search_nodes_pos++;
}
}
else {
next_search_nodes[id * stack_size + next_search_nodes_pos] = nodes[cur].right;
next_search_nodes_pos++;
next_search_nodes[id * stack_size + next_search_nodes_pos] = nodes[cur].left;
next_search_nodes_pos++;
if (next_search_nodes_pos > stack_size) {
printf("Thread conflict might be caused by thread %d, so please try smaller input max_tree_levels\n", id);
(*Judge)++;
}
}
}
}
for (int i = 0; i < next_search_nodes_pos; i++)
next_nodes[id * stack_size + i] = next_search_nodes[id * stack_size + i];
next_nodes_pos = next_search_nodes_pos;
}
*d_distance = best_distance;
*d_index = best_index;
}
template <typename T, int D>
__device__ void search(cuda_kdnode<T> *nodes, size_t *indices, cpu_kdtree::point<T, D> *d_reference_points, cpu_kdtree::point<T, D> &d_query_point, size_t *d_index, T *d_distance, size_t id, int *next_nodes, int *next_search_nodes, int *Judge) {
int best_node = 0;
T best_distance = FLT_MAX;
size_t best_index = 0;
T radius = 0;
search_at_node<T, D>(nodes, indices, d_reference_points, 0, d_query_point, &best_index, &best_distance, &best_node);
radius = sqrt(best_distance); // get range
int cur = best_node;
while (nodes[cur].parent != -1) {
int parent = nodes[cur].parent;
int split_axis = nodes[parent].level % D;
T tmp_dist = FLT_MAX;
size_t tmp_idx;
if (fabs(nodes[parent].split_value - d_query_point.dim[split_axis]) <= radius) {
if (nodes[parent].left != cur)
search_at_node_range(nodes, indices, d_reference_points, d_query_point, nodes[parent].left, radius, &tmp_idx, &tmp_dist, id, next_nodes, next_search_nodes, Judge);
else
search_at_node_range(nodes, indices, d_reference_points, d_query_point, nodes[parent].right, radius, &tmp_idx, &tmp_dist, id, next_nodes, next_search_nodes, Judge);
}
if (tmp_dist < best_distance) {
best_distance = tmp_dist;
best_index = tmp_idx;
}
cur = parent;
}
*d_distance = sqrt(best_distance);
*d_index = best_index;
}
template <typename T, int D>
__global__ void search_batch(cuda_kdnode<T> *nodes, size_t *indices, cpu_kdtree::point<T, D> *d_reference_points, cpu_kdtree::point<T, D> *d_query_points, size_t d_query_count, size_t *d_indices, T *d_distances, int *next_nodes, int *next_search_nodes, int *Judge) {
size_t idx = blockIdx.x * blockDim.x + threadIdx.x;
if (idx >= d_query_count) return; // avoid segfault
search<T, D>(nodes, indices, d_reference_points, d_query_points[idx], &d_indices[idx], &d_distances[idx], idx, next_nodes, next_search_nodes, Judge); // every query points are independent
}
template <typename T, int D>
void search_stream(cuda_kdnode<T> *d_nodes, size_t *d_index, cpu_kdtree::point<T, D> *d_reference_points, cpu_kdtree::point<T, D> *query_stream_points, size_t stream_count, size_t *indices, T *distances) {
unsigned int threads = (unsigned int)(stream_count > 1024 ? 1024 : stream_count);
unsigned int blocks = (unsigned int)(stream_count / threads + (stream_count % threads ? 1 : 0));
cpu_kdtree::point<T, D> *d_query_points;
size_t *d_indices;
T *d_distances;
int *next_nodes;
int *next_search_nodes;
HANDLE_ERROR(cudaMalloc((void**)&d_query_points, sizeof(T) * stream_count * D));
HANDLE_ERROR(cudaMalloc((void**)&d_indices, sizeof(size_t) * stream_count));
HANDLE_ERROR(cudaMalloc((void**)&d_distances, sizeof(T) * stream_count));
HANDLE_ERROR(cudaMalloc((void**)&next_nodes, threads * blocks * stack_size * sizeof(int)));
HANDLE_ERROR(cudaMalloc((void**)&next_search_nodes, threads * blocks * stack_size * sizeof(int)));
HANDLE_ERROR(cudaMemcpy(d_query_points, query_stream_points, sizeof(T) * stream_count * D, cudaMemcpyHostToDevice));
int *Judge = NULL;
search_batch<<<blocks, threads>>> (d_nodes, d_index, d_reference_points, d_query_points, stream_count, d_indices, d_distances, next_nodes, next_search_nodes, Judge);
if(Judge == NULL) {
HANDLE_ERROR(cudaMemcpy(indices, d_indices, sizeof(size_t) * stream_count, cudaMemcpyDeviceToHost));
HANDLE_ERROR(cudaMemcpy(distances, d_distances, sizeof(T) * stream_count, cudaMemcpyDeviceToHost));
}
HANDLE_ERROR(cudaFree(next_nodes));
HANDLE_ERROR(cudaFree(next_search_nodes));
HANDLE_ERROR(cudaFree(d_query_points));
HANDLE_ERROR(cudaFree(d_indices));
HANDLE_ERROR(cudaFree(d_distances));
}
template <typename T, int D = 3> // set dimension of data to default 3
class kdtree {
protected:
int current_axis; // current judging axis
int n_id; // store the total number of nodes
std::vector < typename cpu_kdtree::point<T, D> > *tmp_points; // transfer or temperary points
std::vector < typename cpu_kdtree::point<T, D> > cpu_tmp_points; // for cpu searching
cpu_kdtree::cpu_kdnode<T> *root; // root node
static kdtree<T, D> *cur_tree_ptr;
#ifdef __CUDACC__
cuda_kdnode<T> *d_nodes;
size_t *d_index;
cpu_kdtree::point<T, D>* d_reference_points;
size_t npts;
int num_nodes;
#endif
public:
kdtree() { // constructor for creating a cpu_kdtree
cur_tree_ptr = this; // create a class pointer points to the current class value
n_id = 0; // set total number of points to default 0
}
~kdtree() { // destructor of cpu_kdtree
std::vector <cpu_kdtree::cpu_kdnode<T>*> next_nodes;
next_nodes.push_back(root);
while (next_nodes.size()) {
std::vector <cpu_kdtree::cpu_kdnode<T>*> next_search_nodes;
while (next_nodes.size()) {
cpu_kdtree::cpu_kdnode<T> *cur = next_nodes.back();
next_nodes.pop_back();
if (cur->left)
next_search_nodes.push_back(cur->left);
if (cur->right)
next_search_nodes.push_back(cur->right);
delete cur;
}
next_nodes = next_search_nodes;
}
root = NULL;
#ifdef __CUDACC__
HANDLE_ERROR(cudaFree(d_nodes));
HANDLE_ERROR(cudaFree(d_index));
HANDLE_ERROR(cudaFree(d_reference_points));
#endif
}
void cpu_create(std::vector < typename cpu_kdtree::point<T, D> > &reference_points, size_t max_levels) {
tmp_points = &reference_points;
root = new cpu_kdtree::cpu_kdnode<T>(); // initializing the root node
root->idx = n_id++; // the index of root is 0
root->level = 0; // tree level begins at 0
root->indices.resize(reference_points.size()); // get the number of points
for (size_t i = 0; i < reference_points.size(); i++) {
root->indices[i] = i; // set indices of input points
}
std::vector <cpu_kdtree::cpu_kdnode<T>*> next_nodes; // next nodes
next_nodes.push_back(root); // push back the root node
while (next_nodes.size()) {
std::vector <cpu_kdtree::cpu_kdnode<T>*> next_search_nodes; // next search nodes
while (next_nodes.size()) { // two same WHILE is because we need to make a new vector to store nodes for search
cpu_kdtree::cpu_kdnode<T> *current_node = next_nodes.back(); // handle node one by one (right first)
next_nodes.pop_back(); // pop out current node in order to store next round of nodes
if (current_node->level < max_levels) {
if (current_node->indices.size() > 1) { // split if the nonleaf node contains more than one point
cpu_kdtree::cpu_kdnode<T> *left = new cpu_kdtree::cpu_kdnode<T>();
cpu_kdtree::cpu_kdnode<T> *right = new cpu_kdtree::cpu_kdnode<T>();
left->idx = n_id++; // set the index of current node's left node
right->idx = n_id++;
split(current_node, left, right); // split left and right and determine a node
std::vector <size_t> temp; // empty vecters of int
//temp.resize(current_node->indices.size());
current_node->indices.swap(temp); // clean up current node's indices
current_node->left = left;
current_node->right = right;
current_node->left_idx = left->idx;
current_node->right_idx = right->idx;
if (right->indices.size())
next_search_nodes.push_back(right); // left pop out first
if (left->indices.size())
next_search_nodes.push_back(left);
}
}
}
next_nodes = next_search_nodes; // go deeper within the tree
}
}
static bool sort_points(const size_t a, const size_t b) { // create functor for std::sort
std::vector < typename cpu_kdtree::point<T, D> > &pts = *cur_tree_ptr->tmp_points; // put cur_tree_ptr to current input points' pointer
return pts[a].dim[cur_tree_ptr->current_axis] < pts[b].dim[cur_tree_ptr->current_axis];
}
void split(cpu_kdtree::cpu_kdnode<T> *cur, cpu_kdtree::cpu_kdnode<T> *left, cpu_kdtree::cpu_kdnode<T> *right) {
std::vector < typename cpu_kdtree::point<T, D> > &pts = *tmp_points;
current_axis = cur->level % D; // indicate the judicative dimension or axis
std::sort(cur->indices.begin(), cur->indices.end(), sort_points); // using SortPoints as comparison function to sort the data
size_t mid_value = cur->indices[cur->indices.size() / 2]; // odd in the mid_value, even take the floor
cur->split_value = pts[mid_value].dim[current_axis]; // get the parent node
left->parent = cur; // set the parent of the next search nodes to current node
right->parent = cur;
left->level = cur->level + 1; // level + 1
right->level = cur->level + 1;
left->parent_idx = cur->idx; // set its parent node's index
right->parent_idx = cur->idx;
for (size_t i = 0; i < cur->indices.size(); i++) { // split into left and right half-space one by one
size_t idx = cur->indices[i];
if (pts[idx].dim[current_axis] < cur->split_value)
left->indices.push_back(idx);
else
right->indices.push_back(idx);
}
}
/// create a KD-tree given a pointer to an array of reference points and the number of reference points
/// @param h_reference_points is a host array containing the reference points in (x0, y0, z0, ...., ) order
/// @param reference_count is the number of reference point in the array
/// @param max_levels is the deepest number of tree levels allowed
void create(T *h_reference_points, size_t reference_count, size_t max_levels) {
#ifdef __CUDACC__
if (max_levels > 10) {
std::cout<<"The max_tree_levels should be smaller!"<<std::endl;
exit(1);
}
//bb.init(&h_reference_points[0]);
//aaboundingboxing<T, D>(bb, h_reference_points, reference_count);
std::vector < typename cpu_kdtree::point<T, D> > reference_points(reference_count); // restore the reference points in particular way
for (size_t j = 0; j < reference_count; j++)
for (size_t i = 0; i < D; i++)
reference_points[j].dim[i] = h_reference_points[j * D + i]; // creating a tree on cpu
(*this).cpu_create(reference_points, max_levels); // building a tree on cpu
cpu_kdtree::cpu_kdnode<T> *d_root = (*this).get_root();
num_nodes = (*this).get_num_nodes();
npts = reference_count; // also equals to reference_count
HANDLE_ERROR(cudaMalloc((void**)&d_nodes, sizeof(cuda_kdnode<T>) * num_nodes)); // copy data from host to device
HANDLE_ERROR(cudaMalloc((void**)&d_index, sizeof(size_t) * npts));
HANDLE_ERROR(cudaMalloc((void**)&d_reference_points, sizeof(cpu_kdtree::point<T, D>) * npts));
std::vector < cuda_kdnode<T> > tmp_nodes(num_nodes);
std::vector <size_t> indices(npts);
std::vector <cpu_kdtree::cpu_kdnode<T>*> next_nodes;
size_t cur_pos = 0;
next_nodes.push_back(d_root);
while (next_nodes.size()) {
std::vector <typename cpu_kdtree::cpu_kdnode<T>*> next_search_nodes;
while (next_nodes.size()) {
cpu_kdtree::cpu_kdnode<T> *cur = next_nodes.back();
next_nodes.pop_back();
int id = cur->idx; // the nodes at same level are independent
tmp_nodes[id].level = cur->level;
tmp_nodes[id].parent = cur->parent_idx;
tmp_nodes[id].left = cur->left_idx;
tmp_nodes[id].right = cur->right_idx;
tmp_nodes[id].split_value = cur->split_value;
tmp_nodes[id].num_index = cur->indices.size(); // number of index
if (cur->indices.size()) {
for (size_t i = 0; i < cur->indices.size(); i++)
indices[cur_pos + i] = cur->indices[i];
tmp_nodes[id].index = (int)cur_pos; // beginning index of reference_points that every bottom node has
cur_pos += cur->indices.size(); // store indices continuously for every query_point
}
else {
tmp_nodes[id].index = -1;
}
if (cur->left)
next_search_nodes.push_back(cur->left);
if (cur->right)
next_search_nodes.push_back(cur->right);
}
next_nodes = next_search_nodes;
}
HANDLE_ERROR(cudaMemcpy(d_nodes, &tmp_nodes[0], sizeof(cuda_kdnode<T>) * tmp_nodes.size(), cudaMemcpyHostToDevice));
HANDLE_ERROR(cudaMemcpy(d_index, &indices[0], sizeof(size_t) * indices.size(), cudaMemcpyHostToDevice));
HANDLE_ERROR(cudaMemcpy(d_reference_points, &reference_points[0], sizeof(cpu_kdtree::point<T, D>) * reference_count, cudaMemcpyHostToDevice));
#else
std::vector < typename cpu_kdtree::point<T, D> > reference_points(reference_count); // restore the reference points in particular way
for (size_t j = 0; j < reference_count; j++)
for (size_t i = 0; i < D; i++)
reference_points[j].dim[i] = h_reference_points[j * D + i];
cpu_create(reference_points, max_levels);
cpu_tmp_points = *tmp_points;
#endif
}
int get_num_nodes() const { // get the total number of nodes
return n_id;
}
cpu_kdtree::cpu_kdnode<T>* get_root() const { // get the root node of tree
return root;
}
T cpu_distance(const cpu_kdtree::point<T, D> &a, const cpu_kdtree::point<T, D> &b) {
T distance = 0;
for (size_t i = 0; i < D; i++) {
T d = a.dim[i] - b.dim[i];
distance += d*d;
}
return distance;
}
void cpu_search_at_node(cpu_kdtree::cpu_kdnode<T> *cur, const cpu_kdtree::point<T, D> &query, size_t *index, T *distance, cpu_kdtree::cpu_kdnode<T> **node) {
T best_distance = FLT_MAX; // initialize the best distance to max of floating point
size_t best_index = 0;
std::vector < typename cpu_kdtree::point<T, D> > pts = cpu_tmp_points;
while (true) {
size_t split_axis = cur->level % D;
if (cur->left == NULL) { // risky but acceptable, same goes for right because left and right are in same pace
*node = cur; // pointer points to a pointer
for (size_t i = 0; i < cur->indices.size(); i++) {
size_t idx = cur->indices[i];
T d = cpu_distance(query, pts[idx]); // compute distances
/// if we want to compute k nearest neighbor, we can input the last resul
/// (last_best_dist < dist < best_dist) to select the next point until reaching to k
if (d < best_distance) {
best_distance = d;
best_index = idx; // record the nearest neighbor index
}
}
break; // find the target point then break the loop
}
else if (query.dim[split_axis] < cur->split_value) { // if it has son node, visit the next node on either left side or right side
cur = cur->left;
}
else {
cur = cur->right;
}
}
*index = best_index;
*distance = best_distance;
}
void cpu_search_at_node_range(cpu_kdtree::cpu_kdnode<T> *cur, const cpu_kdtree::point<T, D> &query, T range, size_t *index, T *distance) {
T best_distance = FLT_MAX; // initialize the best distance to max of floating point
size_t best_index = 0;
std::vector < typename cpu_kdtree::point<T, D> > pts = cpu_tmp_points;
std::vector < typename cpu_kdtree::cpu_kdnode<T>*> next_node;
next_node.push_back(cur);
while (next_node.size()) {
std::vector<typename cpu_kdtree::cpu_kdnode<T>*> next_search;
while (next_node.size()) {
cur = next_node.back();
next_node.pop_back();
size_t split_axis = cur->level % D;
if (cur->left == NULL) {
for (size_t i = 0; i < cur->indices.size(); i++) {
size_t idx = cur->indices[i];
T d = cpu_distance(query, pts[idx]);
if (d < best_distance) {
best_distance = d;
best_index = idx;
}
}
}
else {
T d = query.dim[split_axis] - cur->split_value; // computer distance along specific axis or dimension
/// there are three possibilities: on either left or right, and on both left and right
if (fabs(d) > range) { // absolute value of floating point to see if distance will be larger that best_dist
if (d < 0)
next_search.push_back(cur->left); // every left[split_axis] is less and equal to cur->split_value, so it is possible to find the nearest point in this region
else
next_search.push_back(cur->right);
}
else { // it is possible that nereast neighbor will appear on both left and right
next_search.push_back(cur->left);
next_search.push_back(cur->right);
}
}
}
next_node = next_search; // pop out at least one time
}
*index = best_index;
*distance = best_distance;
}
void cpu_search(T *h_query_points, size_t query_count, size_t *h_indices, T *h_distances) {
/// first convert the input query point into specific type
cpu_kdtree::point<T, D> query;
for (size_t j = 0; j < query_count; j++) {
for (size_t i = 0; i < D; i++)
query.dim[i] = h_query_points[j * D + i];
/// find the nearest node, this will be the upper bound for the next time searching
cpu_kdtree::cpu_kdnode<T> *best_node = NULL;
T best_distance = FLT_MAX;
size_t best_index = 0;
T radius = 0; // radius for range
cpu_search_at_node(root, query, &best_index, &best_distance, &best_node); // simple search to rougly determine a result for next search step
radius = sqrt(best_distance); // It is possible that nearest will appear in another region
/// find other possibilities
cpu_kdtree::cpu_kdnode<T> *cur = best_node;
while (cur->parent != NULL) { // every node that you pass will be possible to be the best node
/// go up
cpu_kdtree::cpu_kdnode<T> *parent = cur->parent; // travel back to every node that we pass through
size_t split_axis = (parent->level) % D;
/// search other nodes
size_t tmp_index;
T tmp_distance = FLT_MAX;
if (fabs(parent->split_value - query.dim[split_axis]) <= radius) {
/// search opposite node
if (parent->left != cur)
cpu_search_at_node_range(parent->left, query, radius, &tmp_index, &tmp_distance); // to see whether it is its mother node's left son node
else
cpu_search_at_node_range(parent->right, query, radius, &tmp_index, &tmp_distance);
}
if (tmp_distance < best_distance) {
best_distance = tmp_distance;
best_index = tmp_index;
}
cur = parent;
}
h_indices[j] = best_index;
h_distances[j] = best_distance;
}
}
/// search the KD tree for nearest neighbors to a set of specified query points
/// @param h_query_points an array of query points in (x0, y0, z0, ...) order
/// @param query_count is the number of query points
/// @param indices are the indices to the nearest reference point for each query points
/// @param distances is an array containing the distance between each query point and the nearest reference point
void search(T *h_query_points, size_t query_count, size_t *indices, T *distances) {
#ifdef __CUDACC__
std::vector < typename cpu_kdtree::point<T, D> > query_points(query_count);
for (size_t j = 0; j < query_count; j++)
for (size_t i = 0; i < D; i++)
query_points[j].dim[i] = h_query_points[j * D + i];
cudaDeviceProp prop;
cudaGetDeviceProperties(&prop, 0);
size_t query_memory = D * sizeof(T) * query_count;
size_t N = 3 * query_memory / prop.totalGlobalMem; //consider index and distance, roughly 3 times
if (N > 1) {
N++;
size_t stream_count = query_count / N;
for (size_t n = 0; n < N; n++) {
size_t query_stream_start = n * stream_count;
search_stream(d_nodes, d_index, d_reference_points, &query_points[query_stream_start], stream_count, &indices[query_stream_start], &distances[query_stream_start]);
}
size_t stream_remain_count = query_count - N * stream_count;
if (stream_remain_count > 0) {
size_t query_remain_start = N * stream_count;
search_stream(d_nodes, d_index, d_reference_points, &query_points[query_remain_start], stream_remain_count, &indices[query_remain_start], &distances[query_remain_start]);
}
}
else {
unsigned int threads = (unsigned int)(query_count > 1024 ? 1024 : query_count);
unsigned int blocks = (unsigned int)(query_count / threads + (query_count % threads ? 1 : 0));
cpu_kdtree::point<T, D> *d_query_points; // create a pointer pointing to query points on gpu
size_t *d_indices;
T *d_distances;
int *next_nodes; // create two STACK-like array
int *next_search_nodes;
int *Judge = NULL; // judge variable to see whether one thread is overwrite another thread's memory
HANDLE_ERROR(cudaMalloc((void**)&d_query_points, sizeof(T) * query_count * D));
HANDLE_ERROR(cudaMalloc((void**)&d_indices, sizeof(size_t) * query_count));
HANDLE_ERROR(cudaMalloc((void**)&d_distances, sizeof(T) * query_count));
HANDLE_ERROR(cudaMalloc((void**)&next_nodes, threads * blocks * stack_size * sizeof(int))); // STACK size right now is 50, you can change it if you mean to
HANDLE_ERROR(cudaMalloc((void**)&next_search_nodes, threads * blocks * stack_size * sizeof(int)));
HANDLE_ERROR(cudaMemcpy(d_query_points, &query_points[0], sizeof(T) * query_count * D, cudaMemcpyHostToDevice));
search_batch<<<blocks, threads>>> (d_nodes, d_index, d_reference_points, d_query_points, query_count, d_indices, d_distances, next_nodes, next_search_nodes, Judge);
if (Judge == NULL) { // do the following work if the thread works safely
HANDLE_ERROR(cudaMemcpy(indices, d_indices, sizeof(size_t) * query_count, cudaMemcpyDeviceToHost));
HANDLE_ERROR(cudaMemcpy(distances, d_distances, sizeof(T) * query_count, cudaMemcpyDeviceToHost));
}
HANDLE_ERROR(cudaFree(next_nodes));
HANDLE_ERROR(cudaFree(next_search_nodes));
HANDLE_ERROR(cudaFree(d_query_points));
HANDLE_ERROR(cudaFree(d_indices));
HANDLE_ERROR(cudaFree(d_distances));
}
#else
cpu_search(h_query_points, query_count, indices, distances);
#endif
}
}; //end class kdtree
template <typename T, int D>
kdtree<T, D>* kdtree<T, D>::cur_tree_ptr = NULL; // definition of cur_tree_ptr pointer points to the current class
} //end namespace stim
#endif