string-sorting/external/parallel_string_radix_sort.h at master · rantala/string-sorting · GitHub

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// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

// * Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

// * Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

// * Neither the name of Takuya Akiba nor the names of its

// contributors may be used to endorse or promote products derived from

// this software without specific prior written permission.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef PARALLEL_STRING_RADIX_SORT_H_

#define PARALLEL_STRING_RADIX_SORT_H_

//#ifdef _OPENMP

//#include <omp.h>

//#endif

#include <stdint.h>

#include <algorithm>

#include <cassert>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <string>

#define PSRS_CHECK(expr) \

if (expr) { \

} else { \

fprintf(stderr, "CHECK Failed(%s:%d): %s\n", \

__FILE__, __LINE__, #expr); \

exit(EXIT_FAILURE); \

}

namespace parallel_string_radix_sort {

namespace internal {

/**

* Comparison function class used in |ParallelStringRadixSort|.

template<typename StringType> class Compare;

template<> class Compare<const char*> {

public:

explicit Compare(int depth) : depth_(depth) {}

inline bool operator()(const char* const a, const char* const b) {

return strcmp(a + depth_, b + depth_) < 0;

}

private:

int depth_;

};

template<> class Compare<std::string> {

public:

explicit Compare(int depth) : depth_(depth) {}

inline bool operator()(const std::string &a, const std::string &b) {

return a.compare(depth_, a.length() - depth_,

b, depth_, b.length() - depth_) < 0;

}

private:

int depth_;

};

} // namespace internal

/**

* The class to perform string sorting.

* @param StringType The type of the strings to be sorted.

* This should be either of |const char*| or |std::string|.

template<typename StringType>

class ParallelStringRadixSort {

public:

ParallelStringRadixSort();

~ParallelStringRadixSort();

/**

* Initialize the class.

* @param max_elems the maximum number of the elements to be sorted

void Init(size_t max_elems);

/**

* Sort an array of strings.

* @param strings the array to be sorted

* @param num_elems the number of the elements in the given array

void Sort(StringType *strings, size_t num_elems);

private:

/// The theshold of size of ranges to call |std::sort|

static const size_t kThreshold = 30;

/// The limit of depth to call |std::sort|

static const size_t kDepthLimit = 100;

size_t max_elems_;

StringType *data_, *temp_;

uint8_t *letters8_;

uint16_t *letters16_;

/**

* Release all the allocated resources.

void DeleteAll();

/**

* Sort elements in range [bgn, end),

* which have common prefix with |depth| characters.

* @param flip When false, read from |data_|, write to |temp_| and recurse.

* When true, read from |temp_|, write to |data_| and recurse.

void Sort8(size_t bgn, size_t end, size_t depth, bool flip);

/**

* Sort elements in range [bgn, end),

* which have common prefix with |depth| characters.

* Treat pairs of characters as single super characters.

* @param flip When false, read from |data_|, write to |temp_| and recurse.

* When true, read from |temp_|, write to |data_| and recurse.

void Sort16(size_t bgn, size_t end, size_t depth, bool flip);

/**

* Sort elements in range [bgn, end),

* which have common prefix with |depth| characters.

* Treat pairs of characters as single super characters.

* Builds threads and recurse in parallel.

* @param flip When false, read from |data_|, write to |temp_| and recurse.

* When true, read from |temp_|, write to |data_| and recurse.

void Sort16Parallel(size_t bgn, size_t end, size_t depth, bool flip);

/**

* Sort elements in range [bgn, end),

* which have common prefix with |depth| characters.

* The size of the range determines the action of this function.

* If the size is sufficiently small (smaller than or equal to |kThreshold|),

* we call |std::sort| complete the sorting.

* In doing so, regardless of |flip|, write the result to |data_|.

* If the size is smaller than |1 << 16| then we call |Sort8|,

* otherwise we call |Sort16|.

* If the |depth| is larget than or equal to |kDepthLimit|,

* we also use |std::sort|. This is to avoid stack overflow.

inline void Recurse(size_t bgn, size_t end, size_t depth, bool flip) {

size_t n = end - bgn;

if (depth >= kDepthLimit || n <= kThreshold) {

if (flip) {

for (size_t i = bgn; i < end; ++i) {

std::swap(data_[i], temp_[i]);

}

if (n > 1) {

std::sort(data_ + bgn, data_ + end, internal::Compare<StringType>(depth));

}

} else if (n < (1 << 16)) {

Sort8(bgn, end, depth, flip);

} else {

Sort16(bgn, end, depth, flip);

}

};

template<typename StringType>

ParallelStringRadixSort<StringType>::ParallelStringRadixSort()

: max_elems_(0), temp_(NULL), letters8_(NULL), letters16_(NULL) {}

template<typename StringType>

ParallelStringRadixSort<StringType>::~ParallelStringRadixSort() {

DeleteAll();

}

template<typename StringType>

void ParallelStringRadixSort<StringType>::Init(size_t max_elems) {

DeleteAll();

max_elems_ = max_elems;

temp_ = new StringType[max_elems];

letters8_ = new uint8_t[max_elems];

letters16_ = new uint16_t[max_elems];

PSRS_CHECK(temp_ != NULL && letters8_ != NULL && letters16_ != NULL);

}

template<typename StringType>

void ParallelStringRadixSort<StringType>::DeleteAll() {

delete [] temp_;

delete [] letters8_;

delete [] letters16_;

max_elems_ = 0;

temp_ = NULL;

letters8_ = NULL;

letters16_ = NULL;

}

template<typename StringType>

void ParallelStringRadixSort<StringType>

::Sort(StringType *strings, size_t num_elems) {

assert(num_elems <= max_elems_);

data_ = strings;

Sort16Parallel(0, num_elems, 0, false);

}

template<typename StringType>

void ParallelStringRadixSort<StringType>

::Sort8(size_t bgn, size_t end, size_t depth, bool flip) {

// Here we do not use |new| or |malloc|. This is because:

// 1. these may be heavy bottle-necks under multi-thread, and

// 2. the size is sufficiently small for preventing stack overflow.

size_t cnt[1 << 8] = {};

StringType *src = (flip ? temp_ : data_) + bgn;

StringType *dst = (flip ? data_ : temp_) + bgn;

uint8_t *let = letters8_ + bgn;

size_t n = end - bgn;

for (size_t i = 0; i < n; ++i) {

let[i] = src[i][depth];

}

for (size_t i = 0; i < n; ++i) {

++cnt[let[i]];

}

size_t s = 0;

for (int i = 0; i < 1 << 8; ++i) {

std::swap(cnt[i], s);

s += cnt[i];

}

for (size_t i = 0; i < n; ++i) {

std::swap(dst[cnt[let[i]]++], src[i]);

}

if (flip == false) {

size_t b = 0, e = cnt[0];

for (size_t j = b; j < e; ++j) {

std::swap(src[j], dst[j]);

}

for (size_t i = 1; i < 1 << 8; ++i) {

if (cnt[i] - cnt[i - 1] >= 1) {

Recurse(bgn + cnt[i - 1], bgn + cnt[i], depth + 1, !flip);

}

template<typename StringType>

void ParallelStringRadixSort<StringType>

::Sort16(size_t bgn, size_t end, size_t depth, bool flip) {

size_t *cnt = new size_t[1 << 16]();

PSRS_CHECK(cnt != NULL);

StringType *src = (flip ? temp_ : data_) + bgn;

StringType *dst = (flip ? data_ : temp_) + bgn;

uint16_t *let = letters16_ + bgn;

size_t n = end - bgn;

for (size_t i = 0; i < n; ++i) {

uint16_t x = src[i][depth];

let[i] = x == 0 ? 0 : ((x << 8) | src[i][depth + 1]);

}

for (size_t i = 0; i < n; ++i) {

++cnt[let[i]];

}

size_t s = 0;

for (int i = 0; i < 1 << 16; ++i) {

std::swap(cnt[i], s);

s += cnt[i];

}

for (size_t i = 0; i < n; ++i) {

std::swap(dst[cnt[let[i]]++], src[i]);

}

if (flip == false) {

for (int i = 0; i < 1 << 8; ++i) {

size_t b = i == 0 ? 0 : cnt[(i << 8) - 1];

size_t e = cnt[i << 8];

for (size_t j = b; j < e; ++j) {

std::swap(src[j], dst[j]);

}

for (size_t i = 1; i < 1 << 16; ++i) {

if ((i & 0xFF) != 0 && cnt[i] - cnt[i - 1] >= 1) {

Recurse(bgn + cnt[i - 1], bgn + cnt[i], depth + 2, !flip);

}

delete [] cnt;

}

template<typename StringType>

void ParallelStringRadixSort<StringType>

::Sort16Parallel(size_t bgn, size_t end, size_t depth, bool flip) {

size_t cnt[1 << 16] = {};

StringType *src = (flip ? temp_ : data_) + bgn;

StringType *dst = (flip ? data_ : temp_) + bgn;

uint16_t *let = letters16_ + bgn;

size_t n = end - bgn;

#ifdef _OPENMP

#pragma omp parallel for schedule(static)

#endif

for (size_t i = 0; i < n; ++i) {

uint16_t x = src[i][depth];

let[i] = x == 0 ? 0 : ((x << 8) | src[i][depth + 1]);

}

for (size_t i = 0; i < n; ++i) {

++cnt[let[i]];

}

{

size_t s = 0;

for (int i = 0; i < 1 << 16; ++i) {

std::swap(cnt[i], s);

s += cnt[i];

}

for (size_t i = 0; i < n; ++i) {

std::swap(dst[cnt[let[i]]++], src[i]);

}

if (flip == false) {

#ifdef _OPENMP

#pragma omp parallel for schedule(static)

#endif

for (int i = 0; i < 1 << 8; ++i) {

size_t b = i == 0 ? 0 : cnt[(i << 8) - 1];

size_t e = cnt[i << 8];

for (size_t j = b; j < e; ++j) {

src[j] = dst[j];

}

#ifdef _OPENMP

#pragma omp parallel for schedule(dynamic)

#endif

for (size_t i = 1; i < 1 << 16; ++i) {

if ((i & 0xFF) != 0 && cnt[i] - cnt[i - 1] >= 1) {

Recurse(bgn + cnt[i - 1], bgn + cnt[i], depth + 2, !flip);

}

/**

* Sort an array of strings.

* This function automatically initialize an instance of

* |ParallelStringRadixSort| and perform sorting.

* If you perform sorting more than once, you can avoid the cost of

* initialization using |ParallelStringRadixSort| class by yourself.

* @param strings the array to be sorted

* @param num_elems the number of the elements in the given array

template<typename StringType>

void Sort(StringType *strings, size_t num_elems) {

ParallelStringRadixSort<StringType> psrs;

psrs.Init(num_elems);

psrs.Sort(strings, num_elems);

}

template<typename StringType, size_t kNumElems>

void Sort(StringType (&strings)[kNumElems]) {

Sort(strings, kNumElems);

}

} // namespace parallel_string_radix_sort

#undef PSRS_CHECK

#endif // PARALLEL_STRING_RADIX_SORT_H_

string-sorting/external/parallel_string_radix_sort.h at master · rantala/string-sorting · GitHub

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