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mergesort.cpp File Reference

Mergesort example. More...

`#include <algorithm>`
`#include <boost/smart_ptr.hpp>`
`#include <boost/thread/mutex.hpp>`
`#include <boost/threadpool.hpp>`
`#include <iostream>`
`#include <sstream>`
Include dependency graph for mergesort.cpp:

Go to the source code of this file.

## Classes
class | image
class | merge_job< T >

## Functions
void | print (string text)
template<class T >
string | to_string (const T &value)
unsigned long | get_ms_diff (boost::xtime &start, boost::xtime &end)
int | main (int argc, char *const argv[])

## Variables
boost::mutex | m_io_monitor

## Detailed Description

Mergesort example.

This example shows how to use the threadpool library.

Copyright (c) 2005-2006 Philipp Henkel

Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

http://threadpool.sourceforge.net

Definition in file mergesort.cpp.

## Function Documentation

unsigned long get_ms_diff | ( | boost::xtime & | start,
|  | boost::xtime & | end
| ) |  |

Definition at line 45 of file mergesort.cpp.

46 {
47 boost::xtime::xtime_sec_t start_ms = start.sec * 1000 + start.nsec / 1000000;
48 boost::xtime::xtime_sec_t end_ms = end.sec * 1000 + end.nsec / 1000000;
49 return static_cast<unsigned long>( end_ms - start_ms );
50 }
IOTest.start
start
Definition: IOTest.py:99
end
auto end(reverse_wrapper< T > &w)
Definition: reverse.h:64

int main | ( | int | argc,
|  | char *const | argv[]
| ) |  |

Definition at line 113 of file mergesort.cpp.

114 {
115 print( "MAIN: construct thread pool\n" );
116
117 boost::xtime start;
118 boost::xtime_get( &start, boost::TIME_UTC );
119
120 int exponent = 7;
121 int data_len = 1 << exponent; // = pow(2, exponent)
122
123 print( "MAIN: sort array with " + to_string( data_len ) + " elements.\n" );
124
125 boost::shared_array<image> data( new image[data_len] );
126
127 // fill array with arbitrary values (not sorted ascendingly)
128 for ( int i = 0; i < data_len; i++ ) {
129 data[i] = image( ( data_len - i - 1 ) % 23 );
130 }
131
132 /***************************/
133 /* Standard implementation */
134 /***************************/
135
136 pool tp;
137 tp.size_controller().resize( 5 );
138
139 // merge data array
140 for ( int step = 1; step <= exponent; step++ ) {
141 print( "\nMAIN: merge step " + to_string( step ) + "\n" );
142
143 // divide array into partitions
144 int partition_size = 1 << step;
145 for ( int partition = 0; partition < data_len / partition_size; partition++ ) {
146 // sort partition
147 boost::shared_ptr<merge_job<image>> job(
148 new merge_job<image>( data, partition * partition_size, partition_size ) );
149 // tp->schedule(prio_task_func(5, boost::bind(&merge_job<image>::run, job)));
150 schedule( tp, boost::bind( &merge_job<image>::run, job ) );
151 // schedule(tp, job);
152 }
153 tp.wait(); // wait until all partitions are sorted
154 }
155
156 boost::xtime end;
157 boost::xtime_get( &end, boost::TIME_UTC );
158
159 print( "\nMAIN: duration " + to_string( get_ms_diff( start, end ) ) + " ms \n" );
160
161 print( "\nMAIN: check if array is sorted... \n" );
162
163 // check if array is sorted ascendingly
164 bool ascending = true;
165 for ( int i = 0; i < data_len - 1; i++ ) {
166 if ( data[i + 1] < data[i] ) {
167 ascending = false;
168 }
169 }
170
171 if ( ascending ) {
172 print( "\nMAIN: array is sorted\n" );
173 } else {
174 print( "\nMAIN: array is NOT sorted!\n" );
175 }
176
177 return 0;
178 }
boost::threadpool::thread_pool::wait
void wait(size_t task_threshold=0) const
The current thread of execution is blocked until the sum of all active and pending tasks is equal or ...
Definition: pool.hpp:176
to_string
string to_string(const T &value)
Definition: mergesort.cpp:37
merge_job
Definition: mergesort.cpp:78
get_ms_diff
unsigned long get_ms_diff(boost::xtime &start, boost::xtime &end)
Definition: mergesort.cpp:45
image
Definition: mergesort.cpp:52
std::partition
T partition(T...args)
pool
Definition: PoolClasses.h:11
boost::threadpool::schedule
disable_if< is_void< typename result_of< Function() >::type >, future< typename result_of< Function() >::type >>::type schedule(Pool &pool, const Function &task)
Definition: future.hpp:111
compareRootHistos.tp
tuple tp
Definition: compareRootHistos.py:417
IOTest.start
start
Definition: IOTest.py:99
boost::threadpool::thread_pool::size_controller
size_controller_type size_controller()
Gets the size controller which manages the number of threads in the pool.
Definition: pool.hpp:111
end
auto end(reverse_wrapper< T > &w)
Definition: reverse.h:64
print
void print(string text)
Definition: mergesort.cpp:30

void print | ( | string | text | ) |

Definition at line 30 of file mergesort.cpp.

31 {
32 boost::mutex::scoped_lock lock( m_io_monitor );
33 cout << text;
34 }
std::lock
T lock(T...args)
m_io_monitor
boost::mutex m_io_monitor
Definition: mergesort.cpp:28
std::cout
template<class T >

string to_string | ( | const T & | value | ) |

Definition at line 37 of file mergesort.cpp.

38 {
39 ostringstream ost;
40 ost << value;
41 ost.flush();
42 return ost.str();
43 }
std::ostringstream
STL class.
std::ostringstream::str
T str(T...args)
std::ostringstream::flush
T flush(T...args)

## Variable Documentation

boost::mutex m_io_monitor

Definition at line 28 of file mergesort.cpp.