300 lines
14 KiB
C++
300 lines
14 KiB
C++
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/*
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Copyright (c) 2005-2016 Intel Corporation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/* Bin-packing algorithm that attempts to use minimal number of bins B of
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size V to contain N items of varying sizes. */
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#include <string>
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#include <iostream>
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#include <cmath>
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#include "tbb/atomic.h"
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#include "tbb/task_scheduler_init.h"
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#include "tbb/tick_count.h"
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#include "tbb/flow_graph.h"
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#include "../../common/utility/utility.h"
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using namespace std;
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using namespace tbb;
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using namespace tbb::flow;
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typedef size_t size_type; // to represent non-zero indices, capacities, etc.
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typedef size_t value_type; // the type of items we are attempting to pack into bins
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typedef vector<value_type> bin; // we use a simple vector to represent a bin
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// Our bin packers will be function nodes in the graph that take value_type items and
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// return a dummy value. They will also implicitly send packed bins to the bin_buffer
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// node, and unused items back to the value_pool node:
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typedef multifunction_node<value_type, tuple<value_type, bin>, rejecting> bin_packer;
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// Items are placed into a pool that all bin packers grab from, represent by a queue_node:
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typedef queue_node<value_type> value_pool;
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// Packed bins are placed in this buffer waiting to be serially printed and/or accounted for:
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typedef buffer_node<bin> bin_buffer;
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// Packed bins are taken from the_bin_buffer and processed by the_writer:
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typedef function_node<bin, continue_msg, rejecting> bin_writer;
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// Items are injected into the graph when this node sends them to the_value_pool:
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typedef source_node<value_type> value_source;
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// User-specified globals with default values
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size_type V = 42; // desired capacity for each bin
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size_type N = 1000; // number of elements to generate
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bool verbose = false; // prints bin details and other diagnostics to screen
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bool silent = false; // suppress all output except for time
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int num_bin_packers=-1; // number of concurrent bin packers in operation; default is #threads;
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// larger values can result in more bins at less than full capacity
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size_type optimality=1; // 1 (default) is highest the algorithm can obtain; larger numbers run faster
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// Calculated globals
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size_type min_B; // lower bound on the optimal number of bins
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size_type B; // the answer, i.e. number of bins used by the algorithm
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size_type *input_array; // stores randomly generated input values
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value_type item_sum; // sum of all randomly generated input values
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tbb::atomic<value_type> packed_sum; // sum of all values currently packed into all bins
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tbb::atomic<size_type> packed_items; // number of values currently packed into all bins
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tbb::atomic<size_type> active_bins; // number of active bin_packers
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bin_packer **bins; // the array of bin packers
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// This class is the Body type for bin_packer
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class bin_filler {
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typedef bin_packer::output_ports_type ports_type;
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bin my_bin; // the current bin that this bin_filler is packing
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size_type my_used; // capacity of bin used by current contents (not to be confused with my_bin.size())
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size_type relax, relax_val; // relaxation counter for determining when to settle for a non-full bin
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bin_packer* my_bin_packer; // ptr to the bin packer that this body object is associated with
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size_type bin_index; // index of the encapsulating bin packer in the global bins array
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value_type looking_for; // the minimum size of item this bin_packer will accept
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value_pool* the_value_pool; // the queue of incoming values
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bool done; // flag to indicate that this binpacker has been deactivated
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public:
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bin_filler(size_t bidx, value_pool* _q) :
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my_used(0), relax(0), relax_val(0), my_bin_packer(NULL), bin_index(bidx), looking_for(V), the_value_pool(_q), done(false) {}
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void operator()(const value_type& item, ports_type& p) {
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if (!my_bin_packer) my_bin_packer = bins[bin_index];
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if (done) get<0>(p).try_put(item); // this bin_packer is done packing items; put item back to pool
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else if (item > V) { // signal that packed_sum has reached item_sum at some point
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size_type remaining = active_bins--;
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if (remaining == 1 && packed_sum == item_sum) { // this is the last bin and it has seen everything
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// this bin_packer may not have seen everything, so stay active
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if (my_used>0) get<1>(p).try_put(my_bin);
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my_bin.clear();
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my_used = 0;
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looking_for = V;
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++active_bins;
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}
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else if (remaining == 1) { // this is the last bin, but there are remaining items
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get<0>(p).try_put(V+1); // send out signal
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++active_bins;
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}
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else if (remaining > 1) { // this is not the last bin; deactivate
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if (my_used < V/(1+optimality*.1)) { // this bin is ill-utilized; throw back items and deactivate
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packed_sum -= my_used;
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packed_items -= my_bin.size();
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for (size_type i=0; i<my_bin.size(); ++i)
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get<0>(p).try_put(my_bin[i]);
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the_value_pool->remove_successor(*my_bin_packer); // deactivate
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done = true;
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get<0>(p).try_put(V+1); // send out signal
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}
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else { // this bin is well-utilized; send out bin and deactivate
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the_value_pool->remove_successor(*my_bin_packer); // build no more bins
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done = true;
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if (my_used>0) get<1>(p).try_put(my_bin);
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get<0>(p).try_put(V+1); // send out signal
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}
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}
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}
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else if (item <= V-my_used && item >= looking_for) { // this item can be packed
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my_bin.push_back(item);
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my_used += item;
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packed_sum += item;
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++packed_items;
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looking_for = V-my_used;
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relax = 0;
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if (packed_sum == item_sum) {
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get<0>(p).try_put(V+1); // send out signal
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}
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if (my_used == V) {
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get<1>(p).try_put(my_bin);
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my_bin.clear();
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my_used = 0;
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looking_for = V;
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}
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}
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else { // this item can't be packed; relax constraints
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++relax;
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if (relax >= (N-packed_items)/optimality) { // this bin_packer has looked through enough items
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relax = 0;
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--looking_for; // accept a wider range of items
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if (looking_for == 0 && my_used < V/(1+optimality*.1) && my_used > 0 && active_bins > 1) {
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// this bin_packer is ill-utilized and can't find items; deactivate and throw back items
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size_type remaining = active_bins--;
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if (remaining > 1) { // not the last bin_packer
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the_value_pool->remove_successor(*my_bin_packer); // deactivate
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done = true;
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}
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else active_bins++; // can't deactivate last bin_packer
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packed_sum -= my_used;
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packed_items -= my_bin.size();
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for (size_type i=0; i<my_bin.size(); ++i)
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get<0>(p).try_put(my_bin[i]);
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my_bin.clear();
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my_used = 0;
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}
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else if (looking_for == 0 && (my_used >= V/(1+optimality*.1) || active_bins == 1)) {
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// this bin_packer can't find items but is well-utilized, so send it out and reset
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get<1>(p).try_put(my_bin);
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my_bin.clear();
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my_used = 0;
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looking_for = V;
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}
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}
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get<0>(p).try_put(item); // put unused item back to pool
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}
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}
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};
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// source node uses this to send the values to the value_pool
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class item_generator {
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size_type counter;
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public:
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item_generator() : counter(0) {}
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bool operator()(value_type& m) {
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if (counter<N) {
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m = input_array[counter];
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++counter;
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return true;
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}
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return false;
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}
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};
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// the terminal function_node uses this to gather stats and print bin information
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class bin_printer {
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value_type running_count;
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size_type item_count;
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value_type my_min, my_max;
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double avg;
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public:
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bin_printer() : running_count(0), item_count(0), my_min(V), my_max(0), avg(0) {}
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continue_msg operator()(bin b) {
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value_type sum=0;
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++B;
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if (verbose)
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cout << "[ ";
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for (size_type i=0; i<b.size(); ++i) {
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if (verbose)
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cout << b[i] << " ";
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sum+=b[i];
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++item_count;
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}
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if (sum < my_min) my_min = sum;
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if (sum > my_max) my_max = sum;
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avg += sum;
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running_count += sum;
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if (verbose)
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cout << "]=" << sum << "; Done/Packed/Total cap: " << running_count << "/" << packed_sum << "/" << item_sum
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<< " items:" << item_count << "/" << packed_items << "/" << N << " B=" << B << endl;
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if (item_count == N) { // should be the last; print stats
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avg = avg/(double)B;
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if (!silent)
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cout << "SUMMARY: #Bins used: " << B << "; Avg size: " << avg << "; Max size: " << my_max
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<< "; Min size: " << my_min << "\n Lower bound on optimal #bins: " << min_B
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<< "; Start #bins: " << num_bin_packers << endl;
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}
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return continue_msg(); // need to return something
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}
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};
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int get_default_num_threads() {
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static int threads = 0;
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if (threads == 0)
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threads = task_scheduler_init::default_num_threads();
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return threads;
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}
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int main(int argc, char *argv[]) {
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try {
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utility::thread_number_range threads(get_default_num_threads);
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utility::parse_cli_arguments(argc, argv,
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utility::cli_argument_pack()
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//"-h" option for displaying help is present implicitly
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.positional_arg(threads,"#threads",utility::thread_number_range_desc)
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.arg(verbose,"verbose"," print diagnostic output to screen")
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.arg(silent,"silent"," limits output to timing info; overrides verbose")
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.arg(N,"N"," number of values to pack")
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.arg(V,"V"," capacity of each bin")
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.arg(num_bin_packers,"#packers"," number of concurrent bin packers to use "
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"(default=#threads)")
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.arg(optimality,"optimality","controls optimality of solution; 1 is highest, use\n"
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" larger numbers for less optimal but faster solution")
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);
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if (silent) verbose = false; // make silent override verbose
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// Generate random input data
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srand(42);
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input_array = new value_type[N];
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item_sum = 0;
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for (size_type i=0; i<N; ++i) {
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input_array[i] = rand() % V + 1; // generate items that fit in a bin
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item_sum += input_array[i];
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}
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min_B = (item_sum % V) ? item_sum/V + 1 : item_sum/V;
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tick_count start = tick_count::now();
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for(int p = threads.first; p <= threads.last; p = threads.step(p)) {
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task_scheduler_init init(p);
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packed_sum = 0;
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packed_items = 0;
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B = 0;
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if (num_bin_packers == -1) num_bin_packers = p;
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active_bins = num_bin_packers;
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if (!silent)
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cout << "binpack running with " << item_sum << " capacity over " << N << " items, optimality="
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<< optimality << ", " << num_bin_packers << " bins of capacity=" << V << " on " << p
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<< " threads.\n";
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graph g;
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value_source the_source(g, item_generator(), false);
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value_pool the_value_pool(g);
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make_edge(the_source, the_value_pool);
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bin_buffer the_bin_buffer(g);
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bins = new bin_packer*[num_bin_packers];
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for (int i=0; i<num_bin_packers; ++i) {
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bins[i] = new bin_packer(g, 1, bin_filler(i, &the_value_pool));
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make_edge(the_value_pool, *(bins[i]));
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make_edge(output_port<0>(*(bins[i])), the_value_pool);
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make_edge(output_port<1>(*(bins[i])), the_bin_buffer);
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}
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bin_writer the_writer(g, 1, bin_printer());
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make_edge(the_bin_buffer, the_writer);
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the_source.activate();
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g.wait_for_all();
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for (int i=0; i<num_bin_packers; ++i) {
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delete bins[i];
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}
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delete[] bins;
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}
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utility::report_elapsed_time((tick_count::now() - start).seconds());
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delete[] input_array;
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return 0;
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} catch(std::exception& e) {
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cerr<<"error occurred. error text is :\"" <<e.what()<<"\"\n";
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return 1;
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}
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}
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