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<div class="document" id="logo-distributed-property-map">
<h1 class="title"><a class="reference external" href="http://www.osl.iu.edu/research/pbgl"><img align="middle" alt="Parallel BGL" class="align-middle" src="pbgl-logo.png" /></a> Distributed Property Map</h1>

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<p>A distributed property map adaptor is a property map whose stored
values are distributed across multiple non-overlapping memory spaces
on different processes. Values local to the current process are stored
within a local property map and may be immediately accessed via
<tt class="docutils literal"><span class="pre">get</span></tt> and <tt class="docutils literal"><span class="pre">put</span></tt>. Values stored on remote processes may also be
accessed via <tt class="docutils literal"><span class="pre">get</span></tt> and <tt class="docutils literal"><span class="pre">put</span></tt>, but the behavior differs slightly:</p>
<blockquote>
<ul class="simple">
<li><tt class="docutils literal"><span class="pre">put</span></tt> operations update a local ghost cell and send a &quot;put&quot;
message to the process that owns the value. The owner is free to
update its own &quot;official&quot; value or may ignore the put request.</li>
<li><tt class="docutils literal"><span class="pre">get</span></tt> operations returns the contents of the local ghost
cell. If no ghost cell is available, one is created using a
(customizable) default value.</li>
</ul>
</blockquote>
<p>Using distributed property maps requires a bit more care than using
local, sequential property maps. While the syntax and semantics are
similar, distributed property maps may contain out-of-date
information that can only be guaranteed to be synchronized by
calling the <tt class="docutils literal"><span class="pre">synchronize</span></tt> function in all processes.</p>
<p>To address the issue of out-of-date values, distributed property
maps support multiple <a class="reference internal" href="#consistency-models">consistency models</a> and may be supplied with a
<a class="reference internal" href="#reduction-operation">reduction operation</a>.</p>
<p>Distributed property maps meet the requirements of the <a class="reference external" href="http://www.boost.org/libs/property_map/ReadablePropertyMap.html">Readable
Property Map</a> and, potentially, the <a class="reference external" href="http://www.boost.org/libs/property_map/WritablePropertyMap.html">Writable Property Map</a> and
<a class="reference external" href="http://www.boost.org/libs/property_map/ReadWritePropertyMap.html">Read/Write Property Map</a> concepts. Distributed property maps do
<em>not</em>, however, meet the requirements of the <a class="reference external" href="http://www.boost.org/libs/property_map/LvaluePropertyMap.html">Lvalue Property Map</a>
concept, because elements residing in another process are not
directly addressible. There are several forms of distributed property
maps:</p>
<blockquote>
<ul class="simple">
<li><a class="reference internal" href="#distributed-property-map-adaptor">Distributed property map adaptor</a></li>
<li><a class="reference internal" href="#distributed-iterator-property-map">Distributed iterator property map</a></li>
<li><a class="reference internal" href="#distributed-safe-iterator-property-map">Distributed safe iterator property map</a></li>
<li><a class="reference internal" href="#local-property-map">Local property map</a></li>
</ul>
</blockquote>
<div class="section" id="consistency-models">
<h1>Consistency models</h1>
<p>Distributed property maps offer many consistency models, which affect
how the values read from and written to remote keys relate to the
&quot;official&quot; value for that key stored in the owning process. The
consistency model of a distributed property map can be set with the
member function <tt class="docutils literal"><span class="pre">set_consistency_model</span></tt> to a bitwise-OR of the
flags in the <tt class="docutils literal"><span class="pre">boost::parallel::consistency_model</span></tt> enumeration. The
individual flags are:</p>
<blockquote>
<ul class="simple">
<li><tt class="docutils literal"><span class="pre">cm_forward</span></tt>: The default consistency model, which propagates
values forward from <tt class="docutils literal"><span class="pre">put</span></tt> operations on remote processors to
the owner of the value being changed.</li>
<li><tt class="docutils literal"><span class="pre">cm_backward</span></tt>: After all values have been forwarded or flushed
to the owning processes, each process receives updates values for
each of its ghost cells. After synchronization, the values in
ghost cells are guaranteed to match the values stored on the
owning processor.</li>
<li><tt class="docutils literal"><span class="pre">cm_bidirectional</span></tt>: A combination of both <tt class="docutils literal"><span class="pre">cm_forward</span></tt> and
<tt class="docutils literal"><span class="pre">cm_backward</span></tt>.</li>
<li><tt class="docutils literal"><span class="pre">cm_flush</span></tt>: At the beginning of synchronization, all of the
values stored locally in ghost cells are sent to their owning
processors.</li>
<li><tt class="docutils literal"><span class="pre">cm_reset</span></tt>: Executes a <tt class="docutils literal"><span class="pre">reset()</span></tt> operation after
synchronization, setting the values in each ghost cell to their
default value.</li>
<li><tt class="docutils literal"><span class="pre">cm_clear</span></tt>: Executes a <tt class="docutils literal"><span class="pre">clear()</span></tt> operation after
synchronizing, eliminating all ghost cells.</li>
</ul>
</blockquote>
<p>There are several common combinations of flags that result in
interesting consistency models. Some of these combinations are:</p>
<blockquote>
<ul class="simple">
<li><tt class="docutils literal"><span class="pre">cm_forward</span></tt>: By itself, the forward consistency model enables
algorithms such as <a class="reference external" href="dijkstra_shortest_paths.html">Dijkstra's shortest paths</a> and
<a class="reference external" href="breadth_first_search.html">Breadth-First Search</a> to operate correctly.</li>
<li><tt class="docutils literal"><span class="pre">cm_flush</span> <span class="pre">&amp;</span> <span class="pre">cm_reset</span></tt>: All updates values are queued locally,
then flushed during the synchronization step. Once the flush has
occurred, the ghost cells are restored to their default
values. This consistency model is used by the <a class="reference external" href="page_rank.html">PageRank</a>
implementation to locally accumulate rank for each node.</li>
</ul>
</blockquote>
</div>
<div class="section" id="reduction-operation">
<h1>Reduction operation</h1>
<p>The reduction operation maintains consistency by determining how
multiple writes to a property map are resolved and what the property
map should do if unknown values are requested. More specifically, a
reduction operation is used in two cases:</p>
<blockquote>
<ol class="arabic simple">
<li>When a value is needed for a remote key but no value is
immediately available, the reduction operation provides a
suitable default. For instance, a distributed property map
storing distances may have a reduction operation that returns
an infinite value as the default, whereas a distributed
property map for vertex colors may return white as the
default.</li>
<li>When a value is received from a remote process, the process
owning the key associated with that value must determine which
value---the locally stored value, the value received from a
remote process, or some combination of the two---will be
stored as the &quot;official&quot; value in the property map. The
reduction operation transforms the local and remote values
into the &quot;official&quot; value to be stored.</li>
</ol>
</blockquote>
<p>The reduction operation of a distributed property map can be set with
the <tt class="docutils literal"><span class="pre">set_reduce</span></tt> method of <tt class="docutils literal"><span class="pre">distributed_property_map</span></tt>. The reduce
operation is a function object with two signatures. The first
signature takes a (remote) key and returns a default value for it,
whereas the second signatures takes a key and two values (local first,
then remote) and will return the combined value that will be stored in
the local property map.  Reduction operations must also contain a
static constant <tt class="docutils literal"><span class="pre">non_default_resolver&quot;,</span> <span class="pre">which</span> <span class="pre">states</span> <span class="pre">whether</span> <span class="pre">the</span>
<span class="pre">reduction</span> <span class="pre">operation's</span> <span class="pre">default</span> <span class="pre">value</span> <span class="pre">actually</span> <span class="pre">acts</span> <span class="pre">like</span> <span class="pre">a</span> <span class="pre">default</span>
<span class="pre">value.</span> <span class="pre">It</span> <span class="pre">should</span> <span class="pre">be</span> <span class="pre">``true</span></tt> when the default is meaningful (e.g.,
infinity for a distance) and <tt class="docutils literal"><span class="pre">false</span></tt> when the default should not be
used.</p>
<p>The following reduction operation is used by the distributed PageRank
algorithm. The default rank for a remote node is 0. Rank is
accumulated locally, and then the reduction operation combines local
and remote values by adding them. Combined with a consistency model
that flushes all values to the owner and then resets the values
locally in each step, the resulting property map will compute partial
sums on each processor and then accumulate the results on the owning
processor. The PageRank reduction operation is defined as follows.</p>
<pre class="literal-block">
template&lt;typename T&gt;
struct rank_accumulate_reducer {
  static const bool non_default_resolver = true;

  // The default rank of an unknown node
  template&lt;typename K&gt;
  T operator()(const K&amp;) const { return T(0); }

  template&lt;typename K&gt;
  T operator()(const K&amp;, const T&amp; x, const T&amp; y) const { return x + y; }
};
</pre>
</div>
<div class="section" id="distributed-property-map-adaptor">
<h1>Distributed property map adaptor</h1>
<p>The distributed property map adaptor creates a distributed property
map from a local property map, a <a class="reference external" href="process_group.html">process group</a> over which
distribution should occur, and a <a class="reference external" href="GlobalDescriptor.html">global descriptor</a> type that
indexes the distributed property map.</p>
<div class="section" id="synopsis">
<h2>Synopsis</h2>
<pre class="literal-block">
template&lt;typename ProcessGroup, typename LocalPropertyMap, typename Key,
         typename GhostCellS = gc_mapS&gt;
class distributed_property_map
{
public:
  typedef ... ghost_regions_type;

  distributed_property_map();

  distributed_property_map(const ProcessGroup&amp; pg,
                           const LocalPropertyMap&amp; pm);

  template&lt;typename Reduce&gt;
  distributed_property_map(const ProcessGroup&amp; pg,
                           const LocalPropertyMap&amp; pm,
                           const Reduce&amp; reduce);

  template&lt;typename Reduce&gt; void set_reduce(const Reduce&amp; reduce);
  void set_consistency_model(int model);

  void flush();
  void reset();
  void clear();
};

reference get(distributed_property_map pm, const key_type&amp; key);

void
put(distributed_property_map pm, const key_type&amp; key, const value_type&amp; value);
local_put(distributed_property_map pm, const key_type&amp; key, const value_type&amp; value);

void request(distributed_property_map pm, const key_type&amp; key);

void synchronize(distributed_property_map&amp; pm);

template&lt;typename Key, typename ProcessGroup, typename LocalPropertyMap&gt;
distributed_property_map&lt;ProcessGroup, LocalPropertyMap, Key&gt;
make_distributed_property_map(const ProcessGroup&amp; pg, LocalPropertyMap pmap);

template&lt;typename Key, typename ProcessGroup, typename LocalPropertyMap,
         typename Reduce&gt;
distributed_property_map&lt;ProcessGroup, LocalPropertyMap, Key&gt;
make_distributed_property_map(const ProcessGroup&amp; pg, LocalPropertyMap pmap,
                              Reduce reduce);
</pre>
</div>
<div class="section" id="template-parameters">
<h2>Template parameters</h2>
<dl class="docutils">
<dt><strong>ProcessGroup</strong>:</dt>
<dd>The type of the process group over which the
property map is distributed and is also the medium for
communication.</dd>
<dt><strong>LocalPropertyMap</strong>:</dt>
<dd>The type of the property map that will store values
for keys local to this processor. The <tt class="docutils literal"><span class="pre">value_type</span></tt> of this
property map will become the <tt class="docutils literal"><span class="pre">value_type</span></tt> of the distributed
property map. The distributed property map models the same property
map concepts as the <tt class="docutils literal"><span class="pre">LocalPropertyMap</span></tt>, with one exception: a
distributed property map cannot be an <a class="reference external" href="http://www.boost.org/libs/property_map/LvaluePropertyMap.html">Lvalue Property Map</a>
(because remote values are not addressable), and is therefore
limited to <a class="reference external" href="http://www.boost.org/libs/property_map/ReadWritePropertyMap.html">Read/Write Property Map</a>.</dd>
<dt><strong>Key</strong>:</dt>
<dd>The <tt class="docutils literal"><span class="pre">key_type</span></tt> of the distributed property map, which
must model the <a class="reference external" href="GlobalDescriptor.html">Global Descriptor</a> concept. The process ID type of
the <tt class="docutils literal"><span class="pre">Key</span></tt> parameter must match the process ID type of the
<tt class="docutils literal"><span class="pre">ProcessGroup</span></tt>, and the local descriptor type of the <tt class="docutils literal"><span class="pre">Key</span></tt> must
be convertible to the <tt class="docutils literal"><span class="pre">key_type</span></tt> of the <tt class="docutils literal"><span class="pre">LocalPropertyMap</span></tt>.</dd>
<dt><strong>GhostCellS</strong>:</dt>
<dd><p class="first">A selector type that indicates how ghost cells should be stored in
the distributed property map. There are either two or three
options, depending on your compiler:</p>
<blockquote class="last">
<ul class="simple">
<li><tt class="docutils literal"><span class="pre">boost::parallel::gc_mapS</span></tt> (default): Uses an STL <tt class="docutils literal"><span class="pre">map</span></tt> to
store the ghost cells for each process.</li>
<li><tt class="docutils literal"><span class="pre">boost::parallel::gc_vector_mapS</span></tt>: Uses a sorted STL
<tt class="docutils literal"><span class="pre">vector</span></tt> to store the ghost cells for each process. This
option works well when there are likely to be few insertions
into the ghost cells; for instance, if the only ghost cells used
are for neighboring vertices, the property map can be
initialized with cells for each neighboring vertex, providing
faster lookups than a <tt class="docutils literal"><span class="pre">map</span></tt> and using less space.</li>
<li><tt class="docutils literal"><span class="pre">boost::parallel::gc_hash_mapS</span></tt>: Uses the GCC <tt class="docutils literal"><span class="pre">hash_map</span></tt> to
store ghost cells. This option may improve performance over
<tt class="docutils literal"><span class="pre">map</span></tt> for large problems sizes, where the set of ghost cells
cannot be predetermined.</li>
</ul>
</blockquote>
</dd>
</dl>
</div>
<div class="section" id="member-functions">
<h2>Member functions</h2>
<pre class="literal-block">
distributed_property_map();
</pre>
<p>Default-construct a distributed property map. The property map is in
an invalid state, and may only be used if it is reassigned to a valid
property map.</p>
<hr class="docutils" />
<pre class="literal-block">
distributed_property_map(const ProcessGroup&amp; pg,
                         const LocalPropertyMap&amp; pm);

template&lt;typename Reduce&gt;
distributed_property_map(const ProcessGroup&amp; pg,
                         const LocalPropertyMap&amp; pm,
                         const Reduce&amp; reduce);
</pre>
<p>Construct a property map from a process group and a local property
map. If a <tt class="docutils literal"><span class="pre">reduce</span></tt> operation is not supplied, a default of
<tt class="docutils literal"><span class="pre">basic_reduce&lt;value_type&gt;</span></tt> will be used.</p>
<hr class="docutils" />
<pre class="literal-block">
template&lt;typename Reduce&gt; void set_reduce(const Reduce&amp; reduce);
</pre>
<p>Replace the current reduction operation with the new operation
<tt class="docutils literal"><span class="pre">reduce</span></tt>.</p>
<hr class="docutils" />
<pre class="literal-block">
void set_consistency_model(int model);
</pre>
<p>Sets the consistency model of the distributed property map, which will
take effect on the next synchronization step. See the section
<a class="reference internal" href="#consistency-models">Consistency models</a> for a description of the effect of various
consistency model flags.</p>
<hr class="docutils" />
<pre class="literal-block">
void flush();
</pre>
<p>Emits a message sending the contents of all local ghost cells to the
owners of those cells.</p>
<hr class="docutils" />
<pre class="literal-block">
void reset();
</pre>
<p>Replaces the values stored in each of the ghost cells with the default
value generated by the reduction operation.</p>
<hr class="docutils" />
<pre class="literal-block">
void clear();
</pre>
<p>Removes all ghost cells from the property map.</p>
</div>
<div class="section" id="free-functions">
<h2>Free functions</h2>
<pre class="literal-block">
reference get(distributed_property_map pm, const key_type&amp; key);
</pre>
<p>Retrieves the element in <tt class="docutils literal"><span class="pre">pm</span></tt> associated with the given <tt class="docutils literal"><span class="pre">key</span></tt>. If
the key refers to data stored locally, returns the actual value
associated with the key. If the key refers to nonlocal data, returns
the value of the ghost cell. If no ghost cell exists, the behavior
depends on the current reduction operation: if a reduction operation
has been set and has <tt class="docutils literal"><span class="pre">non_default_resolver</span></tt> set <tt class="docutils literal"><span class="pre">true</span></tt>, then a
ghost cell will be created according to the default value provided by
the reduction operation. Otherwise, the call to <tt class="docutils literal"><span class="pre">get</span></tt> will abort
because no value exists for this remote cell. To avoid this problem,
either set a reduction operation that generates default values,
<tt class="docutils literal"><span class="pre">request()</span></tt> the value and then perform a synchronization step, or
<tt class="docutils literal"><span class="pre">put</span></tt> a value into the cell before reading it.</p>
<hr class="docutils" />
<pre class="literal-block">
void
put(distributed_property_map pm, const key_type&amp; key, const value_type&amp; value);
</pre>
<p>Places the given <tt class="docutils literal"><span class="pre">value</span></tt> associated with <tt class="docutils literal"><span class="pre">key</span></tt> into property map
<tt class="docutils literal"><span class="pre">pm</span></tt>. If the key refers to data stored locally, the value is
immediately updates. If the key refers to data stored in a remote
process, updates (or creates) a local ghost cell containing this
value for the key and sends the new value to the owning process. Note
that the owning process may reject this value based on the reduction
operation, but this will not be detected until the next
synchronization step.</p>
<hr class="docutils" />
<pre class="literal-block">
void
local_put(distributed_property_map pm, const key_type&amp; key, const value_type&amp; value);
</pre>
<p>Equivalent to <tt class="docutils literal"><span class="pre">put(pm,</span> <span class="pre">key,</span> <span class="pre">value)</span></tt>, except that no message is sent
to the owning process when the value is changed for a nonlocal key.</p>
<hr class="docutils" />
<pre class="literal-block">
void synchronize(distributed_property_map&amp; pm);
</pre>
<p>Synchronize the values stored in the distributed property maps. Each
process much execute <tt class="docutils literal"><span class="pre">synchronize</span></tt> at the same time, after which
the ghost cells in every process will reflect the actual value stored
in the owning process.</p>
<hr class="docutils" />
<pre class="literal-block">
void request(distributed_property_map pm, const key_type&amp; key);
</pre>
<p>Request that the element &quot;key&quot; be available after the next
synchronization step. For a non-local key, this means establishing a
ghost cell and requesting.</p>
<hr class="docutils" />
<pre class="literal-block">
template&lt;typename Key, typename ProcessGroup, typename LocalPropertyMap&gt;
distributed_property_map&lt;ProcessGroup, LocalPropertyMap, Key&gt;
make_distributed_property_map(const ProcessGroup&amp; pg, LocalPropertyMap pmap);

template&lt;typename Key, typename ProcessGroup, typename LocalPropertyMap,
         typename Reduce&gt;
distributed_property_map&lt;ProcessGroup, LocalPropertyMap, Key&gt;
make_distributed_property_map(const ProcessGroup&amp; pg, LocalPropertyMap pmap,
                              Reduce reduce);
</pre>
<p>Create a distributed property map over process group <tt class="docutils literal"><span class="pre">pg</span></tt> and local
property map <tt class="docutils literal"><span class="pre">pmap</span></tt>. A default reduction operation will be generated
if it is not provided.</p>
</div>
</div>
<div class="section" id="distributed-iterator-property-map">
<h1>Distributed iterator property map</h1>
<p>The distributed iterator property map adaptor permits the creation of
distributed property maps from random access iterators using the same
syntax as non-distributed iterator property maps. The specialization
is based on a <a class="reference internal" href="#local-property-map">local property map</a>, which contains the
indices for local descriptors and is typically returned to describe
the vertex indices of a distributed graph.</p>
<div class="section" id="id1">
<h2>Synopsis</h2>
<pre class="literal-block">
template&lt;typename RandomAccessIterator, typename ProcessGroup,
         typename GlobalKey, typename LocalMap, typename ValueType,
         typename Reference&gt;
class iterator_property_map&lt;RandomAccessIterator,
                            local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                            ValueType, Reference&gt;
{
public:
  typedef local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt; index_map_type;

  iterator_property_map();
  iterator_property_map(RandomAccessIterator iter, const index_map_type&amp; id);
};

reference get(iterator_property_map pm, const key_type&amp; key);
void put(iterator_property_map pm, const key_type&amp; key, const value_type&amp; value);

template&lt;typename RandomAccessIterator, typename ProcessGroup,
         typename GlobalKey, typename LocalMap&gt;
iterator_property_map&lt;RandomAccessIterator,
                      local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt; &gt;
make_iterator_property_map(RandomAccessIterator iter,
                           local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt; id);
</pre>
</div>
<div class="section" id="id2">
<h2>Member functions</h2>
<pre class="literal-block">
iterator_property_map();
</pre>
<p>Default-constructs a distributed iterator property map. The property
map is in an invalid state, and must be reassigned before it may be
used.</p>
<hr class="docutils" />
<pre class="literal-block">
iterator_property_map(RandomAccessIterator iter, const index_map_type&amp; id);
</pre>
<p>Constructs a distributed iterator property map using the property map
<tt class="docutils literal"><span class="pre">id</span></tt> to map global descriptors to local indices. The random access
iterator sequence <tt class="docutils literal"><span class="pre">[iter,</span> <span class="pre">iter</span> <span class="pre">+</span> <span class="pre">n)</span></tt> must be a valid range, where
<tt class="docutils literal"><span class="pre">[0,</span> <span class="pre">n)</span></tt> is the range of local indices.</p>
</div>
<div class="section" id="id3">
<h2>Free functions</h2>
<pre class="literal-block">
reference get(iterator_property_map pm, const key_type&amp; key);
</pre>
<p>Returns the value associated with the given <tt class="docutils literal"><span class="pre">key</span></tt> from the
distributed property map.</p>
<hr class="docutils" />
<pre class="literal-block">
void put(iterator_property_map pm, const key_type&amp; key, const value_type&amp; value);
</pre>
<p>Associates the value with the given key in the distributed property map.</p>
<hr class="docutils" />
<pre class="literal-block">
template&lt;typename RandomAccessIterator, typename ProcessGroup,
         typename GlobalKey, typename LocalMap, typename ValueType,
         typename Reference&gt;
iterator_property_map&lt;RandomAccessIterator,
                      local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                         ValueType, Reference&gt;
make_iterator_property_map(RandomAccessIterator iter,
                           local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                              ValueType, Reference&gt; id);
</pre>
<p>Creates a distributed iterator property map using the given iterator
<tt class="docutils literal"><span class="pre">iter</span></tt> and local index property map <tt class="docutils literal"><span class="pre">id</span></tt>.</p>
</div>
</div>
<div class="section" id="distributed-safe-iterator-property-map">
<h1>Distributed safe iterator property map</h1>
<p>The distributed safe iterator property map adaptor permits the
creation of distributed property maps from random access iterators
using the same syntax as non-distributed safe iterator property
maps. The specialization is based on a <a class="reference internal" href="#local-property-map">local property map</a>, which
contains the indices for local descriptors and is typically returned
to describe the vertex indices of a distributed graph. Safe iterator
property maps check the indices of accesses to ensure that they are
not out-of-bounds before attempting to access an value.</p>
<div class="section" id="id4">
<h2>Synopsis</h2>
<pre class="literal-block">
template&lt;typename RandomAccessIterator, typename ProcessGroup,
         typename GlobalKey, typename LocalMap, typename ValueType,
         typename Reference&gt;
class safe_iterator_property_map&lt;RandomAccessIterator,
                                 local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                 ValueType, Reference&gt;
{
public:
  typedef local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt; index_map_type;

  safe_iterator_property_map();
  safe_iterator_property_map(RandomAccessIterator iter, std::size_t n,
                             const index_map_type&amp; id);
};

reference get(safe_iterator_property_map pm, const key_type&amp; key);
void put(safe_iterator_property_map pm, const key_type&amp; key, const value_type&amp; value);

template&lt;typename RandomAccessIterator, typename ProcessGroup,
         typename GlobalKey, typename LocalMap, typename ValueType,
         typename Reference&gt;
safe_iterator_property_map&lt;RandomAccessIterator,
                           local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                              ValueType, Reference&gt;
make_safe_iterator_property_map(RandomAccessIterator iter,
                                std::size_t n,
                                local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                                   ValueType, Reference&gt; id);
</pre>
</div>
<div class="section" id="id5">
<h2>Member functions</h2>
<pre class="literal-block">
safe_iterator_property_map();
</pre>
<p>Default-constructs a distributed safe iterator property map. The property
map is in an invalid state, and must be reassigned before it may be
used.</p>
<hr class="docutils" />
<pre class="literal-block">
safe_iterator_property_map(RandomAccessIterator iter, std::size_t n,
                           const index_map_type&amp; id);
</pre>
<p>Constructs a distributed safe iterator property map using the property map
<tt class="docutils literal"><span class="pre">id</span></tt> to map global descriptors to local indices. The random access
iterator sequence <tt class="docutils literal"><span class="pre">[iter,</span> <span class="pre">iter</span> <span class="pre">+</span> <span class="pre">n)</span></tt>.</p>
</div>
<div class="section" id="id6">
<h2>Free functions</h2>
<pre class="literal-block">
reference get(safe_iterator_property_map pm, const key_type&amp; key);
</pre>
<p>Returns the value associated with the given <tt class="docutils literal"><span class="pre">key</span></tt> from the
distributed property map.</p>
<hr class="docutils" />
<pre class="literal-block">
void put(safe_iterator_property_map pm, const key_type&amp; key, const value_type&amp; value);
</pre>
<p>Associates the value with the given key in the distributed property map.</p>
<hr class="docutils" />
<pre class="literal-block">
template&lt;typename RandomAccessIterator, typename ProcessGroup,
         typename GlobalKey, typename LocalMap, typename ValueType,
         typename Reference&gt;
safe_iterator_property_map&lt;RandomAccessIterator,
                           local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                              ValueType, Reference&gt;
make_safe_iterator_property_map(RandomAccessIterator iter,
                                std::size_t n,
                                local_property_map&lt;ProcessGroup, GlobalKey, LocalMap&gt;,
                                                   ValueType, Reference&gt; id);
</pre>
<p>Creates a distributed safe iterator property map using the given iterator
<tt class="docutils literal"><span class="pre">iter</span></tt> and local index property map <tt class="docutils literal"><span class="pre">id</span></tt>. The indices in <tt class="docutils literal"><span class="pre">id</span></tt> must</p>
</div>
</div>
<div class="section" id="local-property-map">
<h1>Local property map</h1>
<p>A property map adaptor that accesses an underlying property map whose
key type is the local part of the <tt class="docutils literal"><span class="pre">Key</span></tt> type for the local subset
of keys. Local property maps are typically used by distributed graph
types for vertex index properties.</p>
<div class="section" id="id7">
<h2>Synopsis</h2>
<pre class="literal-block">
template&lt;typename ProcessGroup, typename GlobalKey, typename LocalMap&gt;
  class local_property_map
  {
  public:
  typedef typename property_traits&lt;LocalMap&gt;::value_type value_type;
  typedef GlobalKey                                      key_type;
  typedef typename property_traits&lt;LocalMap&gt;::reference  reference;
  typedef typename property_traits&lt;LocalMap&gt;::category   category;

  explicit
  local_property_map(const ProcessGroup&amp; process_group = ProcessGroup(),
                     const LocalMap&amp; local_map = LocalMap());

  reference operator[](const key_type&amp; key);
};

reference get(const local_property_map&amp; pm, key_type key);
void put(local_property_map pm, const key_type&amp; key, const value_type&amp; value);
</pre>
</div>
<div class="section" id="id8">
<h2>Template parameters</h2>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">ProcessGroup:</th><td class="field-body">the type of the process group over which the global
keys are distributed.</td>
</tr>
<tr class="field"><th class="field-name">GlobalKey:</th><td class="field-body">The <tt class="docutils literal"><span class="pre">key_type</span></tt> of the local property map, which
must model the <a class="reference external" href="GlobalDescriptor.html">Global Descriptor</a> concept. The process ID type of
the <tt class="docutils literal"><span class="pre">GlobalKey</span></tt> parameter must match the process ID type of the
<tt class="docutils literal"><span class="pre">ProcessGroup</span></tt>, and the local descriptor type of the <tt class="docutils literal"><span class="pre">GlobalKey</span></tt>
must be convertible to the <tt class="docutils literal"><span class="pre">key_type</span></tt> of the <tt class="docutils literal"><span class="pre">LocalMap</span></tt>.</td>
</tr>
<tr class="field"><th class="field-name">LocalMap:</th><td class="field-body">the type of the property map that will store values
for keys local to this processor. The <tt class="docutils literal"><span class="pre">value_type</span></tt> of this
property map will become the <tt class="docutils literal"><span class="pre">value_type</span></tt> of the local
property map. The local property map models the same property
map concepts as the <tt class="docutils literal"><span class="pre">LocalMap</span></tt>.</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="id9">
<h2>Member functions</h2>
<pre class="literal-block">
explicit
local_property_map(const ProcessGroup&amp; process_group = ProcessGroup(),
                   const LocalMap&amp; local_map = LocalMap());
</pre>
<p>Constructs a local property map whose keys are distributed across the
given process group and which accesses the given local map.</p>
<hr class="docutils" />
<pre class="literal-block">
reference operator[](const key_type&amp; key);
</pre>
<p>Access the value associated with the given key, which must be local
to this process.</p>
</div>
<div class="section" id="id10">
<h2>Free functions</h2>
<pre class="literal-block">
reference get(const local_property_map&amp; pm, key_type key);
</pre>
<p>Return the value associated with the given key, which must be local
to this process.</p>
<hr class="docutils" />
<pre class="literal-block">
void put(local_property_map pm, const key_type&amp; key, const value_type&amp; value);
</pre>
<p>Set the value associated with the given key, which must be local to
this process.</p>
<hr class="docutils" />
<p>Copyright (C) 2004, 2005 The Trustees of Indiana University.</p>
<p>Authors: Douglas Gregor and Andrew Lumsdaine</p>
</div>
</div>
</div>
<div class="footer">
<hr class="footer" />
Generated on: 2009-05-31 00:22 UTC.
Generated by <a class="reference external" href="http://docutils.sourceforge.net/">Docutils</a> from <a class="reference external" href="http://docutils.sourceforge.net/rst.html">reStructuredText</a> source.

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