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graphchi-cpp/example_apps/unionfind_connectedcomps.cpp at master · GraphChi/graphchi-cpp · GitHub
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example_apps
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unionfind_connectedcomps.cpp
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example_apps
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unionfind_connectedcomps.cpp
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/*
*
* @file
* @author Aapo Kyrola <akyrola@cs.cmu.edu>
* @version 1.0
*
* @section LICENSE
*
* Copyright [2012] [Aapo Kyrola, Guy Blelloch, Carlos Guestrin / Carnegie Mellon University]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* @section DESCRIPTION
*
* Connected components that uses the Union-Find algorithm. Requires
* O(|V|) of RAM, but only one pass of the data. Thus much faster than
* the completely disk based "connectedcomponents.cpp" example app.
*
* Highly optimized non-idiomatic GraphChi code that uses an overloaded vertex
* class to prevent actually creating the graph in memory.
*
* NOTE/REMARK: THERE IS NO REAL REASON TO USE GRAPHCHI FOR THIS ALGORITHM.
* A SIMPLE CODE THAT READ THE GRAPH ONE EDGE A TIME WOULD BE SUFFICIENT.
*
*/
#
define
GRAPHCHI_DISABLE_COMPRESSION
#
include
<
string
>
#
include
"
graphchi_basic_includes.hpp
"
#
include
"
util/labelanalysis.hpp
"
using
namespace
graphchi
;
vid_t
* sets;
unsigned
int
* setCounts;
//
Union-find
/*
Find operator of Union-Find with path compression
*/
vid_t
Find
(
vid_t
x);
inline
vid_t
Find
(
vid_t
x) {
while
(sets[x] != x) {
x = sets[x] = sets[sets[x]];
}
return
sets[x];
}
typedef
vid_t
VertexDataType;
typedef
bool
EdgeDataType;
//
not relevant
size_t
ne =
0
;
class
UnionFindVertex
:
public
graphchi_vertex
<VertexDataType, EdgeDataType> {
public:
UnionFindVertex
() : graphchi_vertex<VertexDataType, EdgeDataType> () {}
UnionFindVertex
(
vid_t
_id,
graphchi_edge<EdgeDataType> * iptr,
graphchi_edge<EdgeDataType> * optr,
int
indeg,
int
outdeg) :
graphchi_vertex<VertexDataType, EdgeDataType> (_id,
NULL
,
NULL
, indeg, outdeg) {
}
inline
void
add_inedge
(
vid_t
src, EdgeDataType * ptr,
bool
special_edge) {
vid_t
setDst =
Find
(
this
->
vertexid
);
vid_t
setSrc =
Find
(src);
//
If in same component, nothing to do, otherwise, Unite
if
(setSrc != setDst) {
if
(setCounts[setSrc] > setCounts[setDst]) {
//
A is bigger set, merge with A
sets[setDst] = setSrc;
setCounts[setSrc] += setCounts[setDst];
}
else
{
//
or vice versa
sets[setSrc] = setDst;
setCounts[setDst] += setCounts[setSrc];
}
}
ne++;
}
void
add_outedge
(
vid_t
dst, EdgeDataType * ptr,
bool
special_edge) {
assert
(
false
);
}
bool
computational_edges
() {
return
true
;
}
};
/*
*
* GraphChi programs need to subclass GraphChiProgram<vertex-type, edge-type>
* class. The main logic is usually in the update function.
*/
struct
UnionFindProgram
:
public
GraphChiProgram
<VertexDataType, EdgeDataType, UnionFindVertex> {
/*
*
* Vertex update function.
*/
void
update
(UnionFindVertex &vertex, graphchi_context &gcontext) {
//
do nothing -- all done in the special vertex class
}
/*
*
* Called before an iteration starts.
*/
void
before_iteration
(
int
iteration, graphchi_context &gcontext) {
/*
Initialize
*/
sets =
new
vid_t
[gcontext.
nvertices
];
for
(
vid_t
i=
0
; i<gcontext.
nvertices
; i++) sets[i] = i;
setCounts =
new
unsigned
int
[gcontext.
nvertices
];
//
All sets start with 1
for
(
vid_t
i=
0
; i<gcontext.
nvertices
; i++) setCounts[i] =
1
;
}
/*
*
* Called after an iteration has finished.
*/
void
after_iteration
(
int
iteration, graphchi_context &gcontext) {
//
Now find everyone
logstream
(
LOG_INFO
) <<
"
Final finds...
"
<< std::endl;
for
(
size_t
i=
0
; i<gcontext.
nvertices
; i++) {
sets[i] =
Find
(i);
}
}
/*
*
* Called before an execution interval is started.
*/
void
before_exec_interval
(
vid_t
window_st,
vid_t
window_en, graphchi_context &gcontext) {
}
/*
*
* Called after an execution interval has finished.
*/
void
after_exec_interval
(
vid_t
window_st,
vid_t
window_en, graphchi_context &gcontext) {
}
};
int
main
(
int
argc,
const
char
** argv) {
/*
GraphChi initialization will read the command line
arguments and the configuration file.
*/
graphchi_init
(argc, argv);
/*
Metrics object for keeping track of performance counters
and other information. Currently required.
*/
metrics
m
(
"
union-find-connectedcomponents
"
);
/*
Basic arguments for application
*/
std::string filename =
get_option_string
(
"
file
"
);
//
Base filename
int
niters =
1
;
/*
Detect the number of shards or preprocess an input to create them
*/
int
nshards = convert_if_notexists_novalues<EdgeDataType>(filename,
get_option_string
(
"
nshards
"
,
"
auto
"
));
//
Always run with only thread only (code is not thread-safe)
set_conf
(
"
execthreads
"
,
"
1
"
);
/*
Run
*/
UnionFindProgram unionFind;
graphchi_engine<VertexDataType, EdgeDataType, UnionFindVertex >
engine
(filename, nshards,
false
, m);
engine.
set_disable_outedges
(
true
);
engine.
set_only_adjacency
(
true
);
engine.
set_modifies_inedges
(
false
);
engine.
set_disable_vertexdata_storage
();
engine.
run
(unionFind, niters);
/*
Write vertex data
*/
std::string outputfile = filename_vertex_data<VertexDataType>(filename);
FILE
* f =
fopen
(outputfile.
c_str
(),
"
w
"
);
fwrite
(sets,
sizeof
(
vid_t
), engine.
num_vertices
(), f);
fclose
(f);
/*
Analyze
*/
analyze_labels<
vid_t
>(filename);
/*
Report execution metrics
*/
metrics_report
(m);
return
0
;
}
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