CMap in CMap

[Fred]

Hi everyone,

I'm trying to "include" a CMap in another CMap, and it isn't working
very well...

Here's the faulting code:

******* IAMMetaDataCategory.h **********
#pragma once

#include "IAMMetaDataAttribute.h"

class CIAMMetaDataEvent
{
public:
CIAMMetaDataEvent(void);
~CIAMMetaDataEvent(void);

CString m_name;
CString m_resourceId;
CMap <int, int, CIAMMetaDataAttribute, CIAMMetaDataAttribute>EvtAttributes;
};

******* IAMMetaDataAttribute.h **********
#pragma once

class CIAMMetaDataAttribute
{
public:
CIAMMetaDataAttribute(void);
~CIAMMetaDataAttribute(void);

CString m_name;
bool m_multiValued;
CString m_transform;
CString resourceId;

CMap <int, int, int, int> alternateValue;
};

Trying to compile the above code throws the error:
IAMMetaDataCategory.cpp
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afxtempl.h(1339) : error C2248: 'CObject::CObject' :
cannot access private member declared in class 'CObject'
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afx.h(558) : see declaration of 'CObject::CObject'
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afx.h(529) : see declaration of 'CObject'
This diagnostic occurred in the compiler generated function
'CMap<KEY,ARG_KEY,VALUE,ARG_VALUE>::CMap(const
CMap<KEY,ARG_KEY,VALUE,ARG_VALUE> &)'
with
[
KEY=int,
ARG_KEY=int,
VALUE=int,
ARG_VALUE=int
]

Any idea of what the problem is? The problem seems to come from the
second CMap (in IAMMetaDataAttribute), but I can't figure out what's
wrong...

Thanks for your help.

Fred

[Fred]

Post by Fred
Hi everyone,
I'm trying to "include" a CMap in another CMap, and it isn't working
very well...
******* IAMMetaDataCategory.h **********
#pragma once
#include "IAMMetaDataAttribute.h"
class CIAMMetaDataEvent

-> please read "CIAMMetaDataCategory" instead of "CIAMMetaDataEvent"

[snip]

Thanks.

Fred

[Giovanni Dicanio]

I think the problem is that CMap derives from CObject, and CObject declares
*private* copy constructor and operator=.
In fact, if you go to the CObject definition in <afx.h> MFC header file (at
least in VS2008) you can read:

<code>
...
private:
CObject(const CObject& objectSrc); // no implementation
void operator=(const CObject& objectSrc); // no implementation
...
</code>

So, CMap doesn't offer a copy semantic "out of the box".

I would suggest you to use STL std::map container, which is designed in a
way to implement copy semantic out-of-the-box.

In particular, your CMap's:

CMap <int, int, CIAMMetaDataAttribute,
CIAMMetaDataAttribute>EvtAttributes;
CMap <int, int, int, int> alternateValue;

could be substitued by the following std::map's:

std::map< int, CIAMMetaDataAttribute > EvtAttributes;
std::map< int, int, > alternateValue;

Note that std::map does not have the (IMHO) confusing ARG_KEY and ARG_VALUE
templates.
std::map just has the Key and Type template arguments (in its basic form):

map Class (Standard C++ Library)
http://msdn.microsoft.com/en-us/library/s44w4h2s%28VS.80%29.aspx

HTH,
Giovanni

I'm trying to "include" a CMap in another CMap, and it isn't working very
well...
[...]
IAMMetaDataCategory.cpp
c:\program files\microsoft visual studio
cannot access private member declared in class 'CObject'
c:\program files\microsoft visual studio
[...]
This diagnostic occurred in the compiler generated function
'CMap<KEY,ARG_KEY,VALUE,ARG_VALUE>::CMap(const
CMap<KEY,ARG_KEY,VALUE,ARG_VALUE> &)'
with
[
KEY=int,
ARG_KEY=int,
VALUE=int,
ARG_VALUE=int
]
Any idea of what the problem is?

[Fred]

Post by Giovanni Dicanio
I think the problem is that CMap derives from CObject, and CObject
declares *private* copy constructor and operator=.
In fact, if you go to the CObject definition in <afx.h> MFC header file
<code>
...
CObject(const CObject& objectSrc); // no implementation
void operator=(const CObject& objectSrc); // no implementation
...
</code>
So, CMap doesn't offer a copy semantic "out of the box".
I would suggest you to use STL std::map container, which is designed in
a way to implement copy semantic out-of-the-box.
CMap <int, int, CIAMMetaDataAttribute,
CIAMMetaDataAttribute>EvtAttributes;
CMap <int, int, int, int> alternateValue;
std::map< int, CIAMMetaDataAttribute > EvtAttributes;
std::map< int, int, > alternateValue;
Note that std::map does not have the (IMHO) confusing ARG_KEY and
ARG_VALUE templates.
map Class (Standard C++ Library)
http://msdn.microsoft.com/en-us/library/s44w4h2s%28VS.80%29.aspx
HTH,
Giovanni

Hi Giovanni,
thanks for the tip.
In the meantime, I managed to solve my problem by declaring a pointer to
the second CMap instead of the CMap itself.
i.e:
******* IAMMetaDataAttribute.h **********
#pragma once

class CIAMMetaDataAttribute
{
public:
CIAMMetaDataAttribute(void);
~CIAMMetaDataAttribute(void);

CString m_name;
bool m_multiValued;
CString m_transform;
CString resourceId;

CMap <int, int, int, int> *alternateValue;
};

So I guessed I could get out with it this way... but your post about the
std::map object puzzled me ;)
Could you tell me more about this std::map thing? Is it more efficient
than CMap? It seems to be less convenient to manipulate, isn't it?

Thanks again for your help.

Fred

[Giovanni Dicanio]

Post by Fred
thanks for the tip.

You are welcome.

Post by Fred
In the meantime, I managed to solve my problem by declaring a pointer to
the second CMap instead of the CMap itself.
******* IAMMetaDataAttribute.h **********
#pragma once
class CIAMMetaDataAttribute
{
CIAMMetaDataAttribute(void);
~CIAMMetaDataAttribute(void);
CString m_name;
bool m_multiValued;
CString m_transform;
CString resourceId;
CMap <int, int, int, int> *alternateValue;
};

OK, defining CMap as a pointer in above context I think that you are going
to shoot yourself in the foot.

In fact, there is a reason of the previous compiler error about CMap: the
compiler was trying to warn you: "CMap can't be deep-copied, CMap does not
have a copy semantic".
If you define a data member as a pointer to CMap you are shutting up the
compiler.
But you are preparing for troubles. In fact, if two instances of
CIAMMetaDataAttribute are going to be copied, the value of the pointer (i.e.
a memory address) is copied, and not the CMap instance itself.
So, in the above class, you should forbid copy semantic, declaring private
copy constructor and operator= for CIAMMetaDataAttribute.

Or just use std::map, which is copyable.

Post by Fred
So I guessed I could get out with it this way... but your post about the
std::map object puzzled me ;)
Could you tell me more about this std::map thing? Is it more efficient
than CMap? It seems to be less convenient to manipulate, isn't it?

I'm not sure about efficiency. You should do some benchmarks in that regard
(Joe told us an importan lesson: "When you are in doubt, measure.").
I think that STL standard states that std::map insertion is O(log(N)), but
I'm not sure.
Moreover, IIRC, std::map is implemented as a kind of binary tree. If you
really want an hash-map data structure container, it is called hash_map
(probably its namespace is 'stdext', not 'std').
If you are not interested in sorting keys, stdext::hash_map may be faster
than std::map.

Moreover, as already stated, std::map is copyable, and CMap is not.

If I could do a criticism to std::map, it would be that I prefer identifier
names like 'key' and 'value' instead of 'first' and 'second'.

Moreover, I would have liked a member function something like contains() to
check if a key is stored in a std::map instance.
Instead, we have to write code like this:

std::map< string, int > someMap;
...
if ( someMap.find("Connie") == someMap.end() )
{
... "Connie" is not in the map.
}

I would have preferred something like 'someMap.contains("Connie")' instead
of comparing to someMap.end().
(Note that QT QMap has an intuitive method named 'contains' that does just
that: http://qt.nokia.com/doc/4.0/qmap.html#contains )

HTH,
Giovanni

[Fred]

Post by Giovanni Dicanio

Post by Fred
thanks for the tip.

You are welcome.

Post by Fred
In the meantime, I managed to solve my problem by declaring a pointer
to the second CMap instead of the CMap itself.
******* IAMMetaDataAttribute.h **********
#pragma once
class CIAMMetaDataAttribute
{
CIAMMetaDataAttribute(void);
~CIAMMetaDataAttribute(void);
CString m_name;
bool m_multiValued;
CString m_transform;
CString resourceId;
CMap <int, int, int, int> *alternateValue;
};

OK, defining CMap as a pointer in above context I think that you are
going to shoot yourself in the foot.
the compiler was trying to warn you: "CMap can't be deep-copied, CMap
does not have a copy semantic".
If you define a data member as a pointer to CMap you are shutting up the
compiler.
But you are preparing for troubles. In fact, if two instances of
CIAMMetaDataAttribute are going to be copied, the value of the pointer
(i.e. a memory address) is copied, and not the CMap instance itself.
So, in the above class, you should forbid copy semantic, declaring
private copy constructor and operator= for CIAMMetaDataAttribute.
Or just use std::map, which is copyable.

Post by Fred
So I guessed I could get out with it this way... but your post about
the std::map object puzzled me ;)
Could you tell me more about this std::map thing? Is it more efficient
than CMap? It seems to be less convenient to manipulate, isn't it?

I'm not sure about efficiency. You should do some benchmarks in that
regard (Joe told us an importan lesson: "When you are in doubt, measure.").
I think that STL standard states that std::map insertion is O(log(N)),
but I'm not sure.
Moreover, IIRC, std::map is implemented as a kind of binary tree. If you
really want an hash-map data structure container, it is called hash_map
(probably its namespace is 'stdext', not 'std').
If you are not interested in sorting keys, stdext::hash_map may be
faster than std::map.
Moreover, as already stated, std::map is copyable, and CMap is not.
If I could do a criticism to std::map, it would be that I prefer
identifier names like 'key' and 'value' instead of 'first' and 'second'.
Moreover, I would have liked a member function something like contains()
to check if a key is stored in a std::map instance.
std::map< string, int > someMap;
...
if ( someMap.find("Connie") == someMap.end() )
{
... "Connie" is not in the map.
}
I would have preferred something like 'someMap.contains("Connie")'
instead of comparing to someMap.end().
(Note that QT QMap has an intuitive method named 'contains' that does
just that: http://qt.nokia.com/doc/4.0/qmap.html#contains )
HTH,
Giovanni

Thanks again Giovanni for your explanations.
I've followed your advise and I'm implementing the std::map solution :)

Fred

[Goran]

Post by Fred
So I guessed I could get out with it this way... but your post about the
std::map object puzzled me ;)
Could you tell me more about this std::map thing? Is it more efficient
than CMap? It seems to be less convenient to manipulate, isn't it?

I'll try a shot at that question.

Implementation-wise, difference is significant. CMap is a hash map
(http://en.wikipedia.org/wiki/Hash_table), whereas std::map is based
on key ordering. Often, std::map internally uses a data structure
called red-black tree (http://en.wikipedia.org/wiki/Red-black_tree).

As a consequence, they have wildly different performance
characteristics, but never mind that, I don't think anyone can tell
you whether one will perform better on your own data. Speed of your
hashing function when using CMap, and operator< when using std::map,
plays a part, too.

You should also bear in mind that for small data sets, a linear search
on an array will beat any associative container. In that light, for
me, using an associative container is often a matter of convenience
rather than speed (e.g. avoids handling duplicates and I don't have to
write "find" function).

As for convenience, I fail to see how is any STL container less
convenient than it's MFC counterpart. Take a map:

* to insert an element, it's MFCMap.SetAt(key, value) or MFCMap[key] =
value versus STLMap[key] = value or STLMap.insert(SLMapType(key,
value)). With STL map, you have performance-conscious insert overload,
where you can specify the position. That's useful when you use find or
lower_bound and subsequently decide to insert a new element.

* to remove an element, you use MFCMap.RemoveKey versus STLMap.erase,
where erase is overloaded to three options, one of them being
performance-conscious, and other working on a range of elements
(sweet).

* to locate an element, you use MFCMap.Lookup(key, value) or PLookup
versus STLMap.find or lower_bound, both being more performance-
conscious in STLMap ( this is getting annoying now :-) ).

* to iterate, I fail to see how is brain-dead GetStartPosition/
GetNextWhatever and POSITION convention of MFC better than a for,
while or std::for_each.

It should be noted, however, that STL induces a certain amount of
syntax gibberish. To alleviate that, it's best to typedef every
container type and use STL-provided typedefs, e.g.:

typedef std::map<my_key_type, my_value_type> CMyMap;
CMyMap map;
for (CMyMap::const_iterator pItem=map.begin(); pItem != map.end(); +
+pItem)
{
CMyMap::const_reference KeyAndValue = *pItem;
WorkWith(KeyAndValue);
}

To me personally, map is better than CMap in that I prefer writing an
ordering predicate (operator<) to writing a hashing function.
Depending on key structure, a hashing function is more complicated,
and can cause a performance hit more easily.

What you don't have with STL out of the box is serialization.

HTH,

Goran.

[Giovanni Dicanio]

Post by Goran
It should be noted, however, that STL induces a certain amount of
syntax gibberish. To alleviate that, it's best to typedef every
typedef std::map<my_key_type, my_value_type> CMyMap;
CMyMap map;
for (CMyMap::const_iterator pItem=map.begin(); pItem != map.end(); +

Probably the new 'auto' keyword of C++0x (available in VS2010) will make
things better in this regard.

Post by Goran
What you don't have with STL out of the box is serialization.

MFC built-in serialization is not very good IMHO.
XML is better in this regard.

Giovanni

[Joseph M. Newcomer]

MFC classes do not "embed" reasonably. This is great motivation to learn the std::
classes, such as std::map. This was certainly my motivation. Also, std::map has somewhat
better performance than CMap.
joe

On Mon, 9 Nov 2009 12:45:27 +0100, "Giovanni Dicanio"

Post by Giovanni Dicanio
I think the problem is that CMap derives from CObject, and CObject declares
*private* copy constructor and operator=.
In fact, if you go to the CObject definition in <afx.h> MFC header file (at
<code>
...
CObject(const CObject& objectSrc); // no implementation
void operator=(const CObject& objectSrc); // no implementation
...
</code>
So, CMap doesn't offer a copy semantic "out of the box".
I would suggest you to use STL std::map container, which is designed in a
way to implement copy semantic out-of-the-box.
CMap <int, int, CIAMMetaDataAttribute,
CIAMMetaDataAttribute>EvtAttributes;
CMap <int, int, int, int> alternateValue;
std::map< int, CIAMMetaDataAttribute > EvtAttributes;
std::map< int, int, > alternateValue;
Note that std::map does not have the (IMHO) confusing ARG_KEY and ARG_VALUE
templates.
map Class (Standard C++ Library)
http://msdn.microsoft.com/en-us/library/s44w4h2s%28VS.80%29.aspx
HTH,
Giovanni

I'm trying to "include" a CMap in another CMap, and it isn't working very
well...
[...]
IAMMetaDataCategory.cpp
c:\program files\microsoft visual studio
cannot access private member declared in class 'CObject'
c:\program files\microsoft visual studio
[...]
This diagnostic occurred in the compiler generated function
'CMap<KEY,ARG_KEY,VALUE,ARG_VALUE>::CMap(const
CMap<KEY,ARG_KEY,VALUE,ARG_VALUE> &)'
with
[
KEY=int,
ARG_KEY=int,
VALUE=int,
ARG_VALUE=int
]
Any idea of what the problem is?

Joseph M. Newcomer [MVP]
email: ***@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

[Fred]

Ok.
Thanks to all for the answers.
I'm moving to std::

Fred

Post by Joseph M. Newcomer
classes, such as std::map. This was certainly my motivation. Also, std::map has somewhat
better performance than CMap.
joe
On Mon, 9 Nov 2009 12:45:27 +0100, "Giovanni Dicanio"

Post by Giovanni Dicanio
I think the problem is that CMap derives from CObject, and CObject declares
*private* copy constructor and operator=.
In fact, if you go to the CObject definition in <afx.h> MFC header file (at
<code>
...
CObject(const CObject& objectSrc); // no implementation
void operator=(const CObject& objectSrc); // no implementation
...
</code>
So, CMap doesn't offer a copy semantic "out of the box".
I would suggest you to use STL std::map container, which is designed in a
way to implement copy semantic out-of-the-box.
CMap <int, int, CIAMMetaDataAttribute,
CIAMMetaDataAttribute>EvtAttributes;
CMap <int, int, int, int> alternateValue;
std::map< int, CIAMMetaDataAttribute > EvtAttributes;
std::map< int, int, > alternateValue;
Note that std::map does not have the (IMHO) confusing ARG_KEY and ARG_VALUE
templates.
map Class (Standard C++ Library)
http://msdn.microsoft.com/en-us/library/s44w4h2s%28VS.80%29.aspx
HTH,
Giovanni

I'm trying to "include" a CMap in another CMap, and it isn't working very
well...
[...]
IAMMetaDataCategory.cpp
c:\program files\microsoft visual studio
cannot access private member declared in class 'CObject'
c:\program files\microsoft visual studio
[...]
This diagnostic occurred in the compiler generated function
'CMap<KEY,ARG_KEY,VALUE,ARG_VALUE>::CMap(const
CMap<KEY,ARG_KEY,VALUE,ARG_VALUE> &)'
with
[
KEY=int,
ARG_KEY=int,
VALUE=int,
ARG_VALUE=int
]
Any idea of what the problem is?

Joseph M. Newcomer [MVP]
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

[Giovanni Dicanio]

Post by Fred
Thanks to all for the answers.

Note also that you can mix std:: container classes like std::map with
ATL/MFC convenient classes, like CString.
i.e. you can build maps in which keys and/or values are instances of
CString.

Giovanni

[David Ching]

Post by Joseph M. Newcomer
classes, such as std::map. This was certainly my motivation. Also, std::map has somewhat
better performance than CMap.

Ha, when it became apparent MS had no intention of improving its base
classes such as CMap, and the alternative was to learn std::map, you know
what I did? I learned C# and .NET instead! ;) (And Qt after that....)
Call me an escapist, but life is too short.

-- David

[p***@gmail.com]

在 2009年11月9日星期一 UTC+8下午7:02:36，Fred写道：

Post by Fred
Hi everyone,
I'm trying to "include" a CMap in another CMap, and it isn't working
very well...
******* IAMMetaDataCategory.h **********
#pragma once
#include "IAMMetaDataAttribute.h"
class CIAMMetaDataEvent
{
CIAMMetaDataEvent(void);
~CIAMMetaDataEvent(void);
CString m_name;
CString m_resourceId;
CMap <int, int, CIAMMetaDataAttribute, CIAMMetaDataAttribute>EvtAttributes;
};
******* IAMMetaDataAttribute.h **********
#pragma once
class CIAMMetaDataAttribute
{
CIAMMetaDataAttribute(void);
~CIAMMetaDataAttribute(void);
CString m_name;
bool m_multiValued;
CString m_transform;
CString resourceId;
CMap <int, int, int, int> alternateValue;
};
IAMMetaDataCategory.cpp
c:\program files\microsoft visual studio
cannot access private member declared in class 'CObject'
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afx.h(558) : see declaration of 'CObject::CObject'
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afx.h(529) : see declaration of 'CObject'
This diagnostic occurred in the compiler generated function
'CMap<KEY,ARG_KEY,VALUE,ARG_VALUE>::CMap(const
CMap<KEY,ARG_KEY,VALUE,ARG_VALUE> &)'
with
[
KEY=int,
ARG_KEY=int,
VALUE=int,
ARG_VALUE=int
]
Any idea of what the problem is? The problem seems to come from the
second CMap (in IAMMetaDataAttribute), but I can't figure out what's
wrong...
Thanks for your help.
Fred

Title: The core of the core of the big data solutions -- Map
Author: pengwenwei
Email: pww71
Language: c++
Platform: Windows, linux
Technology: Perfect hash algorithm
Level: Advanced
Description: Map algorithm with high performance
Section MFC c++ map stl
SubSection c++ algorithm
License: (GPLv3)

Download demo project - 1070 Kb
Download source - 1070 Kb

Introduction:
For the c++ program, map is used everywhere.And bottleneck of program performance is often the performance of map.Especially in the case of large data,and the business association closely and unable to realize the data distribution and parallel processing condition.So the performance of map becomes the key technology.

In the work experience with telecommunications industry and the information security industry, I was dealing with the big bottom data,especially the most complex information security industry data,all can’t do without map.

For example, IP table, MAC table, telephone number list, domain name resolution table, ID number table query, the Trojan horse virus characteristic code of cloud killing etc..

The map of STL library using binary chop, its has the worst performance.Google Hash map has the optimal performance and memory at present, but it has repeated collision probability.Now the big data rarely use a collision probability map,especially relating to fees, can’t be wrong.

Now I put my algorithms out here,there are three kinds of map,after the build is Hash map.We can test the comparison,my algorithm has the zero probability of collision,but its performance is also better than the hash algorithm, even its ordinary performance has no much difference with Google.

My algorithm is perfect hash algorithm,its key index and the principle of compression algorithm is out of the ordinary,the most important is a completely different structure,so the key index compression is fundamentally different.The most direct benefit for program is that for the original map need ten servers for solutions but now I only need one server.
Declare: the code can not be used for commercial purposes, if for commercial applications,you can contact me with QQ 75293192.
Download:
https://sourceforge.net/projects/pwwhashmap/files

Applications:
First,modern warfare can’t be without the mass of information query, if the query of enemy target information slows down a second, it could lead to the delaying fighter, leading to failure of the entire war. Information retrieval is inseparable from the map, if military products use pwwhashMap instead of the traditional map,you must be the winner.

Scond,the performance of the router determines the surfing speed, just replace open source router code map for pwwHashMap, its speed can increase ten times.
There are many tables to query and set in the router DHCP ptotocol,such as IP,Mac ,and all these are completed by map.But until now,all map are using STL liabrary,its performance is very low,and using the Hash map has error probability,so it can only use multi router packet dispersion treatment.If using pwwHashMap, you can save at least ten sets of equipment.

Third,Hadoop is recognized as the big data solutions at present,and its most fundamental thing is super heavy use of the map,instead of SQL and table.Hadoop assumes the huge amounts of data so that the data is completely unable to move, people must carry on the data analysis in the local.But as long as the open source Hadoop code of the map changes into pwwHashMap, the performance will increase hundredfold without any problems.


Background to this article that may be useful such as an introduction to the basic ideas presented:
http://blog.csdn.net/chixinmuzi/article/details/1727195

[Wenwei Peng]

在 2009年11月9日星期一 UTC+8下午7:02:36，Fred写道：

Post by Fred
Hi everyone,
I'm trying to "include" a CMap in another CMap, and it isn't working
very well...
******* IAMMetaDataCategory.h **********
#pragma once
#include "IAMMetaDataAttribute.h"
class CIAMMetaDataEvent
{
CIAMMetaDataEvent(void);
~CIAMMetaDataEvent(void);
CString m_name;
CString m_resourceId;
CMap <int, int, CIAMMetaDataAttribute, CIAMMetaDataAttribute>EvtAttributes;
};
******* IAMMetaDataAttribute.h **********
#pragma once
class CIAMMetaDataAttribute
{
CIAMMetaDataAttribute(void);
~CIAMMetaDataAttribute(void);
CString m_name;
bool m_multiValued;
CString m_transform;
CString resourceId;
CMap <int, int, int, int> alternateValue;
};
IAMMetaDataCategory.cpp
c:\program files\microsoft visual studio
cannot access private member declared in class 'CObject'
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afx.h(558) : see declaration of 'CObject::CObject'
c:\program files\microsoft visual studio
8\vc\atlmfc\include\afx.h(529) : see declaration of 'CObject'
This diagnostic occurred in the compiler generated function
'CMap<KEY,ARG_KEY,VALUE,ARG_VALUE>::CMap(const
CMap<KEY,ARG_KEY,VALUE,ARG_VALUE> &)'
with
[
KEY=int,
ARG_KEY=int,
VALUE=int,
ARG_VALUE=int
]
Any idea of what the problem is? The problem seems to come from the
second CMap (in IAMMetaDataAttribute), but I can't figure out what's
wrong...
Thanks for your help.
Fred

Title: The core of the core of the big data solutions -- Map
Author: pengwenwei
Email:
Language: c++
Platform: Windows, linux
Technology: Perfect hash algorithm
Level: Advanced
Description: Map algorithm with high performance
Section MFC c++ map stl
SubSection c++ algorithm
License: (GPLv3)

Download demo project - 1070 Kb
Download source - 1070 Kb

Introduction:
For the c++ program, map is used everywhere.And bottleneck of program performance is often the performance of map.Especially in the case of large data,and the business association closely and unable to realize the data distribution and parallel processing condition.So the performance of map becomes the key technology.

In the work experience with telecommunications industry and the information security industry, I was dealing with the big bottom data,especially the most complex information security industry data,all can’t do without map.

For example, IP table, MAC table, telephone number list, domain name resolution table, ID number table query, the Trojan horse virus characteristic code of cloud killing etc..

The map of STL library using binary chop, its has the worst performance.Google Hash map has the optimal performance and memory at present, but it has repeated collision probability.Now the big data rarely use a collision probability map,especially relating to fees, can’t be wrong.

Now I put my algorithms out here,there are three kinds of map,after the build is Hash map.We can test the comparison,my algorithm has the zero probability of collision,but its performance is also better than the hash algorithm, even its ordinary performance has no much difference with Google.

My algorithm is perfect hash algorithm,its key index and the principle of compression algorithm is out of the ordinary,the most important is a completely different structure,so the key index compression is fundamentally different.The most direct benefit for program is that for the original map need ten servers for solutions but now I only need one server.
Declare: the code can not be used for commercial purposes, if for commercial applications,you can contact me with QQ 75293192.
Download:
https://sourceforge.net/projects/pwwhashmap/files

Applications:
First,modern warfare can’t be without the mass of information query, if the query of enemy target information slows down a second, it could lead to the delaying fighter, leading to failure of the entire war. Information retrieval is inseparable from the map, if military products use pwwhashMap instead of the traditional map,you must be the winner.

Scond,the performance of the router determines the surfing speed, just replace open source router code map for pwwHashMap, its speed can increase ten times.
There are many tables to query and set in the router DHCP ptotocol,such as IP,Mac ,and all these are completed by map.But until now,all map are using STL liabrary,its performance is very low,and using the Hash map has error probability,so it can only use multi router packet dispersion treatment.If using pwwHashMap, you can save at least ten sets of equipment.

Third,Hadoop is recognized as the big data solutions at present,and its most fundamental thing is super heavy use of the map,instead of SQL and table.Hadoop assumes the huge amounts of data so that the data is completely unable to move, people must carry on the data analysis in the local.But as long as the open source Hadoop code of the map changes into pwwHashMap, the performance will increase hundredfold without any problems.


Background to this article that may be useful such as an introduction to the basic ideas presented:
http://blog.csdn.net/chixinmuzi/article/details/1727195