ACE的內存管理

分配器?
描述

ACE_Allocator?
ACE中的分配器類的接口類。這些類使用繼承和動態綁定來提供靈活性。

ACE_Static_Allocator?
該分配器管理固定大小的內存。每當收到分配內存的請求時，它就移動內部指針、以返回內存chunk（“大塊”）。它還假定內存一旦被分配，就再也不會被釋放。

ACE_Cached_Allocator?
該分配器預先分配內存池，其中含有特定數目和大小的內存chunk。這些chunk在內部空閑表（free list）中進行維護，并在收到內存請求（malloc()）時被返回。當應用調用free()時，chunk被歸還到內部空閑表、而不是OS中。

ACE_New_Allocator?
為C++ new和delete操作符提供包裝的分配器，也就是，它在內部使用new和delete操作符，以滿足動態內存請求。

#include? " ace/Malloc.h "

// A?chunk?of?size?1K?is?created.?In?our?case?we?decided?to?use?a?simple?array

// as?the?type?for?the?chunk.?Instead?of?this?we?could?use?any?struct?or?class

// that?we?think?is?appropriate.

typedef? char ?MEMORY_BLOCK[ 1024 ];
// Create?an?ACE_Cached_Allocator?which?is?passed?in?the?type?of?the

// “chunk”?that?it?must?pre-allocate?and?assign?on?the?free?list.

// ?Since?the?Cached_Allocator?is?a?template?class?we?can?pretty?much

// pass?it?ANY?type?we?think?is?appropriate?to?be?a?memory?block.

typedef?ACE_Cached_Allocator < MEMORY_BLOCK,ACE_SYNCH_MUTEX > ?Allocator;

class ?MessageManager

{

public :

???? // The?constructor?is?passed?the?number?of?chunks?that?the?allocator

???? // should?pre-allocate?and?maintain?on?its?free?list.

????MessageManager( int ?n_blocks):

??????allocator_(n_blocks),message_count_( 0 )

?????? {

??????????mesg_array_ = new ? char * [n_blocks];

??????} // Allocate?memory?for?a?message?using?the?Allocator.?Remember?the?message
?????? // in?an?array?and?then?increase?the?message?count?of?valid?messages
?????? // on?the?message?array.
?????? void ?allocate_msg( const ? char ? * msg)
?????? {
????????mesg_array_[message_count_] = ( char * )allocator_.malloc(ACE_OS::strlen(msg) + 1 );

??????????ACE_OS::strcpy(mesg_array_[message_count_],msg);

??????????message_count_ ++ ;

??????}

???????

?????? // Free?all?the?memory?that?was?allocated.?This?will?cause?the?chunks

?????? // to?be?returned?to?the?allocator’s?internal?free?list

?????? // and?NOT?to?the?OS.

?????? void ?free_all_msg()

?????? {

?????????? for ( int ?i = 0 ;i < message_count_;i ++ )

??????????????allocator_.free(mesg_array_[i]);

???????????

??????????message_count_ = 0 ;

??????}

???????

?????? // Just?show?all?the?currently?allocated?messages?in?the?message?array.

?????? void ?display_all_msg()

?????? {

?????????? for ( int ?i = 0 ;i < message_count_;i ++ )

??????????????ACE_OS::printf( " %s\n " ,mesg_array_[i]);

??????}

???????

private :

???? char ? ** mesg_array_;

????Allocator?allocator_;

???? int ?message_count_;

} ;

?

int ?main( int ?argc,? char * ?argv[])

{

???? char ?message[ 512 ]? = ? { 0 ????} ;
???? if (argc < 2 )

???? {

????????ACE_DEBUG((LM_DEBUG,? " Usage:?%s?<Number?of?blocks>\n " ,?argv[ 0 ]));

????????exit( 1 );

????}

?????

???? int ?n_blocks = ACE_OS::atoi(argv[ 1 ]);

?????

???? // Instantiate?the?Memory?Manager?class?and?pass?in?the?number?of?blocks

???? // you?want?on?the?internal?free?list.

????MessageManager?mm(n_blocks);

???? // Use?the?Memory?Manager?class?to?assign?messages?and?free?them.

???? // Run?this?in?your?favorite?debug?environment?and?you?will?notice?that?the

???? // amount?of?memory?your?program?uses?after?Memory?Manager?has?been

???? // instantiated?remains?the?same.?That?means?the?Cached?Allocator

???? // controls?or?manages?all?the?memory?for?the?application.

???? // Do?forever.

???? while ( 1 )

???? {

???????? // allocate?the?messages?somewhere

????????ACE_DEBUG((LM_DEBUG, " \n\n\nAllocating?Messages\n " ));

???????? for ( int ?i = 0 ;?i < n_blocks;i ++ ) {

????????????ACE_OS::sprintf(message, " Message?%d:?Hi?There " ,i);
????????????mm.allocate_msg(message);

????????}

?????????

???????? // show?the?messages

????????ACE_DEBUG((LM_DEBUG, " Displaying?the?messages\n " ));

????????Sleep( 2 );

????????mm.display_all_msg();

?????????

???????? // free?up?the?memory?for?the?messages.

????????ACE_DEBUG((LM_DEBUG, " Releasing?Messages\n " ));

????????Sleep( 2 );


????????mm.free_all_msg();

????}
???? return ? 0 ;
}

內存池：

ACE_MMAP_Memory_Pool?
ACE_MMAP_MEMORY_POOL?
使用<mmap(2)>創建內存池。這樣內存就可在進程間共享了。每次更新時，內存都被更新到后備存儲(backing store)。

ACE_Lite_MMAP_Memory_Pool?
ACE_LITE_MMAP_MEMORY_POOL?
使用<mmap(2)>創建內存池。不像前面的映射，它不做后備存儲更新。代價是較低可靠性。

ACE_Sbrk_Memory_Pool?
ACE_SBRK_MEMORY_POOL?
使用<sbrk(2)>調用創建內存池。

ACE_Shared_Memory_Pool?
ACE_SHARED_MEMORY_POOL?
使用系統V <shmget(2)>調用創建內存池。

Memory_Pool?　?
內存可在進程間共享。

ACE_Local_Memory_Pool?
ACE_LOCAL_MEMORY_POOL?
通過C++的new和delete操作符創建局部內存池。該池不能在進程間共享。

?

#include?? " ace/Malloc.h " ?
#include?? " ace/Malloc_T.h " ?
#include?? " ace/Null_Mutex.h "

#include? < ACE / MMAP_Memory_Pool.h >

typedef?ACE_Malloc < ACE_MMAP_Memory_Pool,ACE_Null_Mutex? > ?Malloc;

void ??ReadData();
void ??WriteData();

Malloc? * g_mem;
int ?main( int ?arn, char ? ** arc)
{
????ACE_MMAP_Memory_Pool_Options?options(ACE_DEFAULT_BASE_ADDR,
????????ACE_MMAP_Memory_Pool_Options::ALWAYS_FIXED,
???????????????? 1024 * 10000 );

????ACE_NEW_RETURN(g_mem,Malloc( " abc " , " abc " , & options), - 1 );
???? if (?????arn? > ? 1 )
???? {
????????ReadData();
????}
???? else
???? {
????????WriteData();
????}
????system( " pause " );
????g_mem -> sync();
????delete?g_mem;
???? return ? 0 ;
}

void ??ReadData()
{
???? char ?msg[ 32 ]? = { 0 } ;
???? void ? * data;
????
???? for ( int ?i = ? 0 ;i < ? 10000 ;i ++ )
???? {
????????sprintf(msg, " MSG:?%d " ,i);
???????? if (g_mem -> find(msg,data)? != ? - 1 )
???????? {
????????????ACE_DEBUG((LM_INFO, " %s\n " ,( char * )data));
????????}
????}
????
}

void ?WriteData()
{
????
???? for ( int ?i = 0 ;i < 10000 ;i ++ )
???? {
???????? char * ?buff? = ?( char * )g_mem -> malloc( 1024 );
???????? if (buff? != ?NULL)
???????? {
????????????sprintf(buff, " MSG:?%d " ,i);
????????????g_mem -> bind(buff,( void * )buff);
????????}
????}
}

通過分配器接口使用Malloc類

　　大多數ACE中的容器類都可以接受分配器對象作為參數，以用于容器內的內存管理。因為某些內存分配方案只能用于ACE_Malloc類集，ACE含有一個適配器模板類ACE_Allocator_Adapter，它將ACE_Malloc類適配到ACE_Allocator接口。也就是說，在實例化這個模板之后創建的新類可用于替換任何ACE_Allocator。例如：

typedef ACE_Allocator_Adapter<ACE_Malloc<ACE_SHARED_MEMORY_POOL,ACE_Null_Mutex>> Allocator;

posted on 2006-08-30 14:43 橙子 閱讀(2398) 評論(0)  編輯 收藏 引用 所屬分類: ACE