Patch by Thom Holwerda:

"Phase III .diff for BlockCache.dox.

Not much to change here, some really minor things only. The thing
that makes the .diff large is the fact that many lines were more like
70char than 80char."

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21258 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Niels Sascha Reedijk 2007-05-28 12:18:49 +00:00
parent 8ace9affed
commit dc84754eef

View File

@ -7,6 +7,7 @@
*
* Proofreading:
* David Weizades <ddewbofh@hotmail.com>
* Thom Holwerda <slakje@quicknet.nl>
*
* Corresponds to:
* /trunk/headers/os/support/BlockCache.h rev 19972
@ -15,7 +16,7 @@
/*!
\file BlockCache.h
\brief Implements a mechanism to store and retrieve memory blocks
\brief Implements a mechanism to store and retrieve memory blocks.
*/
/*!
@ -36,52 +37,50 @@
\ingroup libbe
\brief A class that creates and maintains a pool of memory blocks.
In some performance critical code there might come a time where you
require a lot of little blocks of memory that you want to access and
dispose of continuously. Since allocating and freeing memory are
'expensive' operations, it's better to have a pool of memory blocks at
your disposal. Luckily, the Haiku API provides a class that will act
as the administrator of your memory pool, so you will not have to reinvent
the wheel every time.
In some performance critical code there might come a time where you require a
lot of little blocks of memory that you want to access and dispose of
continuously. Since allocating and freeing memory are 'expensive' operations,
it is better to have a pool of memory blocks at your disposal. Luckily, the
Haiku API provides a class that will act as the administrator of your memory
pool, so you will not have to reinvent the wheel every time.
The principle is easy. The constructor takes the number of blocks you
want to create beforehand, the size of the blocks and the method of
want to create beforehand, the size of the blocks, and the method of
allocation. This can either be #B_OBJECT_CACHE or #B_MALLOC_CACHE.
The first one uses C++ operators \c new[] and \c delete[], the second one
uses \c malloc() and \c free(). Unless you have specific demands on
The first one uses C++ operators \c new[] and \c delete[], while the second
one uses \c malloc() and \c free(). Unless you have specific demands on
performance or you want to take care of freeing the objects yourself, either
way works fine.
As soon as you have the memory pool, you can Get() blocks. If the
pre-allocated memory blocks run out, BBlockCache will allocate
new ones, so you will not have to worry about availability. As soon as
you are done you can Save() the memory back into the pool. BBlockCache will
make sure that there will not be more blocks saved than the initial number you
requested when you created the object, so be aware of that.
pre-allocated memory blocks run out, BBlockCache will allocate new ones, so
you will not have to worry about availability. As soon as you are done you can
Save() the memory back into the pool. BBlockCache will make sure that no more
blocks will be saved than the initial number you requested when you created
the object, so be aware of that.
As soon as you got a pointer from the Get() method, you own that
block of memory, this means that you have the liberty to dispose
of it yourself. It also means that when you delete your BBlockCache
instance, any blocks of memory that are checked out will not be destroyed.
In case you might want to delete your objects yourself, make sure you
free the memory the right way. If you created the object as #B_OBJECT_CACHE,
use \c delete[] to free your object. If you created the object as
#B_MALLOC_CACHE, use \c free(). Please note that it defeats the purpose of
this class if your are going to free all the objects yourself since it
basically means that when the pool runs out, Get() will be allocating the
objects by itself.
As soon as you got a pointer from the Get() method, you own that block of
memory; this means that you have the liberty to dispose of it yourself. It
also means that when you delete your BBlockCache instance, any blocks of
memory that are checked out will not be destroyed. In case you might want to
delete your objects yourself, make sure you free the memory the right way. If
you created the object as #B_OBJECT_CACHE, use \c delete[] to free your
object. If you created the object as #B_MALLOC_CACHE, use \c free(). Please
note that it defeats the purpose of this class if your are going to free all
the objects yourself since it basically means that when the pool runs out,
Get() will be allocating the objects by itself.
\note BBlockCache is thread-safe.
*/
/*!
\fn BBlockCache::BBlockCache(uint32 blockCount, size_t blockSize, uint32 allocationType)
\brief Allocate a new memory pool.
\brief Allocate a new memory pool.
\param blockCount The number of free memory blocks you want to allocate
initially. This number is also used as the maximum number of free blocks
that will be kept.
\param blockSize The size of the blocks.
\param blockSize The size of the blocks.
\param allocationType Either #B_OBJECT_CACHE for using \c new[] and
\c delete[] or #B_MALLOC_CACHE for \c malloc() and \c free().
*/
@ -101,8 +100,8 @@
If the pool runs out of free blocks, a new one will be allocated. Please note
that if the size given in the \c blockSize parameter is different from the
size given in the constructor, that a new block of memory will be created.
Only sizes that match the blocks in the memory pool will come from the pool.
size given in the constructor, a new block of memory will be created. Only
sizes that match the blocks in the memory pool will come from the pool.
\param blockSize The required size of the memory block.
\return Returns a pointer to a memory block, or \c NULL if locking the object
@ -114,13 +113,14 @@
\brief Save a block of memory to the memory pool.
The block of memory will only be added to the pool if the \c blockSize is
equal to the size the object was created with and if the maximum number
free blocks in the list will not be exceeded. If not the memory will be freed.
equal to the size the object was created with and if the maximum number of
free blocks in the list will not be exceeded. If not, the memory will be
freed.
Note that it is perfectly valid to pass objects other than those you got from
Get(), but please note that the way it was created conforms to the way memory
is allocated and freed in this pool. Therefor only feed blocks that were
created with \c new[] if the allocation type is #B_OBJECT_CACHE. Likewise
is allocated and freed in this pool. Therefore, only feed blocks that were
created with \c new[] if the allocation type is #B_OBJECT_CACHE. Likewise,
you should only use objects allocated with \c malloc() when the allocation
type is #B_MALLOC_CACHE.
*/