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author | Tiger Wang <ziwei.tiger@hotmail.co.uk> | 2013-11-27 22:35:13 +0100 |
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committer | Tiger Wang <ziwei.tiger@hotmail.co.uk> | 2013-11-27 22:35:13 +0100 |
commit | a6630d32394120a78af56bc612fa3c3449283248 (patch) | |
tree | 2c791266b0f213cd56961299da8d2258b8f85d8e /lib/jsoncpp/src/lib_json/json_batchallocator.h | |
parent | Fixed spawn point being generally in an ocean (diff) | |
parent | Voronoi-related biomegens use the new cVoronoiMap class. (diff) | |
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Diffstat (limited to 'lib/jsoncpp/src/lib_json/json_batchallocator.h')
-rw-r--r-- | lib/jsoncpp/src/lib_json/json_batchallocator.h | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/lib/jsoncpp/src/lib_json/json_batchallocator.h b/lib/jsoncpp/src/lib_json/json_batchallocator.h new file mode 100644 index 000000000..87ea5ed80 --- /dev/null +++ b/lib/jsoncpp/src/lib_json/json_batchallocator.h @@ -0,0 +1,125 @@ +#ifndef JSONCPP_BATCHALLOCATOR_H_INCLUDED +# define JSONCPP_BATCHALLOCATOR_H_INCLUDED + +# include <stdlib.h> +# include <assert.h> + +# ifndef JSONCPP_DOC_EXCLUDE_IMPLEMENTATION + +namespace Json { + +/* Fast memory allocator. + * + * This memory allocator allocates memory for a batch of object (specified by + * the page size, the number of object in each page). + * + * It does not allow the destruction of a single object. All the allocated objects + * can be destroyed at once. The memory can be either released or reused for future + * allocation. + * + * The in-place new operator must be used to construct the object using the pointer + * returned by allocate. + */ +template<typename AllocatedType + ,const unsigned int objectPerAllocation> +class BatchAllocator +{ +public: + typedef AllocatedType Type; + + BatchAllocator( unsigned int objectsPerPage = 255 ) + : freeHead_( 0 ) + , objectsPerPage_( objectsPerPage ) + { +// printf( "Size: %d => %s\n", sizeof(AllocatedType), typeid(AllocatedType).name() ); + assert( sizeof(AllocatedType) * objectPerAllocation >= sizeof(AllocatedType *) ); // We must be able to store a slist in the object free space. + assert( objectsPerPage >= 16 ); + batches_ = allocateBatch( 0 ); // allocated a dummy page + currentBatch_ = batches_; + } + + ~BatchAllocator() + { + for ( BatchInfo *batch = batches_; batch; ) + { + BatchInfo *nextBatch = batch->next_; + free( batch ); + batch = nextBatch; + } + } + + /// allocate space for an array of objectPerAllocation object. + /// @warning it is the responsability of the caller to call objects constructors. + AllocatedType *allocate() + { + if ( freeHead_ ) // returns node from free list. + { + AllocatedType *object = freeHead_; + freeHead_ = *(AllocatedType **)object; + return object; + } + if ( currentBatch_->used_ == currentBatch_->end_ ) + { + currentBatch_ = currentBatch_->next_; + while ( currentBatch_ && currentBatch_->used_ == currentBatch_->end_ ) + currentBatch_ = currentBatch_->next_; + + if ( !currentBatch_ ) // no free batch found, allocate a new one + { + currentBatch_ = allocateBatch( objectsPerPage_ ); + currentBatch_->next_ = batches_; // insert at the head of the list + batches_ = currentBatch_; + } + } + AllocatedType *allocated = currentBatch_->used_; + currentBatch_->used_ += objectPerAllocation; + return allocated; + } + + /// Release the object. + /// @warning it is the responsability of the caller to actually destruct the object. + void release( AllocatedType *object ) + { + assert( object != 0 ); + *(AllocatedType **)object = freeHead_; + freeHead_ = object; + } + +private: + struct BatchInfo + { + BatchInfo *next_; + AllocatedType *used_; + AllocatedType *end_; + AllocatedType buffer_[objectPerAllocation]; + }; + + // disabled copy constructor and assignement operator. + BatchAllocator( const BatchAllocator & ); + void operator =( const BatchAllocator &); + + static BatchInfo *allocateBatch( unsigned int objectsPerPage ) + { + const unsigned int mallocSize = sizeof(BatchInfo) - sizeof(AllocatedType)* objectPerAllocation + + sizeof(AllocatedType) * objectPerAllocation * objectsPerPage; + BatchInfo *batch = static_cast<BatchInfo*>( malloc( mallocSize ) ); + batch->next_ = 0; + batch->used_ = batch->buffer_; + batch->end_ = batch->buffer_ + objectsPerPage; + return batch; + } + + BatchInfo *batches_; + BatchInfo *currentBatch_; + /// Head of a single linked list within the allocated space of freeed object + AllocatedType *freeHead_; + unsigned int objectsPerPage_; +}; + + +} // namespace Json + +# endif // ifndef JSONCPP_DOC_INCLUDE_IMPLEMENTATION + +#endif // JSONCPP_BATCHALLOCATOR_H_INCLUDED + |