Allocates memory in large chunks for better runtime. More...
#include <ogdf/basic/memory/PoolMemoryAllocator.h>
Classes | |
struct | MemElem |
Basic memory element used to realize a linked list of deallocated memory segments. More... | |
Public Member Functions | |
PoolMemoryAllocator () | |
~PoolMemoryAllocator () | |
Static Public Member Functions | |
static void * | allocate (size_t nBytes) |
Allocates memory of size nBytes . More... | |
static bool | checkSize (size_t nBytes) |
Returns true iff allocate can be invoked with nBytes . More... | |
static void | cleanup () |
Frees all allocated memory. More... | |
static void | deallocate (size_t nBytes, void *p) |
Deallocates memory at address p which is of size nBytes . More... | |
static void | deallocateList (size_t nBytes, void *pHead, void *pTail) |
Deallocate a complete list starting at pHead and ending at pTail . More... | |
static void | defrag () |
Defragments the global free lists. More... | |
static void | flushPool () |
Flushes all free but allocated bytes (s_tp) to the thread-global list (s_pool) of allocated bytes. More... | |
static size_t | memoryAllocatedInBlocks () |
Returns the total amount of memory (in bytes) allocated from the system. More... | |
static size_t | memoryInGlobalFreeList () |
Returns the total amount of memory (in bytes) available in the global free lists. More... | |
static size_t | memoryInThreadFreeList () |
Returns the total amount of memory (in bytes) available in the thread's free lists. More... | |
Private Types | |
using | MemElemPtr = MemElem * |
Static Private Member Functions | |
static MemElemPtr | allocateBlock () |
static void | enterCS () |
static void * | fillPool (MemElemPtr &pFreeBytes, uint16_t nBytes) |
static void | leaveCS () |
static void | makeSlices (MemElemPtr p, int nWords, int nSlices) |
static int | slicesPerBlock (uint16_t nBytes) |
static int | slicesPerBlock (uint16_t nBytes, int &nWords) |
static size_t | unguardedMemGlobalFreelist () |
Static Private Attributes | |
static constexpr size_t | BLOCK_SIZE = 8192 |
static constexpr size_t | MIN_BYTES = sizeof(MemElemPtr) |
static BlockChain * | s_blocks |
Holds all allocated memory independently of whether it is cleared in chunks of size BLOCK_SIZE. More... | |
static long long | s_globallyAllocatedBytes |
Holds the number of globally allocated bytes for debugging. More... | |
static thread_local long long | s_locallyAllocatedBytes |
Holds the number of thread-locally allocated bytes for debugging. More... | |
static std::mutex | s_mutex |
static PoolElement | s_pool [TABLE_SIZE] |
Contains allocated but free memory that may be used by all threads. Filled upon exiting a thread that allocated memory that was later freed. More... | |
static thread_local MemElemPtr | s_tp [TABLE_SIZE] |
Contains the allocated but free memory for a single thread. More... | |
static constexpr size_t | TABLE_SIZE = 256 |
Allocates memory in large chunks for better runtime.
Possibly allocates more memory than required. Newly allocated chunks contain BLOCK_SIZE many bytes. Can allocate at most TABLE_SIZE bytes per invocation of allocate.
For each requested memory segment of n
bytes, OGDF_POINTER_SIZE
bytes are allocated in addition to store a pointer to another segment of memory.
This allows to store memory that is requested to be deallocated in a single linked list, and re-distribute it upon later allocation requests, instead of actually decallocating it.
Definition at line 55 of file PoolMemoryAllocator.h.
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private |
Definition at line 61 of file PoolMemoryAllocator.h.
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inline |
Definition at line 71 of file PoolMemoryAllocator.h.
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inline |
Definition at line 73 of file PoolMemoryAllocator.h.
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static |
Allocates memory of size nBytes
.
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staticprivate |
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static |
Returns true iff allocate can be invoked with nBytes
.
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static |
Frees all allocated memory.
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static |
Deallocates memory at address p
which is of size nBytes
.
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static |
Deallocate a complete list starting at pHead
and ending at pTail
.
The elements are assumed to be chained using the first word of each element and elements are of size nBytes
. In contrasting to linear-time element-wise deallocation this method takes constant time.
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static |
Defragments the global free lists.
This methods sorts the global free lists, so that successive elements come after each other. This can improve perfomance for data structure that allocate many elements from the pool like lists and graphs.
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inlinestaticprivate |
Definition at line 117 of file PoolMemoryAllocator.h.
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staticprivate |
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static |
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inlinestaticprivate |
Definition at line 123 of file PoolMemoryAllocator.h.
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staticprivate |
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static |
Returns the total amount of memory (in bytes) allocated from the system.
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static |
Returns the total amount of memory (in bytes) available in the global free lists.
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static |
Returns the total amount of memory (in bytes) available in the thread's free lists.
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inlinestaticprivate |
Definition at line 129 of file PoolMemoryAllocator.h.
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inlinestaticprivate |
Definition at line 134 of file PoolMemoryAllocator.h.
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staticprivate |
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staticconstexprprivate |
Definition at line 68 of file PoolMemoryAllocator.h.
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staticconstexprprivate |
Definition at line 66 of file PoolMemoryAllocator.h.
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staticprivate |
Holds all allocated memory independently of whether it is cleared in chunks of size BLOCK_SIZE.
Definition at line 151 of file PoolMemoryAllocator.h.
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staticprivate |
Holds the number of globally allocated bytes for debugging.
Definition at line 155 of file PoolMemoryAllocator.h.
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staticprivate |
Holds the number of thread-locally allocated bytes for debugging.
Definition at line 157 of file PoolMemoryAllocator.h.
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staticprivate |
Definition at line 163 of file PoolMemoryAllocator.h.
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staticprivate |
Contains allocated but free memory that may be used by all threads. Filled upon exiting a thread that allocated memory that was later freed.
Definition at line 148 of file PoolMemoryAllocator.h.
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staticprivate |
Contains the allocated but free memory for a single thread.
Definition at line 165 of file PoolMemoryAllocator.h.
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staticconstexprprivate |
Definition at line 67 of file PoolMemoryAllocator.h.