343 lines
14 KiB
C++
343 lines
14 KiB
C++
/* $Id$ */
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#ifndef BLOB_HPP
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#define BLOB_HPP
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/** Type-safe version of memcpy().
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* @param d destination buffer
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* @param s source buffer
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* @param num_items number of items to be copied (!not number of bytes!) */
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template <class Titem_>
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FORCEINLINE void MemCpyT(Titem_* d, const Titem_* s, int num_items = 1)
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{
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memcpy(d, s, num_items * sizeof(Titem_));
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}
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/** Base class for simple binary blobs.
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* Item is byte.
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* The word 'simple' means:
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* - no configurable allocator type (always made from heap)
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* - no smart deallocation - deallocation must be called from the same
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* module (DLL) where the blob was allocated
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* - no configurable allocation policy (how big blocks should be allocated)
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* - no extra ownership policy (i.e. 'copy on write') when blob is copied
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* - no thread synchronization at all
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*
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* Internal member layout:
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* 1. The only class member is pointer to the first item (see union ptr_u).
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* 2. Allocated block contains the blob header (see CHdr) followed by the raw byte data.
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* Always, when it allocates memory the allocated size is:
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* sizeof(CHdr) + <data capacity>
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* 3. Two 'virtual' members (m_size and m_max_size) are stored in the CHdr at beginning
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* of the alloated block.
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* 4. The pointer (in ptr_u) points behind the header (to the first data byte).
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* When memory block is allocated, the sizeof(CHdr) it added to it.
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* 5. Benefits of this layout:
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* - items are accessed in the simplest possible way - just dereferencing the pointer,
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* which is good for performance (assuming that data are accessed most often).
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* - sizeof(blob) is the same as the size of any other pointer
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* 6. Drawbacks of this layout:
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* - the fact, that pointer to the alocated block is adjusted by sizeof(CHdr) before
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* it is stored can lead to several confusions:
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* - it is not common pattern so the implementation code is bit harder to read
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* - valgrind can generate warning that allocated block is lost (not accessible)
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* */
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class CBlobBaseSimple {
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protected:
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/** header of the allocated memory block */
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struct CHdr {
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int m_size; ///< actual blob size in bytes
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int m_max_size; ///< maximum (allocated) size in bytes
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};
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/** type used as class member */
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union {
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int8 *m_pData; ///< pointer to the first byte of data
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CHdr *m_pHdr_1; ///< pointer just after the CHdr holding m_size and m_max_size
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} ptr_u;
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public:
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static const int Ttail_reserve = 4; ///< four extra bytes will be always allocated and zeroed at the end
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/** default constructor - initializes empty blob */
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FORCEINLINE CBlobBaseSimple() { InitEmpty(); }
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/** copy constructor */
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FORCEINLINE CBlobBaseSimple(const CBlobBaseSimple& src)
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{
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InitEmpty();
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AppendRaw(src);
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}
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/** destructor */
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FORCEINLINE ~CBlobBaseSimple() { Free(); }
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protected:
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/** initialize the empty blob by setting the ptr_u.m_pHdr_1 pointer to the static CHdr with
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* both m_size and m_max_size containing zero */
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FORCEINLINE void InitEmpty() { static CHdr hdrEmpty[] = {{0, 0}, {0, 0}}; ptr_u.m_pHdr_1 = &hdrEmpty[1]; }
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/** initialize blob by attaching it to the given header followed by data */
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FORCEINLINE void Init(CHdr* hdr) { ptr_u.m_pHdr_1 = &hdr[1]; }
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/** blob header accessor - use it rather than using the pointer arithmetics directly - non-const version */
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FORCEINLINE CHdr& Hdr() { return ptr_u.m_pHdr_1[-1]; }
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/** blob header accessor - use it rather than using the pointer arithmetics directly - const version */
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FORCEINLINE const CHdr& Hdr() const { return ptr_u.m_pHdr_1[-1]; }
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/** return reference to the actual blob size - used when the size needs to be modified */
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FORCEINLINE int& RawSizeRef() { return Hdr().m_size; };
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public:
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/** return true if blob doesn't contain valid data */
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FORCEINLINE bool IsEmpty() const { return RawSize() == 0; }
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/** return the number of valid data bytes in the blob */
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FORCEINLINE int RawSize() const { return Hdr().m_size; };
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/** return the current blob capacity in bytes */
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FORCEINLINE int MaxRawSize() const { return Hdr().m_max_size; };
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/** return pointer to the first byte of data - non-const version */
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FORCEINLINE int8* RawData() { return ptr_u.m_pData; }
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/** return pointer to the first byte of data - const version */
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FORCEINLINE const int8* RawData() const { return ptr_u.m_pData; }
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#if 0 // reenable when needed
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/** return the 32 bit CRC of valid data in the blob */
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FORCEINLINE uint32 Crc32() const {return CCrc32::Calc(RawData(), RawSize());}
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#endif //0
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/** invalidate blob's data - doesn't free buffer */
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FORCEINLINE void Clear() { RawSizeRef() = 0; }
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/** free the blob's memory */
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FORCEINLINE void Free() { if (MaxRawSize() > 0) {RawFree(&Hdr()); InitEmpty();} }
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/** copy data from another blob - replaces any existing blob's data */
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FORCEINLINE void CopyFrom(const CBlobBaseSimple& src) { Clear(); AppendRaw(src); }
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/** overtake ownership of data buffer from the source blob - source blob will become empty */
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FORCEINLINE void MoveFrom(CBlobBaseSimple& src) { Free(); ptr_u.m_pData = src.ptr_u.m_pData; src.InitEmpty(); }
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/** swap buffers (with data) between two blobs (this and source blob) */
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FORCEINLINE void Swap(CBlobBaseSimple& src) { int8 *tmp = ptr_u.m_pData; ptr_u.m_pData = src.ptr_u.m_pData; src.ptr_u.m_pData = tmp; }
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/** append new bytes at the end of existing data bytes - reallocates if necessary */
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FORCEINLINE void AppendRaw(int8 *p, int num_bytes)
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{
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assert(p != NULL);
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if (num_bytes > 0) {
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memcpy(GrowRawSize(num_bytes), p, num_bytes);
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} else {
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assert(num_bytes >= 0);
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}
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}
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/** append bytes from given source blob to the end of existing data bytes - reallocates if necessary */
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FORCEINLINE void AppendRaw(const CBlobBaseSimple& src)
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{
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if (!src.IsEmpty())
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memcpy(GrowRawSize(src.RawSize()), src.RawData(), src.RawSize());
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}
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/** Reallocate if there is no free space for num_bytes bytes.
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* @return pointer to the new data to be added */
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FORCEINLINE int8* MakeRawFreeSpace(int num_bytes)
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{
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assert(num_bytes >= 0);
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int new_size = RawSize() + num_bytes;
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if (new_size > MaxRawSize()) SmartAlloc(new_size);
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FixTail();
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return ptr_u.m_pData + RawSize();
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}
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/** Increase RawSize() by num_bytes.
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* @return pointer to the new data added */
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FORCEINLINE int8* GrowRawSize(int num_bytes)
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{
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int8* pNewData = MakeRawFreeSpace(num_bytes);
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RawSizeRef() += num_bytes;
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return pNewData;
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}
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/** Decrease RawSize() by num_bytes. */
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FORCEINLINE void ReduceRawSize(int num_bytes)
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{
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if (MaxRawSize() > 0 && num_bytes > 0) {
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assert(num_bytes <= RawSize());
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if (num_bytes < RawSize()) RawSizeRef() -= num_bytes;
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else RawSizeRef() = 0;
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}
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}
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/** reallocate blob data if needed */
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void SmartAlloc(int new_size)
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{
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int old_max_size = MaxRawSize();
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if (old_max_size >= new_size) return;
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// calculate minimum block size we need to allocate
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int min_alloc_size = sizeof(CHdr) + new_size + Ttail_reserve;
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// ask allocation policy for some reasonable block size
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int alloc_size = AllocPolicy(min_alloc_size);
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// allocate new block
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CHdr* pNewHdr = RawAlloc(alloc_size);
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// setup header
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pNewHdr->m_size = RawSize();
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pNewHdr->m_max_size = alloc_size - (sizeof(CHdr) + Ttail_reserve);
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// copy existing data
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if (RawSize() > 0)
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memcpy(pNewHdr + 1, ptr_u.m_pData, pNewHdr->m_size);
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// replace our block with new one
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CHdr* pOldHdr = &Hdr();
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Init(pNewHdr);
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if (old_max_size > 0)
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RawFree(pOldHdr);
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}
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/** simple allocation policy - can be optimized later */
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FORCEINLINE static int AllocPolicy(int min_alloc)
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{
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if (min_alloc < (1 << 9)) {
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if (min_alloc < (1 << 5)) return (1 << 5);
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return (min_alloc < (1 << 7)) ? (1 << 7) : (1 << 9);
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}
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if (min_alloc < (1 << 15)) {
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if (min_alloc < (1 << 11)) return (1 << 11);
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return (min_alloc < (1 << 13)) ? (1 << 13) : (1 << 15);
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}
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if (min_alloc < (1 << 20)) {
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if (min_alloc < (1 << 17)) return (1 << 17);
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return (min_alloc < (1 << 19)) ? (1 << 19) : (1 << 20);
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}
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min_alloc = (min_alloc | ((1 << 20) - 1)) + 1;
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return min_alloc;
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}
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/** all allocation should happen here */
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static FORCEINLINE CHdr* RawAlloc(int num_bytes) { return (CHdr*)malloc(num_bytes); }
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/** all deallocations should happen here */
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static FORCEINLINE void RawFree(CHdr* p) { free(p); }
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/** fixing the four bytes at the end of blob data - useful when blob is used to hold string */
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FORCEINLINE void FixTail()
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{
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if (MaxRawSize() > 0) {
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int8 *p = &ptr_u.m_pData[RawSize()];
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for (int i = 0; i < Ttail_reserve; i++) p[i] = 0;
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}
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}
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};
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/** Blob - simple dynamic Titem_ array. Titem_ (template argument) is a placeholder for any type.
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* Titem_ can be any integral type, pointer, or structure. Using Blob instead of just plain C array
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* simplifies the resource management in several ways:
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* 1. When adding new item(s) it automatically grows capacity if needed.
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* 2. When variable of type Blob comes out of scope it automatically frees the data buffer.
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* 3. Takes care about the actual data size (number of used items).
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* 4. Dynamically constructs only used items (as opposite of static array which constructs all items) */
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template <class Titem_, class Tbase_ = CBlobBaseSimple>
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class CBlobT : public CBlobBaseSimple {
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// make template arguments public:
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public:
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typedef Titem_ Titem;
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typedef Tbase_ Tbase;
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static const int Titem_size = sizeof(Titem);
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/** Default constructor - makes new Blob ready to accept any data */
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FORCEINLINE CBlobT() : Tbase() {}
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/** Copy constructor - make new blob to become copy of the original (source) blob */
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FORCEINLINE CBlobT(const Tbase& src) : Tbase(src) {assert((RawSize() % Titem_size) == 0);}
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/** Destructor - ensures that allocated memory (if any) is freed */
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FORCEINLINE ~CBlobT() { Free(); }
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/** Check the validity of item index (only in debug mode) */
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FORCEINLINE void CheckIdx(int idx) { assert(idx >= 0); assert(idx < Size()); }
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/** Return pointer to the first data item - non-const version */
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FORCEINLINE Titem* Data() { return (Titem*)RawData(); }
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/** Return pointer to the first data item - const version */
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FORCEINLINE const Titem* Data() const { return (const Titem*)RawData(); }
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/** Return pointer to the idx-th data item - non-const version */
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FORCEINLINE Titem* Data(int idx) { CheckIdx(idx); return (Data() + idx); }
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/** Return pointer to the idx-th data item - const version */
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FORCEINLINE const Titem* Data(int idx) const { CheckIdx(idx); return (Data() + idx); }
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/** Return number of items in the Blob */
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FORCEINLINE int Size() const { return (RawSize() / Titem_size); }
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/** Free the memory occupied by Blob destroying all items */
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FORCEINLINE void Free()
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{
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assert((RawSize() % Titem_size) == 0);
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int old_size = Size();
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if (old_size > 0) {
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// destroy removed items;
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Titem* pI_last_to_destroy = Data(0);
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for (Titem* pI = Data(old_size - 1); pI >= pI_last_to_destroy; pI--) pI->~Titem_();
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}
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Tbase::Free();
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}
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/** Grow number of data items in Blob by given number - doesn't construct items */
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FORCEINLINE Titem* GrowSizeNC(int num_items) { return (Titem*)GrowRawSize(num_items * Titem_size); }
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/** Grow number of data items in Blob by given number - constructs new items (using Titem_'s default constructor) */
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FORCEINLINE Titem* GrowSizeC(int num_items)
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{
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Titem* pI = GrowSizeNC(num_items);
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for (int i = num_items; i > 0; i--, pI++) new (pI) Titem();
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}
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/** Destroy given number of items and reduce the Blob's data size */
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FORCEINLINE void ReduceSize(int num_items)
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{
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assert((RawSize() % Titem_size) == 0);
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int old_size = Size();
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assert(num_items <= old_size);
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int new_size = (num_items <= old_size) ? (old_size - num_items) : 0;
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// destroy removed items;
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Titem* pI_last_to_destroy = Data(new_size);
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for (Titem* pI = Data(old_size - 1); pI >= pI_last_to_destroy; pI--) pI->~Titem();
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// remove them
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ReduceRawSize(num_items * Titem_size);
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}
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/** Append one data item at the end (calls Titem_'s default constructor) */
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FORCEINLINE Titem* AppendNew()
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{
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Titem& dst = *GrowSizeNC(1); // Grow size by one item
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Titem* pNewItem = new (&dst) Titem(); // construct the new item by calling in-place new operator
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return pNewItem;
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}
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/** Append the copy of given item at the end of Blob (using copy constructor) */
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FORCEINLINE Titem* Append(const Titem& src)
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{
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Titem& dst = *GrowSizeNC(1); // Grow size by one item
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Titem* pNewItem = new (&dst) Titem(src); // construct the new item by calling in-place new operator with copy ctor()
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return pNewItem;
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}
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/** Add given items (ptr + number of items) at the end of blob */
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FORCEINLINE Titem* Append(const Titem* pSrc, int num_items)
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{
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Titem* pDst = GrowSizeNC(num_items);
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Titem* pDstOrg = pDst;
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Titem* pDstEnd = pDst + num_items;
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while (pDst < pDstEnd) new (pDst++) Titem(*(pSrc++));
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return pDstOrg;
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}
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/** Remove item with the given index by replacing it by the last item and reducing the size by one */
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FORCEINLINE void RemoveBySwap(int idx)
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{
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CheckIdx(idx);
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// destroy removed item
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Titem* pRemoved = Data(idx);
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RemoveBySwap(pRemoved);
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}
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/** Remove item given by pointer replacing it by the last item and reducing the size by one */
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FORCEINLINE void RemoveBySwap(Titem* pItem)
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{
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Titem* pLast = Data(Size() - 1);
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assert(pItem >= Data() && pItem <= pLast);
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// move last item to its new place
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if (pItem != pLast) {
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pItem->~Titem_();
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new (pItem) Titem_(*pLast);
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}
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// destroy the last item
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pLast->~Titem_();
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// and reduce the raw blob size
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ReduceRawSize(Titem_size);
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}
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/** Ensures that given number of items can be added to the end of Blob. Returns pointer to the
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* first free (unused) item */
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FORCEINLINE Titem* MakeFreeSpace(int num_items) { return (Titem*)MakeRawFreeSpace(num_items * Titem_size); }
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};
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// simple string implementation
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struct CStrA : public CBlobT<char>
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{
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typedef CBlobT<char> base;
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CStrA(const char* str = NULL) {Append(str);}
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FORCEINLINE CStrA(const CBlobBaseSimple& src) : base(src) {}
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void Append(const char* str) {if (str != NULL && str[0] != '\0') base::Append(str, (int)strlen(str));}
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};
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#endif /* BLOB_HPP */
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