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Diffstat (limited to 'src/misc/blob.hpp')
| -rw-r--r-- | src/misc/blob.hpp | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/src/misc/blob.hpp b/src/misc/blob.hpp new file mode 100644 index 000000000..1a20f3ac2 --- /dev/null +++ b/src/misc/blob.hpp @@ -0,0 +1,342 @@ +/* $Id$ */ + +#ifndef BLOB_HPP +#define BLOB_HPP + +/** Type-safe version of memcpy(). + * @param d destination buffer + * @param s source buffer + * @param num_items number of items to be copied (!not number of bytes!) */ +template <class Titem_> +FORCEINLINE void MemCpyT(Titem_* d, const Titem_* s, int num_items = 1) +{ + memcpy(d, s, num_items * sizeof(Titem_)); +} + + +/** Base class for simple binary blobs. + * Item is byte. + * The word 'simple' means: + * - no configurable allocator type (always made from heap) + * - no smart deallocation - deallocation must be called from the same + * module (DLL) where the blob was allocated + * - no configurable allocation policy (how big blocks should be allocated) + * - no extra ownership policy (i.e. 'copy on write') when blob is copied + * - no thread synchronization at all + * + * Internal member layout: + * 1. The only class member is pointer to the first item (see union ptr_u). + * 2. Allocated block contains the blob header (see CHdr) followed by the raw byte data. + * Always, when it allocates memory the allocated size is: + * sizeof(CHdr) + <data capacity> + * 3. Two 'virtual' members (m_size and m_max_size) are stored in the CHdr at beginning + * of the alloated block. + * 4. The pointer (in ptr_u) points behind the header (to the first data byte). + * When memory block is allocated, the sizeof(CHdr) it added to it. + * 5. Benefits of this layout: + * - items are accessed in the simplest possible way - just dereferencing the pointer, + * which is good for performance (assuming that data are accessed most often). + * - sizeof(blob) is the same as the size of any other pointer + * 6. Drawbacks of this layout: + * - the fact, that pointer to the alocated block is adjusted by sizeof(CHdr) before + * it is stored can lead to several confusions: + * - it is not common pattern so the implementation code is bit harder to read + * - valgrind can generate warning that allocated block is lost (not accessible) + * */ +class CBlobBaseSimple { +protected: + /** header of the allocated memory block */ + struct CHdr { + int m_size; ///< actual blob size in bytes + int m_max_size; ///< maximum (allocated) size in bytes + }; + + /** type used as class member */ + union { + int8 *m_pData; ///< pointer to the first byte of data + CHdr *m_pHdr_1; ///< pointer just after the CHdr holding m_size and m_max_size + } ptr_u; + +public: + static const int Ttail_reserve = 4; ///< four extra bytes will be always allocated and zeroed at the end + + /** default constructor - initializes empty blob */ + FORCEINLINE CBlobBaseSimple() { InitEmpty(); } + /** copy constructor */ + FORCEINLINE CBlobBaseSimple(const CBlobBaseSimple& src) + { + InitEmpty(); + AppendRaw(src); + } + /** destructor */ + FORCEINLINE ~CBlobBaseSimple() { Free(); } +protected: + /** initialize the empty blob by setting the ptr_u.m_pHdr_1 pointer to the static CHdr with + * both m_size and m_max_size containing zero */ + FORCEINLINE void InitEmpty() { static CHdr hdrEmpty[] = {{0, 0}, {0, 0}}; ptr_u.m_pHdr_1 = &hdrEmpty[1]; } + /** initialize blob by attaching it to the given header followed by data */ + FORCEINLINE void Init(CHdr* hdr) { ptr_u.m_pHdr_1 = &hdr[1]; } + /** blob header accessor - use it rather than using the pointer arithmetics directly - non-const version */ + FORCEINLINE CHdr& Hdr() { return ptr_u.m_pHdr_1[-1]; } + /** blob header accessor - use it rather than using the pointer arithmetics directly - const version */ + FORCEINLINE const CHdr& Hdr() const { return ptr_u.m_pHdr_1[-1]; } + /** return reference to the actual blob size - used when the size needs to be modified */ + FORCEINLINE int& RawSizeRef() { return Hdr().m_size; }; + +public: + /** return true if blob doesn't contain valid data */ + FORCEINLINE bool IsEmpty() const { return RawSize() == 0; } + /** return the number of valid data bytes in the blob */ + FORCEINLINE int RawSize() const { return Hdr().m_size; }; + /** return the current blob capacity in bytes */ + FORCEINLINE int MaxRawSize() const { return Hdr().m_max_size; }; + /** return pointer to the first byte of data - non-const version */ + FORCEINLINE int8* RawData() { return ptr_u.m_pData; } + /** return pointer to the first byte of data - const version */ + FORCEINLINE const int8* RawData() const { return ptr_u.m_pData; } +#if 0 // reenable when needed + /** return the 32 bit CRC of valid data in the blob */ + FORCEINLINE uint32 Crc32() const {return CCrc32::Calc(RawData(), RawSize());} +#endif //0 + /** invalidate blob's data - doesn't free buffer */ + FORCEINLINE void Clear() { RawSizeRef() = 0; } + /** free the blob's memory */ + FORCEINLINE void Free() { if (MaxRawSize() > 0) {RawFree(&Hdr()); InitEmpty();} } + /** copy data from another blob - replaces any existing blob's data */ + FORCEINLINE void CopyFrom(const CBlobBaseSimple& src) { Clear(); AppendRaw(src); } + /** overtake ownership of data buffer from the source blob - source blob will become empty */ + FORCEINLINE void MoveFrom(CBlobBaseSimple& src) { Free(); ptr_u.m_pData = src.ptr_u.m_pData; src.InitEmpty(); } + /** swap buffers (with data) between two blobs (this and source blob) */ + 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; } + + /** append new bytes at the end of existing data bytes - reallocates if necessary */ + FORCEINLINE void AppendRaw(int8 *p, int num_bytes) + { + assert(p != NULL); + if (num_bytes > 0) { + memcpy(GrowRawSize(num_bytes), p, num_bytes); + } else { + assert(num_bytes >= 0); + } + } + + /** append bytes from given source blob to the end of existing data bytes - reallocates if necessary */ + FORCEINLINE void AppendRaw(const CBlobBaseSimple& src) + { + if (!src.IsEmpty()) + memcpy(GrowRawSize(src.RawSize()), src.RawData(), src.RawSize()); + } + + /** Reallocate if there is no free space for num_bytes bytes. + * @return pointer to the new data to be added */ + FORCEINLINE int8* MakeRawFreeSpace(int num_bytes) + { + assert(num_bytes >= 0); + int new_size = RawSize() + num_bytes; + if (new_size > MaxRawSize()) SmartAlloc(new_size); + FixTail(); + return ptr_u.m_pData + RawSize(); + } + + /** Increase RawSize() by num_bytes. + * @return pointer to the new data added */ + FORCEINLINE int8* GrowRawSize(int num_bytes) + { + int8* pNewData = MakeRawFreeSpace(num_bytes); + RawSizeRef() += num_bytes; + return pNewData; + } + + /** Decrease RawSize() by num_bytes. */ + FORCEINLINE void ReduceRawSize(int num_bytes) + { + if (MaxRawSize() > 0 && num_bytes > 0) { + assert(num_bytes <= RawSize()); + if (num_bytes < RawSize()) RawSizeRef() -= num_bytes; + else RawSizeRef() = 0; + } + } + /** reallocate blob data if needed */ + void SmartAlloc(int new_size) + { + int old_max_size = MaxRawSize(); + if (old_max_size >= new_size) return; + // calculate minimum block size we need to allocate + int min_alloc_size = sizeof(CHdr) + new_size + Ttail_reserve; + // ask allocation policy for some reasonable block size + int alloc_size = AllocPolicy(min_alloc_size); + // allocate new block + CHdr* pNewHdr = RawAlloc(alloc_size); + // setup header + pNewHdr->m_size = RawSize(); + pNewHdr->m_max_size = alloc_size - (sizeof(CHdr) + Ttail_reserve); + // copy existing data + if (RawSize() > 0) + memcpy(pNewHdr + 1, ptr_u.m_pData, pNewHdr->m_size); + // replace our block with new one + CHdr* pOldHdr = &Hdr(); + Init(pNewHdr); + if (old_max_size > 0) + RawFree(pOldHdr); + } + /** simple allocation policy - can be optimized later */ + FORCEINLINE static int AllocPolicy(int min_alloc) + { + if (min_alloc < (1 << 9)) { + if (min_alloc < (1 << 5)) return (1 << 5); + return (min_alloc < (1 << 7)) ? (1 << 7) : (1 << 9); + } + if (min_alloc < (1 << 15)) { + if (min_alloc < (1 << 11)) return (1 << 11); + return (min_alloc < (1 << 13)) ? (1 << 13) : (1 << 15); + } + if (min_alloc < (1 << 20)) { + if (min_alloc < (1 << 17)) return (1 << 17); + return (min_alloc < (1 << 19)) ? (1 << 19) : (1 << 20); + } + min_alloc = (min_alloc | ((1 << 20) - 1)) + 1; + return min_alloc; + } + + /** all allocation should happen here */ + static FORCEINLINE CHdr* RawAlloc(int num_bytes) { return (CHdr*)malloc(num_bytes); } + /** all deallocations should happen here */ + static FORCEINLINE void RawFree(CHdr* p) { free(p); } + /** fixing the four bytes at the end of blob data - useful when blob is used to hold string */ + FORCEINLINE void FixTail() + { + if (MaxRawSize() > 0) { + int8 *p = &ptr_u.m_pData[RawSize()]; + for (int i = 0; i < Ttail_reserve; i++) p[i] = 0; + } + } +}; + +/** Blob - simple dynamic Titem_ array. Titem_ (template argument) is a placeholder for any type. + * Titem_ can be any integral type, pointer, or structure. Using Blob instead of just plain C array + * simplifies the resource management in several ways: + * 1. When adding new item(s) it automatically grows capacity if needed. + * 2. When variable of type Blob comes out of scope it automatically frees the data buffer. + * 3. Takes care about the actual data size (number of used items). + * 4. Dynamically constructs only used items (as opposite of static array which constructs all items) */ +template <class Titem_, class Tbase_ = CBlobBaseSimple> +class CBlobT : public CBlobBaseSimple { + // make template arguments public: +public: + typedef Titem_ Titem; + typedef Tbase_ Tbase; + + static const int Titem_size = sizeof(Titem); + + /** Default constructor - makes new Blob ready to accept any data */ + FORCEINLINE CBlobT() : Tbase() {} + /** Copy constructor - make new blob to become copy of the original (source) blob */ + FORCEINLINE CBlobT(const Tbase& src) : Tbase(src) {assert((RawSize() % Titem_size) == 0);} + /** Destructor - ensures that allocated memory (if any) is freed */ + FORCEINLINE ~CBlobT() { Free(); } + /** Check the validity of item index (only in debug mode) */ + FORCEINLINE void CheckIdx(int idx) { assert(idx >= 0); assert(idx < Size()); } + /** Return pointer to the first data item - non-const version */ + FORCEINLINE Titem* Data() { return (Titem*)RawData(); } + /** Return pointer to the first data item - const version */ + FORCEINLINE const Titem* Data() const { return (const Titem*)RawData(); } + /** Return pointer to the idx-th data item - non-const version */ + FORCEINLINE Titem* Data(int idx) { CheckIdx(idx); return (Data() + idx); } + /** Return pointer to the idx-th data item - const version */ + FORCEINLINE const Titem* Data(int idx) const { CheckIdx(idx); return (Data() + idx); } + /** Return number of items in the Blob */ + FORCEINLINE int Size() const { return (RawSize() / Titem_size); } + /** Free the memory occupied by Blob destroying all items */ + FORCEINLINE void Free() + { + assert((RawSize() % Titem_size) == 0); + int old_size = Size(); + if (old_size > 0) { + // destroy removed items; + Titem* pI_last_to_destroy = Data(0); + for (Titem* pI = Data(old_size - 1); pI >= pI_last_to_destroy; pI--) pI->~Titem_(); + } + Tbase::Free(); + } + /** Grow number of data items in Blob by given number - doesn't construct items */ + FORCEINLINE Titem* GrowSizeNC(int num_items) { return (Titem*)GrowRawSize(num_items * Titem_size); } + /** Grow number of data items in Blob by given number - constructs new items (using Titem_'s default constructor) */ + FORCEINLINE Titem* GrowSizeC(int num_items) + { + Titem* pI = GrowSizeNC(num_items); + for (int i = num_items; i > 0; i--, pI++) new (pI) Titem(); + } + /** Destroy given number of items and reduce the Blob's data size */ + FORCEINLINE void ReduceSize(int num_items) + { + assert((RawSize() % Titem_size) == 0); + int old_size = Size(); + assert(num_items <= old_size); + int new_size = (num_items <= old_size) ? (old_size - num_items) : 0; + // destroy removed items; + Titem* pI_last_to_destroy = Data(new_size); + for (Titem* pI = Data(old_size - 1); pI >= pI_last_to_destroy; pI--) pI->~Titem(); + // remove them + ReduceRawSize(num_items * Titem_size); + } + /** Append one data item at the end (calls Titem_'s default constructor) */ + FORCEINLINE Titem* AppendNew() + { + Titem& dst = *GrowSizeNC(1); // Grow size by one item + Titem* pNewItem = new (&dst) Titem(); // construct the new item by calling in-place new operator + return pNewItem; + } + /** Append the copy of given item at the end of Blob (using copy constructor) */ + FORCEINLINE Titem* Append(const Titem& src) + { + Titem& dst = *GrowSizeNC(1); // Grow size by one item + Titem* pNewItem = new (&dst) Titem(src); // construct the new item by calling in-place new operator with copy ctor() + return pNewItem; + } + /** Add given items (ptr + number of items) at the end of blob */ + FORCEINLINE Titem* Append(const Titem* pSrc, int num_items) + { + Titem* pDst = GrowSizeNC(num_items); + Titem* pDstOrg = pDst; + Titem* pDstEnd = pDst + num_items; + while (pDst < pDstEnd) new (pDst++) Titem(*(pSrc++)); + return pDstOrg; + } + /** Remove item with the given index by replacing it by the last item and reducing the size by one */ + FORCEINLINE void RemoveBySwap(int idx) + { + CheckIdx(idx); + // destroy removed item + Titem* pRemoved = Data(idx); + RemoveBySwap(pRemoved); + } + /** Remove item given by pointer replacing it by the last item and reducing the size by one */ + FORCEINLINE void RemoveBySwap(Titem* pItem) + { + Titem* pLast = Data(Size() - 1); + assert(pItem >= Data() && pItem <= pLast); + // move last item to its new place + if (pItem != pLast) { + pItem->~Titem_(); + new (pItem) Titem_(*pLast); + } + // destroy the last item + pLast->~Titem_(); + // and reduce the raw blob size + ReduceRawSize(Titem_size); + } + /** Ensures that given number of items can be added to the end of Blob. Returns pointer to the + * first free (unused) item */ + FORCEINLINE Titem* MakeFreeSpace(int num_items) { return (Titem*)MakeRawFreeSpace(num_items * Titem_size); } +}; + +// simple string implementation +struct CStrA : public CBlobT<char> +{ + typedef CBlobT<char> base; + CStrA(const char* str = NULL) {Append(str);} + FORCEINLINE CStrA(const CBlobBaseSimple& src) : base(src) {} + void Append(const char* str) {if (str != NULL && str[0] != '\0') base::Append(str, (int)strlen(str));} +}; + +#endif /* BLOB_HPP */ |