| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | #pragma once | ||
| 2 | |||
| 3 | /**\file | ||
| 4 | * \brief Provides implementation of simple short memory block | ||
| 5 | * | ||
| 6 | * A declaration of plain memory block allocation strategy. | ||
| 7 | * */ | ||
| 8 | |||
| 9 | #include "na64util/mem/alloc.hh" | ||
| 10 | #include "na64util/str-fmt.hh" | ||
| 11 | |||
| 12 | #include <cassert> | ||
| 13 | |||
| 14 | namespace na64dp { | ||
| 15 | namespace errors { | ||
| 16 | |||
| 17 | /**\brief Indicates exhaustion of the statically pre-allocated block */ | ||
| 18 | class PreallocatedBlockExhausted : public GenericRuntimeError { | ||
| 19 | public: | ||
| 20 | const void * blockPtr; | ||
| 21 | const size_t preallocatedBlockLength | ||
| 22 | , lastRequestedLength | ||
| 23 | ; | ||
| 24 | |||
| 25 | ✗ | PreallocatedBlockExhausted( void * blockPtr_ | |
| 26 | , size_t preallocatedBlockLength_ | ||
| 27 | , size_t lastRequestedLength_ | ||
| 28 | ✗ | ) : GenericRuntimeError( util::format( | |
| 29 | "Pre-allocated memory block %p of" | ||
| 30 | " size %zub depleted with last" | ||
| 31 | " allocation of size %zub." | ||
| 32 | , blockPtr_ | ||
| 33 | , preallocatedBlockLength_ | ||
| 34 | , lastRequestedLength_ | ||
| 35 | ).c_str() ) | ||
| 36 | ✗ | , blockPtr(blockPtr_) | |
| 37 | ✗ | , preallocatedBlockLength(preallocatedBlockLength_) | |
| 38 | ✗ | , lastRequestedLength(lastRequestedLength_) | |
| 39 | ✗ | {} | |
| 40 | }; | ||
| 41 | |||
| 42 | } // namespace ::na64dp::errors | ||
| 43 | |||
| 44 | namespace mem { | ||
| 45 | |||
| 46 | /**\brief A single, limited memory block | ||
| 47 | * | ||
| 48 | * This is an extremely simple allocator strategy implementation. It is | ||
| 49 | * designed for a single-pass with low allocations (in fact, it does not | ||
| 50 | * even de-allocates memory). It is expected that this allocator will | ||
| 51 | * leverage CPU cache for computation-intensive operations by avoiding | ||
| 52 | * memory fragmentation and benefit from CPU cache an small data chunks. | ||
| 53 | * | ||
| 54 | * Recommended usage is for short, CPU-intensive calculations with arithmetics, | ||
| 55 | * container lookup, with few insertions of data ~10kbytes. Do not use it for | ||
| 56 | * general purpose. | ||
| 57 | * | ||
| 58 | * \warning | ||
| 59 | * De-allocation of managed memory block is done only on the deletion of | ||
| 60 | * strategy itself. | ||
| 61 | * \warning | ||
| 62 | * Memory block capacity is limited, it won't resize on the overflow | ||
| 63 | */ | ||
| 64 | class PlainBlock { | ||
| 65 | public: | ||
| 66 | typedef uint32_t Size_t; | ||
| 67 | private: | ||
| 68 | char *_block ///< First byte addr of mem block | ||
| 69 | , *_blockEnd ///< Last byte addr of mem block | ||
| 70 | , *_cur ///< Current position in mem block | ||
| 71 | ; | ||
| 72 | protected: // except for "Allocator<>" | ||
| 73 | ///\brief Allocates memory sub-block | ||
| 74 | /// | ||
| 75 | /// Accessed by `Allocator` instance. | ||
| 76 | 67 | template<typename T> T * acquire(Size_t sz) { | |
| 77 | 67 | _cur += sz*sizeof(T); | |
| 78 |
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67 | if( _cur >= _blockEnd ) { |
| 79 | ✗ | throw errors::PreallocatedBlockExhausted( | |
| 80 | ✗ | _block, _blockEnd - _block, sz); | |
| 81 | } | ||
| 82 | 67 | return reinterpret_cast<T *>(_cur - sz*sizeof(T)); | |
| 83 | } | ||
| 84 | ///\brief Frees memory sub-block | ||
| 85 | /// | ||
| 86 | /// Accessed by `Allocator` instance. | ||
| 87 | 86 | template<typename T> void release(T * p, Size_t sz) { | |
| 88 | // ... do nothing | ||
| 89 | } | ||
| 90 | ///\brief Returns maximum capacity of objects of certain type | ||
| 91 | /// | ||
| 92 | /// Accessed by `Allocator` instance. | ||
| 93 | template<typename T> Size_t max_for() const noexcept { | ||
| 94 | return (_blockEnd - _cur)/sizeof(T); | ||
| 95 | } | ||
| 96 | public: | ||
| 97 | /// Explicitly prohibit the copy ctr to avoid copying | ||
| 98 | PlainBlock( const PlainBlock & ) = delete; | ||
| 99 | |||
| 100 | /// Constructs the block of certain size (in bytes) | ||
| 101 | 10 | PlainBlock( void * blockBgn, size_t len ) { | |
| 102 | 10 | _block = _cur = static_cast<char*>(blockBgn); | |
| 103 | 10 | _blockEnd = _block + len; | |
| 104 | 10 | } | |
| 105 | |||
| 106 | /// Does nothing. | ||
| 107 | 10 | ~PlainBlock() {;} | |
| 108 | |||
| 109 | /// Returns handle (allocator) to typed "pool" | ||
| 110 | template<typename T> Allocator<T, PlainBlock> of() { return Allocator<T, PlainBlock>(*this); } | ||
| 111 | |||
| 112 | /// Sets the "current" pointer to the beginning of the block, thus | ||
| 113 | /// invalidating all previous allocations. | ||
| 114 | 18 | void reset() { _cur = _block; } | |
| 115 | |||
| 116 | #if 0 | ||
| 117 | /// A "fast" object allocation method forwarding its arguments to ctr | ||
| 118 | /// | ||
| 119 | /// \returns `std::shared_ptr` with proper deleter | ||
| 120 | template<typename T, typename... Args> std::shared_ptr<T> | ||
| 121 | create_object( Args&&... args ) { | ||
| 122 | return std::allocate_shared< T, Allocator<T, PlainBlock> >( | ||
| 123 | of<T>(), std::forward<Args>(args)...); | ||
| 124 | } | ||
| 125 | #endif | ||
| 126 | |||
| 127 | template<typename T, typename Strategy> friend class Allocator; | ||
| 128 | }; | ||
| 129 | |||
| 130 | #if 0 | ||
| 131 | /// A "fast" object allocation function acting on top of our default allocator | ||
| 132 | template<typename T, typename... Args> std::shared_ptr<T> | ||
| 133 | fast_new( PlainBlock & alloc, Args&&... args ) { | ||
| 134 | return std::allocate_shared< T, | ||
| 135 | na64dp::mem::Allocator<T, PlainBlock> >( alloc.of<T>(), | ||
| 136 | std::forward<Args>(args)...); | ||
| 137 | } | ||
| 138 | #endif | ||
| 139 | |||
| 140 | } // namespace ::na64dp::mem | ||
| 141 | } // namespace na64dp | ||
| 142 | |||
| 143 |