The Tor Browser: gfx/angle/src/compiler/PoolAlloc.h@6474c204b198 (annotated)

gfx/angle/src/compiler/PoolAlloc.h@6474c204b198 (annotated)

gfx/angle/src/compiler/PoolAlloc.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 //
 // Copyright (c) 2002-2010 The ANGLE Project Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 #ifndef _POOLALLOC_INCLUDED_
 #define _POOLALLOC_INCLUDED_
 #ifdef _DEBUG
 #define GUARD_BLOCKS  // define to enable guard block sanity checking
 #endif
 //
 // This header defines an allocator that can be used to efficiently
 // allocate a large number of small requests for heap memory, with the
 // intention that they are not individually deallocated, but rather
 // collectively deallocated at one time.
 //
 // This simultaneously
 //
 // * Makes each individual allocation much more efficient; the
 //     typical allocation is trivial.
 // * Completely avoids the cost of doing individual deallocation.
 // * Saves the trouble of tracking down and plugging a large class of leaks.
 //
 // Individual classes can use this allocator by supplying their own
 // new and delete methods.
 //
 // STL containers can use this allocator by using the pool_allocator
 // class as the allocator (second) template argument.
 //
 #include <stddef.h>
 #include <string.h>
 #include <vector>
 // If we are using guard blocks, we must track each indivual
 // allocation.  If we aren't using guard blocks, these
 // never get instantiated, so won't have any impact.
 //
 class TAllocation {
 public:
     TAllocation(size_t size, unsigned char* mem, TAllocation* prev = 0) :
         size(size), mem(mem), prevAlloc(prev) {
         // Allocations are bracketed:
         //    [allocationHeader][initialGuardBlock][userData][finalGuardBlock]
         // This would be cleaner with if (guardBlockSize)..., but that
         // makes the compiler print warnings about 0 length memsets,
         // even with the if() protecting them.
 #ifdef GUARD_BLOCKS
         memset(preGuard(), guardBlockBeginVal, guardBlockSize);
         memset(data(),      userDataFill,       size);
         memset(postGuard(), guardBlockEndVal,   guardBlockSize);
 #endif
     }
     void check() const {
         checkGuardBlock(preGuard(),  guardBlockBeginVal, "before");
         checkGuardBlock(postGuard(), guardBlockEndVal,   "after");
     }
     void checkAllocList() const;
     // Return total size needed to accomodate user buffer of 'size',
     // plus our tracking data.
     inline static size_t allocationSize(size_t size) {
         return size + 2 * guardBlockSize + headerSize();
     }
     // Offset from surrounding buffer to get to user data buffer.
     inline static unsigned char* offsetAllocation(unsigned char* m) {
         return m + guardBlockSize + headerSize();
     }
 private:
     void checkGuardBlock(unsigned char* blockMem, unsigned char val, const char* locText) const;
     // Find offsets to pre and post guard blocks, and user data buffer
     unsigned char* preGuard()  const { return mem + headerSize(); }
     unsigned char* data()      const { return preGuard() + guardBlockSize; }
     unsigned char* postGuard() const { return data() + size; }
     size_t size;                  // size of the user data area
     unsigned char* mem;           // beginning of our allocation (pts to header)
     TAllocation* prevAlloc;       // prior allocation in the chain
     // Support MSVC++ 6.0
     const static unsigned char guardBlockBeginVal;
     const static unsigned char guardBlockEndVal;
     const static unsigned char userDataFill;
     const static size_t guardBlockSize;
 #ifdef GUARD_BLOCKS
     inline static size_t headerSize() { return sizeof(TAllocation); }
 #else
     inline static size_t headerSize() { return 0; }
 #endif
 };
 //
 // There are several stacks.  One is to track the pushing and popping
 // of the user, and not yet implemented.  The others are simply a
 // repositories of free pages or used pages.
 //
 // Page stacks are linked together with a simple header at the beginning
 // of each allocation obtained from the underlying OS.  Multi-page allocations
 // are returned to the OS.  Individual page allocations are kept for future
 // re-use.
 //
 // The "page size" used is not, nor must it match, the underlying OS
 // page size.  But, having it be about that size or equal to a set of
 // pages is likely most optimal.
 //
 class TPoolAllocator {
 public:
     TPoolAllocator(int growthIncrement = 8*1024, int allocationAlignment = 16);
     //
     // Don't call the destructor just to free up the memory, call pop()
     //
     ~TPoolAllocator();
     //
     // Call push() to establish a new place to pop memory too.  Does not
     // have to be called to get things started.
     //
     void push();
     //
     // Call pop() to free all memory allocated since the last call to push(),
     // or if no last call to push, frees all memory since first allocation.
     //
     void pop();
     //
     // Call popAll() to free all memory allocated.
     //
     void popAll();
     //
     // Call allocate() to actually acquire memory.  Returns 0 if no memory
     // available, otherwise a properly aligned pointer to 'numBytes' of memory.
     //
     void* allocate(size_t numBytes);
     //
     // There is no deallocate.  The point of this class is that
     // deallocation can be skipped by the user of it, as the model
     // of use is to simultaneously deallocate everything at once
     // by calling pop(), and to not have to solve memory leak problems.
     //
 protected:
     friend struct tHeader;
     struct tHeader {
         tHeader(tHeader* nextPage, size_t pageCount) :
             nextPage(nextPage),
             pageCount(pageCount)
 #ifdef GUARD_BLOCKS
           , lastAllocation(0)
 #endif
             { }
         ~tHeader() {
 #ifdef GUARD_BLOCKS
             if (lastAllocation)
                 lastAllocation->checkAllocList();
 #endif
         }
         tHeader* nextPage;
         size_t pageCount;
 #ifdef GUARD_BLOCKS
         TAllocation* lastAllocation;
 #endif
     };
     struct tAllocState {
         size_t offset;
         tHeader* page;
     };
     typedef std::vector<tAllocState> tAllocStack;
     // Track allocations if and only if we're using guard blocks
     void* initializeAllocation(tHeader* block, unsigned char* memory, size_t numBytes) {
 #ifdef GUARD_BLOCKS
         new(memory) TAllocation(numBytes, memory, block->lastAllocation);
         block->lastAllocation = reinterpret_cast<TAllocation*>(memory);
 #endif
         // This is optimized entirely away if GUARD_BLOCKS is not defined.
         return TAllocation::offsetAllocation(memory);
     }
     size_t pageSize;        // granularity of allocation from the OS
     size_t alignment;       // all returned allocations will be aligned at
                             // this granularity, which will be a power of 2
     size_t alignmentMask;
     size_t headerSkip;      // amount of memory to skip to make room for the
                             //      header (basically, size of header, rounded
                             //      up to make it aligned
     size_t currentPageOffset;  // next offset in top of inUseList to allocate from
     tHeader* freeList;      // list of popped memory
     tHeader* inUseList;     // list of all memory currently being used
     tAllocStack stack;      // stack of where to allocate from, to partition pool
     int numCalls;           // just an interesting statistic
     size_t totalBytes;      // just an interesting statistic
 private:
     TPoolAllocator& operator=(const TPoolAllocator&);  // dont allow assignment operator
     TPoolAllocator(const TPoolAllocator&);  // dont allow default copy constructor
 };
 //
 // There could potentially be many pools with pops happening at
 // different times.  But a simple use is to have a global pop
 // with everyone using the same global allocator.
 //
 extern TPoolAllocator* GetGlobalPoolAllocator();
 extern void SetGlobalPoolAllocator(TPoolAllocator* poolAllocator);
 //
 // This STL compatible allocator is intended to be used as the allocator
 // parameter to templatized STL containers, like vector and map.
 //
 // It will use the pools for allocation, and not
 // do any deallocation, but will still do destruction.
 //
 template<class T>
 class pool_allocator {
 public:
     typedef size_t size_type;
     typedef ptrdiff_t difference_type;
     typedef T* pointer;
     typedef const T* const_pointer;
     typedef T& reference;
     typedef const T& const_reference;
     typedef T value_type;
     template<class Other>
     struct rebind {
         typedef pool_allocator<Other> other;
     };
     pointer address(reference x) const { return &x; }
     const_pointer address(const_reference x) const { return &x; }
     pool_allocator() : allocator(GetGlobalPoolAllocator()) { }
     pool_allocator(TPoolAllocator& a) : allocator(&a) { }
     pool_allocator(const pool_allocator<T>& p) : allocator(p.allocator) { }
     template <class Other>
     pool_allocator<T>& operator=(const pool_allocator<Other>& p) {
       allocator = p.allocator;
       return *this;
     }
     template<class Other>
     pool_allocator(const pool_allocator<Other>& p) : allocator(&p.getAllocator()) { }
 #if defined(__SUNPRO_CC) && !defined(_RWSTD_ALLOCATOR)
     // libCStd on some platforms have a different allocate/deallocate interface.
     // Caller pre-bakes sizeof(T) into 'n' which is the number of bytes to be
     // allocated, not the number of elements.
     void* allocate(size_type n) {
         return getAllocator().allocate(n);
     }
     void* allocate(size_type n, const void*) {
         return getAllocator().allocate(n);
     }
     void deallocate(void*, size_type) {}
 #else
     pointer allocate(size_type n) {
         return reinterpret_cast<pointer>(getAllocator().allocate(n * sizeof(T)));
     }
     pointer allocate(size_type n, const void*) {
         return reinterpret_cast<pointer>(getAllocator().allocate(n * sizeof(T)));
     }
     void deallocate(pointer, size_type) {}
 #endif  // _RWSTD_ALLOCATOR
     void construct(pointer p, const T& val) { new ((void *)p) T(val); }
     void destroy(pointer p) { p->T::~T(); }
     bool operator==(const pool_allocator& rhs) const { return &getAllocator() == &rhs.getAllocator(); }
     bool operator!=(const pool_allocator& rhs) const { return &getAllocator() != &rhs.getAllocator(); }
     size_type max_size() const { return static_cast<size_type>(-1) / sizeof(T); }
     size_type max_size(int size) const { return static_cast<size_type>(-1) / size; }
     void setAllocator(TPoolAllocator* a) { allocator = a; }
     TPoolAllocator& getAllocator() const { return *allocator; }
 protected:
     TPoolAllocator* allocator;
 };
 #endif // _POOLALLOC_INCLUDED_

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gfx/angle/src/compiler/PoolAlloc.h@6474c204b198 (annotated)

gfx/angle/src/compiler/PoolAlloc.h