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Rename Allocator.expand to reallocateInPlace

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Rename and extend Allocator.expand to reallocateInPlace. The problem is
that realloc for example doesn't guarante that the shrinking of the
memory block won't cause address change. So not only expanding should
have "in place" version, but the shrinking as well.
This commit is contained in:
Eugen Wissner
2017-01-18 09:33:39 +01:00
parent c7eb233fc7
commit 5fa9bd7b49
3 changed files with 85 additions and 59 deletions
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44
source/tanya/memory/mmappool.d
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@ -231,7 +231,10 @@ final class MmapPool : Allocator
}
/**
* Expands a memory block in place.
* Reallocates a memory block in place if possible or returns
* $(D_KEYWORD false). This function cannot be used to allocate or
* deallocate memory, so if $(D_PARAM p) is $(D_KEYWORD null) or
* $(D_PARAM size) is `0`, it should return $(D_KEYWORD false).
*
* Params:
* p = A pointer to the memory block.
@ -239,16 +242,18 @@ final class MmapPool : Allocator
*
* Returns: $(D_KEYWORD true) if successful, $(D_KEYWORD false) otherwise.
*/
bool expand(ref void[] p, in size_t size) shared nothrow @nogc
bool reallocateInPlace(ref void[] p, in size_t size) shared nothrow @nogc
{
if (size <= p.length)
{
return true;
}
if (p is null)
if (p is null || size == 0)
{
return false;
}
if (size <= p.length)
{
// Leave the block as is.
p = p.ptr[0 .. size];
return true;
}
Block block1 = cast(Block) (p.ptr - BlockEntry.sizeof);
if (block1.size >= size)
@ -298,22 +303,22 @@ final class MmapPool : Allocator
nothrow unittest
{
void[] p;
assert(!MmapPool.instance.expand(p, 5));
assert(!MmapPool.instance.reallocateInPlace(p, 5));
assert(p is null);
p = MmapPool.instance.allocate(1);
auto orig = p.ptr;
assert(MmapPool.instance.expand(p, 2));
assert(MmapPool.instance.reallocateInPlace(p, 2));
assert(p.length == 2);
assert(p.ptr == orig);
assert(MmapPool.instance.expand(p, 4));
assert(MmapPool.instance.reallocateInPlace(p, 4));
assert(p.length == 4);
assert(p.ptr == orig);
assert(MmapPool.instance.expand(p, 2));
assert(p.length == 4);
assert(MmapPool.instance.reallocateInPlace(p, 2));
assert(p.length == 2);
assert(p.ptr == orig);
MmapPool.instance.deallocate(p);
@ -339,17 +344,12 @@ final class MmapPool : Allocator
}
return false;
}
else if (size <= p.length)
{
// Leave the block as is.
p = p.ptr[0 .. size];
return true;
}
else if (expand(p, size))
else if (reallocateInPlace(p, size))
{
return true;
}
// Can't extend, allocate a new block, copy and delete the previous.
// Can't reallocate in place, allocate a new block,
// copy and delete the previous one.
void[] reallocP = allocate(size);
if (reallocP is null)
{
@ -587,7 +587,7 @@ final class MmapPool : Allocator
}
// A lot of allocations/deallocations, but it is the minimum caused a
// segmentation fault because MmapPool expand moves a block wrong.
// segmentation fault because MmapPool reallocateInPlace moves a block wrong.
unittest
{
auto a = MmapPool.instance.allocate(16);
@ -602,7 +602,7 @@ unittest
MmapPool.instance.deallocate(c);
a = MmapPool.instance.allocate(50);
MmapPool.instance.expand(a, 64);
MmapPool.instance.reallocateInPlace(a, 64);
MmapPool.instance.deallocate(a);
a = MmapPool.instance.allocate(1);