doylet/Dqn
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Improve realloc for MemBuffers in default callback

Browse Source 
Realloc now works for arbitrary length of blocks in MemBuffers and also works
slightly more efficiently than the old implementation.
This commit is contained in:
Doyle Thai 2017-05-06 17:28:57 +10:00
parent 6fe75928f0
commit f9555d8edb
2 changed files with 224 additions and 68 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

235
dqn.h
View File

@ -125,9 +125,9 @@ typedef struct DqnTempBuffer
} DqnTempBuffer;
DQN_FILE_SCOPE bool DqnMemBuffer_InitWithFixedMem (DqnMemBuffer *const buffer, u8 *const mem, const size_t memSize, const u32 byteAlign = 4); // Use preallocated memory, no further allocations, returns NULL on allocate if out of space
DQN_FILE_SCOPE bool DqnMemBuffer_InitWithFixedSize(DqnMemBuffer *const buffer, size_t size, const bool zeroClear, const u32 byteAlign = 4); // Single allocation from platform, no further allocations, returns NULL of allocate if out of space
DQN_FILE_SCOPE bool DqnMemBuffer_Init (DqnMemBuffer *const buffer, size_t size, const bool zeroClear, const u32 byteAlign = 4); // Allocates from platform dynamically as space runs out
DQN_FILE_SCOPE bool DqnMemBuffer_InitWithFixedMem (DqnMemBuffer *const buffer, u8 *const mem, const size_t memSize, const u32 byteAlign = 4); // Use preallocated memory, no further allocations, returns NULL on allocate if out of space
DQN_FILE_SCOPE bool DqnMemBuffer_InitWithFixedSize(DqnMemBuffer *const buffer, size_t size, const bool zeroClear, const u32 byteAlign = 4); // Single allocation from platform, no further allocations, returns NULL of allocate if out of space
DQN_FILE_SCOPE bool DqnMemBuffer_Init (DqnMemBuffer *const buffer, size_t size, const bool zeroClear, const u32 byteAlign = 4); // Allocates from platform dynamically as space runs out
DQN_FILE_SCOPE void *DqnMemBuffer_Allocate (DqnMemBuffer *const buffer, size_t size); // Returns NULL if out of space and buffer is using fixed memory/size, or platform allocation fails
DQN_FILE_SCOPE void DqnMemBuffer_Free (DqnMemBuffer *const buffer); // Frees all blocks belonging to this buffer
@ -143,6 +143,13 @@ DQN_FILE_SCOPE void DqnMemBuffer_ClearCurrBlock(DqnMemBuffer *const buffer, con
DQN_FILE_SCOPE DqnTempBuffer DqnMemBuffer_BeginTempRegion(DqnMemBuffer *const buffer);
DQN_FILE_SCOPE void DqnMemBuffer_EndTempRegion (DqnTempBuffer tempBuffer);
// (OPTIONAL) DqnMemBuffer Advanced API
// This is useful for forcing a new block to be used. AllocateCompatibleBlock
// will fail if the supplied buffer has flags set such that the buffer is not
// allowed to have new blocks.
DQN_FILE_SCOPE DqnMemBufferBlock *DqnMemBuffer_AllocateCompatibleBlock(const DqnMemBuffer *const buffer, size_t size);
DQN_FILE_SCOPE bool DqnMemBuffer_AttachBlock (DqnMemBuffer *const buffer, DqnMemBufferBlock *const newBlock);
////////////////////////////////////////////////////////////////////////////////
// DqnMemAPI - Memory API, For using custom allocators
////////////////////////////////////////////////////////////////////////////////
@ -175,7 +182,12 @@ typedef struct DqnMemAPICallbackInfo
union {
struct { size_t requestSize; }; // DqnMemAPICallbackType_Alloc
struct { void *ptrToFree; }; // DqnMemAPICallbackType_Free
struct { size_t newRequestSize; void *oldMemPtr; }; // DqnMemAPICallbackType_Realloc
struct
{
size_t newRequestSize;
void *oldMemPtr;
size_t oldSize;
}; // DqnMemAPICallbackType_Realloc
};
} DqnMemAPICallbackInfo;
@ -267,10 +279,13 @@ bool DqnArray_Grow(DqnArray<T> *array)
size_t newCapacity = (size_t)(array->capacity * GROWTH_FACTOR);
if (newCapacity == array->capacity) newCapacity++;
size_t allocateSize = (size_t)newCapacity * sizeof(T);
size_t oldSize = (size_t)array->capacity * sizeof(T);
size_t newSize = (size_t)newCapacity * sizeof(T);
DqnMemAPICallbackResult memResult = {};
DqnMemAPICallbackInfo info = DqnMemAPICallback_InfoAskReallocInternal(
array->memAPI, array->data, allocateSize);
array->memAPI, array->data, oldSize, newSize);
array->memAPI.callback(info, &memResult);
DQN_ASSERT(memResult.type == DqnMemAPICallbackType_Realloc);
@ -1311,6 +1326,38 @@ DqnMemBuffer_AllocateBlockInternal(u32 byteAlign, size_t size)
return result;
}
DQN_FILE_SCOPE DqnMemBufferBlock *
DqnMemBuffer_AllocateCompatibleBlock(const DqnMemBuffer *const buffer, size_t size)
{
if (!buffer) return NULL;
if (buffer->flags & DqnMemBufferFlag_IsFixedMemoryFromUser) return NULL;
if (!(buffer->flags & DqnMemBufferFlag_IsExpandable)) return NULL;
DqnMemBufferBlock *block =
DqnMemBuffer_AllocateBlockInternal(buffer->byteAlign, size);
return block;
}
DQN_FILE_SCOPE bool DqnMemBuffer_AttachBlock(DqnMemBuffer *const buffer,
DqnMemBufferBlock *const newBlock)
{
if (!buffer || !newBlock) return false;
if (buffer->flags & DqnMemBufferFlag_IsFixedMemoryFromUser) return false;
// TODO(doyle): If we make InitWithFixedSize buffer the Is_Expandable
// flag is not set. But if you free the buffery and try to allocate to
// it again since the flag is not set, the buffer becomes useless as we
// can't allocate to it anymore. How should we solve this?
if (buffer->flags & DqnMemBufferFlag_IsExpandable)
{
newBlock->prevBlock = buffer->block;
buffer->block = newBlock;
return true;
}
return false;
}
DQN_FILE_SCOPE bool DqnMemBuffer_InitWithFixedMem(DqnMemBuffer *const buffer,
u8 *const mem,
const size_t memSize,
@ -1374,33 +1421,32 @@ DQN_FILE_SCOPE void *DqnMemBuffer_Allocate(DqnMemBuffer *const buffer, size_t si
if (!buffer->block ||
(buffer->block->used + alignedSize) > buffer->block->size)
{
if (buffer->flags & DqnMemBufferFlag_IsFixedMemoryFromUser) return NULL;
size_t newBlockSize;
// TODO(doyle): Allocate block size based on the aligned size or
// a minimum block size? Not allocate based on the current block
// size
if (buffer->block) newBlockSize = DQN_MAX(alignedSize, buffer->block->size);
else newBlockSize = alignedSize;
// TODO(doyle): If we make InitWithFixedSize buffer the Is_Expandable
// flag is not set. But if you free the buffery and try to allocate to
// it again since the flag is not set, the buffer becomes useless as we
// can't allocate to it anymore. How should we solve this?
if (buffer->flags & DqnMemBufferFlag_IsExpandable)
DqnMemBufferBlock *newBlock = DqnMemBuffer_AllocateCompatibleBlock(buffer, newBlockSize);
if (newBlock)
{
size_t newBlockSize;
// TODO(doyle): Allocate block size based on the aligned size or
// a minimum block size? Not allocate based on the current block
// size
if (buffer->block)
newBlockSize = DQN_MAX(alignedSize, buffer->block->size);
else
newBlockSize = alignedSize;
if (!DqnMemBuffer_AttachBlock(buffer, newBlock))
{
// IMPORTANT(doyle): This should be impossible, considering that
// AllocateCompatibleBlock checks the preconditions that the new
// block should be able to be attached.
DqnMemBufferBlock *newBlock = DqnMemBuffer_AllocateBlockInternal(
buffer->byteAlign, newBlockSize);
if (!newBlock) return NULL;
newBlock->prevBlock = buffer->block;
buffer->block = newBlock;
// But if we somehow reach this, we need to free the block
// otherwise memory is leaked.
DQN_ASSERT(DQN_INVALID_CODE_PATH);
return NULL;
}
}
else
{
// TODO: Better notifying to user, out of space in buffer
// TODO: Better notifying to user, out of space in buffer OR buffer
// is configured such that new blocks are not allowed.
return NULL;
}
}
@ -1418,7 +1464,7 @@ DQN_FILE_SCOPE void *DqnMemBuffer_Allocate(DqnMemBuffer *const buffer, size_t si
void *result = alignedResult;
buffer->block->used += (alignedSize + alignmentOffset);
DQN_ASSERT(buffer->block->used <= buffer->block->size);
return result;
}
@ -1511,13 +1557,15 @@ DQN_FILE_SCOPE void DqnMemBuffer_EndTempRegion(DqnTempBuffer tempBuffer)
FILE_SCOPE inline DqnMemAPICallbackInfo
DqnMemAPICallback_InfoAskReallocInternal(const DqnMemAPI memAPI,
void *const oldMemPtr,
const size_t size)
const size_t oldSize,
const size_t newSize)
{
DqnMemAPICallbackInfo info = {};
info.type = DqnMemAPICallbackType_Realloc;
info.userContext = memAPI.userContext;
info.newRequestSize = size;
info.newRequestSize = newSize;
info.oldMemPtr = oldMemPtr;
info.oldSize = oldSize;
return info;
}
@ -1556,6 +1604,7 @@ void DqnMemAPI_ValidateCallbackInfo(DqnMemAPICallbackInfo info)
case DqnMemAPICallbackType_Realloc:
{
DQN_ASSERT(info.oldSize > 0);
DQN_ASSERT(info.requestSize > 0);
DQN_ASSERT(info.oldMemPtr);
}
@ -1580,7 +1629,7 @@ DqnMemAPI_DefaultUseCallocCallbackInternal(DqnMemAPICallbackInfo info,
case DqnMemAPICallbackType_Alloc:
{
result->type = info.type;
result->newMemPtr = DqnMem_Alloc(info.requestSize);
result->newMemPtr = DqnMem_Calloc(info.requestSize);
}
break;
@ -1635,44 +1684,109 @@ DqnMemAPI_DefaultUseMemBufferCallbackInternal(DqnMemAPICallbackInfo info,
// without having to worry about part of blocks holding data
// belonging to other objects.
DQN_ASSERT(result);
DQN_ASSERT(!buffer->block->prevBlock);
DQN_ASSERT(info.oldMemPtr == buffer->block->memory);
result->type = info.type;
// TODO(doyle): In regards to above, we have no way of ensuring that
// the user doesn't use this buffer elsewhere, which would
// invalidate all our assumptions. We can fix this maybe, by making
// the DefaultUseMemBuffer allocate its own DqnMemBuffer privately
// that the user can't see externally to enforce this invariant.
size_t alignedSize = DQN_ALIGN_POW_N(info.newRequestSize, buffer->byteAlign);
if (alignedSize > buffer->block->size)
u8 *oldPtr = (u8 *)info.oldMemPtr;
DqnMemBufferBlock *currBlock = buffer->block;
for (;;)
{
DqnMemBufferBlock *oldBlock = buffer->block;
result->newMemPtr = DqnMemBuffer_Allocate(buffer, alignedSize);
// NOTE(doyle): Block containing our data must exist otherwise
// it has been invalidly deleted without us knowing, or it
// doesn't belong to the buffer the memAPI is using
if (!currBlock) DQN_ASSERT(DQN_INVALID_CODE_PATH);
if (result->newMemPtr)
if (oldPtr >= currBlock->memory &&
oldPtr < (currBlock->memory + currBlock->size))
{
DqnMemBufferBlock *newBlock = buffer->block;
DQN_ASSERT(oldBlock != newBlock);
break;
}
for (u32 i = 0; i < oldBlock->used; i++)
newBlock->memory[i] = oldBlock->memory[i];
currBlock = currBlock->prevBlock;
}
newBlock->used = oldBlock->used;
DqnMemBuffer_FreeBlock(buffer, oldBlock);
size_t alignedSize =
DQN_ALIGN_POW_N(info.newRequestSize, buffer->byteAlign);
// If true, then this block ONLY has data that this MemAPI has
// allocated which means it's valid for us to completely free it
// or allocate further within it.
DqnMemBufferBlock *const oldBlock = currBlock;
if (info.oldSize == oldBlock->used)
{
// NOTE(doyle): If size is the same as used, then I'm pretty
// sure this guarantees that the old memory is a ptr to the
// base of the memory block.
DQN_ASSERT(oldPtr == oldBlock->memory);
if (alignedSize > oldBlock->size)
{
result->newMemPtr =
DqnMemBuffer_Allocate(buffer, alignedSize);
if (result->newMemPtr)
{
DqnMemBufferBlock *newBlock = buffer->block;
DQN_ASSERT(oldBlock != newBlock);
for (u32 i = 0; i < oldBlock->used; i++)
newBlock->memory[i] = oldBlock->memory[i];
newBlock->used = alignedSize;
DqnMemBuffer_FreeBlock(buffer, oldBlock);
}
}
else
{
// Otherwise, the current block still has enough space
// so we can realloc in place.
// TODO(doyle): Somewhat hacky, we clear the curr block
// pointer, and don't zero it out, and just reallocate
// the aligned size.
DqnMemBuffer_ClearCurrBlock(buffer, false);
result->newMemPtr =
DqnMemBuffer_Allocate(buffer, alignedSize);
}
return;
}
// TODO(doyle): How to free the left over data from the old block?
// TODO(doyle): Think about putting the old realloc block, not at
// the front of the list, since when we realloc, we search our block
// list for the mem block that contains our data anyway so the
// realloc block does NOT have to be at the front of the list to use
// it.
// If we place the block behind the front of the list, then we also
// need to fix the logic above using Allocate() which will
// automatically place the block in front of the list. This way we
// can take advantage of whatever free space is left in the block we
// just left, instead of leaving it dead.
// TODO(doyle): If this code branch occurs, then when we get around
// to implementing memory profiling, we're going to want to mark
// this as dead memory.
// Otherwise, the more difficult case. This block contains other
// data that has been allocated to it. The easy option is to
// just allocate a new block and leave the old data lying around.
// We force a new block to be attached which will hold our realloced
// data.
DqnMemBufferBlock *newBlock =
DqnMemBuffer_AllocateCompatibleBlock(buffer, alignedSize);
if (newBlock)
{
if (DqnMemBuffer_AttachBlock(buffer, newBlock))
{
DQN_ASSERT(buffer->block != oldBlock &&
buffer->block == newBlock);
result->newMemPtr = buffer->block->memory;
for (u32 i = 0; i < info.oldSize; i++)
newBlock->memory[i] = oldPtr[i];
newBlock->used = alignedSize;
}
}
else
{
// Otherwise, the current block still has enough space so we can
// realloc in place.
// TODO(doyle): Somewhat hacky, we clear the curr block pointer,
// and don't zero it out, and just reallocate the aligned size.
DqnMemBuffer_ClearCurrBlock(buffer, false);
result->newMemPtr = DqnMemBuffer_Allocate(buffer, alignedSize);
}
DQN_ASSERT(!buffer->block->prevBlock);
}
break;
@ -1701,7 +1815,6 @@ DQN_FILE_SCOPE DqnMemAPI DqnMemAPI_DefaultUseMemBuffer(DqnMemBuffer *const buffe
// TODO(doyle): We assert that the buffer has to be a brand new mem buffer.
// Is this the correct design choice?
DQN_ASSERT(buffer && buffer->block);
DQN_ASSERT(!buffer->block->prevBlock && buffer->block->used == 0);
DqnMemAPI result = {};
result.callback = DqnMemAPI_DefaultUseMemBufferCallbackInternal;

57
dqn_unit_test.cpp
View File

@ -845,16 +845,59 @@ void ArrayTest()
ArrayTestMemAPIInternal(&array, DqnMemAPI_DefaultUseCalloc());
DqnMemBuffer largeEnoughBuffer = {};
DqnMemBuffer_Init(&largeEnoughBuffer, DQN_MEGABYTE(1), false);
ArrayTestMemAPIInternal(&array, DqnMemAPI_DefaultUseMemBuffer(&largeEnoughBuffer));
DqnMemBuffer_Free(&largeEnoughBuffer);
{
size_t size = DQN_MEGABYTE(1);
// Empty buffer
{
DqnMemBuffer_Init(&largeEnoughBuffer, size, false);
ArrayTestMemAPIInternal(
&array, DqnMemAPI_DefaultUseMemBuffer(&largeEnoughBuffer));
DqnMemBuffer_Free(&largeEnoughBuffer);
}
// Allocate data to buffer, and cause realloc to have to create a new
// block
{
DqnMemBuffer_Init(&largeEnoughBuffer, size, false);
size_t usedSize = (size_t)(size * 0.5f);
u8 *usedData =
(u8 *)DqnMemBuffer_Allocate(&largeEnoughBuffer, usedSize);
for (u32 i = 0; i < usedSize; i++)
usedData[i] = 'a';
ArrayTestMemAPIInternal(
&array, DqnMemAPI_DefaultUseMemBuffer(&largeEnoughBuffer));
DqnMemBuffer_Free(&largeEnoughBuffer);
}
}
DqnMemBuffer smallBuffer = {};
DqnMemBuffer_Init(&smallBuffer, 8, false);
ArrayTestMemAPIInternal(&array, DqnMemAPI_DefaultUseMemBuffer(&smallBuffer));
DqnMemBuffer_Free(&smallBuffer);
{
size_t size = 8;
// Empty small buffer
{
DqnMemBuffer_Init(&smallBuffer, size, false);
ArrayTestMemAPIInternal(
&array, DqnMemAPI_DefaultUseMemBuffer(&smallBuffer));
DqnMemBuffer_Free(&smallBuffer);
}
// TODO(doyle): Doesn't work for now since after freeing a fixed size
// Allocate data to buffer, force realloc to have to create a new block
{
DqnMemBuffer_Init(&smallBuffer, size, false);
size_t usedSize = (size_t)(size * 0.5f);
u8 *usedData = (u8 *)DqnMemBuffer_Allocate(&smallBuffer, usedSize);
for (u32 i = 0; i < usedSize; i++)
usedData[i] = 'a';
ArrayTestMemAPIInternal(
&array, DqnMemAPI_DefaultUseMemBuffer(&smallBuffer));
DqnMemBuffer_Free(&smallBuffer);
}
}
// TODO(doyle): Doesn't work for now since after freeing a fixed size
// buffer, it becomes useless as the not set Is_Expandable flag blocks any
// further allocations.
#if 0