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MemoryPool: store slots at the beginning of the pool

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This commit is contained in:
Benoit Blanchon
2023-06-14 11:41:03 +02:00
parent 56b3b4d5a9
commit 437307a955
1 changed files with 14 additions and 39 deletions
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53
src/ArduinoJson/Memory/MemoryPool.hpp
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@ -62,7 +62,7 @@ class MemoryPool {
}
size_t size() const {
size_t total = size_t(end_ - right_);
size_t total = size_t(right_ - begin_);
for (auto node = strings_; node; node = node->next)
total += sizeofString(node->length);
return total;
@ -77,8 +77,9 @@ class MemoryPool {
overflowed_ = true;
return 0;
}
right_ -= bytes;
return right_;
auto p = right_;
right_ += bytes;
return p;
}
template <typename TAdaptedString>
@ -166,13 +167,13 @@ class MemoryPool {
}
void clear() {
right_ = end_;
right_ = begin_;
overflowed_ = false;
deallocAllStrings();
}
bool canAlloc(size_t bytes) const {
return begin_ + bytes <= right_;
return right_ + bytes <= end_;
}
// Workaround for missing placement new
@ -181,43 +182,17 @@ class MemoryPool {
}
ptrdiff_t shrinkToFit() {
ptrdiff_t bytes_reclaimed = squash();
if (bytes_reclaimed == 0)
return 0;
auto oldBegin = begin_;
auto newCapacity = size_t(right_ - begin_);
void* old_ptr = begin_;
void* new_ptr = allocator_->reallocate(old_ptr, capacity());
begin_ =
reinterpret_cast<char*>(allocator_->reallocate(begin_, newCapacity));
end_ = right_ = begin_ + newCapacity;
ptrdiff_t ptr_offset =
static_cast<char*>(new_ptr) - static_cast<char*>(old_ptr);
movePointers(ptr_offset);
return ptr_offset - bytes_reclaimed;
return begin_ - oldBegin;
}
private:
ptrdiff_t squash() {
char* new_right = addPadding(begin_);
if (new_right >= right_)
return 0;
size_t right_size = static_cast<size_t>(end_ - right_);
memmove(new_right, right_, right_size);
ptrdiff_t bytes_reclaimed = right_ - new_right;
right_ = new_right;
end_ = new_right + right_size;
return bytes_reclaimed;
}
// Move all pointers together
// This funcion is called after a realloc.
void movePointers(ptrdiff_t offset) {
begin_ += offset;
right_ += offset;
end_ += offset;
}
void deallocAllStrings() {
while (strings_) {
auto node = strings_;
@ -228,8 +203,8 @@ class MemoryPool {
void allocPool(size_t capa) {
auto buf = capa ? reinterpret_cast<char*>(allocator_->allocate(capa)) : 0;
begin_ = buf;
end_ = right_ = buf ? buf + capa : 0;
begin_ = right_ = buf;
end_ = buf ? buf + capa : 0;
ARDUINOJSON_ASSERT(isAligned(begin_));
ARDUINOJSON_ASSERT(isAligned(right_));
ARDUINOJSON_ASSERT(isAligned(end_));