OpenVDB
5.2.0
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Concurrent, page-based, dynamically-sized linear data structure with O(1) random access and STL-compliant iterators. It is primarily intended for applications that concurrently insert (a possibly unkown number of) elements into a dynamically growing linear array, and fast random access to said elements. More...
#include <PagedArray.h>
Classes | |
class | ConstIterator |
class | Iterator |
class | Page |
class | ValueBuffer |
Public Types | |
using | ValueType = ValueT |
Public Member Functions | |
PagedArray ()=default | |
Default constructor. More... | |
~PagedArray () | |
Destructor removed all allocated pages. More... | |
PagedArray (const PagedArray &)=delete | |
PagedArray & | operator= (const PagedArray &)=delete |
size_t | push_back (const ValueType &value) |
Thread safe insertion, adds a new element at the end and increases the container size by one and returns the linear offset for the inserted element. More... | |
size_t | push_back_unsafe (const ValueType &value) |
Slightly faster than the thread-safe push_back above. More... | |
void | shrink_to_fit () |
Reduce the page table to fix the current size. More... | |
ValueType & | operator[] (size_t i) |
Return a reference to the value at the specified offset. More... | |
const ValueType & | operator[] (size_t i) const |
Return a const-reference to the value at the specified offset. More... | |
void | fill (const ValueType &v) |
Set all elements in the page table to the specified value. More... | |
bool | copy (ValueType *p, size_t count) const |
Copy the first count values in this PageArray into a raw c-style array, assuming it to be at least count elements long. More... | |
void | copy (ValueType *p) const |
void | resize (size_t size) |
Resize this array to the specified size. More... | |
void | resize (size_t size, const ValueType &v) |
Resize this array to the specified size and initialize all values to v. More... | |
size_t | size () const |
Return the number of elements in this array. More... | |
size_t | capacity () const |
Return the maximum number of elements that this array can contain without allocating more memory pages. More... | |
size_t | freeCount () const |
Return the number of additional elements that can be added to this array without allocating more memory pages. More... | |
size_t | pageCount () const |
Return the number of allocated memory pages. More... | |
size_t | memUsage () const |
Return the memory footprint of this array in bytes. More... | |
bool | isEmpty () const |
Return true if the container contains no elements. More... | |
bool | isPartiallyFull () const |
Return true if the page table is partially full, i.e. the last non-empty page contains less than pageSize() elements. More... | |
void | clear () |
Removes all elements from the array and delete all pages. More... | |
Iterator | begin () |
Return a non-const iterator pointing to the first element. More... | |
Iterator | end () |
Return a non-const iterator pointing to the past-the-last element. More... | |
void | sort () |
Parallel sort of all the elements in ascending order. More... | |
void | invSort () |
Parallel sort of all the elements in descending order. More... | |
void | merge (PagedArray &other) |
Transfer all the elements (and pages) from the other array to this array. More... | |
void | print (std::ostream &os=std::cout) const |
Print information for debugging. More... | |
ConstIterator | cbegin () const |
Return a const iterator pointing to the first element. More... | |
ConstIterator | begin () const |
Return a const iterator pointing to the first element. More... | |
ConstIterator | cend () const |
Return a const iterator pointing to the past-the-last element. More... | |
ConstIterator | end () const |
Return a const iterator pointing to the past-the-last element. More... | |
template<typename Functor > | |
void | sort (Functor func) |
Parallel sort of all the elements based on a custom functor with the api: More... | |
Static Public Member Functions | |
static size_t | pageSize () |
Return the number of elements per memory page. More... | |
static size_t | log2PageSize () |
Return log2 of the number of elements per memory page. More... | |
Friends | |
class | ValueBuffer |
Concurrent, page-based, dynamically-sized linear data structure with O(1) random access and STL-compliant iterators. It is primarily intended for applications that concurrently insert (a possibly unkown number of) elements into a dynamically growing linear array, and fast random access to said elements.
This data structure employes contiguous pages of elements (like a std::deque) which avoids moving data when the capacity is out-grown and new pages are allocated. The size of the pages can be controlled with the Log2PageSize template parameter (defaults to 1024 elements of type ValueT). The TableT template parameter is used to define the data structure for the page table. The default, std::vector, offers fast random access in exchange for slower push_back, whereas std:deque offers faster push_back but slower random access.
There are three fundamentally different ways to insert elements to this container - each with different advanteges and disadvanteges.
The simplest way to insert elements is to use PagedArray::push_back e.g.
or with TBB task-based multi-threading
PagedArray::push_back has the advantage that it's thread-safe and preserves the ordering of the inserted elements. In fact it returns the linear offset to the added element which can then be used for fast O(1) random access. The disadvantage is it's the slowest of the three different ways of inserting elements.
The fastest way (by far) to insert elements by means of a PagedArray::ValueBuffer, e.g.
or
or with TBB task-based multi-threading
or with TBB thread-local storage for even better performance (due to fewer concurrent instantiations of partially full ValueBuffers)
This technique generally outperforms PagedArray::push_back, std::vector::push_back, std::deque::push_back and even tbb::concurrent_vector::push_back. Additionally it is thread-safe as long as each thread has it's own instance of a PagedArray::ValueBuffer. The only disadvantage is the ordering of the elements is undefined if multiple instance of a PagedArray::ValueBuffer are employed. This is typically the case in the context of multi-threading, where the ordering of inserts are undefined anyway. Note that a local scope can be used to guarentee that the ValueBuffer has inserted all its elements by the time the scope ends. Alternatively the ValueBuffer can be explicitly flushed by calling ValueBuffer::flush.
The third way to insert elements is to resize the container and use random access, e.g.
or in terms of the random access iterator
While this approach is both fast and thread-safe it suffers from the major disadvantage that the problem size, i.e. number of elements, needs to be known in advance. If that's the case you might as well consider using std::vector or a raw c-style array! In other words the PagedArray is most useful in the context of applications that involve multi-threading of dynamically growing linear arrays that require fast random access.
using ValueType = ValueT |
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default |
Default constructor.
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inline |
Destructor removed all allocated pages.
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delete |
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inline |
Return a non-const iterator pointing to the first element.
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Return a const iterator pointing to the first element.
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Return the maximum number of elements that this array can contain without allocating more memory pages.
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Return a const iterator pointing to the first element.
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Return a const iterator pointing to the past-the-last element.
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inline |
Removes all elements from the array and delete all pages.
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Copy the first count values in this PageArray into a raw c-style array, assuming it to be at least count elements long.
p | pointer to an array that will used as the destination of the copy. |
count | number of elements to be copied. |
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inline |
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Return a non-const iterator pointing to the past-the-last element.
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inline |
Return a const iterator pointing to the past-the-last element.
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Set all elements in the page table to the specified value.
v | value to be filled in all the existing pages of this PagedArray. |
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Return the number of additional elements that can be added to this array without allocating more memory pages.
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Parallel sort of all the elements in descending order.
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Return true if the container contains no elements.
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Return true if the page table is partially full, i.e. the last non-empty page contains less than pageSize() elements.
When the page table is partially full calling merge() or using a ValueBuffer will rearrange the ordering of existing elements.
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inlinestatic |
Return log2 of the number of elements per memory page.
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inline |
Return the memory footprint of this array in bytes.
void merge | ( | PagedArray< ValueT, Log2PageSize, TableT > & | other | ) |
Transfer all the elements (and pages) from the other array to this array.
other | non-const reference to the PagedArray that will be merged into this PagedArray. |
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delete |
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inline |
Return a reference to the value at the specified offset.
i | linear offset of the value to be accessed. |
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inline |
Return a const-reference to the value at the specified offset.
i | linear offset of the value to be accessed. |
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Return the number of allocated memory pages.
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inlinestatic |
Return the number of elements per memory page.
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inline |
Print information for debugging.
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inline |
Thread safe insertion, adds a new element at the end and increases the container size by one and returns the linear offset for the inserted element.
value | value to be added to this PagedArray |
Constant time complexity. May allocate a new page.
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inline |
Slightly faster than the thread-safe push_back above.
value | value to be added to this PagedArray |
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inline |
Resize this array to the specified size.
size | number of elements that this PageArray will contain. |
Will grow or shrink the page table to contain the specified number of elements. It will affect the size(), iteration will go over all those elements, push_back will insert after them and operator[] can be used directly access them.
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inline |
Resize this array to the specified size and initialize all values to v.
size | number of elements that this PageArray will contain. |
v | value of all the size values. |
Will grow or shrink the page table to contain the specified number of elements. It will affect the size(), iteration will go over all those elements, push_back will insert after them and operator[] can be used directly access them.
void shrink_to_fit | ( | ) |
Reduce the page table to fix the current size.
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inline |
Return the number of elements in this array.
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inline |
Parallel sort of all the elements in ascending order.
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inline |
Parallel sort of all the elements based on a custom functor with the api:
which returns true if a comes before b.
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friend |