Queue now uses a freelist to minimize allocations.

This commit is contained in:
Ferdinand Majerech 2014-08-04 02:16:34 +02:00
parent 1f55fccc26
commit 063d9754d7

View file

@ -45,6 +45,10 @@ struct Queue(T)
Node* last_ = null; Node* last_ = null;
/// Cursor pointing to the current node in iteration. /// Cursor pointing to the current node in iteration.
Node* cursor_ = null; Node* cursor_ = null;
/// The first element of a linked list of freed Nodes available for recycling.
Node* freeList_ = null;
/// Length of the queue. /// Length of the queue.
size_t length_ = 0; size_t length_ = 0;
@ -54,9 +58,15 @@ struct Queue(T)
@disable int opCmp(ref Queue); @disable int opCmp(ref Queue);
/// Destroy the queue, deallocating all its elements. /// Destroy the queue, deallocating all its elements.
@safe nothrow ~this() @trusted nothrow ~this()
{ {
while(!empty) { pop(); } while(!empty) { pop(); }
while(freeList_ !is null)
{
auto toFree = freeList_;
freeList_ = toFree.next_;
free(toFree);
}
cursor_ = last_ = first_ = null; cursor_ = last_ = first_ = null;
length_ = 0; length_ = 0;
} }
@ -90,9 +100,19 @@ struct Queue(T)
/// Push new item to the queue. /// Push new item to the queue.
void push(T item) @trusted nothrow void push(T item) @trusted nothrow
{ {
Node* newLast = allocate!Node(item, cast(Node*)null); Node* newLast;
if(freeList_ !is null)
{
newLast = freeList_;
freeList_ = freeList_.next_;
*newLast = Node(item, null);
}
else
{
newLast = allocate!Node(item, cast(Node*)null);
}
if(last_ !is null) { last_.next_ = newLast; } if(last_ !is null) { last_.next_ = newLast; }
if(first_ is null) { first_ = newLast; } if(first_ is null) { first_ = newLast; }
last_ = newLast; last_ = newLast;
++length_; ++length_;
} }
@ -139,10 +159,13 @@ struct Queue(T)
} }
body body
{ {
T result = peek(); T result = peek();
Node* temp = first_; Node* popped = first_;
first_ = first_.next_; first_ = first_.next_;
free(temp);
Node* oldFree = freeList_;
freeList_ = popped;
freeList_.next_ = oldFree;
if(--length_ == 0) if(--length_ == 0)
{ {
assert(first_ is null); assert(first_ is null);