-
Notifications
You must be signed in to change notification settings - Fork 14
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
9 changed files
with
211 additions
and
20 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,118 @@ | ||
defmodule ExWebRTC.RTP.JitterBuffer.Heap do | ||
@moduledoc false | ||
# Implementation of a heap (min-heap by default) | ||
# | ||
# At the moment, this module uses a regular `Map` (with O(log n) access) to store the data. | ||
# | ||
# TODO: Run performance tests and determine if it would be better to use: | ||
# - ETS | ||
# - :array | ||
# - some other data structure? | ||
|
||
@type comparator :: (term(), term() -> boolean()) | ||
|
||
@opaque t :: %__MODULE__{ | ||
comparator: comparator(), | ||
tree: %{non_neg_integer() => term()} | ||
} | ||
|
||
defstruct [:comparator, :tree] | ||
|
||
defimpl Enumerable do | ||
alias ExWebRTC.RTP.JitterBuffer.Heap | ||
|
||
def count(heap), do: {:ok, map_size(heap.tree)} | ||
def member?(heap, elem), do: {:ok, heap.tree |> Map.values() |> Enum.member?(elem)} | ||
|
||
def reduce(_heap, {:halt, acc}, _fun), do: {:halted, acc} | ||
def reduce(heap, {:suspend, acc}, fun), do: {:suspended, acc, &reduce(heap, &1, fun)} | ||
def reduce(heap, {:cont, acc}, _fun) when map_size(heap.tree) == 0, do: {:done, acc} | ||
|
||
def reduce(heap, {:cont, acc}, fun) do | ||
elem = Heap.root(heap) | ||
|
||
heap |> Heap.pop() |> reduce(fun.(elem, acc), fun) | ||
end | ||
|
||
def slice(_heap), do: {:error, __MODULE__} | ||
end | ||
|
||
@spec new(comparator()) :: t() | ||
def new(comparator \\ &</2) do | ||
%__MODULE__{ | ||
comparator: comparator, | ||
tree: %{} | ||
} | ||
end | ||
|
||
@spec root(t()) :: term() | ||
def root(heap) do | ||
heap.tree[0] | ||
end | ||
|
||
@spec size(t()) :: non_neg_integer() | ||
def size(heap) do | ||
map_size(heap.tree) | ||
end | ||
|
||
@spec push(t(), term()) :: t() | ||
def push(heap, elem) do | ||
idx = map_size(heap.tree) | ||
tree = Map.put(heap.tree, idx, elem) | ||
|
||
restore_heap(%{heap | tree: tree}, idx) | ||
end | ||
|
||
@spec pop(t()) :: t() | ||
def pop(heap) | ||
|
||
def pop(heap) when map_size(heap.tree) < 2, do: %{heap | tree: %{}} | ||
|
||
def pop(heap) do | ||
last_idx = map_size(heap.tree) - 1 | ||
%{0 => _first, ^last_idx => last} = heap.tree | ||
|
||
tree = | ||
heap.tree | ||
|> Map.delete(last_idx) | ||
|> Map.put(0, last) | ||
|
||
heapify(%{heap | tree: tree}, 0) | ||
end | ||
|
||
defp restore_heap(heap, 0), do: heap | ||
|
||
defp restore_heap(heap, idx) do | ||
p = parent(idx) | ||
|
||
heap | ||
|> heapify(p) | ||
|> restore_heap(p) | ||
end | ||
|
||
defp heapify(heap, i) do | ||
n = map_size(heap.tree) | ||
|
||
max_idx = | ||
[i, left(i), right(i)] | ||
|> Stream.filter(&(&1 < n)) | ||
|> Enum.max_by(&heap.tree[&1], heap.comparator, fn -> nil end) | ||
|
||
if max_idx != i do | ||
%{^i => t1, ^max_idx => t2} = heap.tree | ||
|
||
tree = | ||
heap.tree | ||
|> Map.put(i, t2) | ||
|> Map.put(max_idx, t1) | ||
|
||
heapify(%{heap | tree: tree}, max_idx) | ||
else | ||
heap | ||
end | ||
end | ||
|
||
defp left(i), do: 2 * i + 1 | ||
defp right(i), do: 2 * i + 2 | ||
defp parent(i), do: div(i - 1, 2) | ||
end |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.