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stream_collection.ex
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stream_collection.ex
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defmodule Bandit.HTTP2.StreamCollection do
@moduledoc false
# Represents a collection of stream IDs and what process IDs are running them. An instance of
# this struct is contained within each `Bandit.HTTP2.Connection` struct and is responsible for
# encapsulating the data about the streams which are currently active within the connection.
#
# This collection has a number of useful properties:
#
# * Process IDs are accessible by stream id
# * Process IDs are deletable by themselves (ie: deletion is via PID)
# * The collection is able to determine if a stream not currently contained in this collection
# represents a previously seen stream (in which case it is considered to be in a 'closed'
# state), or if it is a stream ID of a stream that has yet to be created
require Integer
defstruct last_stream_id: 0,
stream_count: 0,
id_to_pid: %{},
pid_to_id: %{}
@typedoc "A map from stream id to pid"
@type t :: %__MODULE__{
last_stream_id: Bandit.HTTP2.Stream.stream_id(),
stream_count: non_neg_integer(),
id_to_pid: %{Bandit.HTTP2.Stream.stream_id() => pid()},
pid_to_id: %{pid() => Bandit.HTTP2.Stream.stream_id()}
}
@spec get_pids(t()) :: [pid()]
def get_pids(collection), do: Map.values(collection.id_to_pid)
@spec get_pid(t(), Bandit.HTTP2.Stream.stream_id()) :: pid() | :new | :closed | :invalid
def get_pid(_collection, stream_id) when Integer.is_even(stream_id), do: :invalid
def get_pid(collection, stream_id) when stream_id > collection.last_stream_id, do: :new
def get_pid(collection, stream_id) do
case Map.get(collection.id_to_pid, stream_id) do
pid when is_pid(pid) -> pid
nil -> :closed
end
end
@spec insert(t(), Bandit.HTTP2.Stream.stream_id(), pid()) :: t()
def insert(collection, stream_id, pid) do
%__MODULE__{
last_stream_id: stream_id,
stream_count: collection.stream_count + 1,
id_to_pid: Map.put(collection.id_to_pid, stream_id, pid),
pid_to_id: Map.put(collection.pid_to_id, pid, stream_id)
}
end
# Dialyzer insists on the atom() here even though it doesn't make sense
@spec delete(t(), pid()) :: t() | atom()
def delete(collection, pid) do
case Map.pop(collection.pid_to_id, pid) do
{nil, _} ->
collection
{stream_id, new_pid_to_id} ->
%{
collection
| id_to_pid: Map.delete(collection.id_to_pid, stream_id),
pid_to_id: new_pid_to_id
}
end
end
@spec stream_count(t()) :: non_neg_integer()
def stream_count(collection), do: collection.stream_count
@spec last_stream_id(t()) :: Bandit.HTTP2.Stream.stream_id()
def last_stream_id(collection), do: collection.last_stream_id
end