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Simple ETS cache for Phoenix
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defmodule PhoenixCache.Bucket do | |
use GenServer | |
alias :ets, as: Ets | |
@expired_after 6 * 60 | |
def start_link(args \\ []) do | |
GenServer.start_link(__MODULE__, args, name: __MODULE__) | |
end | |
def set(key, value) do | |
GenServer.cast(__MODULE__, {:set, key, value}) | |
end | |
@doc """ | |
Custom TTL for cache entry | |
ttl: Time to live in second | |
""" | |
def set(key, value, ttl) do | |
GenServer.cast(__MODULE__, {:set, key, value, ttl}) | |
end | |
def get(key) do | |
GenServer.call(__MODULE__, {:get, key}) | |
end | |
def delete(key) do | |
GenServer.cast(__MODULE__, {:delete, key}) | |
end | |
# Server callbacks | |
# Server (callbacks) | |
@impl true | |
def init(state) do | |
Ets.new(:simple_cache, [:set, :protected, :named_table]) | |
{:ok, state} | |
end | |
def handle_call({:get, key}, _from, state) do | |
rs = Ets.lookup(:simple_cache, key) |> List.first() | |
if rs == nil do | |
{:reply, {:error, :not_found}, state} | |
else | |
expired_at = elem(rs, 2) | |
cond do | |
NaiveDateTime.diff(NaiveDateTime.utc_now(), expired_at) > 0 -> | |
{:reply, {:error, :expired}, state} | |
true -> | |
{:reply, {:ok, elem(rs, 1)}, state} | |
end | |
end | |
end | |
@doc """ | |
Default TTL | |
""" | |
def handle_cast({:set, key, val}, state) do | |
expired_at = | |
NaiveDateTime.utc_now() | |
|> NaiveDateTime.add(@expired_after, :second) | |
Ets.insert(:simple_cache, {key, val, expired_at}) | |
{:noreply, state} | |
end | |
@doc """ | |
Custom TTL | |
""" | |
def handle_cast({:set, key, val, ttl}, state) do | |
inserted_at = | |
NaiveDateTime.utc_now() | |
|> NaiveDateTime.add(ttl, :second) | |
Ets.insert(:simple_cache, {key, val, inserted_at}) | |
{:noreply, state} | |
end | |
@impl true | |
def handle_cast({:delete, key}, state) do | |
Ets.delete(:simple_cache, key) | |
{:noreply, state} | |
end | |
end |
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defmodule PhoenixCache.Plug.Cache doimport Plug.Conn | |
# 6 minute | |
@default_ttl 6 * 60 | |
def init(ttl \\ nil), do: ttl | |
def call(conn, ttl \\ nil) do | |
ttl = ttl || @default_ttl | |
# Chỉ cache với GET requestif conn.method == "GET" do# tạo key từ request path và query param, thông thường# thì cùng path và cùng param thì kết quả là giống nhau | |
key = "#{conn.request_path}-#{conn.query_string}" | |
case PhoenixCache.Bucket.get(key) do | |
{:ok, body} -> | |
IO.puts("PLUG HIT") | |
# nếu đã cache thì trả về ngay | |
conn | |
|> send_resp(200, body) | |
|> halt | |
_ -> | |
IO.puts("PLUG MISS") | |
# nếu chưa cache thì xử lý như bình thường | |
conn | |
|> assign(:ttl, ttl) | |
|> register_before_send(&cache_before_send/1) # gọi hàm này trước khi trả vềendelse | |
conn | |
endend | |
def cache_before_send(conn) do# nếu request đuợc xử lý thành công thì cacheif conn.status == 200 dokey = "#{conn.request_path}-#{conn.query_string}"data = conn.resp_body | |
PhoenixCache.Bucket.set(key, data, conn.assigns[:ttl] || @default_ttl) | |
conn | |
else# không thì kệ chúng mày | |
conn | |
endend | |
end |
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