Add note about calling interrupt and close immediately

Closes: #315

You can not call close immediately after interrupt. It will result in
undefined behavior. Instead, shim a small `Process.sleep/1` in and it
should mitigate the issue.

Author: warmwaffles

CHANGELOG.md

@@ -4,6 +4,9 @@
 
 - changed: Removed `Exqlite.bind/3`, please use `bind/2` instead.
 - changed: Improved multi-threaded access to underlying sqlite resource.
+- changed: Document issue with calling `close/1` immediately after calling
+  `interrupt/1`. If you encounter the issue where the entire BEAM crashes, put
+  a short sleep between the call to `interrupt/1` and `close/1`.
 
 ## v0.28.0
 

lib/exqlite/sqlite3.ex

@@ -86,6 +86,15 @@ defmodule Exqlite.Sqlite3 do
 
   @doc """
   Interrupt a long-running query.
+
+  > #### Warning {: .warning}
+  > If you are going to interrupt a long running process, it is unsafe to call
+  > `close/1` immediately after. You run the risk of undefined behavior. This
+  > is a limitation of the sqlite library itself. Please see the documentation
+  > https://www.sqlite.org/c3ref/interrupt.html for more information.
+  >
+  > If close must be called after, it is best to put a short sleep in order to
+  > let sqlite finish doing its book keeping.
   """
   @spec interrupt(db() | nil) :: :ok | {:error, reason()}
   def interrupt(nil), do: :ok

test/exqlite/sqlite3_test.exs

@@ -792,7 +792,7 @@ defmodule Exqlite.Sqlite3Test do
 
       Process.sleep(100)
       :ok = Sqlite3.interrupt(conn)
-
+      Process.sleep(100)
       :ok = Sqlite3.close(conn)
     end
   end