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Merged
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May 8, 2022
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GenServer: Rename continue argument in handle_continue/2 #11793

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39 changes: 21 additions & 18 deletions lib/elixir/lib/gen_server.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -434,10 +434,10 @@ defmodule GenServer do
except the process is hibernated before entering the loop. See
`c:handle_call/3` for more information on hibernation.
Returning `{:ok, state, {:continue, continue}}` is similar to
Returning `{:ok, state, {:continue, continue_arg}}` is similar to
`{:ok, state}` except that immediately after entering the loop,
the `c:handle_continue/2` callback will be invoked with the value
`continue` as first argument.
the `c:handle_continue/2` callback will be invoked with `continue_arg`
as the first argument and `state` as the second one.
Returning `:ignore` will cause `start_link/3` to return `:ignore` and
the process will exit normally without entering the loop or calling
Expand All @@ -460,7 +460,7 @@ defmodule GenServer do
"""
@callback init(init_arg :: term) ::
{:ok, state}
| {:ok, state, timeout | :hibernate | {:continue, term}}
| {:ok, state, timeout | :hibernate | {:continue, continue_arg :: term}}
| :ignore
| {:stop, reason :: any}
when state: any
Expand All @@ -487,9 +487,10 @@ defmodule GenServer do
`GenServer` causes garbage collection and leaves a continuous heap that
minimises the memory used by the process.
Returning `{:reply, reply, new_state, {:continue, continue}}` is similar to
`{:reply, reply, new_state}` except `c:handle_continue/2` will be invoked
immediately after with the value `continue` as first argument.
Returning `{:reply, reply, new_state, {:continue, continue_arg}}` is similar to
`{:reply, reply, new_state}` except that `c:handle_continue/2` will be invoked
immediately after with `continue_arg` as the first argument and
`state` as the second one.
Hibernating should not be used aggressively as too much time could be spent
garbage collecting. Normally it should only be used when a message is not
Expand All @@ -512,7 +513,7 @@ defmodule GenServer do
process exits without replying as the caller will be blocking awaiting a
reply.
Returning `{:noreply, new_state, timeout | :hibernate | {:continue, continue}}`
Returning `{:noreply, new_state, timeout | :hibernate | {:continue, continue_arg}}`
is similar to `{:noreply, new_state}` except a timeout, hibernation or continue
occurs as with a `:reply` tuple.
Expand All @@ -528,9 +529,10 @@ defmodule GenServer do
"""
@callback handle_call(request :: term, from, state :: term) ::
{:reply, reply, new_state}
| {:reply, reply, new_state, timeout | :hibernate | {:continue, term}}
| {:reply, reply, new_state,
timeout | :hibernate | {:continue, continue_arg :: term}}
| {:noreply, new_state}
| {:noreply, new_state, timeout | :hibernate | {:continue, term}}
| {:noreply, new_state, timeout | :hibernate | {:continue, continue_arg :: term}}
| {:stop, reason, reply, new_state}
| {:stop, reason, new_state}
when reply: term, new_state: term, reason: term
Expand All @@ -551,9 +553,10 @@ defmodule GenServer do
`{:noreply, new_state}` except the process is hibernated before continuing the
loop. See `c:handle_call/3` for more information.
Returning `{:noreply, new_state, {:continue, continue}}` is similar to
Returning `{:noreply, new_state, {:continue, continue_arg}}` is similar to
`{:noreply, new_state}` except `c:handle_continue/2` will be invoked
immediately after with the value `continue` as first argument.
immediately after with `continue_arg` as the first argument and
`state` as the second one.
Returning `{:stop, reason, new_state}` stops the loop and `c:terminate/2` is
called with the reason `reason` and state `new_state`. The process exits with
Expand All @@ -564,7 +567,7 @@ defmodule GenServer do
"""
@callback handle_cast(request :: term, state :: term) ::
{:noreply, new_state}
| {:noreply, new_state, timeout | :hibernate | {:continue, term}}
| {:noreply, new_state, timeout | :hibernate | {:continue, continue_arg :: term}}
| {:stop, reason :: term, new_state}
when new_state: term

Expand All @@ -581,12 +584,12 @@ defmodule GenServer do
"""
@callback handle_info(msg :: :timeout | term, state :: term) ::
{:noreply, new_state}
| {:noreply, new_state, timeout | :hibernate | {:continue, term}}
| {:noreply, new_state, timeout | :hibernate | {:continue, continue_arg :: term}}
| {:stop, reason :: term, new_state}
when new_state: term

@doc """
Invoked to handle `continue` instructions.
Invoked to handle continue instructions.
It is useful for performing work after initialization or for splitting the work
in a callback in multiple steps, updating the process state along the way.
Expand All @@ -596,11 +599,11 @@ defmodule GenServer do
This callback is optional. If one is not implemented, the server will fail
if a continue instruction is used.
"""
@callback handle_continue(continue :: term, state :: term) ::
@callback handle_continue(continue_arg, state :: term) ::
{:noreply, new_state}
| {:noreply, new_state, timeout | :hibernate | {:continue, term}}
| {:noreply, new_state, timeout | :hibernate | {:continue, continue_arg}}
| {:stop, reason :: term, new_state}
when new_state: term
when new_state: term, continue_arg: term
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I'm in doubt whether we can use the same variable for two continue_arg values that could be different.

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We cannot but in this case they are the same. We can only return a continue_arg that handle_continue accepts.


@doc """
Invoked when the server is about to exit. It should do any cleanup required.
Expand Down