View Source Edeliver.Relup.Instructions.SuspendChannels (edeliver v1.9.2)
This upgrade instruction suspends the websocket processes
connected to phoenix channels to avoid that new channel events will be processed during the code upgrade / downgrade process. It will be appended to the instructions after the "point of no return" but before any application code is reloaded. It should be used in conjunction with and after the
Edeliver.Relup.Instructions.SuspendRanchAcceptors
instruction which avoids that new websockets processes for phoenix channels are started.
To make sure that the websocket connections can be found on the node, use this instruction after the
Edeliver.Relup.Instructions.CheckRanchConnections
instruction which will abort the upgrade if ranch (websocket) connections cannot be found in the supervision tree. Use the
Edeliver.Relup.Instructions.ResumeRanchAcceptors
instruction at the end of your instructions list to resume the websocket processes and re-enable handling channel messages.
Suspending and resuming websocket processes for
phoenix channels requires a recent phoenix version
which handles sys events for websockets. It also
requires that the builtin phoenix pubsub backend
Phoenix.PubSub.PG2 is used for the phoenix channels.
Link to this section Summary
Functions
Returns name of the application. This name is taken as argument
for the run/1 function and is required to access the acceptor processes
through the supervision tree
Suspends a list of processes. Because suspending a process might take a while depending on the length
of the message queue or duration of current operation processed by the pid, suspending is done
asynchronously for each process by spawning a new process which calls :sys.suspend/2 and then waiting
for all results before returning from this function. Be careful when using :infinity as timeout,
because this function might hang for infinite time if one of the process does not handle sys events.
Calls the run/1 function of this module
This module depends on the Edeliver.Relup.Instructions.CheckRanchAcceptors and
the Edeliver.Relup.Instructions.CheckRanchConnections module which must be loaded
before this instruction for upgrades and unload after this instruction for downgrades.
Appends this instruction to the instructions after the "point of no return" but before any instruction which loads or unloads new code, (re-)starts or stops any running processes, or (re-)starts or stops any application or the emulator.
Callback implementation for Edeliver.Relup.Instruction.modify_relup/2.
Suspends all websocket channels to avoid handling new channel events during the upgrade. This is possible only in recent phoenix versions since handling sys events is required for suspending. If an older version is used, a warning is printed that suspending is not supported.
Link to this section Functions
@spec arguments( %Edeliver.Relup.Instructions{ changed_modules: term(), down_instructions: term(), down_version: term(), up_instructions: term(), up_version: term() }, Edeliver.Relup.Config.t() ) :: term()
Returns name of the application. This name is taken as argument
for the run/1 function and is required to access the acceptor processes
through the supervision tree
@spec bulk_suspend(processes :: [pid()], timeout :: pos_integer() | :infinity) :: :ok | {:errors, count :: pos_integer(), [{pid :: pid(), reason :: term()}]} | :not_supported
Suspends a list of processes. Because suspending a process might take a while depending on the length
of the message queue or duration of current operation processed by the pid, suspending is done
asynchronously for each process by spawning a new process which calls :sys.suspend/2 and then waiting
for all results before returning from this function. Be careful when using :infinity as timeout,
because this function might hang for infinite time if one of the process does not handle sys events.
@spec call_this(arguments :: [term()]) :: Instruction.instruction() | Instruction.instructions()
Calls the run/1 function of this module
from the relup file during hot code upgrade
@spec dependencies() :: [instruction_module :: atom()]
@spec dependencies() :: [Edeliver.Relup.Instructions.CheckRanchAcceptors]
This module depends on the Edeliver.Relup.Instructions.CheckRanchAcceptors and
the Edeliver.Relup.Instructions.CheckRanchConnections module which must be loaded
before this instruction for upgrades and unload after this instruction for downgrades.
@spec insert_where() :: Instruction.insert_fun()
Appends this instruction to the instructions after the "point of no return" but before any instruction which loads or unloads new code, (re-)starts or stops any running processes, or (re-)starts or stops any application or the emulator.
Callback implementation for Edeliver.Relup.Instruction.modify_relup/2.
@spec run(otp_application_name :: atom()) :: :ok
Suspends all websocket channels to avoid handling new channel events during the upgrade. This is possible only in recent phoenix versions since handling sys events is required for suspending. If an older version is used, a warning is printed that suspending is not supported.