mcc v1.1.1 Mcc.Async.Writer
Async writer module.
The writer is a group of GenServer
process, which support write mcc cache
table asynchronously.
Why we need the module?
As we all know, in general, the write operations are heavy, especially if
using transaction to write cache. Rely on async writer, the upper application
can get the data from source database and retrun as soon as possible rather
than wait for the write operation to complete.
When async write, this module will dispatch the keys to different GenServer
process depend on hash of key. So that, the async writer will avoid the single
point from the GenServer
process.
Link to this section Summary
Link to this section Functions
child_spec(arg)
Returns a specification to start this module under a supervisor.
See Supervisor
.
init(_)
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
args
is the argument term (second argument) passed to start_link/3
.
Returning {:ok, state}
will cause start_link/3
to return
{:ok, pid}
and the process to enter its loop.
Returning {:ok, state, timeout}
is similar to {:ok, state}
except handle_info(:timeout, state)
will be called after timeout
milliseconds if no messages are received within the timeout.
Returning {:ok, state, :hibernate}
is similar to {:ok, state}
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
{: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.
Returning :ignore
will cause start_link/3
to return :ignore
and
the process will exit normally without entering the loop or calling
c:terminate/2
. If used when part of a supervision tree the parent
supervisor will not fail to start nor immediately try to restart the
GenServer
. The remainder of the supervision tree will be started
and so the GenServer
should not be required by other processes.
It can be started later with Supervisor.restart_child/2
as the child
specification is saved in the parent supervisor. The main use cases for
this are:
- The
GenServer
is disabled by configuration but might be enabled later. - An error occurred and it will be handled by a different mechanism than the
Supervisor
. Likely this approach involves callingSupervisor.restart_child/2
after a delay to attempt a restart.
Returning {:stop, reason}
will cause start_link/3
to return
{:error, reason}
and the process to exit with reason reason
without
entering the loop or calling c:terminate/2
.
Callback implementation for GenServer.init/1
.
put(key, mod, func, args)
Async put operation.
This function support upper application write the cache table using async
approach, and the key will be dispatched to different GenServer
process
depend on hash of the key
.
start_link(id)
start_link(atom()) :: GenServer.on_start()
start_link(atom()) :: GenServer.on_start()
Start the GenServer
process and link it.