ZenMonitor v1.0.0 ZenMonitor.Local.Tables View Source
ZenMonitor.Local.Tables
owns tables that are shared between multiple ZenMonitor.Local
components.
See nodes/0
and references/0
for more information.
Link to this section Summary
Functions
Returns a specification to start this module under a supervisor
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Nodes holds cached information about remote node compatibility
References holds the set of authoritative monitor references
Link to this section Functions
Returns a specification to start this module under a supervisor.
See Supervisor
.
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
.
Nodes holds cached information about remote node compatibility
This information is stored in one of the following structures:
For compatible nodes { remote_node, :compatible } ^—-key—-^ ^—value—^
For incompatible nodes { remote_node, {:incompatible, enforce_until, attempts} } ^—-key—-^ ^———————-value————————-^
enforce_until
is the time (as reported by System.monotonic_time(:milliseconds)) after which
this cache entry should no longer be enforced.
attempts
is the number of consecutive connect attempts that have failed, this value is useful
for calculating geometric backoff values
References holds the set of authoritative monitor references
These references are stored in this structure:
{ {subscriber_pid, monitor_reference}, {remote_node, remote_pid} } ^——————-key————————-^ ^—————value————^
There is a compound key of {subscriber_pid, monitor_reference} this allows for lookup of a given reference (if the subscriber is known, by convention it will be the calling process, self()) or the retrieval of all active monitors for a subscriber.