View Source ZenMonitor.Local.Connector (ZenMonitor v2.1.0)
ZenMonitor.Local.Connector performs a variety of duties. For every remote that a the local
is interested in monitoring processes on there will be a dedicated ZenMonitor.Local.Connector.
This collection of Connectors are managed by a GenRegistry registered under the
ZenMonitor.Local.Connector atom.
Connecting and Monitoring the remote ZenMonitor.Proxy
Connectors, as their name suggests, connect to the ZenMonitor.Proxy on the remote node that they
are responsible for. They do this using standard ERTS Distribution, by invoking the remote
Proxy's ping command. A Remote is considered compatible if the ping command returns the :pong
atom, otherwise it will be marked incompatible.
Connectors manage their remote node's status in the global node status cache, and provide
facilities for efficient querying of remote status, see compatibility/1 and
cached_compatibility/1
Batching and Updating the remote ZenMonitor.Proxy
When a local process wishes to monitor a remote process, the Connector will be informed of this
fact with a call to monitor/3. The Connector is responsible for maintaining a local record of
this monitor for future fan-out and for efficiently batching up these requests to be delivered
to the remote ZenMonitor.Proxy.
Fan-out of Dead Summaries
Periodically, the ZenMonitor.Proxy (technically the ZenMonitor.Proxy.Batcher) on the remote
node will send a "Dead Summary". This is a message from the remote that informs the Connector
of all the processes the Connector has monitored that have gone down since the last summary.
The Connector uses it's local records to generate a batch of down dispatches. These are
messages that look identical to the messages provided by Process.monitor/1 when a process goes
down. It is sometimes necessary for the original monitoring process to be able to discern
whether the :DOWN message originated from ERTS or from ZenMonitor, to aid this, ZenMonitor
will wrap the original reason in a tuple of {:zen_monitor, original_reason}.
The fan-out messages are sent to ZenMonitor.Local for eventual delivery via
ZenMonitor.Local.Dispatcher, see those modules for more information.
Fan-out of nodedown / ZenMonitor.Proxy down
The Connector is also responsible for monitoring the remote node and dealing with nodedown (or
the node becoming incompatible, either due to the ZenMonitor.Proxy crashing or a code change).
If the Connector detects that the remote it is responsible for is down or no longer compatible,
it will fire every established monitor with {:zen_monitor, :nodedown}. It uses the same
mechanism as for Dead Summaries, see ZenMonitor.Local and ZenMonitor.Local.Dispatcher for
more information.
Link to this section Summary
Functions
Check the cached compatibility status for a remote node
Returns a specification to start this module under a supervisor.
Gets the chunk size from the Application Environment
Puts the chunk size into the Application Environment
Determine the effective compatibility of a remote node
Connect to the provided remote
Asynchronously demonitors a pid.
Get a connector from the registry by destination
Get a connector from the registry by remote node
Callback implementation for GenServer.init/1.
Asynchronously monitors a pid.
Retrieves all the monitors established between the target and the subscriber
Gets the sweep interval from the Application Environment
Puts the sweep interval into the Application Environment
Link to this section Types
Specs
cached_compatibility() :: compatibility() | :miss | {:expired, integer()} | :unavailable
Specs
compatibility() :: :compatible | :incompatible
Specs
Specs
Specs
t() :: ZenMonitor.Local.Connector
Link to this section Functions
Specs
cached_compatibility(remote :: node()) :: cached_compatibility()
Check the cached compatibility status for a remote node
This will only perform a fast client-side lookup in the ETS table. If an authoritative entry is
found it will be returned (either :compatible, :incompatible, or :unavailable). If no
entry is found then :miss is returned. If an expired entry is found then
{:expired, attempts} is returned.
Returns a specification to start this module under a supervisor.
See Supervisor.
Specs
chunk_size() :: integer()
Gets the chunk size from the Application Environment
The chunk size is the maximum number of subscriptions that will be sent during each sweep, see ZenMonitor.Local.Connector's @chunk_size for the default value
This can be controlled at boot and runtime with the {:zen_monitor, :connector_chunk_size}
setting, see ZenMonitor.Local.Connector.chunk_size/1 for runtime convenience functionality.
Specs
chunk_size(value :: integer()) :: :ok
Puts the chunk size into the Application Environment
This is a simple convenience function for overwriting the {:zen_monitor, :connector_chunk_size} setting at runtime.
Specs
compatibility(remote :: node()) :: compatibility()
Determine the effective compatibility of a remote node
This will attempt a fast client-side lookup in the ETS table. Only a positive :compatible
record will result in :compatible, otherwise the effective compatibility is :incompatible
Specs
connect(remote :: node()) :: compatibility()
Connect to the provided remote
This function will not consult the cache before calling into the GenServer, the GenServer will consult with the cache before attempting to connect, this allows for many callers to connect with the server guaranteeing that only one attempt will actually perform network work.
If the compatibility of a remote host is needed instead, callers should use the
compatibility/1 or cached_compatibility/1 functions. compatibility/1 will provide the
effective compatibility, cached_compatibility/1 is mainly used internally but can provide more
detailed information about the cache status of the remote. Neither of these methods,
compatibility/1 nor cached_compatibility/1, will perform network work or call into the
GenServer.
Specs
demonitor(target :: ZenMonitor.destination(), ref :: reference()) :: :ok
Asynchronously demonitors a pid.
Specs
get(target :: ZenMonitor.destination()) :: pid()
Get a connector from the registry by destination
Specs
Get a connector from the registry by remote node
Callback implementation for GenServer.init/1.
Specs
monitor( target :: ZenMonitor.destination(), ref :: reference(), subscriber :: pid() ) :: :ok
Asynchronously monitors a pid.
Specs
monitors(target :: ZenMonitor.destination(), subscriber :: pid()) :: [ reference() ]
Retrieves all the monitors established between the target and the subscriber
Specs
sweep_interval() :: integer()
Gets the sweep interval from the Application Environment
The sweep interval is the number of milliseconds to wait between sweeps, see ZenMonitor.Local.Connector's @sweep_interval for the default value
This can be controlled at boot and runtime with the {:zen_monitor, :connector_sweep_interval}
setting, see ZenMonitor.Local.Connector.sweep_interval/1 for runtime convenience
functionality.
Specs
sweep_interval(value :: integer()) :: :ok
Puts the sweep interval into the Application Environment
This is a simple convenience function for overwriting the {:zen_monitor, :connector_sweep_interval} setting at runtime.