-spec del_lock(Id) -> true when Id :: id().

Equivalent to del_lock(Id, [node() | nodes()]).

-spec del_lock(Id, Nodes) -> true when Id :: id(), Nodes :: [node()].

Deletes the lock Id synchronously.

-spec disconnect() -> [node()].

Disconnect from all other nodes known to global.

A list of node names (in an unspecified order) is returned which corresponds to the nodes that were disconnected. All disconnect operations performed have completed when global:disconnect/0 returns.

The disconnects will be made in such a way that only the current node will be removed from the cluster of global nodes. If prevent_overlapping_partitions is enabled and you disconnect, from other nodes in the cluster of global nodes, by other means, global on the other nodes may partition the remaining nodes in order to ensure that no overlapping partitions appear. Even if prevent_overlapping_partitions is disabled, you should preferably use global:disconnect/0 in order to remove current node from a cluster of global nodes, since you otherwise likely will create overlapping partitions which might cause problems.

Note that if the node is going to be halted, there is no need to remove it from a cluster of global nodes explicitly by calling global:disconnect/0 before halting it. The removal from the cluster is taken care of automatically when the node halts regardless of whether prevent_overlapping_partitions is enabled or not.

If current node has been configured to be part of a global group, only connected and/or synchronized nodes in that group are known to global, so global:disconnect/0 will only disconnect from those nodes. If current node is not part of a global group, all connected visible nodes will be known to global, so global:disconnect/0 will disconnect from all those nodes.

Note that information about connected nodes does not instantaneously reach global, so the caller might see a node part of the result returned by nodes() while it still is not known to global. The disconnect operation will, however, still not cause any overlapping partitions when prevent_overlapping_partitions is enabled. If prevent_overlapping_partitions is disabled, overlapping partitions might form in this case.

Note that when prevent_overlapping_partitions is enabled, you may see warning reports on other nodes when they detect that current node has disconnected. These are in this case completely harmless and can be ignored.

-spec notify_all_name(Name, Pid1, Pid2) -> none when Name :: term(), Pid1 :: pid(), Pid2 :: pid().

The function unregisters both pids and sends the message {global_name_conflict, Name, OtherPid} to both processes.

Can be used as a name resolving function for register_name/3 and re_register_name/3.

-spec random_exit_name(Name, Pid1, Pid2) -> pid() when Name :: term(), Pid1 :: pid(), Pid2 :: pid().

The function randomly selects one of the pids for registration and kills the other one.

Can be used as a name resolving function for register_name/3 and re_register_name/3.

-spec random_notify_name(Name, Pid1, Pid2) -> pid() when Name :: term(), Pid1 :: pid(), Pid2 :: pid().

The function randomly selects one of the pids for registration, and sends the message {global_name_conflict, Name} to the other pid.

Can be used as a name resolving function for register_name/3 and re_register_name/3.

-spec re_register_name(Name, Pid) -> yes when Name :: term(), Pid :: pid().

Equivalent to re_register_name(Name, Pid, fun random_exit_name/3).

-spec re_register_name(Name, Pid, Resolve) -> yes when Name :: term(), Pid :: pid(), Resolve :: method().

Atomically changes the registered name Name on all nodes to refer to Pid.

Function Resolve has the same behavior as in register_name/2,3.

-spec register_name(Name, Pid) -> yes | no when Name :: term(), Pid :: pid().

Equivalent to register_name(Name, Pid, fun random_exit_name/3).

-spec register_name(Name, Pid, Resolve) -> yes | no
                       when Name :: term(), Pid :: pid(), Resolve :: method().

Globally associates name Name with a pid, that is, globally notifies all nodes of a new global name in a network of Erlang nodes.

When new nodes are added to the network, they are informed of the globally registered names that already exist. The network is also informed of any global names in newly connected nodes. If any name clashes are discovered, function Resolve is called. Its purpose is to decide which pid is correct. If the function crashes, or returns anything other than one of the pids, the name is unregistered. This function is called once for each name clash.

Warning

If you plan to change code without restarting your system, you must use an external fun (fun Module:Function/Arity) as function Resolve. If you use a local fun, you can never replace the code for the module that the fun belongs to.

Three predefined resolve functions exist: random_exit_name/3, random_notify_name/3, and notify_all_name/3.

This function is completely synchronous, that is, when this function returns, the name is either registered on all nodes or none.

The function returns yes if successful, no if it fails. For example, no is returned if an attempt is made to register an already registered process or to register a process with a name that is already in use.

Note

Releases up to and including Erlang/OTP R10 did not check if the process was already registered. The global name table could therefore become inconsistent. The old (buggy) behavior can be chosen by giving the Kernel application variable global_multi_name_action the value allow.

If a process with a registered name dies, or the node goes down, the name is unregistered on all nodes.

-spec registered_names() -> [Name] when Name :: term().

Returns a list of all globally registered names.

-spec send(Name, Msg) -> Pid when Name :: term(), Msg :: term(), Pid :: pid().

Sends message Msg to the pid globally registered as Name.

If Name is not a globally registered name, the calling function exits with reason {badarg, {Name, Msg}}.

-spec set_lock(Id) -> boolean() when Id :: id().

Equivalent to set_lock(Id, [node() | nodes()], infinity).

-spec set_lock(Id, Nodes) -> boolean() when Id :: id(), Nodes :: [node()].

Equivalent to set_lock(Id, Nodes, infinity).

-spec set_lock(Id, Nodes, Retries) -> boolean() when Id :: id(), Nodes :: [node()], Retries :: retries().

Sets a lock on the specified nodes on using id/0.

If a lock already exists on ResourceId for another requester than LockRequesterId, and Retries is not equal to 0, the process sleeps for a while and tries to execute the action later. When Retries attempts have been made, false is returned, otherwise true. If Retries is infinity, true is eventually returned (unless the lock is never released).

This function is completely synchronous.

If a process that holds a lock dies, or the node goes down, the locks held by the process are deleted.

The global name server keeps track of all processes sharing the same lock, that is, if two processes set the same lock, both processes must delete the lock.

This function does not address the problem of a deadlock. A deadlock can never occur as long as processes only lock one resource at a time. A deadlock can occur if some processes try to lock two or more resources. It is up to the application to detect and rectify a deadlock.

Note

Avoid the following values of ResourceId, otherwise Erlang/OTP does not work properly:

• dist_ac
• global
• mnesia_adjust_log_writes
• mnesia_table_lock

-spec sync() -> ok | {error, Reason :: term()}.

Synchronizes the global name server with all nodes known to this node.

These are the nodes that are returned from nodes(). When this function returns, the global name server receives global information from all nodes. This function can be called when new nodes are added to the network.

The only possible error reason Reason is {"global_groups definition error", Error}.

-spec trans(Id, Fun) -> Res | aborted when Id :: id(), Fun :: trans_fun(), Res :: term().

Equivalent to trans(Id, Fun, [node() | nodes()], infinity).

-spec trans(Id, Fun, Nodes) -> Res | aborted
               when Id :: id(), Fun :: trans_fun(), Nodes :: [node()], Res :: term().

Equivalent to trans(Id, Fun, Nodes, infinity).

-spec trans(Id, Fun, Nodes, Retries) -> Res | aborted
               when
                   Id :: id(),
                   Fun :: trans_fun(),
                   Nodes :: [node()],
                   Retries :: retries(),
                   Res :: term().

Sets a lock on Id (using set_lock/3).

If this succeeds, Fun() is evaluated and the result Res is returned. Returns aborted if the lock attempt fails. If Retries is set to infinity, the transaction does not abort.

infinity is the default setting and is used if no value is specified for Retries.

-spec unregister_name(Name) -> _ when Name :: term().

Removes the globally registered name Name from the network of Erlang nodes.

-spec whereis_name(Name) -> pid() | undefined when Name :: term().

Returns the pid with the globally registered name Name. Returns undefined if the name is not globally registered.