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<cref>
<header>
<copyright>
<year>1998</year><year>2016</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>erl_global</title>
<prepared>Gordon Beaton</prepared>
<responsible>Gordon Beaton</responsible>
<docno></docno>
<approved>Gordon Beaton</approved>
<checked>Gordon Beaton</checked>
<date>1998-07-03</date>
<rev>A</rev>
<file>erl_global.xml</file>
</header>
<lib>erl_global</lib>
<libsummary>Access globally registered names.</libsummary>
<description>
<note><p>The support for VxWorks is deprecated as of OTP 22, and
will be removed in OTP 23.</p></note>
<note><p>The old legacy <c>erl_interface</c> library (functions
with prefix <c>erl_</c>) is deprecated as of OTP 22, and will be
removed in OTP 23. This does not apply to the <c>ei</c>
library. Reasonably new <c>gcc</c> compilers will issue deprecation
warnings. In order to disable these warnings, define the macro
<c>EI_NO_DEPR_WARN</c>.</p></note>
<p>This module provides support for registering, looking
up, and unregistering names in the <c>global</c> module.
For more information, see
<seealso marker="kernel:global"><c>kernel:global</c></seealso>.</p>
<p>Notice that the functions below perform an RPC using an open file
descriptor provided by the caller. This file descriptor must
not be used for other traffic during the global operation, as the
function can then receive unexpected data and fail.</p>
</description>
<funcs>
<func>
<name since=""><ret>char **</ret><nametext>erl_global_names(fd,count)</nametext></name>
<fsummary>Obtain list of global names.</fsummary>
<type>
<v>int fd;</v>
<v>int *count;</v>
</type>
<desc>
<p>Retrieves a list of all known global names.</p>
<list type="bulleted">
<item><c>fd</c> is an open descriptor to an Erlang
connection.</item>
<item><c>count</c> is the address of an integer, or
<c>NULL</c>. If <c>count</c> is not <c>NULL</c>, it is
set by the function to the number of names found.</item>
</list>
<p>On success, the function returns an array of strings, each
containing a single registered name, and sets
<c>count</c> to
the number of names found. The array is terminated
by a single <c>NULL</c> pointer. On failure, the function returns
<c>NULL</c> and <c>count</c> is not modified.</p>
<note>
<p>It is the caller's responsibility to free the array
afterwards. It has been allocated by the function with a
single call to <c>malloc()</c>, so a single
<c>free()</c> is all that is necessary.</p>
</note>
</desc>
</func>
<func>
<name since=""><ret>int</ret><nametext>erl_global_register(fd,name,pid)</nametext></name>
<fsummary>Register a name in global.</fsummary>
<type>
<v>int fd;</v>
<v>const char *name;</v>
<v>ETERM *pid;</v>
</type>
<desc>
<p>Registers a name in <c>global</c>.</p>
<list type="bulleted">
<item><c>fd</c> is an open descriptor to an Erlang
connection.</item>
<item><c>name</c> is the name to register in
<c>global</c>.</item>
<item><c>pid</c> is the pid that is to be associated with
<c>name</c>. This value is returned by <c>global</c>
when processes request the location of <c>name</c>.
</item>
</list>
<p>Returns <c>0</c> on success, otherwise <c>-1</c>.</p>
</desc>
</func>
<func>
<name since=""><ret>int</ret><nametext>erl_global_unregister(fd,name)</nametext></name>
<fsummary>Unregister a name from global.</fsummary>
<type>
<v>int fd;</v>
<v>const char *name;</v>
</type>
<desc>
<p>Unregisters a name from <c>global</c>.</p>
<list type="bulleted">
<item><c>fd</c> is an open descriptor to an Erlang
connection.</item>
<item><c>name</c> is the name to unregister from
<c>global</c>.</item>
</list>
<p>Returns <c>0</c> on success, otherwise <c>-1</c>.</p>
</desc>
</func>
<func>
<name since=""><ret>ETERM *</ret><nametext>erl_global_whereis(fd,name,node)</nametext></name>
<fsummary>Look up a name in global.</fsummary>
<type>
<v>int fd;</v>
<v>const char *name;</v>
<v>char *node;</v>
</type>
<desc>
<p>Looks up a name in <c>global</c>.</p>
<list type="bulleted">
<item><c>fd</c> is an open descriptor to an Erlang
connection.</item>
<item><c>name</c> is the name that is to be looked up in
<c>global</c>.</item>
</list>
<p>If <c>node</c> is not <c>NULL</c>, it is a pointer to a
buffer where the function can fill in the name of the node where
<c>name</c> is found. <c>node</c> can be
passed directly to <c>erl_connect()</c> if necessary.</p>
<p>On success, the function returns an Erlang pid containing the address
of the specified name, and the node is initialized to
the node name where <c>name</c> is found. On failure,
<c>NULL</c> is returned and <c>node</c> is not
modified.</p>
</desc>
</func>
</funcs>
</cref>
