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diff --git a/lib/kernel/doc/src/rpc.xml b/lib/kernel/doc/src/rpc.xml index c323a84e50..f8d81d749d 100644 --- a/lib/kernel/doc/src/rpc.xml +++ b/lib/kernel/doc/src/rpc.xml @@ -25,328 +25,388 @@ <title>rpc</title> <prepared>Claes Wikstrom</prepared> <docno>1</docno> - <date>96-09-10</date> + <date>1996-09-10</date> <rev>A</rev> </header> <module>rpc</module> - <modulesummary>Remote Procedure Call Services</modulesummary> + <modulesummary>Remote Procedure Call services.</modulesummary> <description> - <p>This module contains services which are similar to remote - procedure calls. It also contains broadcast facilities and + <p>This module contains services similar to Remote + Procedure Calls. It also contains broadcast facilities and parallel evaluators. A remote procedure call is a method to call a function on a remote node and collect the answer. It is used for collecting information on a remote node, or for running a function with some specific side effects on the remote node.</p> </description> + <datatypes> <datatype> <name name="key"/> <desc> - <p>As returned by <seealso marker="#async_call/4"> - <c>async_call/4</c>.</seealso></p> + <p>As returned by + <seealso marker="#async_call/4"><c>async_call/4</c></seealso>.</p> </desc> </datatype> </datatypes> + <funcs> <func> - <name name="call" arity="4"/> - <fsummary>Evaluate a function call on a node</fsummary> + <name name="abcast" arity="2"/> + <fsummary>Broadcast a message asynchronously to a registered process on + all nodes.</fsummary> <desc> - <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> on the node - <c><anno>Node</anno></c> and returns the corresponding value <c><anno>Res</anno></c>, or - <c>{badrpc, <anno>Reason</anno>}</c> if the call fails.</p> + <p>Equivalent to <c>abcast([node()|nodes()], <anno>Name</anno>, + <anno>Msg</anno>)</c>.</p> </desc> </func> + <func> - <name name="call" arity="5"/> - <fsummary>Evaluate a function call on a node</fsummary> + <name name="abcast" arity="3"/> + <fsummary>Broadcast a message asynchronously to a registered process on + specific nodes.</fsummary> <desc> - <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> on the node - <c><anno>Node</anno></c> and returns the corresponding value <c><anno>Res</anno></c>, or - <c>{badrpc, <anno>Reason</anno>}</c> if the call fails. <c><anno>Timeout</anno></c> is - a timeout value in milliseconds. If the call times out, - <c><anno>Reason</anno></c> is <c>timeout</c>.</p> - <p>If the reply arrives after the call times out, no message - will contaminate the caller's message queue, since this - function spawns off a middleman process to act as (a void) - destination for such an orphan reply. This feature also makes - this function more expensive than <c>call/4</c> at - the caller's end.</p> + <p>Broadcasts the message <c><anno>Msg</anno></c> asynchronously to + the registered process <c><anno>Name</anno></c> on the specified + nodes.</p> + </desc> + </func> + + <func> + <name name="async_call" arity="4"/> + <fsummary>Evaluate a function call on a node, asynchronous + version.</fsummary> + <desc> + <p>Implements <em>call streams with promises</em>, a type of + RPC that does not suspend the caller until the result is + finished. Instead, a key is returned, which can be used + later to collect the value. The key can be viewed as a + promise to deliver the answer.</p> + <p>In this case, the key <c><anno>Key</anno></c> is returned, which + can be used in a subsequent call to + <seealso marker="#yield/1"><c>yield/1</c></seealso> or + <seealso marker="#nb_yield/1"><c>nb_yield/1,2</c></seealso> + to retrieve the value of evaluating <c>apply(<anno>Module</anno>, + <anno>Function</anno>, <anno>Args</anno>)</c> on node + <c><anno>Node</anno></c>.</p> </desc> </func> + <func> <name name="block_call" arity="4"/> - <fsummary>Evaluate a function call on a node in the RPC server's context</fsummary> + <fsummary>Evaluate a function call on a node in the RPC server's + context.</fsummary> <desc> - <p>Like <c>call/4</c>, but the RPC server at <c><anno>Node</anno></c> does + <p>Same as <seealso marker="#call/4"><c>call/4</c></seealso>, + but the RPC server at <c><anno>Node</anno></c> does not create a separate process to handle the call. Thus, this function can be used if the intention of the call is to block the RPC server from any other incoming requests until - the request has been handled. The function can also be used + the request has been handled. The function can also be used for efficiency reasons when very small fast functions are - evaluated, for example BIFs that are guaranteed not to + evaluated, for example, BIFs that are guaranteed not to suspend.</p> </desc> </func> + <func> <name name="block_call" arity="5"/> - <fsummary>Evaluate a function call on a node in the RPC server's context</fsummary> + <fsummary>Evaluate a function call on a node in the RPC server's + context.</fsummary> <desc> - <p>Like <c>block_call/4</c>, but with a timeout value in - the same manner as <c>call/5</c>.</p> + <p>Same as + <seealso marker="#block_call/4"><c>block_call/4</c></seealso>, + but with a time-out value in the same manner as + <seealso marker="#call/5"><c>call/5</c></seealso>.</p> </desc> </func> + <func> - <name name="async_call" arity="4"/> - <fsummary>Evaluate a function call on a node, asynchronous version</fsummary> + <name name="call" arity="4"/> + <fsummary>Evaluate a function call on a node.</fsummary> <desc> - <p>Implements <em>call streams with promises</em>, a type of - RPC which does not suspend the caller until the result is - finished. Instead, a key is returned which can be used at a - later stage to collect the value. The key can be viewed as a - promise to deliver the answer.</p> - <p>In this case, the key <c><anno>Key</anno></c> is returned, which can be - used in a subsequent call to <c>yield/1</c> or - <c>nb_yield/1,2</c> to retrieve the value of evaluating - <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> on the node <c><anno>Node</anno></c>.</p> + <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, + <anno>Args</anno>)</c> on node <c><anno>Node</anno></c> and returns + the corresponding value <c><anno>Res</anno></c>, or + <c>{badrpc, <anno>Reason</anno>}</c> if the call fails.</p> </desc> </func> + <func> - <name name="yield" arity="1"/> - <fsummary>Deliver the result of evaluating a function call on a node (blocking)</fsummary> + <name name="call" arity="5"/> + <fsummary>Evaluate a function call on a node.</fsummary> <desc> - <p>Returns the promised answer from a previous - <c>async_call/4</c>. If the answer is available, it is - returned immediately. Otherwise, the calling process is - suspended until the answer arrives from <c>Node</c>.</p> + <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, + <anno>Args</anno>)</c> on node <c><anno>Node</anno></c> and returns + the corresponding value <c><anno>Res</anno></c>, or + <c>{badrpc, <anno>Reason</anno>}</c> if the call fails. + <c><anno>Timeout</anno></c> is + a time-out value in milliseconds. If the call times out, + <c><anno>Reason</anno></c> is <c>timeout</c>.</p> + <p>If the reply arrives after the call times out, no message + contaminates the caller's message queue, as this + function spawns off a middleman process to act as (a void) + destination for such an orphan reply. This feature also makes + this function more expensive than <c>call/4</c> at + the caller's end.</p> </desc> </func> + <func> - <name name="nb_yield" arity="1"/> - <fsummary>Deliver the result of evaluating a function call on a node (non-blocking)</fsummary> + <name name="cast" arity="4"/> + <fsummary>Run a function on a node ignoring the result.</fsummary> <desc> - <p>Equivalent to <c>nb_yield(<anno>Key</anno>, 0)</c>.</p> + <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, + <anno>Args</anno>)</c> on node + <c><anno>Node</anno></c>. No response is delivered and the calling + process is not suspended until the evaluation is complete, as + is the case with + <seealso marker="#call/4"><c>call/4,5</c></seealso>.</p> </desc> </func> + <func> - <name name="nb_yield" arity="2"/> - <fsummary>Deliver the result of evaluating a function call on a node (non-blocking)</fsummary> + <name name="eval_everywhere" arity="3"/> + <fsummary>Run a function on all nodes, ignoring the result.</fsummary> <desc> - <p>This is a non-blocking version of <c>yield/1</c>. It returns - the tuple <c>{value, <anno>Val</anno>}</c> when the computation has - finished, or <c>timeout</c> when <c><anno>Timeout</anno></c> milliseconds - has elapsed.</p> + <p>Equivalent to <c>eval_everywhere([node()|nodes()], + <anno>Module</anno>, <anno>Function</anno>, + <anno>Args</anno>)</c>.</p> </desc> </func> + + <func> + <name name="eval_everywhere" arity="4"/> + <fsummary>Run a function on specific nodes, ignoring the + result.</fsummary> + <desc> + <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, + <anno>Args</anno>)</c> on + the specified nodes. No answers are collected.</p> + </desc> + </func> + + <func> + <name name="multi_server_call" arity="2"/> + <fsummary>Interact with the servers on a number of nodes.</fsummary> + <desc> + <p>Equivalent to <c>multi_server_call([node()|nodes()], + <anno>Name</anno>, <anno>Msg</anno>)</c>.</p> + </desc> + </func> + + <func> + <name name="multi_server_call" arity="3"/> + <fsummary>Interact with the servers on a number of nodes.</fsummary> + <desc> + <p>Can be used when interacting with servers called + <c><anno>Name</anno></c> on the specified nodes. It is assumed that + the servers receive messages in the format + <c>{From, <anno>Msg</anno>}</c> and reply using + <c>From ! {<anno>Name</anno>, Node, <anno>Reply</anno>}</c>, where + <c>Node</c> is the name of the node where the server is located. + The function returns <c>{<anno>Replies</anno>, + <anno>BadNodes</anno>}</c>, where <c><anno>Replies</anno></c> is a + list of all <c><anno>Reply</anno></c> values, and + <c><anno>BadNodes</anno></c> is one of the following:</p> + <list type="bulleted"> + <item>A list of the nodes that do not exist</item> + <item>A list of the nodes where the server does not exist</item> + <item>A list of the nodes where the server terminatd before sending + any reply.</item> + </list> + </desc> + </func> + <func> <name name="multicall" arity="3"/> - <fsummary>Evaluate a function call on a number of nodes</fsummary> + <fsummary>Evaluate a function call on a number of nodes.</fsummary> <desc> - <p>Equivalent to <c>multicall([node()|nodes()], <anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>, infinity)</c>.</p> + <p>Equivalent to <c>multicall([node()|nodes()], <anno>Module</anno>, + <anno>Function</anno>, <anno>Args</anno>, infinity)</c>.</p> </desc> </func> + <func> <name name="multicall" arity="4" clause_i="1"/> - <fsummary>Evaluate a function call on a number of nodes</fsummary> + <fsummary>Evaluate a function call on a number of nodes.</fsummary> <desc> - <p>Equivalent to <c>multicall(<anno>Nodes</anno>, <anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>, infinity)</c>.</p> + <p>Equivalent to <c>multicall(<anno>Nodes</anno>, <anno>Module</anno>, + <anno>Function</anno>, <anno>Args</anno>, infinity)</c>.</p> </desc> </func> + <func> <name name="multicall" arity="4" clause_i="2"/> - <fsummary>Evaluate a function call on a number of nodes</fsummary> + <fsummary>Evaluate a function call on a number of nodes.</fsummary> <desc> - <p>Equivalent to <c>multicall([node()|nodes()], <anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>, <anno>Timeout</anno>)</c>.</p> + <p>Equivalent to <c>multicall([node()|nodes()], <anno>Module</anno>, + <anno>Function</anno>, <anno>Args</anno>, + <anno>Timeout</anno>)</c>.</p> </desc> </func> + <func> <name name="multicall" arity="5"/> - <fsummary>Evaluate a function call on a number of nodes</fsummary> + <fsummary>Evaluate a function call on a number of nodes.</fsummary> <desc> - <p>In contrast to an RPC, a multicall is an RPC which is sent + <p>In contrast to an RPC, a multicall is an RPC that is sent concurrently from one client to multiple servers. This is - useful for collecting some information from a set of nodes, + useful for collecting information from a set of nodes, or for calling a function on a set of nodes to achieve some side effects. It is semantically the same as iteratively making a series of RPCs on all the nodes, but the multicall - is faster as all the requests are sent at the same time + is faster, as all the requests are sent at the same time and are collected one by one as they come back.</p> - <p>The function evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> - on the specified nodes and collects the answers. It returns - <c>{<anno>ResL</anno>, <anno>BadNodes</anno>}</c>, where <c><anno>BadNodes</anno></c> is a list + <p>The function evaluates <c>apply(<anno>Module</anno>, + <anno>Function</anno>, <anno>Args</anno>)</c> + on the specified nodes and collects the answers. It returns + <c>{<anno>ResL</anno>, <anno>BadNodes</anno>}</c>, where + <c><anno>BadNodes</anno></c> is a list of the nodes that terminated or timed out during computation, and <c><anno>ResL</anno></c> is a list of the return values. <c><anno>Timeout</anno></c> is a time (integer) in milliseconds, or <c>infinity</c>.</p> <p>The following example is useful when new object code is to - be loaded on all nodes in the network, and also indicates - some side effects RPCs may produce:</p> + be loaded on all nodes in the network, and indicates + some side effects that RPCs can produce:</p> <code type="none"> -%% Find object code for module Mod -{Mod, Bin, File} = code:get_object_code(Mod), +%% Find object code for module Mod +{Mod, Bin, File} = code:get_object_code(Mod), -%% and load it on all nodes including this one +%% and load it on all nodes including this one {ResL, _} = rpc:multicall(code, load_binary, [Mod, File, Bin]), %% and then maybe check the ResL list.</code> </desc> </func> + <func> - <name name="cast" arity="4"/> - <fsummary>Run a function on a node ignoring the result</fsummary> + <name name="nb_yield" arity="1"/> + <fsummary>Deliver the result of evaluating a function call on a node + (non-blocking).</fsummary> <desc> - <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> on the node - <c><anno>Node</anno></c>. No response is delivered and the calling - process is not suspended until the evaluation is complete, as - is the case with <c>call/4,5</c>.</p> + <p>Equivalent to <c>nb_yield(<anno>Key</anno>, 0)</c>.</p> </desc> </func> + <func> - <name name="eval_everywhere" arity="3"/> - <fsummary>Run a function on all nodes, ignoring the result</fsummary> + <name name="nb_yield" arity="2"/> + <fsummary>Deliver the result of evaluating a function call on a node + (non-blocking).</fsummary> <desc> - <p>Equivalent to <c>eval_everywhere([node()|nodes()], <anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c>.</p> + <p>Non-blocking version of + <seealso marker="#yield/1"><c>yield/1</c></seealso>. It returns + the tuple <c>{value, <anno>Val</anno>}</c> when the computation is + finished, or <c>timeout</c> when <c><anno>Timeout</anno></c> + milliseconds has elapsed.</p> </desc> </func> + <func> - <name name="eval_everywhere" arity="4"/> - <fsummary>Run a function on specific nodes, ignoring the result</fsummary> + <name name="parallel_eval" arity="1"/> + <fsummary>Evaluate many function calls on all nodes in + parallel.</fsummary> <desc> - <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> on - the specified nodes. No answers are collected.</p> + <p>Evaluates, for every tuple in <c><anno>FuncCalls</anno></c>, + <c>apply(<anno>Module</anno>, <anno>Function</anno>, + <anno>Args</anno>)</c> on some node in + the network. Returns the list of return values, in the same + order as in <c><anno>FuncCalls</anno></c>.</p> </desc> </func> + <func> - <name name="abcast" arity="2"/> - <fsummary>Broadcast a message asynchronously to a registered process on all nodes</fsummary> + <name name="pinfo" arity="1"/> + <fsummary>Information about a process.</fsummary> <desc> - <p>Equivalent to <c>abcast([node()|nodes()], <anno>Name</anno>, <anno>Msg</anno>)</c>.</p> + <p>Location transparent version of the BIF + <seealso marker="erts:erlang#process_info/1"><c>erlang:process_info/1</c></seealso> in <c>ERTS</c>.</p> </desc> </func> + <func> - <name name="abcast" arity="3"/> - <fsummary>Broadcast a message asynchronously to a registered process on specific nodes</fsummary> + <name name="pinfo" arity="2" clause_i="1"/> + <name name="pinfo" arity="2" clause_i="2"/> + <fsummary>Information about a process.</fsummary> <desc> - <p>Broadcasts the message <c><anno>Msg</anno></c> asynchronously to - the registered process <c><anno>Name</anno></c> on the specified nodes.</p> + <p>Location transparent version of the BIF + <seealso marker="erts:erlang#process_info/2"><c>erlang:process_info/2</c></seealso> in <c>ERTS</c>.</p> + </desc> + </func> + + <func> + <name name="pmap" arity="3"/> + <fsummary>Parallell evaluation of mapping a function over a + list.</fsummary> + <desc> + <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, + [<anno>Elem</anno>|<anno>ExtraArgs</anno>])</c> for every element + <c><anno>Elem</anno></c> in <c><anno>List1</anno></c>, in parallel. + Returns the list of return values, in the same order as in + <c><anno>List1</anno></c>.</p> </desc> </func> + <func> <name name="sbcast" arity="2"/> - <fsummary>Broadcast a message synchronously to a registered process on all nodes</fsummary> + <fsummary>Broadcast a message synchronously to a registered process on + all nodes.</fsummary> <desc> - <p>Equivalent to <c>sbcast([node()|nodes()], <anno>Name</anno>, <anno>Msg</anno>)</c>.</p> + <p>Equivalent to <c>sbcast([node()|nodes()], <anno>Name</anno>, + <anno>Msg</anno>)</c>.</p> </desc> </func> + <func> <name name="sbcast" arity="3"/> - <fsummary>Broadcast a message synchronously to a registered process on specific nodes</fsummary> + <fsummary>Broadcast a message synchronously to a registered process on + specific nodes.</fsummary> <desc> <p>Broadcasts the message <c><anno>Msg</anno></c> synchronously to - the registered process <c><anno>Name</anno></c> on the specified nodes.</p> - <p>Returns <c>{<anno>GoodNodes</anno>, <anno>BadNodes</anno>}</c>, where <c><anno>GoodNodes</anno></c> - is the list of nodes which have <c><anno>Name</anno></c> as a registered - process.</p> + the registered process <c><anno>Name</anno></c> on the specified + nodes.</p> + <p>Returns <c>{<anno>GoodNodes</anno>, <anno>BadNodes</anno>}</c>, + where <c><anno>GoodNodes</anno></c> is the list of nodes that have + <c><anno>Name</anno></c> as a registered process.</p> <p>The function is synchronous in the sense that it is known that all servers have received the message when the call returns. It is not possible to know that the servers have - actually processed the message.</p> + processed the message.</p> <p>Any further messages sent to the servers, after this - function has returned, will be received by all servers after + function has returned, are received by all servers after this message.</p> </desc> </func> + <func> <name name="server_call" arity="4"/> - <fsummary>Interact with a server on a node</fsummary> + <fsummary>Interact with a server on a node.</fsummary> <desc> - <p>This function can be used when interacting with a server - called <c><anno>Name</anno></c> at node <c><anno>Node</anno></c>. It is assumed that - the server receives messages in the format - <c>{From, <anno>Msg</anno>}</c> and replies using <c>From ! {<anno>ReplyWrapper</anno>, <anno>Node</anno>, <anno>Reply</anno>}</c>. This function makes such + <p>Can be used when interacting with a server called + <c><anno>Name</anno></c> on node <c><anno>Node</anno></c>. It is + assumed that the server receives messages in the format + <c>{From, <anno>Msg</anno>}</c> and replies using + <c>From ! {<anno>ReplyWrapper</anno>, <anno>Node</anno>, + <anno>Reply</anno>}</c>. This function makes such a server call and ensures that the entire call is packed into - an atomic transaction which either succeeds or fails. It + an atomic transaction, which either succeeds or fails. It never hangs, unless the server itself hangs.</p> - <p>The function returns the answer <c><anno>Reply</anno></c> as produced by - the server <c><anno>Name</anno></c>, or <c>{error, <anno>Reason</anno>}</c>.</p> - </desc> - </func> - <func> - <name name="multi_server_call" arity="2"/> - <fsummary>Interact with the servers on a number of nodes</fsummary> - <desc> - <p>Equivalent to <c>multi_server_call([node()|nodes()], <anno>Name</anno>, <anno>Msg</anno>)</c>.</p> - </desc> - </func> - <func> - <name name="multi_server_call" arity="3"/> - <fsummary>Interact with the servers on a number of nodes</fsummary> - <desc> - <p>This function can be used when interacting with servers - called <c><anno>Name</anno></c> on the specified nodes. It is assumed that - the servers receive messages in the format <c>{From, <anno>Msg</anno>}</c> - and reply using <c>From ! {<anno>Name</anno>, Node, <anno>Reply</anno>}</c>, where - <c>Node</c> is the name of the node where the server is - located. The function returns <c>{<anno>Replies</anno>, <anno>BadNodes</anno>}</c>, - where <c><anno>Replies</anno></c> is a list of all <c><anno>Reply</anno></c> values and - <c><anno>BadNodes</anno></c> is a list of the nodes which did not exist, or - where the server did not exist, or where the server terminated - before sending any reply.</p> - </desc> - </func> - <func> - <name name="safe_multi_server_call" arity="2"/> - <name name="safe_multi_server_call" arity="3"/> - <fsummary>Interact with the servers on a number of nodes (deprecated)</fsummary> - <desc> - <warning> - <p>This function is deprecated. Use - <c>multi_server_call/2,3</c> instead.</p> - </warning> - <p>In Erlang/OTP R6B and earlier releases, - <c>multi_server_call/2,3</c> could not handle the case - where the remote node exists, but there is no server called - <c><anno>Name</anno></c>. Instead this function had to be used. In - Erlang/OTP R7B and later releases, however, the functions are - equivalent, except for this function being slightly slower.</p> - </desc> - </func> - <func> - <name name="parallel_eval" arity="1"/> - <fsummary>Evaluate several function calls on all nodes in parallel</fsummary> - <desc> - <p>For every tuple in <c><anno>FuncCalls</anno></c>, evaluates - <c>apply(<anno>Module</anno>, <anno>Function</anno>, <anno>Args</anno>)</c> on some node in - the network. Returns the list of return values, in the same - order as in <c><anno>FuncCalls</anno></c>.</p> - </desc> - </func> - <func> - <name name="pmap" arity="3"/> - <fsummary>Parallell evaluation of mapping a function over a list </fsummary> - <desc> - <p>Evaluates <c>apply(<anno>Module</anno>, <anno>Function</anno>, [<anno>Elem</anno>|<anno>ExtraArgs</anno>])</c>, - for every element <c><anno>Elem</anno></c> in <c><anno>List1</anno></c>, in parallel. - Returns the list of return values, in the same order as in - <c><anno>List1</anno></c>.</p> - </desc> - </func> - <func> - <name name="pinfo" arity="1"/> - <fsummary>Information about a process</fsummary> - <desc> - <p>Location transparent version of the BIF - <seealso marker="erts:erlang#process_info/1"> - <c>process_info/1</c></seealso>.</p> + <p>The function returns the answer <c><anno>Reply</anno></c> as + produced by the server <c><anno>Name</anno></c>, or + <c>{error, <anno>Reason</anno>}</c>.</p> </desc> </func> + <func> - <name name="pinfo" arity="2"/> - <fsummary>Information about a process</fsummary> + <name name="yield" arity="1"/> + <fsummary>Deliver the result of evaluating a function call on a node + (blocking).</fsummary> <desc> - <p>Location transparent version of the BIF - <seealso marker="erts:erlang#process_info/2"> - <c>process_info/2</c></seealso>.</p> + <p>Returns the promised answer from a previous + <seealso marker="#async_call/4"><c>async_call/4</c></seealso>. + If the answer is available, it is + returned immediately. Otherwise, the calling process is + suspended until the answer arrives from <c>Node</c>.</p> </desc> </func> </funcs> |