diff options
| -rw-r--r-- | erts/doc/src/match_spec.xml | 149 | ||||
| -rw-r--r-- | lib/runtime_tools/doc/src/dbg.xml | 60 | ||||
| -rw-r--r-- | lib/stdlib/doc/src/ets.xml | 5 |
3 files changed, 155 insertions, 59 deletions
diff --git a/erts/doc/src/match_spec.xml b/erts/doc/src/match_spec.xml index 3944f24f84..7be3d15de6 100644 --- a/erts/doc/src/match_spec.xml +++ b/erts/doc/src/match_spec.xml @@ -33,21 +33,15 @@ <file>match_spec.xml</file> </header> <p>A "match specification" (match_spec) is an Erlang term describing a - small "program" that will try to match something (either the - parameters to a function as used in the <c><![CDATA[erlang:trace_pattern/2]]></c> - BIF, or the objects in an ETS table.). + small "program" that will try to match something. It can be used + to either control tracing with + <seealso marker="erlang#trace_pattern/3">erlang:trace_pattern/3</seealso> + or to search for objects in an ETS table with for example + <seealso marker="stdlib:ets#select/2">ets:select/2</seealso>. The match_spec in many ways works like a small function in Erlang, but is interpreted/compiled by the Erlang runtime system to something much more efficient than calling an Erlang function. The match_spec is also very limited compared to the expressiveness of real Erlang functions.</p> - <p>Match specifications are given to the BIF <c><![CDATA[erlang:trace_pattern/2]]></c> to - execute matching of function arguments as well as to define some actions - to be taken when the match succeeds (the <c><![CDATA[MatchBody]]></c> part). Match - specifications can also be used in ETS, to specify objects to be - returned from an <c><![CDATA[ets:select/2]]></c> call (or other select - calls). The semantics and restrictions differ slightly when using - match specifications for tracing and in ETS, the differences are - defined in a separate paragraph below.</p> <p>The most notable difference between a match_spec and an Erlang fun is of course the syntax. Match specifications are Erlang terms, not Erlang code. A match_spec also has a somewhat strange concept of @@ -382,6 +376,51 @@ the pid() of the current process.</p> </section> + <marker id="match_target"></marker> + <section> + <title>Match target</title> + <p>Each execution of a match specification is done against + a match target term. The format and content of the target term + depends on the context in which the match is done. The match + target for ETS is always a full table tuple. The match target + for call trace is always a list of all function arguments. The + match target for event trace depends on the event type, see + table below.</p> + <table> + <row> + <cell align="left" valign="middle">Context</cell> + <cell align="left" valign="middle">Type</cell> + <cell align="left" valign="middle">Match target</cell> + <cell align="left" valign="middle">Description</cell> + </row> + <row> + <cell align="left" valign="middle">ETS</cell> + <cell align="left" valign="middle"></cell> + <cell align="left" valign="middle">{Key, Value1, Value2, ...}</cell> + <cell align="left" valign="middle">A table object</cell> + </row> + <row> + <cell align="left" valign="middle">Trace</cell> + <cell align="left" valign="middle">call</cell> + <cell align="left" valign="middle">[Arg1, Arg2, ...]</cell> + <cell align="left" valign="middle">Function arguments</cell> + </row> + <row> + <cell align="left" valign="middle">Trace</cell> + <cell align="left" valign="middle">send</cell> + <cell align="left" valign="middle">[Receiver, Message]</cell> + <cell align="left" valign="middle">Receiving process/port and message term</cell> + </row> + <row> + <cell align="left" valign="middle">Trace</cell> + <cell align="left" valign="middle">'receive'</cell> + <cell align="left" valign="middle">[Node, Sender, Message]</cell> + <cell align="left" valign="middle">Sending node, process/port and message term</cell> + </row> + <tcaption>Match target depending on context</tcaption> + </table> + </section> + <section> <title>Variables and literals</title> <p>Variables take the form <c><![CDATA['$<number>']]></c> where @@ -396,10 +435,8 @@ <c><![CDATA[MatchCondition]]></c> parts, only variables bound previously may be used. As a special case, in the <c><![CDATA[MatchCondition/MatchBody]]></c> parts, the variable <c><![CDATA['$_']]></c> - expands to the whole expression which matched the - <c><![CDATA[MatchHead]]></c> (i.e., the whole parameter list to the possibly - traced function or the whole matching object in the ets table) - and the variable <c><![CDATA['$$']]></c> expands to a list + expands to the whole <seealso marker="#match_target">match target</seealso> + term and the variable <c><![CDATA['$$']]></c> expands to a list of the values of all bound variables in order (i.e. <c><![CDATA[['$1','$2', ...]]]></c>). </p> @@ -480,8 +517,8 @@ <p>For each tuple in the <c><![CDATA[MatchExpression]]></c> list and while no match has succeeded:</p> <list type="bulleted"> - <item>Match the <c><![CDATA[MatchHead]]></c> part against the arguments to the - function, + <item>Match the <c><![CDATA[MatchHead]]></c> part against the + match target term, binding the <c><![CDATA['$<number>']]></c> variables (much like in <c><![CDATA[ets:match/2]]></c>). If the <c><![CDATA[MatchHead]]></c> cannot match the arguments, the match fails. @@ -522,13 +559,10 @@ term. The <c><![CDATA[ActionTerm]]></c>'s are executed as in an imperative language, i.e. for their side effects. Functions with side effects are also allowed when tracing.</p> - <p>In ETS the match head is a <c><![CDATA[tuple()]]></c> (or a single match - variable) while it is a list (or a single match variable) when - tracing.</p> </section> <section> - <title>ETS Examples</title> + <title>Tracing Examples</title> <p>Match an argument list of three where the first and third arguments are equal:</p> <code type="none"><![CDATA[ @@ -585,42 +619,6 @@ parameter list with a single variable is a special case. In all other cases the <c><![CDATA[MatchHead]]></c> has to be a <em>proper</em> list. </p> - <p>Match all objects in an ets table where the first element is - the atom 'strider' and the tuple arity is 3 and return the whole - object.</p> - <code type="none"><![CDATA[ -[{{strider,'_','_'}, - [], - ['$_']}] - ]]></code> - <p>Match all objects in an ets table with arity > 1 and the first - element is 'gandalf', return element 2.</p> - <code type="none"><![CDATA[ -[{'$1', - [{'==', gandalf, {element, 1, '$1'}},{'>=',{size, '$1'},2}], - [{element,2,'$1'}]}] - ]]></code> - <p>In the above example, if the first element had been the key, - it's much more efficient to match that key in the <c><![CDATA[MatchHead]]></c> - part than in the <c><![CDATA[MatchConditions]]></c> part. The search space of - the tables is restricted with regards to the <c><![CDATA[MatchHead]]></c> so - that only objects with the matching key are searched. - </p> - <p>Match tuples of 3 elements where the second element is either - 'merry' or 'pippin', return the whole objects.</p> - <code type="none"><![CDATA[ -[{{'_',merry,'_'}, - [], - ['$_']}, - {{'_',pippin,'_'}, - [], - ['$_']}] - ]]></code> - <p>The function <c><![CDATA[ets:test_ms/2]]></c> can be useful for testing - complicated ets matches.</p> - </section> - <section> - <title>Tracing Examples</title> <p>Only generate trace message if trace control word is set to 1:</p> <code type="none"><![CDATA[ [{'_', @@ -658,5 +656,42 @@ {'_',[],[]}] ]]></code> </section> + + <section> + <title>ETS Examples</title> + <p>Match all objects in an ets table where the first element is + the atom 'strider' and the tuple arity is 3 and return the whole + object.</p> + <code type="none"><![CDATA[ +[{{strider,'_','_'}, + [], + ['$_']}] + ]]></code> + <p>Match all objects in an ets table with arity > 1 and the first + element is 'gandalf', return element 2.</p> + <code type="none"><![CDATA[ +[{'$1', + [{'==', gandalf, {element, 1, '$1'}},{'>=',{size, '$1'},2}], + [{element,2,'$1'}]}] + ]]></code> + <p>In the above example, if the first element had been the key, + it's much more efficient to match that key in the <c><![CDATA[MatchHead]]></c> + part than in the <c><![CDATA[MatchConditions]]></c> part. The search space of + the tables is restricted with regards to the <c><![CDATA[MatchHead]]></c> so + that only objects with the matching key are searched. + </p> + <p>Match tuples of 3 elements where the second element is either + 'merry' or 'pippin', return the whole objects.</p> + <code type="none"><![CDATA[ +[{{'_',merry,'_'}, + [], + ['$_']}, + {{'_',pippin,'_'}, + [], + ['$_']}] + ]]></code> + <p>The function <c><![CDATA[ets:test_ms/2]]></c> can be useful for testing + complicated ets matches.</p> + </section> </chapter> diff --git a/lib/runtime_tools/doc/src/dbg.xml b/lib/runtime_tools/doc/src/dbg.xml index 103b8b52e9..49b11ddc3c 100644 --- a/lib/runtime_tools/doc/src/dbg.xml +++ b/lib/runtime_tools/doc/src/dbg.xml @@ -439,6 +439,50 @@ Error: fun containing local erlang function calls ('is_atomm' called in guard)\ global calls (and functions).</p> </desc> </func> + + + <func> + <name>tpe(Event, MatchSpec) -> {ok, MatchDesc} | {error, term()}</name> + <fsummary>Set pattern for traced event</fsummary> + <type> + <v>Event = send | 'receive'</v> + <v>MatchSpec = integer() | Built-inAlias | [] | match_spec()</v> + <v>Built-inAlias = x | c | cx</v> + <v>MatchDesc = [MatchInfo]</v> + <v>MatchInfo = {saved, integer()} | MatchNum</v> + <v>MatchNum = {matched, node(), 1} | {matched, node(), 0, RPCError}</v> + </type> + <desc> + <p>This function associates a match specification with trace event + <c>send</c> or <c>'receive'</c>. By default all executed <c>send</c> + and <c>'receive'</c> events are traced if enabled for a process. + A match specification can be used to filter traced events + based on sender, receiver and/or message content.</p> + <p>For a description of the <c>match_spec()</c> syntax, + please turn to the <em>User's guide</em> part of the online + documentation for the runtime system (<em>erts</em>). The + chapter <seealso marker="erts:match_spec"><em>Match Specifications in Erlang</em></seealso> + explains the general match specification "language".</p> + <p>For <c>send</c>, the matching is done on the list <c>[Receiver, Msg]</c>. + <c>Receiver</c> is the process or port identity of the receiver and + <c>Msg</c> is the message term. The pid of the sending process can be + accessed with the guard function <c>self/0</c>.</p> + <p>For <c>'receive'</c>, the matching is done on the list <c>[Node, Sender, Msg]</c>. + <c>Node</c> is the node name of the sender. <c>Sender</c> is the + process or port identity of the sender, or the atom + <c>undefined</c> if the sender is not known (which may + be the case for remote senders). <c>Msg</c> is the + message term. The pid of the receiving process can be + accessed with the guard function <c>self/0</c>.</p> + <p>All nodes added with <seealso marker="#n-1"><c>n/1</c></seealso> or + <seealso marker="#tracer-3"><c>tracer/3</c></seealso> will + be affected by this call.</p> + <p>The return value is the same as for + <seealso marker="#tp-2"><c>tp/2</c></seealso>. The number of matched + events are never larger than 1 as <c>tpe/2</c> does not + accept any form of wildcards for argument <c>Event</c>.</p> + </desc> + </func> <func> <name>ctp()</name> <fsummary>Clear call trace pattern for the specified functions</fsummary> @@ -563,6 +607,22 @@ Error: fun containing local erlang function calls ('is_atomm' called in guard)\ </desc> </func> <func> + <name>ctpe(Event) -> {ok, MatchDesc} | {error, term()}</name> + <fsummary>Clear trace pattern for the specified event</fsummary> + <type> + <v>Event = send | 'receive'</v> + <v>MatchDesc = [MatchNum]</v> + <v>MatchNum = {matched, node(), 1} | {matched, node(), 0, RPCError}</v> + </type> + <desc> + <p>This function clears match specifications for the specified + trace event (<c>send</c> or <c>'receive'</c>). It will revert back + to the default behavior of tracing all triggered events.</p> + <p>The return value follow the same style as for + <seealso marker="#ctp-1"><c>ctp/1</c></seealso>.</p> + </desc> + </func> + <func> <name>ltp() -> ok</name> <fsummary>List saved and built-in match specifications on the console.</fsummary> <desc> diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml index 2d69c201bc..b32638f04d 100644 --- a/lib/stdlib/doc/src/ets.xml +++ b/lib/stdlib/doc/src/ets.xml @@ -123,8 +123,9 @@ <p>Some of the functions uses a <em>match specification</em>, match_spec. A brief explanation is given in <seealso marker="#select/2">select/2</seealso>. For a detailed - description, see the chapter "Match specifications in Erlang" in - <em>ERTS User's Guide</em>.</p> + description, see chapter + <seealso marker="erts:match_spec">Match Specifications in Erlang</seealso> + in <em>ERTS User's Guide</em>.</p> </section> <datatypes> |