path: root/lib/et/doc/src/et_collector.xml

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  <header>
    <copyright>
      <year>2002</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

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      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
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    </legalnotice>

    <title>et_collector</title>
    <prepared>H&aring;kan Mattsson</prepared>
    <responsible>H&aring;kan Mattsson</responsible>
    <docno></docno>
    <approved>H&aring;kan Mattsson</approved>
    <checked></checked>
    <date></date>
    <rev>%VSN%</rev>
    <file>et_collector.xml</file>
  </header>
  <module>et_collector</module>
  <modulesummary>Collect trace events and provide a backing storage appropriate for iteration </modulesummary>
  <description>
    <p>Interface module for the Event Trace (ET) application</p>
  </description>
  <funcs>
    <func>
      <name>start_link(Options) -> {ok, CollectorPid} | {error, Reason}</name>
      <fsummary>Start a collector process</fsummary>
      <type>
        <v>Options = [option()]</v>
        <v>option() = {parent_pid, pid()} | {event_order, event_order()} | {dict_insert, {filter, collector}, collector_fun()} | {dict_insert, {filter, event_filter_name()}, event_filter_fun()} | {dict_insert, {subscriber, pid()}, dict_val()} | {dict_insert, dict_key(), dict_val()} | {dict_delete, dict_key()} | {trace_client, trace_client()} | {trace_global, boolean()} |  {trace_pattern, trace_pattern()} | {trace_port, integer()} |  {trace_max_queue, integer()}</v>
        <v>event_order() = trace_ts | event_ts</v>
        <v>trace_pattern() = {report_module(), extended_dbg_match_spec()} | undefined</v>
        <v>report_module() = atom() | undefined &lt;v>extended_dbg_match_spec()() = detail_level() | dbg_match_spec()</v>
        <v>detail_level() = min | max | integer(X) when X =&lt; 0, X >= 100</v>
        <v>trace_client() =  {event_file, file_name()} | {dbg_trace_type(), dbg_trace_parameters()}</v>
        <v>file_name() = string()</v>
        <v>collector_fun() = trace_filter_fun() | event_filter_fun()</v>
        <v>trace_filter_fun() = fun(TraceData) -> false | true | {true, NewEvent}</v>
        <v>event_filter_fun() = fun(Event) -> false | true | {true, NewEvent}</v>
        <v>event_filter_name() = atom()</v>
        <v>TraceData = erlang_trace_data()</v>
        <v>Event = NewEvent = record(event)</v>
        <v>dict_key() = term()</v>
        <v>dict_val() = term()</v>
        <v>CollectorPid = pid()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Start a collector process.</p>
        <p>The collector collects trace events and keeps them ordered by their
          timestamp. The timestamp may either reflect the time when the
          actual trace data was generated (trace_ts) or when the trace data
          was transformed into an event record (event_ts). If the time stamp
          is missing in the trace data (missing timestamp option to
          erlang:trace/4) the trace_ts will be set to the event_ts.</p>
        <p>Events are reported to the collector directly with the report
          function or indirectly via one or more trace clients. All reported
          events are first filtered thru the collector filter before they are
          stored by the collector. By replacing the default collector filter
          with a customized dito it is possible to allow any trace data as
          input. The collector filter is a dictionary entry with the
          predefined key {filter, collector} and the value is a fun of
          arity 1. See et_selector:make_event/1 for interface details,
          such as which erlang:trace/1 tuples that are accepted.</p>
        <p>The collector has a built-in dictionary service. Any term may be
          stored as value in the dictionary and bound to a unique key. When
          new values are inserted with an existing key, the new values will
          overwrite the existing ones. Processes may subscribe on dictionary
          updates by using {subscriber, pid()} as dictionary key. All
          dictionary updates will be propagated to the subscriber processes
          matching the pattern {{subscriber, '_'}, '_'} where the first '_'
          is interpreted as a pid().</p>

        <p>In global trace mode, the collector will automatically
        start tracing on all connected Erlang nodes. When a node
        connects, a port tracer will be started on that node and a
        corresponding trace client on the collector node.</p>

        <p>Default values:</p>
        <list type="bulleted">
          <item>parent_pid - self().</item>
          <item>event_order - trace_ts.</item>
          <item>trace_global - false.</item>
          <item>trace_pattern - undefined.</item>
          <item>trace_port - 4711.</item>
          <item>trace_max_queue - 50.</item>
        </list>
      </desc>
    </func>
    <func>
      <name>stop(CollectorPid) -> ok</name>
      <fsummary>Stop a collector process</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
      </type>
      <desc>
        <p>Stop a collector process.</p>
      </desc>
    </func>
    <func>
      <name>save_event_file(CollectorPid, FileName, Options) -> ok | {error, Reason}</name>
      <fsummary>Save the events to a file</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>FileName = string()</v>
        <v>Options = [option()]</v>
        <v>Reason = term()</v>
        <v>option() = event_option() | file_option() | table_option()</v>
        <v>event_option() = existing</v>
        <v>file_option() = write | append</v>
        <v>table_option() = keep | clear</v>
      </type>
      <desc>
        <p>Save the events to a file.</p>
        <p>By default the currently stored events (existing) are
          written to a brand new file (write) and the events are
          kept (keep) after they have been written to the file.</p>
        <p>Instead of keeping the events after writing them to file,
          it is possible to remove all stored events after they
          have successfully written to file (clear).</p>
        <p>The options defaults to existing, write and keep.</p>
      </desc>
    </func>
    <func>
      <name>load_event_file(CollectorPid, FileName) -> {ok, BadBytes} | exit(Reason)</name>
      <fsummary>Load the event table from a file</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>FileName = string()</v>
        <v>BadBytes = integer(X) where X >= 0</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Load the event table from a file.</p>
      </desc>
    </func>
    <func>
      <name>report(Handle, TraceOrEvent) -> {ok, Continuation} | exit(Reason)</name>
      <name>report_event(Handle, DetailLevel, FromTo, Label, Contents) -> {ok, Continuation} | exit(Reason)</name>
      <name>report_event(Handle, DetailLevel, From, To, Label, Contents) -> {ok, Continuation} | exit(Reason)</name>
      <fsummary>Report an event to the collector</fsummary>
      <type>
        <v>Handle = Initial | Continuation</v>
        <v>Initial = collector_pid()</v>
        <v>collector_pid() = pid()</v>
        <v>Continuation = record(table_handle)</v>
        <v>TraceOrEvent = record(event) | dbg_trace_tuple() | end_of_trace</v>
        <v>Reason = term()</v>
        <v>DetailLevel = integer(X) when X =&lt; 0, X >= 100</v>
        <v>From        = actor()</v>
        <v>To          = actor()</v>
        <v>FromTo      = actor()</v>
        <v>Label       = atom() | string() | term()</v>
        <v>Contents    = [{Key, Value}] | term()</v>
        <v>actor()  = term()</v>
      </type>
      <desc>
        <p>Report an event to the collector.</p>
        <p>All events are filtered thru the collector filter, which
          optionally may transform or discard the event. The first
          call should use the pid of the collector process as
          report handle, while subsequent calls should use the
          table handle.</p>
      </desc>
    </func>
    <func>
      <name>make_key(Type, Stuff) -> Key</name>
      <fsummary>Make a key out of an event record or an old key</fsummary>
      <type>
        <v>Type = record(table_handle) | trace_ts | event_ts</v>
        <v>Stuff = record(event) | Key</v>
        <v>Key = record(event_ts) | record(trace_ts)</v>
      </type>
      <desc>
        <p>Make a key out of an event record or an old key.</p>
      </desc>
    </func>
    <func>
      <name>get_table_handle(CollectorPid) -> Handle</name>
      <fsummary>Return a table handle</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>Handle = record(table_handle)</v>
      </type>
      <desc>
        <p>Return a table handle.</p>
      </desc>
    </func>
    <func>
      <name>get_global_pid() -> CollectorPid | exit(Reason)</name>
      <fsummary>Return a the identity of the globally registered collector if there is any</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Return a the identity of the globally registered
          collector if there is any.</p>
      </desc>
    </func>
    <func>
      <name>change_pattern(CollectorPid, RawPattern) -> {old_pattern, TracePattern}</name>
      <fsummary>Change active trace pattern globally on all trace nodes</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>RawPattern = {report_module(), extended_dbg_match_spec()}</v>
        <v>report_module() = atom() | undefined</v>
        <v>extended_dbg_match_spec()() = detail_level() | dbg_match_spec()</v>
        <v>RawPattern = detail_level()</v>
        <v>detail_level() = min | max | integer(X) when X =&lt; 0, X >= 100</v>
        <v>TracePattern = {report_module(), dbg_match_spec_match_spec()}</v>
      </type>
      <desc>
        <p>Change active trace pattern globally on all trace nodes.</p>
      </desc>
    </func>
    <func>
      <name>dict_insert(CollectorPid, {filter, collector}, FilterFun) -> ok</name>
      <name>dict_insert(CollectorPid, {subscriber, SubscriberPid}, Void) -> ok</name>
      <name>dict_insert(CollectorPid, Key, Val) -> ok</name>
      <fsummary>Insert a dictionary entry and send a {et, {dict_insert, Key, Val}} tuple to all registered subscribers.</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>FilterFun = filter_fun() </v>
        <v>SubscriberPid = pid()</v>
        <v>Void = term()</v>
        <v>Key = term()</v>
        <v>Val = term()</v>
      </type>
      <desc>
        <p>Insert a dictionary entry
          and send a {et, {dict_insert, Key, Val}} tuple
          to all registered subscribers.</p>
        <p>If the entry is a new subscriber, it will imply that
          the new subscriber process first will get one message
          for each already stored dictionary entry, before it
          and all old subscribers will get this particular entry.
          The collector process links to and then supervises the
          subscriber process. If the subscriber process dies it
          will imply that it gets unregistered as with a normal
          dict_delete/2.</p>
      </desc>
    </func>
    <func>
      <name>dict_lookup(CollectorPid, Key) -> [Val]</name>
      <fsummary>Lookup a dictionary entry and return zero or one value</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>FilterFun = filter_fun() </v>
        <v>CollectorPid = pid()</v>
        <v>Key = term()</v>
        <v>Val = term()</v>
      </type>
      <desc>
        <p>Lookup a dictionary entry and return zero or one value.</p>
      </desc>
    </func>
    <func>
      <name>dict_delete(CollectorPid, Key) -> ok</name>
      <fsummary>Delete a dictionary entry and send a {et, {dict_delete, Key}} tuple to all registered subscribers.</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>SubscriberPid = pid()</v>
        <v>Key = {subscriber, SubscriberPid} | term()</v>
      </type>
      <desc>
        <p>Delete a dictionary entry
          and send a {et, {dict_delete, Key}} tuple
          to all registered subscribers.</p>
        <p>If the deleted entry is a registered subscriber, it will
          imply that the subscriber process gets is unregistered as
          subscriber as well as it gets it final message.</p>
      </desc>
    </func>
    <func>
      <name>dict_match(CollectorPid, Pattern) -> [Match]</name>
      <fsummary>Match some dictionary entries</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>Pattern = '_' | {key_pattern(), val_pattern()}</v>
        <v>key_pattern() = ets_match_object_pattern()</v>
        <v>val_pattern() = ets_match_object_pattern()</v>
        <v>Match = {key(), val()}</v>
        <v>key() = term()</v>
        <v>val() = term()</v>
      </type>
      <desc>
        <p>Match some dictionary entries</p>
      </desc>
    </func>
    <func>
      <name>multicast(_CollectorPid, Msg) -> ok</name>
      <fsummary>Sends a message to all registered subscribers</fsummary>
      <type>
        <v>CollectorPid = pid()</v>
        <v>CollectorPid = pid()</v>
        <v>Msg = term()</v>
      </type>
      <desc>
        <p>Sends a message to all registered subscribers.</p>
      </desc>
    </func>
    <func>
      <name>start_trace_client(CollectorPid, Type, Parameters) -> file_loaded | {trace_client_pid, pid()} | exit(Reason)</name>
      <fsummary>Load raw Erlang trace from a file, port or process.</fsummary>
      <type>
        <v>Type       = dbg_trace_client_type()</v>
        <v>Parameters = dbg_trace_client_parameters()</v>
        <v>Pid        = dbg_trace_client_pid()</v>
      </type>
      <desc>
        <p>Load raw Erlang trace from a file, port or process.</p>
      </desc>
    </func>
    <func>
      <name>iterate(Handle, Prev, Limit) -> NewAcc</name>
      <fsummary>Iterates over the currently stored events</fsummary>
      <desc>
        <p>Short for iterate(Handle, Prev, Limit, undefined, Prev) -&gt; NewAcc</p>
      </desc>
    </func>
    <func>
      <name>iterate(Handle, Prev, Limit, Fun, Acc) -> NewAcc</name>
      <fsummary>Iterate over the currently stored events</fsummary>
      <type>
        <v>Handle = collector_pid() | table_handle()</v>
        <v>Prev = first | last | event_key()</v>
        <v>Limit = done() | forward() | backward()</v>
        <v>collector_pid() = pid()</v>
        <v>table_handle() = record(table_handle)</v>
        <v>event_key() = record(event) | record(event_ts) | record(trace_ts)</v>
        <v>done() = 0</v>
        <v>forward() = infinity | integer(X) where X > 0</v>
        <v>backward() = '-infinity' | integer(X) where X &lt; 0</v>
        <v>Fun = fun(Event, Acc) -> NewAcc &lt;v>Acc = NewAcc = term()</v>
      </type>
      <desc>
        <p>Iterate over the currently stored events.</p>
        <p>Iterates over the currently stored events and applies
          a function for each event. The iteration may be performed
          forwards or backwards and may be limited to a maximum
          number of events (abs(Limit)).</p>
      </desc>
    </func>
    <func>
      <name>clear_table(Handle) -> ok</name>
      <fsummary>Clear the event table</fsummary>
      <type>
        <v>Handle = collector_pid() | table_handle()</v>
        <v>collector_pid() = pid()</v>
        <v>table_handle() = record(table_handle)</v>
      </type>
      <desc>
        <p>Clear the event table.</p>
      </desc>
    </func>
  </funcs>
  
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