ttb
Module
ttb
Module Summary
A base for building trace tools for distributed systems.
Description
The Trace Tool Builder, ttb
, is a base for building trace tools for distributed systems.
When using ttb
, do not use module dbg
in application Runtime_Tools in parallel.
Exports
start_trace(Nodes, Patterns, FlagSpec, Opts) -> Result
Types
This function is a shortcut allowing to start a trace with one command. Each tuple in Patterns
is converted to a list, which in turn is passed to ttb:tpl/2,3,4
.
The call:
> ttb:start_trace([Node, OtherNode], [{mod, foo, []}, {mod, bar, 2}], {all, call}, [{file, File}, {handler,{fun myhandler/4, S}}]).
is equivalent to:
> ttb:start_trace([Node, OtherNode], [{file, File}, {handler,{fun myhandler/4, S}}]), ttb:tpl(mod, foo, []), ttb:tpl(mod, bar, 2, []), ttb:p(all, call).
tracer() -> Result
Equivalent to tracer(node())
.
tracer(Shortcut) -> Result
Types
Handy shortcuts for common tracing settings.
shell
is equivalent to tracer(node(),[{file, {local, "ttb"}}, shell])
.
dbg
is equivalent to tracer(node(),[{shell, only}])
.
tracer(Nodes) -> Result
Equivalent to tracer(Nodes,[])
.
tracer(Nodes,Opts) -> Result
Types
Starts a file trace port on all specified nodes and points the system tracer for sequential tracing to the same port.
Options:
Filename
The specified
Filename
is prefixed with the node name. DefaultFilename
isttb
.File={wrap,Filename,Size,Count}
Can be used if the size of the trace logs must be limited. Default values are
Size=128*1024
andCount=8
.Client
When tracing diskless nodes,
ttb
must be started from an external "trace control node" with disk access, andClient
must be{local, File}
. All trace information is then sent to the trace control node where it is written to file.queue_size
When tracing to shell or
{local,File}
, an ip trace driver is used internally. The ip trace driver has a queue of maximumQueueSize
messages waiting to be delivered. If the driver cannot deliver messages as fast as they are produced, the queue size might be exceeded and messages are dropped. This parameter is optional, and is only useful if many{drop,N}
trace messages are received by the trace handler. It has no meaning if shell or{local,File}
is not used. Seedbg:trace_port/2
for more information about the ip trace driver.process_info
Indicates if process information is to be collected. If
PI = true
(which is default), each process identifierPid
is replaced by a tuple{Pid,ProcessInfo,Node}
, whereProcessInfo
is the registered process name, its globally registered name, or its initial function. To turn off this functionality, setPI = false
.{shell, ShellSpec}
Indicates that trace messages are to be printed on the console as they are received by the tracing process. This implies trace client
{local, File}
. IfShellSpec
isonly
(instead oftrue
), no trace logs are stored.shell
Shortcut for
{shell, true}
.timer
Indicates that the trace is to be automatically stopped after
MSec
milliseconds.StopOpts
are passed to commandttb:stop/2
if specified (default is[]
). Notice that the timing is approximate, as delays related to network communication are always present. The timer starts afterttb:p/2
is issued, so you can set up your trace patterns before.overload_check
-
Allows to enable overload checking on the nodes under trace.
Module:Function(check)
is performed eachMSec
millisecond. If the check returnstrue
, the tracing is disabled on a specified node.Module:Function
must be able to handle at least three atoms:init
,check
, andstop
.init
andstop
allows you to initialize and clean up the check environment.When a node gets overloaded, it is not possible to issue
ttb:p/2
or any command from thettb:tp/2,3,4
family, as it would lead to inconsistent tracing state (different trace specifications on different nodes). flush
Periodically flushes all file trace port clients (see
dbg:flush_trace_port/1
). When enabled, the buffers are freed eachMSec
millisecond. This option is not allowed with{file, {local, File}}
tracing.{resume, FetchTimeout}
-
Enables the autoresume feature. When enabled, remote nodes try to reconnect to the controlling node if they are restarted. The feature requires application Runtime_Tools to be started (so it has to be present in the
.boot
scripts if the traced nodes run with embedded Erlang). If this is not possible, resume can be performed manually by startingRuntime_Tools
remotely usingrpc:call/4
.ttb
tries to fetch all logs from a reconnecting node before reinitializing the trace. This must finish withinFetchTimeout
milliseconds or is aborted.By default, autostart information is stored in a file named
ttb_autostart.bin
on each node. If this is not desired (for example, on diskless nodes), a custom module handling autostart information storage and retrieval can be provided by specifying environment variablettb_autostart_module
for the application Runtime_Tools. The module must respond to the following API:write_config(Data) -> ok
Stores the provided data for further retrieval. It is important to realize that the data storage used must not be affected by the node crash.
read_config() -> {ok, Data} | {error, Error}
Retrieves configuration stored with
write_config(Data)
.delete_config() -> ok
-
Deletes configuration stored with
write_config(Data)
. Notice that after this call any subsequent calls toread_config
must return{error, Error}
.
resume
implies the defaultFetchTimeout
, which is 10 seconds
p(Item,Flags) -> Return
Types
Sets the specified trace flags on the specified processes or ports. Flag timestamp
is always turned on.
See the Reference Manual for module dbg
for the possible trace flags. Parameter MatchDesc
is the same as returned from dbg:p/2
.
Processes can be specified as registered names, globally registered names, or process identifiers. Ports can be specified as registered names or port identifiers. If a registered name is specified, the flags are set on processes/ports with this name on all active nodes.
Issuing this command starts the timer for this trace if option timer
is specified with tracer/2
.
tp, tpl, tpe, ctp, ctpl, ctpg, ctpe
These functions are to be used with trace flag call
, send
, and 'receive'
for setting and clearing trace patterns.
When trace flag call
is set on a process, function calls are traced on that process if a trace pattern is set for the called function.
The send
and 'receive'
flags enable tracing of all messages sent and received by the process/port. Trace patterns set with tpe
may limit traced messages based on the message content, the sender, and/or the receiver.
Trace patterns specify how to trace a function or a message by using match specifications. Match specifications are described in the ERTS User's Guide
.
These functions are equivalent to the corresponding functions in module dbg
, but all calls are stored in the history. The history buffer makes it easy to create configuration files; the same trace environment can be set up many times, for example, to compare two test runs. It also reduces the amount of typing when using ttb
from the Erlang shell.
tp
Sets trace patterns on global function calls.
tpl
Sets trace patterns on local and global function calls.
tpe
Sets trace patterns on messages.
ctp
Clears trace patterns on local and global function calls.
ctpl
Clears trace patterns on local function calls.
ctpg
Clears trace patterns on global function calls.
ctpe
Clears trace patterns on messages.
With tp
and tpl
, one of the match specification shortcuts can be used (for example, ttb:tp(foo_module, caller)
).
The shortcuts are as follows:
-
return
- for[{'_',[],[{return_trace}]}]
(report the return value from a traced function) -
caller
- for[{'_',[],[{message,{caller}}]}]
(report the calling function) -
{codestr, Str}
- fordbg:fun2ms/1
arguments passed as strings (example:"fun(_) -> return_trace() end"
)
list_history() -> History
Types
All calls to ttb
is stored in the history. This function returns the current content of the history. Any entry can be reexecuted with run_history/1
or stored in a configuration file with write_config/2,3
.
run_history(N) -> ok | {error, Reason}
Types
Executes the specified entry or entries from the history list. To list history, use list_history/0
.
write_config(ConfigFile,Config)
Equivalent to write_config(ConfigFile,Config,[])
.
write_config(ConfigFile,Config,Opts) -> ok | {error,Reason}
Types
Creates or extends a configuration file, which can be used for restoring a specific configuration later.
The contents of the configuration file can either be fetched from the history or specified directly as a list of {Mod,Func,Args}
.
If the complete history is to be stored in the configuration file, Config
must be all
. If only a selected number of entries from the history are to be stored, Config
must be a list of integers pointing out the entries to be stored.
If Opts
is not specified or if it is []
, ConfigFile
is deleted and a new file is created. If Opts = [append]
, ConfigFile
is not deleted. The new information is appended at the end of the file.
run_config(ConfigFile) -> ok | {error,Reason}
Types
Executes all entries in the specified configuration file. Notice that the history of the last trace is always available in file ttb_last_config
.
run_config(ConfigFile,NumList) -> ok | {error,Reason}
Types
Executes selected entries from the specified configuration file. NumList
is a list of integers pointing out the entries to be executed.
To list the contents of a configuration file, use list_config/1
.
Notice that the history of the last trace is always available in file ttb_last_config
.
list_config(ConfigFile) -> Config | {error,Reason}
Types
Lists all entries in the specified configuration file.
write_trace_info(Key,Info) -> ok
Types
File .ti
contains {Key,ValueList}
tuples. This function adds Data
to the ValueList
associated with Key
. All information written with this function is included in the call to the format handler.
seq_trigger_ms() -> MatchSpec
Equivalent to seq_trigger_ms(all)
.
seq_trigger_ms(Flags) -> MatchSpec
Types
A match specification can turn on or off sequential tracing. This function returns a match specification, which turns on sequential tracing with the specified Flags
.
This match specification can be specified as the last argument to tp
or tpl
. The activated Item
then becomes a trigger for sequential tracing. This means that if the item is called on a process with trace flag call
set, the process is "contaminated" with token seq_trace
.
If Flags = all
, all possible flags are set.
The possible values for SeqTraceFlag
are available in seq_trace
.
For a description of the match_spec()
syntax, see section Match Specifications in Erlang
in ERTS, which explains the general match specification "language".
The system tracer for sequential tracing is automatically initiated by ttb
when a trace port is started with ttb:tracer/0,1,2
.
An example of how to use function seq_trigger_ms/0,1
follows:
(tiger@durin)5> ttb:tracer(). {ok,[tiger@durin]} (tiger@durin)6> ttb:p(all,call). {ok,{[all],[call]}} (tiger@durin)7> ttb:tp(mod,func,ttb:seq_trigger_ms()). {ok,[{matched,1},{saved,1}]} (tiger@durin)8>
Whenever mod:func(...)
is called after this, token seq_trace
is set on the executing process.
stop()
Equivalent to stop([])
.
stop(Opts) -> stopped | {stopped, Dir}
Types
Stops tracing on all nodes. Logs and trace information files are sent to the trace control node and stored in a directory named ttb_upload_FileName-Timestamp
, where Filename
is the one provided with {file, File}
during trace setup and Timestamp
is of the form yyyymmdd-hhmmss
. Even logs from nodes on the same machine as the trace control node are moved to this directory. The history list is saved to a file named ttb_last_config
for further reference (as it is no longer accessible through history and configuration management functions, like ttb:list_history/0
).
Options:
nofetch
Indicates that trace logs are not to be collected after tracing is stopped.
{fetch, Dir}
Allows specification of the directory to fetch the data to. If the directory already exists, an error is thrown.
format
Indicates the trace logs to be formatted after tracing is stopped. All logs in the fetch directory are merged.
return_fetch_dir
Indicates the return value to be
{stopped, Dir}
and not juststopped
. This impliesfetch
.
get_et_handler()
Returns the et
handler, which can be used with format/2
or tracer/2
.
Example: ttb:format(Dir, [{handler, ttb:get_et_handler()}])
.
format(File)
Equivalent to format(File,[])
.
format(File,Options) -> ok | {error, Reason}
Types
This can be the name of a binary log, a list of such logs, or the name of a directory containing one or more binary logs.
File descriptor of the destination fileOut
. The trace message. For details, see the Reference Manual for module erlang
. Includes the keys flags
, client
, and node
. If handler
is specified as option to the tracer function, this is also included. Also, all information written with function write_trace_info/2
is included.
Reads the specified binary trace log(s). The logs are processed in the order of their time stamps as long as option disable_sort
is not specified.
If FormatHandler = {Function,InitialState}
, Function
is called for each trace message.
If FormatHandler = get_et_handler()
, et_viewer
in application ET is used for presenting the trace log graphically. ttb
provides a few different filters that can be selected from menu Filters and scaling in the et_viewer
.
If FormatHandler
is not specified, a default handler is used presenting each trace message as a text line.
The state returned from each call of Function
is passed to the next call, even if the next call is to format a message from another log file.
If Out
is specified, FormatHandler
gets the file descriptor to Out
as the first parameter.
Out
is ignored if the et
format handler is used.
Wrap logs can be formatted one by one or all at once. To format one of the wrap logs in a set, specify the exact file name. To format the whole set of wrap logs, specify the name with *
instead of the wrap count. For examples, see the User's Guide
.
© 2010–2017 Ericsson AB
Licensed under the Apache License, Version 2.0.