Provided by: erlang-manpages_16.b.3-dfsg-1ubuntu2.2_all 
NAME
ttb - 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, dbg shall not be used in parallel.
EXPORTS
start_trace(Nodes, Patterns, FlagSpec, Opts) -> Result
Types:
Result = see p/2
Nodes = see tracer/2
Patterns = [tuple()]
FlagSpec = {Procs, Flags}
Proc = see p/2
Flags = see p/2
Opts = see tracer/2
This function is a shortcut allowing to start a trace with one command. Each tuple in Patterns is
converted to list which is in turn passed to ttb:tpl. The call:
ttb:start_trace([Node, OtherNode],
[{mod, foo, []}, {mod, bar, 2}],
{all, call},
[{file, File}, {handler,{fun myhandler/4, S}}])
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
This is equivalent to tracer(node()).
tracer(Shortcut) -> Result
Types:
Shortcut = shell | dbg
shell is equivalent to tracer(node(),[{file, {local, "ttb"}}, shell]).
dbg is equivalent to tracer(node(),[{shell, only}]).
tracer(Nodes) -> Result
This is equivalent to tracer(Nodes,[]).
tracer(Nodes,Opts) -> Result
Types:
Result = {ok, ActivatedNodes} | {error,Reason}
Nodes = atom() | [atom()] | all | existing | new
Opts = Opt | [Opt]
Opt = {file,Client} | {handler, FormatHandler} | {process_info,PI} | shell | {shell, ShellSpec}
| {timer, TimerSpec} | {overload_check, {MSec, Module, Function}} | {flush, MSec} | resume |
{resume, FetchTimeout}
TimerSpec = MSec | {MSec, StopOpts}
MSec = FetchTimeout = integer()
Module = Function = atom()
StopOpts = see stop/2
Client = File | {local, File}
File = Filename | Wrap
Filename = string()
Wrap = {wrap,Filename} | {wrap,Filename,Size,Count}
FormatHandler = See format/2
PI = true | false
ShellSpec = true | false | only
This function starts a file trace port on all given nodes and also points the system tracer for
sequential tracing to the same port.
The given Filename will be prefixed with the node name. Default Filename is "ttb".
File={wrap,Filename,Size,Count} can be used if the size of the trace logs must be limited. Default
values are Size=128*1024 and Count=8.
When tracing diskless nodes, ttb must be started from an external "trace control node" with disk
access, and Client must be {local, File}. All trace information is then sent to the trace control
node where it is written to file.
The process_info option indicates if process information should be collected. If PI = true (which
is default), each process identifier Pid is replaced by a tuple {Pid,ProcessInfo,Node}, where
ProcessInfo is the process' registered name its globally registered name, or its initial function.
It is possible to turn off this functionality by setting PI = false.
The {shell, ShellSpec} option indicates that the trace messages should be printed on the console
as they are received by the tracing process. This implies {local, File} trace client. If the
ShellSpec is only (instead of true), no trace logs are stored.
The shell option is a shortcut for {shell, true}.
The timer option indicates that the trace should be automatically stopped after MSec milliseconds.
StopOpts are passed to ttb:stop/2 command if specified (default is []). Note that the timing is
approximate, as delays related to network communication are always present. The timer starts after
ttb:p/2 is issued, so you can set up your trace patterns before.
The overload_check option allows to enable overload checking on the nodes under trace.
Module:Function(check) is performed each MSec milliseconds. If the check returns true, the tracing
is disabled on a given node.
Module:Function should be able to handle at least three atoms: init, check and stop. init and stop
give the user a possibility to initialize and clean up the check environment.
When a node gets overloaded, it is not possible to issue ttb:p nor any command from the ttb:tp
family, as it would lead to inconsistent tracing state (different trace specifications on
different node).
The flush option periodically flushes all file trace port clients (see dbg:flush_trace_port/1).
When enabled, the buffers are freed each MSec milliseconds. This option is not allowed with {file,
{local, File}} tracing.
{resume, FetchTimeout} enables the autoresume feature. Whenever enabled, remote nodes try to
reconnect to the controlling node in case they were restarted. The feature requires runtime_tools
application 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 may be performed manually by starting
runtime_tools remotely using rpc:call/4.
ttb tries to fetch all logs from a reconnecting node before reinitializing the trace. This has to
finish within FetchTimeout milliseconds or is aborted
By default, autostart information is stored in a file called ttb_autostart.bin on each node. If
this is not desired (i.e. on diskless nodes), a custom module to handle autostart information
storage and retrieval can be provided by specifying ttb_autostart_module environment variable for
the runtime_tools application. The module has to respond to the following API:
write_config(Data) -> ok:
Store 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}:
Retrieve configuration stored with write_config(Data).
delete_config() -> ok:
Delete configuration stored with write_config(Data). Note that after this call any subsequent
calls to read_config must return {error, Error}.
The resume option implies the default FetchTimeout, which is 10 seconds
p(Procs,Flags) -> Return
Types:
Return = {ok,[{Procs,MatchDesc}]}
Procs = Process | [Process] | all | new | existing
Process = pid() | atom() | {global,atom()}
Flags = Flag | [Flag]
This function sets the given trace flags on the given processes. The timestamp flag is always
turned on.
Please turn to the Reference manual for module dbg for details about the possible trace flags. The
parameter MatchDesc is the same as returned from dbg:p/2
Processes can be given as registered names, globally registered names or process identifiers. If a
registered name is given, the flags are set on processes with this name on all active nodes.
Issuing this command starts the timer for this trace if timer option was specified with tracer/2.
tp, tpl, ctp, ctpl, ctpg
These functions should be used in combination with the call trace flag for setting and clearing
trace patterns. When the call trace flag is set on a process, function calls will be traced on
that process if a trace pattern has been set for the called function. Trace patterns specifies how
to trace a function by using match specifications. Match specifications are described in the
User's Guide for the erlang runtime system erts.
These functions are equivalent to the corresponding functions in dbg, but all calls are stored in
the history. The history buffer makes it easy to create config files so that the same trace
environment can be setup several times, e.g. if you want to compare two test runs. It also reduces
the amount of typing when using ttb from the erlang shell.
tp:
Set trace pattern on global function calls
tpl:
Set trace pattern on local and global function calls
ctp:
Clear trace pattern on local and global function calls
ctpl:
Clear trace pattern on local function calls
ctpg:
Clear trace pattern on global function calls
With tp and tpl one of match specification shortcuts may be used (example: ttb:tp(foo_module,
caller)). The shortcuts are:
list_history() -> History
Types:
History = [{N,Func,Args}]
All calls to ttb is stored in the history. This function returns the current content of the
history. Any entry can be re-executed with run_history/1 or stored in a config file with
write_config/2/3.
run_history(N) -> ok | {error, Reason}
Types:
N = integer() | [integer()]
Executes the given entry or entries from the history list. History can be listed with
list_history/0.
write_config(ConfigFile,Config)
Equivalent to write_config(ConfigFile,Config,[]).
write_config(ConfigFile,Config,Opts) -> ok | {error,Reason}
Types:
ConfigFile = string()
Config = all | [integer()] | [{Mod,Func,Args}]
Mod = atom()
Func = atom()
Args = [term()]
Opts = Opt | [Opt]
Opt = append
This function creates or extends a config file which can be used for restoring a specific
configuration later.
The content of the config file can either be fetched from the history or given directly as a list
of {Mod,Func,Args}.
If the complete history is to be stored in the config file Config should be all. If only a
selected number of entries from the history should be stored, Config should be a list of integers
pointing out the entries to be stored.
If Opts is not given or if it is [], ConfigFile is deleted and a new file is created. If Opts =
[append], ConfigFile will not be deleted. The new information will be appended at the end of the
file.
run_config(ConfigFile) -> ok | {error,Reason}
Types:
ConfigFile = string()
Executes all entries in the given config file. Note that the history of the last trace is always
available in the file named ttb_last_config.
run_config(ConfigFile,NumList) -> ok | {error,Reason}
Types:
ConfigFile = string()
NumList = [integer()]
Executes selected entries from the given config file. NumList is a list of integers pointing out
the entries to be executed.
The content of a config file can be listed with list_config/1.
Note that the history of the last trace is always available in the file named ttb_last_config.
list_config(ConfigFile) -> Config | {error,Reason}
Types:
ConfigFile = string()
Config = [{N,Func,Args}]
Lists all entries in the given config file.
write_trace_info(Key,Info) -> ok
Types:
Key = term()
Info = Data | fun() -> Data
Data = term()
The .ti file contains {Key,ValueList} tuples. This function adds Data to the ValueList associated
with Key. All information written with this function will be included in the call to the format
handler.
seq_trigger_ms() -> MatchSpec
Equivalent to seq_trigger_ms(all)
seq_trigger_ms(Flags) -> MatchSpec
Types:
MatchSpec = match_spec()
Flags = all | SeqTraceFlag | [SeqTraceFlag]
SeqTraceFlag = atom()
A match specification can turn on or off sequential tracing. This function returns a match
specification which turns on sequential tracing with the given Flags.
This match specification can be given as the last argument to tp or tpl. The activated Item will
then become a trigger for sequential tracing. This means that if the item is called on a process
with the call trace flag set, the process will be "contaminated" with the seq_trace token.
If Flags = all, all possible flags are set.
Please turn to the reference manual for the seq_trace module in the kernel application to see the
possible values for SeqTraceFlag. For a description of the match_spec() syntax, please turn to the
User's guide for the runtime system (erts). The chapter Match Specification in Erlang explains the
general match specification "language".
Note:
The system tracer for sequential tracing is automatically initiated by ttb when a trace port is
started with ttb:tracer/0/1/2.
Example of how to use the seq_trigger_ms/0/1 function:
(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, the seq_trace token will be set on the executing
process.
stop()
Equivalent to stop([]).
stop(Opts) -> stopped | {stopped, Dir}
Types:
Opts = Opt | [Opt]
Opt = nofetch | {fetch_dir, Dir} | format | {format, FormatOpts} | return_fetch_dir
Dir = string()
FormatOpts = see format/2
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 will be not longer
accessible through history and configuration management functions (like ttb:list_history/0).
The nofetch option indicates that trace logs shall not be collected after tracing is stopped.
The {fetch, Dir} option allows to specify the directory to fetch the data to. If the directory
already exists, an error is thrown.
The format option indicates that the trace logs shall be formatted after tracing is stopped. All
logs in the fetch directory will be merged. You may use {format, FormatOpts} to pass additional
arguments to format/2.
The return_fetch_dir option indicates that the return value should be {stopped, Dir} and not just
stopped. This implies fetch.
get_et_handler()
The et handler returned by the function may be used with format/2 or tracer/2. Example:
ttb:format(Dir, [{handler, ttb:get_et_handler()}]).
format(File)
Same as format(File,[]).
format(File,Options) -> ok | {error, Reason}
Types:
File = string() | [string()]
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.
Options = Opt | [Opt]
Opt = {out,Out} | {handler,FormatHandler} | disable_sort
Out = standard_io | string()
FormatHandler = {Function, InitialState}
Function = fun(Fd,Trace,TraceInfo,State) -> State
Fd = standard_io | FileDescriptor
This is the file descriptor of the destination file Out
Trace = tuple()
This is the trace message. Please turn to the Reference manual for the erlangmodule for
details.
TraceInfo = [{Key,ValueList}]
This includes the keys flags, client and node, and if handler is given as option to the
tracer function, this is also included. In addition all information written with the
write_trace_info/2function is included.
Reads the given binary trace log(s). The logs are processed in the order of their timestamp as
long as disable_sort option is not given.
If FormatHandler = {Function,InitialState}, Function will be called for each trace message. If
FormatHandler = get_et_handler(), et_viewer in the Event Tracer application (et) is used for
presenting the trace log graphically. ttb provides a few different filters which can be selected
from the Filter menu in the et_viewer. If FormatHandler is not given, a default handler is used
which presents each trace message as a line of text.
The state returned from each call of Function is passed to the next call, even if next call is to
format a message from another log file.
If Out is given, FormatHandler gets the file descriptor to Out as the first parameter.
Out is ignored if et format handler is used.
Wrap logs can be formatted one by one or all in one go. To format one of the wrap logs in a set,
give the exact name of the file. To format the whole set of wrap logs, give the name with '*'
instead of the wrap count. See examples in the ttb User's Guide.