table of contents
other versions
- wheezy 1:15.b.1-dfsg-4+deb7u1
- wheezy-backports 1:17.3-dfsg-4~bpo70+1
- jessie 1:17.3-dfsg-4+deb8u1
- jessie-backports 1:19.2.1+dfsg-2~bpo8+1
- testing 1:19.2.1+dfsg-2
- unstable 1:19.2.1+dfsg-2
- experimental 1:19.3.1+dfsg-1
ttb(3erl) | Erlang Module Definition | ttb(3erl) |
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)
This is equivalent to tracer(node()).
Types:
Shortcut = shell | dbg
shell is equivalent to tracer(node(),[{file, {local,
"ttb"}}, shell]).
dbg is equivalent to tracer(node(),[{shell, only}]).
This is equivalent to tracer(Nodes,[]).
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:
The resume option implies the default FetchTimeout, which is 10
seconds
- 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}.
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.
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.
With tp and tpl one of match specification shortcuts may be used
(example: ttb:tp(foo_module, caller)). The shortcuts are:
- 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
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.
Types:
N = integer() | [integer()]
Executes the given entry or entries from the history list. History can be listed
with list_history/0.
Equivalent to write_config(ConfigFile,Config,[]).
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.
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.
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.
Types:
ConfigFile = string()
Config = [{N,Func,Args}]
Lists all entries in the given config file.
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.
Equivalent to seq_trigger_ms(all)
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".
Example of how to use the seq_trigger_ms/0/1 function:
Note:
The system tracer for sequential tracing is automatically initiated by
ttb when a trace port is started with ttb:tracer/0/1/2.
(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.
Equivalent to stop([]).
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.
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()}]).
Same as format(File,[]).
Types:
File = string() | [string()]
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 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]
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.
observer 2.0.2 | Ericsson AB |