sys模块¶

A functional interface to system messages.

install/2/3

结构:

install(Name, FuncSpec) -> ok
install(Name, FuncSpec, Timeout) -> ok
类型:
Name = name()
FuncSpec = {Func, FuncState} | {FuncId, Func, FuncState}
FuncId = term()
Func = dbg_fun()
FuncState = term()
Timeout = timeout()

说明:

开启备用函数调试功能。
这种函数的一个示例是触发器，等待某些特殊事件并在生成事件时执行某些操作的函数。
如:打开低级别跟踪。

每当生成系统事件时都会调用Func。
此函数将返回done或新的Func状态。
函数返回done或函数失败，就会被删除。
如果调试功能需要安装多次，则必须为每个安装指定唯一的FuncId

debug_options()¶

结构:

debug_options(Options) -> [dbg_opt()]
类型:
Options = [Opt]
Opt =
    trace |
    log |
    {log, integer() >= 1} |
    statistics |
    {log_to_file, FileName} |
    {install, FuncSpec}
FileName = file:name()
FuncSpec = {Func, FuncState} | {FuncId, Func, FuncState}
FuncId = term()
Func = dbg_fun()
FuncState = term()

说明:

Can be used by a process that initiates a debug structure from a list of options.
The values of argument Opt are the same as for the corresponding functions.

handle_system_msg()¶

结构:

handle_system_msg(Msg, From, Parent, Module, Debug, Misc) ->
                 no_return()
类型:
Msg = term()
From = {pid(), Tag :: term()}
Parent = pid()
Module = module()
Debug = [dbg_opt()]
Misc = term()

说明:

This function is used by a process module to take care of system messages.
The process receives a {system, From, Msg} message and passes Msg and From to this function.

This function never returns. It calls either of the following functions:
  1. Module:system_continue(Parent, NDebug, Misc), where the process continues the execution.
  2. Module:system_terminate(Reason, Parent, Debug, Misc), if the process is to terminate.
Module must export the following:
  1. system_continue/3
  2. system_terminate/4
  3. system_code_change/4
  4. system_get_state/1
  5. system_replace_state/2