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Touch-up the markup of the DarwinLog.md documentation.

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llvm-svn: 289518
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Jason Molenda 2016-12-13 05:54:17 +00:00
parent 1e57fa487b
commit 30011bf4a8
1 changed files with 29 additions and 29 deletions
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58
lldb/docs/structured_data/DarwinLog.md
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@ -6,7 +6,7 @@ This document describes the DarwinLog logging feature.
## StructuredDataDarwinLog feature
The DarwinLog feature supports logging os_log*() and NSLog() messages
The DarwinLog feature supports logging `os_log`*() and `NSLog`() messages
to the command-line lldb console, as well as making those messages
available to LLDB clients via the event system. Starting with fall
2016 OSes, Apple platforms introduce a new fire-hose, stream-style
@ -17,9 +17,9 @@ However, it also increases the work needed on the consumer end when
log messages are desired.
The debugserver binary has been modified to support collection of
os_log*()/NSLog() messages, selection of which messages appear in the
`os_log`*()/`NSLog`() messages, selection of which messages appear in the
stream, and fine-grained filtering of what gets passed on to the LLDB
client. DarwinLog also tracks the activity chain (i.e. os_activity()
client. DarwinLog also tracks the activity chain (i.e. `os_activity`()
hierarchy) in effect at the time the log messages were issued. The
user is able to configure a number of aspects related to the
formatting of the log message header fields.
@ -30,11 +30,11 @@ macOS system; hence, the plugin support is built into all LLDB
clients, not just those built on an Apple platform.
StructuredDataDarwinLog implements the 'DarwinLog' feature type, and
the plugin name for it shows up as 'darwin-log'.
the plugin name for it shows up as `darwin-log`.
The user interface to the darwin-log support is via the following:
* 'plugin structured-data darwin-log enable' command
* `plugin structured-data darwin-log enable` command
This is the main entry point for enabling the command. It can be
set before launching a process or while the process is running.
@ -55,32 +55,32 @@ The user interface to the darwin-log support is via the following:
This command is sticky. Once enabled, it will stay enabled for
future process launches.
* 'plugin structured-data darwin-log disable' command
* `plugin structured-data darwin-log disable` command
Executing this command disables os_log() capture in the currently
running process and signals LLDB to stop attempting to launch
new processes with DarwinLog support enabled.
* 'settings set \
plugin.structured-data.darwin-log.enable-on-startup'
* `settings set
plugin.structured-data.darwin-log.enable-on-startup true`
and
'settings set \
plugin.structured-data.darwin-log.auto-enable-options -- {options}'
`settings set
plugin.structured-data.darwin-log.auto-enable-options -- `{options}
When enable-on-startup is set to true, then LLDB will automatically
When `enable-on-startup` is set to `true`, then LLDB will automatically
enable DarwinLog on startup of relevant processes. It will use the
content provided in the auto-enable-options settings as the
options to pass to the enable command.
Note the '--' required after auto-enable-command. That is necessary
for raw commands like settings set. The '--' will not become part
Note the `--` required after auto-enable-command. That is necessary
for raw commands like settings set. The `--` will not become part
of the options for the enable command.
### Message flow and related performance considerations
os_log()-style collection is not free. The more data that must be
`os_log`()-style collection is not free. The more data that must be
processed, the slower it will be. There are several knobs available
to the developer to limit how much data goes through the pipe, and how
much data ultimately goes over the wire to the LLDB client. The
@ -91,12 +91,12 @@ The flow of data looks like the following:
1. Data comes into debugserver from the low-level OS facility that
receives log messages. The data that comes through this pipe can
be limited or expanded by the '--debug', '--info' and
'--all-processes' options of the 'plugin structured-data darwin-log
enable' command. options. Exclude as many categories as possible
be limited or expanded by the `--debug`, `--info` and
`--all-processes` options of the `plugin structured-data darwin-log
enable` command options. Exclude as many categories as possible
here (also the default). The knobs here are very coarse - for
example, whether to include os_log_info()-level or
os_log_debug()-level info, or to include callstacks in the log
example, whether to include `os_log_info()`-level or
`os_log_debug()`-level info, or to include callstacks in the log
message event data.
2. The debugserver process filters the messages that arrive through a
@ -108,12 +108,12 @@ The flow of data looks like the following:
message gets the no-match (i.e. fall-through) action. The no-match
action defaults to accepting but may be set to reject.
Filters can be added via the enable command's '--filter
Filters can be added via the enable command's '`--filter`
{filter-spec}' option. Filters are added in order, and multiple
--filter entries can be provided to the enable command.
`--filter` entries can be provided to the enable command.
Filters take the following form:
```
{action} {attribute} {op}
{action} :=
@ -122,7 +122,7 @@ The flow of data looks like the following:
{attribute} :=
category | // The log message category
subsystem | // The log message subsystem}
subsystem | // The log message subsystem
activity | // The child-most activity in force
// at the time the message was logged.
activity-chain | // The complete activity chain, specified
@ -138,11 +138,11 @@ The flow of data looks like the following:
match {exact-match-text} |
regex {search-regex} // uses C++ std::regex
// ECMAScript variant.
e.g.
--filter "accept subsystem match com.example.mycompany.myproduct"
--filter "accept subsystem regex com.example.+"
--filter "reject category regex spammy-system-[[:digit:]]+"
```
e.g.
`--filter "accept subsystem match com.example.mycompany.myproduct"`
`--filter "accept subsystem regex com.example.+"`
`--filter "reject category regex spammy-system-[[:digit:]]+"`
3. Messages that are accepted by the log message filter get sent to
the lldb client, where they are mapped to the
@ -154,7 +154,7 @@ e.g.
### Log message display
Several settings control aspects of displaying log messages in
command-line LLDB. See the enable command's help for a description
command-line LLDB. See the `enable` command's help for a description
of these.