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Diffstat (limited to 'lldb/docs')
| -rw-r--r-- | lldb/docs/structured_data/DarwinLog.md | 160 | ||||
| -rw-r--r-- | lldb/docs/structured_data/StructuredDataPlugins.md | 136 |
2 files changed, 0 insertions, 296 deletions
diff --git a/lldb/docs/structured_data/DarwinLog.md b/lldb/docs/structured_data/DarwinLog.md deleted file mode 100644 index 19c3c4b201d..00000000000 --- a/lldb/docs/structured_data/DarwinLog.md +++ /dev/null @@ -1,160 +0,0 @@ -# Change Notes - -## Summary - -This document describes the DarwinLog logging feature. - -## StructuredDataDarwinLog feature - -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 -logging system where the bulk of the log processing happens on the log -consumer side. This reduces logging impact on the system when there -are no consumers, making it cheaper to include logging at all times. -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 -stream, and fine-grained filtering of what gets passed on to the LLDB -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. - -The DarwinLog support is written in a way which should support the -lldb client side on non-Apple clients talking to an Apple device or -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 user interface to the darwin-log support is via the following: - -* '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. - If the user wants to squelch seeing info-level or debug-level - messages, which is the default behavior, then the enable command - must be made prior to launching the process; otherwise, the - info-level and debug-level messages will always show up. Also, - there is a similar "echo os_log()/NSLog() messages to target - process stderr" mechanism which is properly disabled when enabling - the DarwinLog support prior to launch. This cannot be squelched - if enabling DarwinLog after launch. - - See the help for this command. There are a number of options - to shrink or expand the number of messages that are processed - on the remote side and sent over to the client, and other - options to control the formatting of messages displayed. - - This command is sticky. Once enabled, it will stay enabled for - future process launches. - -* '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' - - and - - 'settings set \ - plugin.structured-data.darwin-log.auto-enable-options -- {options}' - - 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 - 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 -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 -user's goal should be to ensure he or she only collects as many log -messages are needed, but no more. - -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 - 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 - message event data. - -2. The debugserver process filters the messages that arrive through a - message log filter that may be fully customized by the user. It - works similar to a rules-based packet filter: a set of rules are - matched against the log message, each rule tried in sequential - order. The first rule that matches then either accepts or rejects - the message. If the log message does not match any rule, then the - 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 - {filter-spec}' option. Filters are added in order, and multiple - --filter entries can be provided to the enable command. - - Filters take the following form: - - {action} {attribute} {op} - - {action} := - accept | - reject - - {attribute} := - category | // The log message category - 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 - // as {parent-activity}:{child-activity}: - // {grandchild-activity} - message | // The fully expanded message contents. - // Note this one is expensive because it - // requires expanding the message. Avoid - // this if possible, or add it further - // down the filter chain. - - {op} := - 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:]]+" - -3. Messages that are accepted by the log message filter get sent to - the lldb client, where they are mapped to the - StructuredDataDarwinLog plugin. By default, command-line lldb will - issue a Process-level event containing the log message content, and - will request the plugin to print the message if the plugin is - enabled to do so. - -### Log message display - -Several settings control aspects of displaying log messages in -command-line LLDB. See the enable command's help for a description -of these. - - diff --git a/lldb/docs/structured_data/StructuredDataPlugins.md b/lldb/docs/structured_data/StructuredDataPlugins.md deleted file mode 100644 index bd4d6bea130..00000000000 --- a/lldb/docs/structured_data/StructuredDataPlugins.md +++ /dev/null @@ -1,136 +0,0 @@ -# Change Notes - -## Overview - -This document describes an infrastructural feature called Structured -Data plugins. See the DarwinLog.md doc for a description of one -such plugin that makes use of this feature. - -## StructuredDataPlugin - -StructuredDataPlugin instances have the following characteristics: - -* Each plugin instance is bound to a single Process instance. - -* Each StructuredData feature has a type name that identifies the - feature. For instance, the type name for the DarwinLog feature is - "DarwinLog". This feature type name is used in various places. - -* The process monitor reports the list of supported StructuredData - features advertised by the process monitor. Process goes through the - list of supported feature type names, and asks each known - StructuredDataPlugin if it can handle the feature. The first plugin - that supports the feature is mapped to that Process instance for - that feature. Plugins are only mapped when the process monitor - advertises that a feature is supported. - -* The feature may send asynchronous messages in StructuredData format - to the Process instance. Process instances route the asynchronous - structured data messages to the plugin mapped to that feature type, - if one exists. - -* Plugins can request that the Process instance forward on - configuration data to the process monitor if the plugin needs/wants - to configure the feature. Plugins may call the new Process method - - ```C++ - virtual Error - ConfigureStructuredData(const ConstString &type_name, - const StructuredData::ObjectSP &config_sp) - ``` - - where type_name is the feature name and config_sp points to the - configuration structured data, which may be nullptr. - -* Plugins for features present in a process are notified when modules - are loaded into the Process instance via this StructuredDataPlugin - method: - - ```C++ - virtual void - ModulesDidLoad(Process &process, ModuleList &module_list); - ``` - -* Plugins may optionally broadcast their received structured data as - an LLDB process-level event via the following new Process call: - - ```C++ - void - BroadcastStructuredData(const StructuredData::ObjectSP &object_sp, - const lldb::StructuredDataPluginSP &plugin_sp); - ``` - - IDE clients might use this feature to receive information about the - process as it is running to monitor memory usage, CPU usage, and - logging. - - Internally, the event type created is an instance of - EventDataStructuredData. - -* In the case where a plugin chooses to broadcast a received - StructuredData event, the command-line LLDB Debugger instance - listens for them. The Debugger instance then gives the plugin an - opportunity to display info to either the debugger output or error - stream at a time that is safe to write to them. The plugin can - choose to display something appropriate regarding the structured - data that time. - -* Plugins can provide a ProcessLaunchInfo filter method when the - plugin is registered. If such a filter method is provided, then - when a process is about to be launched for debugging, the filter - callback is invoked, given both the launch info and the target. The - plugin may then alter the launch info if needed to better support - the feature of the plugin. - -* The plugin is entirely independent of the type of Process-derived - class that it is working with. The only requirements from the - process monitor are the following feature-agnostic elements: - - * Provide a way to discover features supported by the process - monitor for the current process. - - * Specify the list of supported feature type names to Process. - The process monitor does this by calling the following new - method on Process: - - ```C++ - void - MapSupportedStructuredDataPlugins(const StructuredData::Array - &supported_type_names) - ``` - - The supported_type_names specifies an array of string entries, - where each entry specifies the name of a StructuredData feature. - - * Provide a way to forward on configuration data for a feature type - to the process monitor. This is the manner by which LLDB can - configure a feature, perhaps based on settings or commands from - the user. The following virtual method on Process (described - earlier) does the job: - - ```C++ - virtual Error - ConfigureStructuredData(const ConstString &type_name, - const StructuredData::ObjectSP &config_sp) - ``` - - * Listen for asynchronous structured data packets from the process - monitor, and forward them on to Process via this new Process - member method: - - ```C++ - bool - RouteAsyncStructuredData(const StructuredData::ObjectSP object_sp) - ``` - -* StructuredData producers must send their top-level data as a - Dictionary type, with a key called 'type' specifying a string value, - where the value is equal to the StructuredData feature/type name - previously advertised. Everything else about the content of the - dictionary is entirely up to the feature. - -* StructuredDataPlugin commands show up under 'plugin structured-data - plugin-name'. - -* StructuredDataPlugin settings show up under - 'plugin.structured-data.{plugin-name}. |
