#Tracing

This page documents the Tracing CDP domain supported by Lynx DevTool.

#Overview

• Scope: global-and-instance
• CDP domain: Tracing

#Standard Methods

• Tracing.end
• Tracing.start

#Lynx Extensions

#Tracing.getStartupTracingConfig

Returns the stored startup tracing configuration string.

• Origin: lynx-extension
• Source: devtool/lynx_devtool/agent/domain_agent/inspector_tracing_agent.cc

#Parameters

No parameters.

#Returns

#Notes

• Dispatches through LynxGlobalDevToolMediator on the global DevTool task runner.
• Reads GlobalDevToolPlatformFacade::GetTraceController()->GetStartupTracingConfig().
• The trace controller stores the configuration as an opaque string. Lynx does not parse or validate it in this CDP method.
• Returns a CDP error with message Failed to get trace controller when no trace controller is available.
• If the global mediator has no default task runner, the current handler does not send an explicit CDP response.

#Examples

Read startup tracing config

Request:

{
  "id": 1,
  "method": "Tracing.getStartupTracingConfig"
}

Response:

{
  "id": 1,
  "result": {
    "config": "{\"traceConfig\":{\"includedCategories\":[\"*\"]}}"
  }
}

#Tracing.getStartupTracingFile

Emits a Tracing.tracingComplete event for the stored startup tracing file.

• Origin: lynx-extension
• Source: devtool/lynx_devtool/agent/domain_agent/inspector_tracing_agent.cc

#Parameters

No parameters.

#Returns

No return fields.

#Events

• Tracing.tracingComplete

#Notes

• Dispatches through LynxGlobalDevToolMediator on the global DevTool task runner.
• Reads GlobalDevToolPlatformFacade::GetTraceController()->GetStartupTracingFilePath().
• When a startup tracing file path exists, the method first sends an empty OK response and then sends Tracing.tracingComplete.
• Tracing.tracingComplete.params.stream is a FileStream handle encoded as a string. Read it with IO.read and close it with IO.close.
• Tracing.tracingComplete.params.dataLossOccurred is true when the file cannot be opened as a stream.
• Tracing.tracingComplete.params.isStartupTracing is true for this method.
• Returns a CDP error with message Startup Tracing is running when no file is available because tracing is still active.
• Returns a CDP error with message Failed to get startup tracing file when no file is available and tracing is not active.
• Returns a CDP error with message Failed to get trace controller when no trace controller is available.

#Examples

Request the startup tracing file

Request:

{
  "id": 1,
  "method": "Tracing.getStartupTracingFile"
}

Response:

{
  "id": 1,
  "result": {}
}

Startup tracing complete event

Response:

{
  "method": "Tracing.tracingComplete",
  "params": {
    "dataLossOccurred": false,
    "stream": "1",
    "isStartupTracing": true
  }
}

#Tracing.setStartupTracingConfig

Stores an opaque startup tracing configuration string.

• Origin: lynx-extension
• Source: devtool/lynx_devtool/agent/domain_agent/inspector_tracing_agent.cc

#Parameters

#Returns

No return fields.

#Notes

• Dispatches through LynxGlobalDevToolMediator on the global DevTool task runner.
• Writes params.config to GlobalDevToolPlatformFacade::GetTraceController()->SetStartupTracingConfig().
• The trace controller stores the configuration as an opaque string. Lynx does not parse or validate it in this CDP method.
• Returns an empty OK response when params.config is present.
• Returns a CDP error with message Set Startup Tracing config is null when params.config is missing.
• Returns a CDP error with message Failed to get trace controller when no trace controller is available.
• If the global mediator has no default task runner, the current handler does not send an explicit CDP response.

#Examples

Store startup tracing config

Request:

{
  "id": 1,
  "method": "Tracing.setStartupTracingConfig",
  "params": {
    "config": "{\"traceConfig\":{\"includedCategories\":[\"*\"]}}"
  }
}

Response:

{
  "id": 1,
  "result": {}
}