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(source: https://hackmd.io/@polkadot/jip1 from 2024-12-09)

JIP-1: Debug message host call

A host call for passing a debugging message from the service/authorizer to the hosting environment for logging to the node operator.

Host-call specification​

Index: 100 Name: log Input registers: ω7⋯+5\omega_{7\dots+5} Output registers: {}\{\}

  • level = ω7\omega_7
  • target = {∅when ω8=0∧ω9=0μω8⋯+ω9otherwise\begin{cases}\varnothing &\text{when } \omega_8 = 0 \wedge \omega_9 = 0 \\ \mu_{\omega_8\dots+\omega_9} &\text{otherwise}\end{cases}
  • message = μω10⋯+ω11\mu_{\omega_{10}\dots+\omega_{11}}

Side-effects​

No side-effects if memory access is invalid.

Otherwise, express a message to user according to the user-agent.

Suggestions & examples​

Levels definition​

  • 0: User agent displays as fatal error ⛔️
  • 1: User agent displays as warning ⚠️
  • 2: User agent displays as important information ℹ️
  • 3: User agent displays as helpful information 💁
  • 4: User agent displays as pedantic information 🪡

Display format for console logging​

Note that <CORE> is assumed to be the integer index of the core on which the PVM is executing, which may not exist (e.g. in the On-Transfer logic).

Note that <SERVICE_ID> is assumed to be the integer index of the service for which the PVM is executing, which may not exist (e.g. in the Is-Authorized logic).

<YYYY-MM-DD hh-mm-ss> <LEVEL>[@<CORE>]?[#<SERVICE_ID>]? [<TARGET>]? <MESSAGE>

Example log item​

2025/01/01 12:10:42 DEBUG@1#42 bootstrap-refine Hello world!

Format for JSON logging​

{
    "time": "<YYYY-MM-DD hh-mm-ss>",
    "level": "<LEVEL>",
    "message": "<MESSAGE>",
    "target": "<TARGET>" | null
    "service": "<SERVICE_ID>" | null
    "core": "<CORE>" | null
}