# 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`
Gas usage: 0
Input registers: $\omega_{7\dots+5}$
Output registers: $\{\}$

- `level` = $\omega_7$
- `target` = $\begin{cases}\varnothing &\text{when } \omega_8 = 0 \wedge \omega_9 = 0 \\ \mu_{\omega_8\dots+\omega_9} &\text{otherwise}\end{cases}$
- `message` = $\mu_{\omega_{10}\dots+\omega_{11}}$

### 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
}