Jorijn van der Graaf
8e7f8c5f3b
The notes had agents start `crafter-build <flag> -r` in the background and run `crafter-debug ls --wait 60s` straight after. That raced the build: the first agent to follow them ran the plain build's stub, which said "no debug build yet" and exited, since the client `ls --wait` needs is one of the things the debug build compiles, and it polled by hand until the build was done. The race came from the order, so the order changes: build with the flag in the foreground, which ends once the app and the client are built, then start the app with -r in the background, then `ls --wait`, which now only waits for what it is for, the app registering. A launcher that polls for the build instead was tried and dropped: a shell loop that reruns itself each second, and waits out its whole --wait when no build is coming at all. The consumer notes, the client's guide and the README say so, and the stub and the not-yet-built launcher name the step that was skipped. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
54 lines
4.3 KiB
Markdown
54 lines
4.3 KiB
Markdown
## Crafter.Debug
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This app can be driven while it runs: call its commands, read and set its state, pause and step it, wait for conditions, read its log, take screenshots. It is only in debug builds, under this project's debug flag (the notes above name it, usually `--debug-api`).
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### Driving it
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- Build with the debug flag first, in the foreground: `crafter-build <debug flag>`. That build also compiles the client `./build/crafter-debug` runs. The first one takes a few minutes.
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- Then start the app in the background, since it does not exit: `crafter-build <debug flag> -r`.
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- From the project directory, use `./build/crafter-debug`:
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- `ls --wait 60s` until it is listed; `status`, `cmds`, `help <command>`, `get '*'`
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- `call <command> key=value ...`, `set <path> <value>`
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- `pause --when '<condition>'` then `wait --paused`; `step 3`, `resume`
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- `wait '<condition>'`, `wait --frames 30`, `wait --event <Name>`
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- `trace <path> --frames 120`, `log --level warn`, `log --follow` (under Monitor)
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- `screenshot`: open the PNG it prints with Read
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- `quit` when done
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- `./build/crafter-debug guide` is the full reference. Errors name the next step.
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- Exit codes: 2 usage, 3 no instance, 4 app and client from different versions, 5 timed out, 6 the app answered an error.
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- Requests run when the app calls `Debug::Pump()`, once per frame; `status` shows when it last did.
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- Stopping the background `-r` task can leave the app running. Stop it with `quit`, or `quit --force` if its loop is stuck.
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- Run long `wait`s in the background, and chain short steps with `&&`.
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- `debugger` prints how to attach lldb or gdb for breakpoints and memory.
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### Coding with it
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Missing a command or watch for the task at hand? Add it. It is debug-only code.
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- **Where it goes:**
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- The hook points sit in `main`, under the project's debug define, or in a shim module: `Debug::Session debug({ .name = "..." });` after `ThreadPool::Start()`, and `Debug::Pump()` once per frame on the app's thread.
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- Registrations go in debug-only sources, which `project.cpp` adds only when the flag is on.
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- **Pause and step** hold only what is gated on them. In a frame loop: `while (acc >= dt && Debug::Advance()) { Tick(); acc -= dt; }`. In a fixed-step loop: `Debug::Paused()` and `Debug::TakeSteps()`.
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- **Registering** (`import Crafter.Debug;`, namespace `Crafter::Debug`):
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```cpp
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struct SpawnArgs { Debug::Required<std::string> kind; float x = 0; float y = 0; }; // fields become key=value
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Debug::Command("World_Spawn", "Spawn an entity; returns its id.",
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[](const SpawnArgs& a) -> Debug::Result<std::int32_t> {
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if (!world) return Debug::Error{ "NoWorld", "no world loaded; call Level_Load first" };
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return world->Spawn(*a.kind, a.x, a.y);
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});
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Debug::Watch("physics.gravity", gravity, { .min = -50, .max = 0, .help = "m/s^2" }); // get and set
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Debug::Watch("scene", [] { return SceneName(); }); // read-only
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Debug::Sample("solver.residual", residual); // hot code, any thread; `trace --history`
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Debug::Check(mass > 0, "physics", "body {} has mass {}", id, mass); // a soft assert; also Log, LogWarn, LogError, Emit
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```
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- **Rules:**
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- **Threading:** handlers, getters and setters run on the app's thread inside `Pump`, so they read state without locks, but must not block. For a result that takes frames (a GPU readback, a network round trip), return `Debug::Async<T>` with a poller.
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- **Reuse the app's own paths:** call the same code the UI or game uses, rather than re-implementing it in the command, because a re-implemented command drifts from the real behaviour.
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- **Errors** are `Debug::Error{ "Code", "message" }`, with the message saying what to do next.
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- **Names:** commands are `Area_Verb`; watches are dotted paths.
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- **Per-object state** goes through a `Debug::Group` member, `Debug::Group debug{ std::format("fort{}", slot) }`, which prefixes paths and unregisters with its owner. It can't be moved, so keep such objects in `std::unique_ptr` or `std::deque`.
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- **Types:** arguments and results are aggregates (public fields with default initializers), scoped enums, strings, numbers or std containers. For anything else, specialize `Debug::Codec<T>`.
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- **Screenshots:** `Debug::SetCapture` makes them work. Crafter.Debug's README has the Crafter.Graphics version.
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