Three coordinated fixes that together close the "ESP-IDF compile takes
5-7 min every time" gap and prevent the failure mode where a user clicking
compile multiple times spawns six ninja processes that peel each other
apart on a modest VPS.
What was wrong
- /compile/start generated a fresh uuid4 every call, so 6 clicks = 6
independent builds racing each other. Saw load average 30 on the prod
VPS during a real BMP280 attempt today.
- No concurrency limit anywhere; asyncio.create_task() fired without
gating.
- ccache was wired in last week (PR #149) but reported 18,350 cacheable
calls and **0 hits** because the build dir was a fresh
tempfile.TemporaryDirectory(prefix='espidf_') per compile. The random
/tmp/espidf_<random>/ path baked into -I and -fmacro-prefix-map flags
→ different command line every compile → ccache hash miss every time.
What this PR does
1. Job deduplication (`backend/app/api/routes/compile.py`)
- New `_job_key(files, board_fqbn)` returns SHA-256 of normalised file
names + contents + board. Order-independent.
- New `JOB_BY_KEY: dict[str, str]` indexes hash → job_id.
- `compile_start` checks JOB_BY_KEY before spawning a new task; if a
job for this exact content is already pending or running, returns
the existing job_id (logs `[compile] dedup hit — reusing job <id>`).
- `_purge_expired_jobs` evicts both COMPILE_JOBS and JOB_BY_KEY,
keeping the index consistent. Edge case where two jobs share a key
(old finished, new running) is handled — only evict the key entry
if it still points at the purged job.
2. Concurrency control (`backend/app/api/routes/compile.py`)
- `_COMPILE_SEMAPHORE = asyncio.Semaphore(2)` global cap on
simultaneous compiles.
- `_target_lock(board_fqbn)` returns a per-target asyncio.Lock so
concurrent compiles to the SAME board (sharing the persistent build
dir) serialise. Different boards still run in parallel up to the
semaphore cap.
- `_compile_job` acquires sema → per-target lock → flips state to
`running` → calls `_run_compile`. Pending state now accurately
reflects "queued waiting for resources".
3. Persistent build dir (`backend/app/services/espidf_compiler.py`)
- New `_prepare_persistent_project_dir(idf_target)` materialises
`/var/lib/velxio-build/<target>/project/` from the template on
first use; on subsequent compiles it wipes only `main/` and
`user_libs/` (the per-compile parts) and leaves `build/` alone so
ninja's incremental cache + ccache .o files survive.
- Toolchain version sentinel (`.idf_version`) wipes the whole target
dir if the ESP-IDF or arduino-esp32 version changes — cached
objects from the old toolchain are no longer ABI-compatible.
- `compile()` is now a thin dispatcher: persistent path or fallback
to the legacy `tempfile.TemporaryDirectory()` flow. The actual
build logic was extracted into `_compile_in_dir()` so both paths
share one implementation, no duplication.
- Escape hatch: `VELXIO_PERSISTENT_BUILD_DIR=0` env var falls back
to the tempfile path without rebuilding the image. Critical for
production safety.
4. ccache normalisation (`Dockerfile.standalone`)
- + `ENV CCACHE_BASEDIR=/var/lib/velxio-build` makes ccache canonicalise
absolute paths under that prefix when computing the cache key.
Robustens hits against any future subdir rearrangement.
5. Docker compose (`docker-compose.yml`)
- + named volume `velxio-build:/var/lib/velxio-build` so the persistent
build dir survives `docker compose up -d --build`.
- + env `VELXIO_PERSISTENT_BUILD_DIR=1` (default ON; users disable
without rebuilding).
Expected impact
- Cold first compile per container per target: unchanged (~5-7 min).
- Same sketch re-compiled: ~2-5 s (everything cached).
- Different sketch, same target: ~5-30 s (only user code + new lib steps
rebuild; ESP-IDF base hits cache).
- Different sketch with new libraries: ~30-90 s (new lib component
compiles; rest hits cache).
- Concurrent clicks on same example: 1 build, others poll the same
job_id. No more six-ninja meltdown.
Tests
- `test/backend/unit/test_compile_dedup.py` covers `_job_key` stability +
variance and `_purge_expired_jobs` consistency (including the
"two jobs share a key" edge case).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Cold first compile per container is unchanged (cache empty). Subsequent
compiles drop from ~5-7 minutes to ~30-60 seconds because every ESP-IDF
base object (FreeRTOS, lwIP, esp_wifi, libsodium, soc, hal, …) hits the
cache. The user's BMP280 example, which hangs on cold compile, completes
near-instantly on the second attempt.
Why a transparent cache is safe: ccache hashes the preprocessed source +
flags + compiler. A cache hit only happens when the input is byte-for-byte
identical to a prior compile. Different sketches with different libraries
still get correct cache misses; there is no path where one project's
output contaminates another.
Changes
- Dockerfile.standalone: install ccache, set CCACHE_DIR=/var/cache/ccache,
IDF_CCACHE_ENABLE=1, configure 2 GB cap with compression. Compression
(level 6) cuts cache disk usage by ~40% with negligible CPU overhead.
- docker-compose.yml: named volume `ccache:/var/cache/ccache` so the
cache survives `docker compose up -d --build` (without it, every image
rebuild discards the cache).
- backend/app/services/espidf_compiler.py: pass `-DCCACHE_ENABLE=1` to
cmake when IDF_CCACHE_ENABLE is truthy. ESP-IDF's project.cmake
(`set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)` on line 374)
is what actually wires ccache in; without the cmake -D flag the env
var alone has no effect because we don't go through idf.py.
Escape hatch: set IDF_CCACHE_ENABLE=0 in compose env to disable without
rebuilding the image.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Resolves several install pain points reported by users (#108, #120) and
removes the obligatory upstream-clone step that confused contributors and
slowed down every Docker build.
Install fixes:
- nginx: server_name → catch-all default_server, drop Debian's stock site
so reverse-proxied users no longer get the "Welcome to nginx" page.
- entrypoint: auto-generate SECRET_KEY at first boot, persisted under
data/.secret_key. backend/.env is now optional in docker-compose.yml.
- backend: add greenlet>=3.0.0 (SQLAlchemy async dep that was missing on
some Python builds — caused uvicorn startup failures on WSL).
Wokwi libs come from npm:
- @wokwi/elements 1.9.2, avr8js 0.21.0, rp2040js 1.3.2 are pinned in
frontend/package.json. Vite aliases removed.
- Dockerfile.standalone no longer clones avr8js / rp2040js / wokwi-elements
/ wokwi-boards. Frontend stage is just COPY + npm install + build:docker.
- Board SVGs vendored under frontend/public/boards/ (10 deduped against
existing files, 2 truly new). third-party/wokwi-* clones become reference-
only credits — generate-component-metadata.ts skips gracefully when absent.
Production config split out:
- docker-compose.prod.yml, deploy/nginx.prod.conf, nginx-host-velxio*.conf,
update-third-party.bat removed. Production deployment lives in its own
repo: https://github.com/velxio/velxio-prod (host nginx + HTTPS + backups
+ pinned upstream commit).
Verified locally: 1161 frontend tests pass, build:docker completes clean.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
- Dockerfile: download pre-built .so + ROM from velxio public release
instead of building from private qemu-lcgamboa source
- espidf_compiler: normalize any WiFi SSID → "Velxio-GUEST" for QEMU
compatibility (channel 6, open auth)
- docker-compose.yml: unified dev/prod using Dockerfile.standalone
- .dockerignore: exclude qemu-lcgamboa source from Docker context
- .gitignore: ignore prebuilt/ binaries, keep .gitkeep
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Backend:
- project_files.py: read/write sketch files to /app/data/projects/{id}/
- GET /api/projects/{id}: load project by ID (public = anyone, private = owner only)
- create/update write files to disk volume; delete removes them
- ProjectResponse includes files[] list loaded from disk
Frontend:
- /project/:id canonical route -> ProjectByIdPage
- ProjectPage (legacy /:username/:slug) redirects to /project/:id after load
- SaveProjectModal sends files[] and navigates to /project/{id} after save
- DATA_DIR env var in both compose files
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Mount ./data:/app/data in both compose files and set DATABASE_URL to
the absolute path /app/data/velxio.db so the database survives container
restarts and updates. Create /app/data in Dockerfile.standalone.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
davidmonterocrespo24