sapling/eden
Meyer Jacobs e3b86cf77d debug: introduce binding layer for propagating error metadata to Python
Summary:
Implements based Rust-Python binding layer for error metadata propagation.

We introduce a new type, `TaggedExceptionData`, which carries CommonMetadata and the original (without metadata) error message for a Rust Anyhow error. This class is passed to RustError and can be accessed in Python (somewhat awkwardly) via indexing:
```
except error.RustError as e:
    fault = e.args[0].fault()
    typename = e.args[0].typename()
    message = e.args[0].message()
```
As far as I can tell, due to limitations in cpython-rs, this can't be made more ergonomic without introducing a Python shim around the Rust binding layer, which could adapt the cpython-rs classes to use whatever API we'd like.

Currently, anyhow errors that are not otherwise special-cased will be converted into RustError, with both the original error message and any attached metadata printed as shown below
```
  abort: intentional error for debugging with message 'intentional_error'
  error has type name taggederror::IntentionalError and fault None
```
We can of course re-raise the error if desired to maintain the previous behavior for handling a RustError.

If we'd like other, specialized Rust Python Exception types to carry metadata (such as `IndexedLogError`), we'll need to modify them to accept a `TaggedExceptionData` like `RustError`.

Renamed the "cause an error in pure rust command" function to `debugcauserusterror`, and instead used the name `debugthrowrustexception` for a command which causes an error in rust which is converted to a Python exception across the binding layer.

Introduced a simple integration test which exercises `debugthrowrustexception`.

Added a basic handler for RustError to scmutil.py

Reviewed By: DurhamG

Differential Revision: D22517796

fbshipit-source-id: 0409489243fe739a26958aad48f608890eb93aa0
2020-07-16 19:30:00 -07:00
..
fs add 4k random writes benchmark 2020-07-14 16:13:37 -07:00
integration revlog: turn on head-based-commit-transaction for tests 2020-07-08 14:33:58 -07:00
locale add a copyright header to glibc_en.po 2019-04-26 14:38:27 -07:00
mononoke edenapi_types: add metadata field to DataEntry 2020-07-16 13:32:19 -07:00
scm debug: introduce binding layer for propagating error metadata to Python 2020-07-16 19:30:00 -07:00
scripts packaging: use scheduled tasks 2020-06-10 19:29:15 -07:00
test_support enable asynchronous integration tests 2020-06-15 15:53:50 -07:00
test-data enable treemanifest in snapshots 2019-08-28 18:46:03 -07:00
win add .clang-format 2020-04-28 08:42:03 -07:00
.clang-format Cut FOR_EACH_KV 2020-06-10 19:29:43 -07:00
.gitignore eden: wire up mac contbuild 2019-02-05 21:52:30 -08:00
Eden.project.toml Eden.project.toml file for Nuclide 2018-04-26 11:05:23 -07:00