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# -*- coding: utf-8 -*-
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
"""
Outputter to generate Rust code for metrics.
"""
import enum
import json
from pathlib import Path
from typing import Any, Dict, Optional, Union
from . import __version__
from . import metrics
from . import pings
from . import tags
from . import util
def rust_datatypes_filter(value):
"""
A Jinja2 filter that renders Rust literals.
Based on Python's JSONEncoder, but overrides:
- dicts and sets to raise an error
- sets to vec![] (used in labels)
- enums to become Class::Value
- lists to vec![] (used in send_in_pings)
- null to None
- strings to "value".into()
- Rate objects to a CommonMetricData initializer
(for external Denominators' Numerators lists)
"""
class RustEncoder(json.JSONEncoder):
def iterencode(self, value):
if isinstance(value, dict):
raise ValueError("RustEncoder doesn't know dicts {}".format(str(value)))
elif isinstance(value, enum.Enum):
yield (value.__class__.__name__ + "::" + util.Camelize(value.name))
elif isinstance(value, set):
yield "vec!["
first = True
for subvalue in sorted(list(value)):
if not first:
yield ", "
yield from self.iterencode(subvalue)
first = False
yield "]"
elif isinstance(value, list):
yield "vec!["
first = True
for subvalue in list(value):
if not first:
yield ", "
yield from self.iterencode(subvalue)
first = False
yield "]"
elif value is None:
yield "None"
# `CowStr` is a `str`, so needs to be before next case
elif isinstance(value, metrics.CowString):
yield f'::std::borrow::Cow::from("{value.inner}")'
elif isinstance(value, str):
yield f"{json.dumps(value)}.into()"
elif isinstance(value, metrics.Rate):
yield "CommonMetricData("
first = True
for arg_name in util.common_metric_args:
if hasattr(value, arg_name):
if not first:
yield ", "
yield f"{util.camelize(arg_name)} = "
yield from self.iterencode(getattr(value, arg_name))
first = False
yield ")"
else:
yield from super().iterencode(value)
return "".join(RustEncoder().iterencode(value))
def ctor(obj):
"""
Returns the scope and name of the constructor to use for a metric object.
Necessary because LabeledMetric<T> is constructed using LabeledMetric::new
not LabeledMetric<T>::new
"""
if getattr(obj, "labeled", False):
return "LabeledMetric::new"
return class_name(obj.type) + "::new"
def type_name(obj):
"""
Returns the Rust type to use for a given metric or ping object.
"""
if getattr(obj, "labeled", False):
return "LabeledMetric<{}>".format(class_name(obj.type))
generate_enums = getattr(obj, "_generate_enums", []) # Extra Keys? Reasons?
if len(generate_enums):
generic = None
for name, suffix in generate_enums:
if len(getattr(obj, name)):
generic = util.Camelize(obj.name) + suffix
else:
if isinstance(obj, metrics.Event):
generic = "NoExtra"
else:
generic = "No" + suffix
return "{}<{}>".format(class_name(obj.type), generic)
generate_structure = getattr(obj, "_generate_structure", [])
if len(generate_structure):
generic = util.Camelize(obj.name) + "Object"
return "{}<{}>".format(class_name(obj.type), generic)
return class_name(obj.type)
def extra_type_name(typ: str) -> str:
"""
Returns the corresponding Rust type for event's extra key types.
"""
if typ == "boolean":
return "bool"
elif typ == "string":
return "String"
elif typ == "quantity":
return "u32"
else:
return "UNSUPPORTED"
def structure_type_name(typ: str) -> str:
"""
Returns the corresponding Rust type for structure items.
"""
if typ == "boolean":
return "bool"
elif typ == "string":
return "String"
elif typ == "number":
return "i64"
else:
return "UNSUPPORTED"
def class_name(obj_type):
"""
Returns the Rust class name for a given metric or ping type.
"""
if obj_type == "ping":
return "Ping"
if obj_type.startswith("labeled_"):
obj_type = obj_type[8:]
return util.Camelize(obj_type) + "Metric"
def extra_keys(allowed_extra_keys):
"""
Returns the &'static [&'static str] ALLOWED_EXTRA_KEYS for impl ExtraKeys
"""
return "&[" + ", ".join([f'"{key}"' for key in allowed_extra_keys]) + "]"
class Category:
"""
Data struct holding information about a metric to be used in the template.
"""
def __init__(
self,
name: str,
objs: Dict[str, Union[metrics.Metric, pings.Ping, tags.Tag]],
contains_pings: bool,
):
self.name = name
self.objs = objs
self.contains_pings = contains_pings
def output_rust(
objs: metrics.ObjectTree, output_dir: Path, options: Optional[Dict[str, Any]] = None
) -> None:
"""
Given a tree of objects, output Rust code to `output_dir`.
:param objs: A tree of objects (metrics and pings) as returned from
`parser.parse_objects`.
:param output_dir: Path to an output directory to write to.
:param options: options dictionary, not currently used for Rust
"""
if options is None:
options = {}
template = util.get_jinja2_template(
"rust.jinja2",
filters=(
("rust", rust_datatypes_filter),
("snake_case", util.snake_case),
("camelize", util.camelize),
("type_name", type_name),
("extra_type_name", extra_type_name),
("structure_type_name", structure_type_name),
("ctor", ctor),
("extra_keys", extra_keys),
),
)
filename = "glean_metrics.rs"
filepath = output_dir / filename
categories = []
for category_key, category_val in objs.items():
contains_pings = any(
isinstance(obj, pings.Ping) for obj in category_val.values()
)
cat = Category(category_key, category_val, contains_pings)
categories.append(cat)
with filepath.open("w", encoding="utf-8") as fd:
fd.write(
template.render(
parser_version=__version__,
categories=categories,
extra_metric_args=util.extra_metric_args,
common_metric_args=util.common_metric_args,
)
)