Re: [PATCH v1 1/7] qapi: scripts: add a generator for qapi's examples

[Daniel P . Berrangé]

On Tue, Sep 05, 2023 at 09:48:40PM +0200, Victor Toso wrote:
> This generator has two goals:
>  1. Mechanical validation of QAPI examples
>  2. Generate the examples in a JSON format to be consumed for extra
>     validation.
> 
> The generator iterates over every Example section, parsing both server
> and client messages. The generator prints any inconsistency found, for
> example:
> 
>  |  Error: Extra data: line 1 column 39 (char 38)
>  |  Location: cancel-vcpu-dirty-limit at qapi/migration.json:2017
>  |  Data: {"execute": "cancel-vcpu-dirty-limit"},
>  |      "arguments": { "cpu-index": 1 } }
> 
> The generator will output other JSON file with all the examples in the
> QAPI module that they came from. This can be used to validate the
> introspection between QAPI/QMP to language bindings, for example:
> 
>  | { "examples": [
>  |   {
>  |     "id": "ksuxwzfayw",
>  |     "client": [
>  |     {
>  |       "sequence-order": 1
>  |       "message-type": "command",
>  |       "message":
>  |       { "arguments":
>  |         { "device": "scratch", "size": 1073741824 },
>  |         "execute": "block_resize"
>  |       },
>  |    } ],
>  |    "server": [
>  |    {
>  |      "sequence-order": 2
>  |      "message-type": "return",
>  |      "message": { "return": {} },
>  |    } ]
>  |    }
>  |  ] }
> 
> Note that the order matters, as read by the Example section and
> translated into "sequence-order". A language binding project can then
> consume this files to Marshal and Unmarshal, comparing if the results
> are what is to be expected.
> 
> RFC discussion:
>     https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg04641.html
> 
> Signed-off-by: Victor Toso <victortoso@redhat.com>
> ---
>  scripts/qapi/dumpexamples.py | 194 +++++++++++++++++++++++++++++++++++
>  scripts/qapi/main.py         |   2 +
>  2 files changed, 196 insertions(+)
>  create mode 100644 scripts/qapi/dumpexamples.py
> 
> diff --git a/scripts/qapi/dumpexamples.py b/scripts/qapi/dumpexamples.py
> new file mode 100644
> index 0000000000..c14ed11774
> --- /dev/null
> +++ b/scripts/qapi/dumpexamples.py
> @@ -0,0 +1,194 @@
> +"""
> +Dump examples for Developers
> +"""
> +# Copyright (c) 2022 Red Hat Inc.
> +#
> +# Authors:
> +#  Victor Toso <victortoso@redhat.com>
> +#
> +# This work is licensed under the terms of the GNU GPL, version 2.
> +# See the COPYING file in the top-level directory.
> +
> +# Just for type hint on self
> +from __future__ import annotations
> +
> +import os
> +import json
> +import random
> +import string
> +
> +from typing import Dict, List, Optional
> +
> +from .schema import (
> +    QAPISchema,
> +    QAPISchemaType,
> +    QAPISchemaVisitor,
> +    QAPISchemaEnumMember,
> +    QAPISchemaFeature,
> +    QAPISchemaIfCond,
> +    QAPISchemaObjectType,
> +    QAPISchemaObjectTypeMember,
> +    QAPISchemaVariants,
> +)
> +from .source import QAPISourceInfo
> +
> +
> +def gen_examples(schema: QAPISchema,
> +                 output_dir: str,
> +                 prefix: str) -> None:
> +    vis = QAPISchemaGenExamplesVisitor(prefix)
> +    schema.visit(vis)
> +    vis.write(output_dir)
> +
> +
> +def get_id(random, size: int) -> str:
> +    letters = string.ascii_lowercase
> +    return ''.join(random.choice(letters) for i in range(size))
> +
> +
> +def next_object(text, start, end, context) -> Dict:
> +    # Start of json object
> +    start = text.find("{", start)
> +    end = text.rfind("}", start, end+1)
> +
> +    # try catch, pretty print issues
> +    try:
> +        ret = json.loads(text[start:end+1])
> +    except Exception as e:
> +        print("Error: {}\nLocation: {}\nData: {}\n".format(
> +              str(e), context, text[start:end+1]))

This prints an error, but the caller ignores this and carries on
as normal.

After applying this series, we still have multiple errors being
printed on console

Error: Expecting ',' delimiter: line 12 column 19 (char 336)
Location: query-blockstats at 
../storage-daemon/qapi/../../qapi/block-core.json:1259

Error: Expecting property name enclosed in double quotes: line 7 column 19 
(char 264)
Location: query-rocker-of-dpa-flows at ../qapi/rocker.json:256

Error: Expecting value: line 28 column 15 (char 775)
Location: query-spice at ../qapi/ui.json:372


If we have errors detected, we need to terminate the build by
making the generator exit, to force fixing of the problems.

This patch then needs to be moved to the end of the series, as
we need all the fixes applied to the schemas, before we enable
validation, to avoid breaking 'git bisect' build tests.


> +        return {}
> +    else:
> +        return ret
> +
> +
> +def parse_text_to_dicts(text: str, context: str) -> List[Dict]:
> +    examples, clients, servers = [], [], []
> +
> +    count = 1
> +    c, s = text.find("->"), text.find("<-")
> +    while c != -1 or s != -1:
> +        if c == -1 or (s != -1 and s < c):
> +            start, target = s, servers
> +        else:
> +            start, target = c, clients
> +
> +        # Find the client and server, if any
> +        if c != -1:
> +            c = text.find("->", start + 1)
> +        if s != -1:
> +            s = text.find("<-", start + 1)
> +
> +        # Find the limit of current's object.
> +        # We first look for the next message, either client or server. If 
> none
> +        # is avaible, we set the end of the text as limit.
> +        if c == -1 and s != -1:
> +            end = s
> +        elif c != -1 and s == -1:
> +            end = c
> +        elif c != -1 and s != -1:
> +            end = (c < s) and c or s
> +        else:
> +            end = len(text) - 1
> +
> +        message = next_object(text, start, end, context)
> +        if len(message) > 0:
> +            message_type = "return"
> +            if "execute" in message:
> +                message_type = "command"
> +            elif "event" in message:
> +                message_type = "event"
> +
> +            target.append({
> +                "sequence-order": count,
> +                "message-type": message_type,
> +                "message": message
> +            })
> +            count += 1
> +
> +    examples.append({"client": clients, "server": servers})
> +    return examples
> +
> +
> +def parse_examples_of(self: QAPISchemaGenExamplesVisitor,
> +                      name: str):
> +
> +    assert(name in self.schema._entity_dict)
> +    obj = self.schema._entity_dict[name]
> +    assert((obj.doc is not None))
> +    module_name = obj._module.name
> +
> +    # We initialize random with the name so that we get consistent example
> +    # ids over different generations. The ids of a given example might
> +    # change when adding/removing examples, but that's acceptable as the
> +    # goal is just to grep $id to find what example failed at a given test
> +    # with minimum chorn over regenerating.
> +    random.seed(name, version=2)
> +
> +    for s in obj.doc.sections:
> +        if s.name != "Example":
> +            continue
> +
> +        if module_name not in self.target:
> +            self.target[module_name] = []
> +
> +        context = f'''{name} at {obj.info.fname}:{obj.info.line}'''
> +        examples = parse_text_to_dicts(s.text, context)
> +        for example in examples:
> +            self.target[module_name].append({
> +                    "id": get_id(random, 10),
> +                    "client": example["client"],
> +                    "server": example["server"]
> +            })
> +
> +
> +class QAPISchemaGenExamplesVisitor(QAPISchemaVisitor):
> +
> +    def __init__(self, prefix: str):
> +        super().__init__()
> +        self.target = {}
> +        self.schema = None
> +
> +    def visit_begin(self, schema):
> +        self.schema = schema
> +
> +    def visit_end(self):
> +        self.schema = None
> +
> +    def write(self: QAPISchemaGenExamplesVisitor,
> +              output_dir: str) -> None:
> +        for filename, content in self.target.items():
> +            pathname = os.path.join(output_dir, "examples", filename)
> +            odir = os.path.dirname(pathname)
> +            os.makedirs(odir, exist_ok=True)
> +            result = {"examples": content}
> +
> +            with open(pathname, "w") as outfile:
> +                outfile.write(json.dumps(result, indent=2, sort_keys=True))
> +
> +    def visit_command(self: QAPISchemaGenExamplesVisitor,
> +                      name: str,
> +                      info: Optional[QAPISourceInfo],
> +                      ifcond: QAPISchemaIfCond,
> +                      features: List[QAPISchemaFeature],
> +                      arg_type: Optional[QAPISchemaObjectType],
> +                      ret_type: Optional[QAPISchemaType],
> +                      gen: bool,
> +                      success_response: bool,
> +                      boxed: bool,
> +                      allow_oob: bool,
> +                      allow_preconfig: bool,
> +                      coroutine: bool) -> None:
> +
> +        if gen:
> +            parse_examples_of(self, name)
> +
> +    def visit_event(self: QAPISchemaGenExamplesVisitor,
> +                    name: str,
> +                    info: Optional[QAPISourceInfo],
> +                    ifcond: QAPISchemaIfCond,
> +                    features: List[QAPISchemaFeature],
> +                    arg_type: Optional[QAPISchemaObjectType],
> +                    boxed: bool):
> +
> +        parse_examples_of(self, name)
> diff --git a/scripts/qapi/main.py b/scripts/qapi/main.py
> index 316736b6a2..cf9beac3c9 100644
> --- a/scripts/qapi/main.py
> +++ b/scripts/qapi/main.py
> @@ -13,6 +13,7 @@
>  
>  from .commands import gen_commands
>  from .common import must_match
> +from .dumpexamples import gen_examples
>  from .error import QAPIError
>  from .events import gen_events
>  from .introspect import gen_introspect
> @@ -54,6 +55,7 @@ def generate(schema_file: str,
>      gen_events(schema, output_dir, prefix)
>      gen_introspect(schema, output_dir, prefix, unmask)
>  
> +    gen_examples(schema, output_dir, prefix)
>  
>  def main() -> int:
>      """
> -- 
> 2.41.0
> 
> 

With regards,
Daniel
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