build/rbe/action_diff.py

#!/usr/bin/env fuchsia-vendored-python
# Copyright 2023 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Recursively report differences between actions and their inputs.

Usage:
  See --help.
"""

import argparse
import dataclasses
import itertools
import os
import sys

import remote_action
import reproxy_logs
import remotetool
import cl_utils
import fuchsia

from api.log import log_pb2
from pathlib import Path
from typing import (
    AbstractSet,
    Callable,
    Dict,
    Iterable,
    Optional,
    Sequence,
    Tuple,
)

_SCRIPT_BASENAME = Path(__file__).name


def msg(text: str):
    print(f"[{_SCRIPT_BASENAME}] {text}")


def _main_arg_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        description="Recursively finds input differences of a remote output.",
    )
    parser.add_argument(
        "--reproxy_logs",
        type=Path,
        help="reproxy logs (.rrpl or .rpl) or the directories containing them",
        required=True,
        metavar="PATH",
        nargs=2,
    )

    group = parser.add_mutually_exclusive_group(required=True)
    # Analysis starts with either a common --output_file or a pair of
    # --action_digests.
    group.add_argument(
        "--action_digests",
        type=str,
        help="Action digests from the two reproxy logs that had unexpectedly different outcomes, format: SHA256SUM/SIZE.",
        metavar="DIGEST",
        nargs=2,
    )
    group.add_argument(
        "--output_file",
        type=Path,
        help="Remote output to compare, that was common to actions in the two reproxy logs.",
        metavar="FILE",
    )

    parser.add_argument(
        "--limit",
        type=int,
        default=0,
        help="Limit number of root causes to display (0=unlimited).",
        metavar="LIMIT",
    )
    return parser


_MAIN_ARG_PARSER = _main_arg_parser()


@dataclasses.dataclass
class RootCause(object):
    explanation: Sequence[str]

    def __str__(self) -> str:
        return "\n  ".join(self.explanation)


def verbose_root_cause(explanation: Sequence[str], indent: str):
    for line in explanation:
        print(f"{indent}{line}")
    return RootCause(explanation=explanation)


class ActionDiffer(object):
    def __init__(
        self,
        left: reproxy_logs.ReproxyLog,
        right: reproxy_logs.ReproxyLog,
        reproxy_cfg: Dict[str, str],
    ):
        self._left = left
        self._right = right
        self._remotetool = remotetool.RemoteTool(reproxy_cfg)

    @property
    def left(self) -> reproxy_logs.ReproxyLog:
        return self._left

    @property
    def right(self) -> reproxy_logs.ReproxyLog:
        return self._right

    @property
    def reproxy_cfg(self) -> Dict[str, str]:
        return self._remote_tool.config

    def trace_artifact(self, filepath: Path) -> Iterable[RootCause]:
        """Recursively finds action and output differences.

        Prints findings to stdout.

        Args:
          filepath: output file to compare, relative to the working dir.
              There should be a unique LogRecord of a remote action in both the
              left and right records that names this file as an output.

        Yields:
          reasons for differences.
        """
        visited = set()  # cache already visited paths
        yield from self._trace_artifact(filepath, visited, 0)

    def _trace_artifact(
        self, filepath: Path, visited: AbstractSet[Path], level: int
    ) -> Iterable[RootCause]:
        """Recursively finds action and output differences.

        Prints findings to stdout.

        Args:
          filepath: output file to compare, relative to the working dir.
              There should be a unique LogRecord of a remote action in both the
              left and right records that names this file as an output.
          visited: set of outputs already queried (modify-by-reference).
          level: recursion level, used for formatting output.
        """
        indent = "  " * level
        print(f"{indent}-------- Examining {filepath} --------")

        # Avoid re-visiting the same intermediate.
        if filepath in visited:
            print(f"{indent}(already visited earlier)")
            return
        else:
            visited.add(filepath)

        def root_cause(explanation: Sequence[str]) -> RootCause:
            return verbose_root_cause(
                [f"path: {filepath}"] + explanation, indent
            )

        left_record = self.left.records_by_output_file.get(filepath, None)
        right_record = self.right.records_by_output_file.get(filepath, None)
        if left_record is None:
            yield root_cause(
                [f"File not found among left log's action outputs: {filepath}"]
            )
            return
        if right_record is None:
            yield root_cause(
                [f"File not found among right log's action outputs: {filepath}"]
            )
            return
        # TODO: fetch and report differences between inputs

        left_entry = left_record.remote_metadata.output_file_digests
        left_file_digest = left_entry[str(filepath)]
        right_entry = right_record.remote_metadata.output_file_digests
        right_file_digest = right_entry[str(filepath)]
        if left_file_digest == right_file_digest:
            print(
                f"{indent}Digest of {filepath} already matches: {left_file_digest}"
            )
            return

        # Digests do not match, so query the two actions that produced them
        left_action_digest = left_record.remote_metadata.action_digest
        right_action_digest = right_record.remote_metadata.action_digest
        # Possible reasons for not finding an action:
        #   * file is a source input
        #   * file was produced by a local action (possibly from racing)
        if not left_action_digest:
            yield root_cause(
                [
                    f"Could not find an action from the left log that produced {filepath}"
                ]
            )
            return

        print(f"{indent}left action digest of {filepath}: {left_action_digest}")

        if not right_action_digest:
            yield root_cause(
                [
                    f"Could not find an action from the right log that produced {filepath}"
                ]
            )
            return

        print(
            f"{indent}right action digest of {filepath}: {right_action_digest}"
        )

        command_pb = left_record.command
        remote_working_dir = Path(
            command_pb.remote_working_directory or command_pb.working_directory
        )

        yield from self._trace_actions(
            left_action_digest,
            right_action_digest,
            visited,
            level,
            remote_working_dir=remote_working_dir,
        )

    def trace_actions(
        self,
        left_action_digest: str,
        right_action_digest: str,
    ) -> Iterable[RootCause]:
        """Recursively finds action differences through their inputs.

        Prints findings to stdout.

        Args:
          left_action_digest: digest for an action from the left reproxy log.
          right_action_digest: digest for an action from the right reproxy log.

        Yields:
          reasons for differences.
        """
        visited = set()  # cache already visited paths
        yield from self._trace_actions(
            left_action_digest, right_action_digest, visited, 0
        )

    def _trace_actions(
        self,
        left_action_digest: str,
        right_action_digest: str,
        visited: AbstractSet[Path],
        level: int,
        remote_working_dir: Optional[Path] = None,
    ) -> Iterable[RootCause]:
        indent = "  " * level

        if not remote_working_dir:
            left_record = self.left.records_by_action_digest.get(
                left_action_digest, None
            )
            if left_record is None:
                print(
                    f"{indent}Unable to find log record with action digest {left_action_digest}"
                )
                return
            command_pb = left_record.command
            remote_working_dir = Path(
                command_pb.remote_working_directory
                or command_pb.working_directory
            )

        def root_cause(explanation: Sequence[str]) -> RootCause:
            return verbose_root_cause(explanation, indent)

        # Run remotetool on each action digest.
        left_action = self._remotetool.show_action(digest=left_action_digest)
        right_action = self._remotetool.show_action(digest=right_action_digest)

        # Compare.
        diff = left_action.diff(right_action)

        have_root_cause = False
        if diff.command_unified_diffs:
            # If the commands are different, we've found one root cause
            # difference, and there is not need to analyze any further.
            yield root_cause(
                [
                    f"Actions {left_action_digest} and {right_action_digest} have different remote commands:"
                ]
                + diff.command_unified_diffs
            )
            have_root_cause = True

        platform_diffs = list(diff.platform_diffs.report())
        if platform_diffs:
            yield root_cause(
                [f"Found differences in remote action platform:"]
                + platform_diffs
            )
            have_root_cause = True

        if diff.input_diffs.left_only or diff.input_diffs.right_only:
            yield root_cause(
                [f"{indent}Input sets are not identical:"]
                + list(diff.input_diffs.report())
            )
            have_root_cause = True

        if have_root_cause:
            # Already root-caused a difference.  Stop.
            return

        # Recursively query common inputs that are different.
        # Note: iteration ordering of dictionary can be nondeterministic.
        for path, (
            left_digest,
            right_digest,
        ) in diff.input_diffs.value_diffs.items():
            # Determine whether or not path refers to an input or
            # some (possibly remotely produced) intermediate.
            if not remote_working_dir in path.parents:
                yield root_cause(
                    [
                        f"Input {path} does not come from a remote action.",
                        f"Digests: {left_digest}",
                        f"     vs. {right_digest}",
                    ]
                )
                continue  # This is a root-cause.

            # This is an intermediate output.
            # path from show_action is relative to exec_root,
            # but trace_artifact() expects a path relative to working_dir.
            output_relpath = path.relative_to(remote_working_dir)
            print(f"{indent}Remote output file {output_relpath} differs.")
            print(f"{indent}Digests: {left_digest}")
            print(f"{indent}     vs. {right_digest}")
            print(f"{indent}[{level}](")
            yield from self._trace_artifact(output_relpath, visited, level + 1)
            print(f"{indent})[{level}]")


def main(argv: Sequence[str]) -> int:
    main_args = _MAIN_ARG_PARSER.parse_args(argv)

    logs = reproxy_logs.parse_logs(main_args.reproxy_logs)
    # len(logs) == 2, enforced by _MAIN_ARG_PARSER.

    cfg_path = remotetool._REPROXY_CFG
    reproxy_cfg = remotetool.read_config_file_lines(
        cfg_path.read_text().splitlines()
    )

    left, right = logs
    differ = ActionDiffer(left=left, right=right, reproxy_cfg=reproxy_cfg)

    if main_args.output_file:
        # Compare starting with an artifact produced in both reproxy logs.
        root_causes_iter = differ.trace_artifact(main_args.output_file)
    elif main_args.action_digests:
        # Compare starting with action digests from their respective reproxy
        # logs.  This is useful if one of the actions failed to produce
        # the expected outputs.
        left_digest, right_digest = main_args.action_digests
        root_causes_iter = differ.trace_actions(left_digest, right_digest)
    else:
        raise ValueError("Required: --action_digests or --output_file")

    if main_args.limit == 0:
        root_causes = list(root_causes_iter)
    else:
        root_causes = list(
            itertools.islice(root_causes_iter, 0, main_args.limit)
        )

    print("======== Summary of root causes of differences ========")
    for i, c in enumerate(root_causes):
        print(f"{i}: {c}\n")
    return 0


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))