|
| 1 | +from __future__ import annotations |
| 2 | + |
| 3 | +from collections import deque |
| 4 | +from typing import TYPE_CHECKING, Callable, Optional |
| 5 | + |
| 6 | +if TYPE_CHECKING: |
| 7 | + from syft_migration.base import MigratableObject |
| 8 | + from syft_migration.schema import PackageProtocolSchema |
| 9 | + |
| 10 | +# A migration transforms one MigratableObject instance into another version. |
| 11 | +MigrationFn = Callable[["MigratableObject"], "MigratableObject"] |
| 12 | + |
| 13 | + |
| 14 | +class MigrationError(Exception): |
| 15 | + """Raised when an object cannot be registered, located, or migrated.""" |
| 16 | + |
| 17 | + |
| 18 | +def _has_identity(cls: type[MigratableObject]) -> bool: |
| 19 | + """Whether ``cls`` pins both identity fields (i.e. is a concrete version). |
| 20 | +
|
| 21 | + The base class and abstract intermediates leave the fields required (no |
| 22 | + default), so they have no identity and are not registered. |
| 23 | + """ |
| 24 | + name_field = cls.model_fields.get("canonical_name") |
| 25 | + version_field = cls.model_fields.get("version") |
| 26 | + if name_field is None or version_field is None: |
| 27 | + return False |
| 28 | + return not (name_field.is_required() or version_field.is_required()) |
| 29 | + |
| 30 | + |
| 31 | +def _identity(cls: type[MigratableObject]) -> tuple[str, str]: |
| 32 | + """Return (canonical_name, version) for a concrete subclass. |
| 33 | +
|
| 34 | + Raises ``MigrationError`` if ``cls`` does not pin both fields (the base class |
| 35 | + and abstract intermediates leave them required, so they have no identity). |
| 36 | + """ |
| 37 | + if not _has_identity(cls): |
| 38 | + raise MigrationError( |
| 39 | + f"{cls.__name__} does not pin canonical_name/version and has no identity" |
| 40 | + ) |
| 41 | + return ( |
| 42 | + str(cls.model_fields["canonical_name"].default), |
| 43 | + str(cls.model_fields["version"].default), |
| 44 | + ) |
| 45 | + |
| 46 | + |
| 47 | +class MigrationRegistry: |
| 48 | + """All known object versions, migrations, and protocol schemas for ONE package.""" |
| 49 | + |
| 50 | + def __init__(self) -> None: |
| 51 | + # canonical_name -> {version: object_class} |
| 52 | + self.objects: dict[str, dict[str, type[MigratableObject]]] = {} |
| 53 | + # canonical_name -> {(from_version, to_version): migration_fn} |
| 54 | + self.migrations: dict[str, dict[tuple[str, str], MigrationFn]] = {} |
| 55 | + self.current_protocol_schema: Optional[PackageProtocolSchema] = None |
| 56 | + self.history_protocol_schemas: dict[str, PackageProtocolSchema] = {} |
| 57 | + |
| 58 | + # -- objects ----------------------------------------------------------- |
| 59 | + def register_object_version(self, cls: type[MigratableObject]) -> None: |
| 60 | + if not _has_identity(cls): |
| 61 | + return |
| 62 | + canonical_name, version = _identity(cls) |
| 63 | + existing = self.objects.get(canonical_name, {}).get(version) |
| 64 | + if existing is not None and existing is not cls: |
| 65 | + raise MigrationError( |
| 66 | + f"Object {(canonical_name, version)} already registered as " |
| 67 | + f"{existing.__name__}, cannot re-register as {cls.__name__}" |
| 68 | + ) |
| 69 | + self.objects.setdefault(canonical_name, {})[version] = cls |
| 70 | + |
| 71 | + def get_class(self, canonical_name: str, version: str) -> type[MigratableObject]: |
| 72 | + try: |
| 73 | + return self.objects[canonical_name][version] |
| 74 | + except KeyError: |
| 75 | + raise MigrationError( |
| 76 | + f"No object registered for {(canonical_name, version)}" |
| 77 | + ) |
| 78 | + |
| 79 | + def versions(self, canonical_name: str) -> list[str]: |
| 80 | + return list(self.objects.get(canonical_name, {})) |
| 81 | + |
| 82 | + def latest_version(self, canonical_name: str) -> str: |
| 83 | + schema = self.current_protocol_schema |
| 84 | + if schema is not None and canonical_name in schema.object_versions: |
| 85 | + return schema.object_versions[canonical_name] |
| 86 | + versions = self.versions(canonical_name) |
| 87 | + if not versions: |
| 88 | + raise MigrationError(f"No versions registered for {canonical_name!r}") |
| 89 | + return max(versions) |
| 90 | + |
| 91 | + # -- migrations -------------------------------------------------------- |
| 92 | + def register_migration( |
| 93 | + self, |
| 94 | + canonical_name: str, |
| 95 | + from_version: str, |
| 96 | + to_version: str, |
| 97 | + fn: MigrationFn, |
| 98 | + ) -> None: |
| 99 | + """Register ``fn`` as the migration from ``from_version`` to ``to_version``.""" |
| 100 | + edges = self.migrations.setdefault(canonical_name, {}) |
| 101 | + edges[(from_version, to_version)] = fn |
| 102 | + |
| 103 | + def migration( |
| 104 | + self, canonical_name: str, from_version: str, to_version: str |
| 105 | + ) -> Callable[[MigrationFn], MigrationFn]: |
| 106 | + """Decorator form of :meth:`register_migration` for named functions.""" |
| 107 | + |
| 108 | + def decorator(fn: MigrationFn) -> MigrationFn: |
| 109 | + self.register_migration( |
| 110 | + canonical_name=canonical_name, |
| 111 | + from_version=from_version, |
| 112 | + to_version=to_version, |
| 113 | + fn=fn, |
| 114 | + ) |
| 115 | + return fn |
| 116 | + |
| 117 | + return decorator |
| 118 | + |
| 119 | + def migration_path( |
| 120 | + self, canonical_name: str, from_version: str, to_version: str |
| 121 | + ) -> list[MigrationFn]: |
| 122 | + """Return the migration functions to apply, in order, via BFS over edges.""" |
| 123 | + if from_version == to_version: |
| 124 | + return [] |
| 125 | + # all migrations for this class |
| 126 | + edges = self.migrations.get(canonical_name, {}) |
| 127 | + # BFS queue of (current_version, path_to_current) |
| 128 | + queue: deque[tuple[str, list[MigrationFn]]] = deque([(from_version, [])]) |
| 129 | + # seen versions |
| 130 | + seen = {from_version} |
| 131 | + while queue: |
| 132 | + current, path = queue.popleft() |
| 133 | + for (src, dst), func in edges.items(): |
| 134 | + if src != current or dst in seen: |
| 135 | + continue |
| 136 | + next_path = [*path, func] |
| 137 | + if dst == to_version: |
| 138 | + return next_path |
| 139 | + seen.add(dst) |
| 140 | + queue.append((dst, next_path)) |
| 141 | + raise MigrationError( |
| 142 | + f"No migration path for {canonical_name!r} from {from_version} to {to_version}" |
| 143 | + ) |
| 144 | + |
| 145 | + # -- protocol schemas -------------------------------------------------- |
| 146 | + def register_protocol_schema( |
| 147 | + self, schema: PackageProtocolSchema, *, current: bool = True |
| 148 | + ) -> None: |
| 149 | + """Register a schema, keeping the object registry and schemas in sync. |
| 150 | +
|
| 151 | + Every object the schema pins must already be registered (objects auto-register |
| 152 | + when their class is defined); registering a schema that references an unknown |
| 153 | + object/version raises before the schema is stored. |
| 154 | + """ |
| 155 | + for canonical_name, version in schema.object_versions.items(): |
| 156 | + self.get_class(canonical_name=canonical_name, version=version) |
| 157 | + self.history_protocol_schemas[schema.package_version] = schema |
| 158 | + if current: |
| 159 | + self.current_protocol_schema = schema |
| 160 | + |
| 161 | + def schema_for_package_version(self, package_version: str) -> PackageProtocolSchema: |
| 162 | + if ( |
| 163 | + self.current_protocol_schema is not None |
| 164 | + and self.current_protocol_schema.package_version == package_version |
| 165 | + ): |
| 166 | + return self.current_protocol_schema |
| 167 | + try: |
| 168 | + return self.history_protocol_schemas[package_version] |
| 169 | + except KeyError: |
| 170 | + raise MigrationError( |
| 171 | + f"No protocol schema registered for package version {package_version!r}" |
| 172 | + ) |
| 173 | + |
| 174 | + |
| 175 | +# Default per-import registry used by MigratableObject.__init_subclass__. |
| 176 | +default_registry = MigrationRegistry() |
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