以前是结合使用对于adapter 的dispatch 有过简单说明，以下结合源码分析下
内部参考处理
- 参考处理
def dispatch(
self,
macro_name: str,
macro_namespace: Optional[str] = None,
packages: Optional[List[str]] = None, # eventually remove since it's fully deprecated
) -> MacroGenerator:
search_packages: List[Optional[str]]
# 对于macro 包含了 . 的调用进行处理，所以自己开发的macro 注意命名
if "." in macro_name:
suggest_macro_namespace, suggest_macro_name = macro_name.split(".", 1)
msg = (
f'In adapter.dispatch, got a macro name of "{macro_name}", '
f'but "." is not a valid macro name component. Did you mean '
f'`adapter.dispatch("{suggest_macro_name}", '
f'macro_namespace="{suggest_macro_namespace}")`?'
)
raise CompilationError(msg)
if packages is not None:
raise MacroDispatchArgError(macro_name)
# 对于package 的搜索，此
search_packages = self._get_search_packages(macro_namespace)
attempts = []
# 进行遍历操作
for package_name in search_packages:
for prefix in self._get_adapter_macro_prefixes():
search_name = f"{prefix}__{macro_name}"
try:
# this uses the namespace from the context
macro = self._namespace.get_from_package(package_name, search_name)
except CompilationError:
# Only raise CompilationError if macro is not found in
# any package
macro = None
if package_name is None:
attempts.append(search_name)
else:
attempts.append(f"{package_name}.{search_name}")
if macro is not None:
return macro
searched = ", ".join(repr(a) for a in attempts)
msg = f"In dispatch: No macro named '{macro_name}' found within namespace: '{macro_namespace}'\n Searched for: {searched}"
raise CompilationError(msg)
- 包搜索处理
会包含搜索顺序以及搜索包的处理，与官方文档介绍是一致的
def _get_search_packages(self, namespace: Optional[str] = None) -> List[Optional[str]]:
search_packages: List[Optional[str]] = [None]
if namespace is None:
search_packages = [None]
elif isinstance(namespace, str):
macro_search_order = self._adapter.config.get_macro_search_order(namespace)
if macro_search_order:
search_packages = macro_search_order
elif not macro_search_order and namespace in self._adapter.config.dependencies:
search_packages = [self.config.project_name, namespace]
else:
raise CompilationError(
f"In adapter.dispatch, got a {type(namespace)} macro_namespace argument "
f'("{namespace}"), but macro_namespace should be None or a string.'
)
return search_packages
- macronamespace 处理
class MacroNamespace(Mapping):
def __init__(
self,
global_namespace: FlatNamespace, # root package macros
local_namespace: FlatNamespace, # packages for *this* node
global_project_namespace: FlatNamespace, # internal packages
packages: Dict[str, FlatNamespace], # non-internal packages
):
self.global_namespace: FlatNamespace = global_namespace
self.local_namespace: FlatNamespace = local_namespace
self.packages: Dict[str, FlatNamespace] = packages
self.global_project_namespace: FlatNamespace = global_project_namespace
def _search_order(self) -> Iterable[Union[FullNamespace, FlatNamespace]]:
yield self.local_namespace # local package
yield self.global_namespace # root package
# TODO CT-211
yield self.packages # type: ignore[misc] # non-internal packages
yield {
# TODO CT-211
GLOBAL_PROJECT_NAME: self.global_project_namespace, # type: ignore[misc] # dbt
}
yield self.global_project_namespace # other internal project besides dbt
# provides special keys method for MacroNamespace iterator
# returns keys from local_namespace, global_namespace, packages,
# global_project_namespace
def _keys(self) -> Set[str]:
keys: Set[str] = set()
for search in self._search_order():
keys.update(search)
return keys
# special iterator using special keys
def __iter__(self) -> Iterator[str]:
for key in self._keys():
yield key
def __len__(self):
return len(self._keys())
def __getitem__(self, key: str) -> NamespaceMember:
for dct in self._search_order():
if key in dct:
return dct[key]
raise KeyError(key)
def get_from_package(self, package_name: Optional[str], name: str) -> Optional[MacroGenerator]:
if package_name is None:
return self.get(name)
elif package_name == GLOBAL_PROJECT_NAME:
return self.global_project_namespace.get(name)
elif package_name in self.packages:
return self.packages[package_name].get(name)
else:
raise PackageNotFoundForMacroError(package_name)
- macro prefix 的处理
可以看到先是当前adapter 的，然后是其他adapter （通过依赖指定的），之后是default
def _get_adapter_macro_prefixes(self) -> List[str]:
# order matters for dispatch:
# 1. current adapter
# 2. any parent adapters (dependencies)
# 3. 'default'
search_prefixes = get_adapter_type_names(self._adapter.type()) + ["default"]
return search_prefixes
- get_adapter_type_names 的处理
def get_adapter_type_names(self, name: Optional[str]) -> List[str]:
return [p.adapter.type() for p in self.get_adapter_plugins(name)]
- get_adapter_plugins 部分会进行依赖plugin 的处理
注意dependencies 这个也是我们开发plugin 定义的一个，也会进行查找
def get_adapter_plugins(self, name: Optional[str]) -> List[AdapterPlugin]:
"""Iterate over the known adapter plugins. If a name is provided,
iterate in dependency order over the named plugin and its dependencies.
"""
if name is None:
return list(self.plugins.values())
plugins: List[AdapterPlugin] = []
seen: Set[str] = set()
plugin_names: List[str] = [name]
while plugin_names:
plugin_name = plugin_names[0]
plugin_names = plugin_names[1:]
try:
plugin = self.plugins[plugin_name]
except KeyError:
raise DbtInternalError(f"No plugin found for {plugin_name}") from None
plugins.append(plugin)
seen.add(plugin_name)
for dep in plugin.dependencies:
if dep not in seen:
plugin_names.append(dep)
return plugins
说明
结合官方文档以及源码可以更好的了解dbt adapter dispatch 的内部处理
参考资料
core/dbt/context/macros.py
core/dbt/context/providers.py
https://docs.getdbt.com/reference/dbt-jinja-functions/dispatch
https://docs.getdbt.com/reference/dbt-jinja-functions/adapter