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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
/**
* Utility macros for declaring global initializers
*
* Should NOT be included by other header files. Include only in source files.
*
* Initializers are arranged in an acyclic directed dependency graph. Declaring
* a cycle will lead to a runtime error.
*
* Initializer functions take a parameter of type ::mongo::InitializerContext*.
* They throw to indicate failure, stopping further intializer processing.
*/
#pragma once
#include <string>
#include <vector>
#include "mongo/base/initializer.h"
#include "mongo/base/status.h"
/**
* Macro to define an initializer function named "NAME" with the default
* prerequisite set, that is `("default")`, and no explicit dependents.
*
* The default set of prerequisites for initializer functions has one member,
* called "default". It refers to a do-nothing initializer called "default"
* defined by this init system, which serves as a partition point. It splits
* the graph into two broad phases. In practice, most initializers can omit
* their prerequisites and dependents, and use the MONGO_INITIALIZER macro, and
* such rules will be constrained to occur _after_ the "default" sequence
* point. Some special rules perform early preparation like options parsing,
* and several initializers might depend on these, so they will typically
* specify that they happen _before_ the "default" sequence point.
*
* The pre-"default" phase is further broken down into an orderly series of
* internal stages. (See util/options_parser/startup_option_init.cpp).
*
* See MONGO_INITIALIZER_GENERAL.
*
* Usage:
* MONGO_INITIALIZER(myModule)(::mongo::InitializerContext* context) {
* ...
* }
*/
#define MONGO_INITIALIZER(NAME) MONGO_INITIALIZER_GENERAL(NAME, ("default"), ())
/**
* Macro to define an initializer function named "NAME" that depends on the initializers
* specified in PREREQUISITES to have been completed, but names no explicit dependents.
*
* See MONGO_INITIALIZER_GENERAL.
*
* Usage:
* MONGO_INITIALIZER_WITH_PREREQUISITES(myGlobalStateChecker,
* ("globalStateInitialized", "stacktraces"))(
* ::mongo::InitializerContext* context) {
* }
*/
#define MONGO_INITIALIZER_WITH_PREREQUISITES(NAME, PREREQUISITES) \
MONGO_INITIALIZER_GENERAL(NAME, PREREQUISITES, ())
#define MONGO_INITIALIZER_STRIP_PARENS_(...) __VA_ARGS__
/**
* Macro to define an initializer that depends on PREREQUISITES and has DEPENDENTS as explicit
* dependents.
*
* NAME is any legitimate name for a C++ symbol.
* PREREQUISITES is a tuple of strings surrounded by parens, e.g., ("a", "b", "c"), or ().
* DEPENDENTS is a tuple of strings surrounded by parens.
*
* At run time, the full set of prerequisites for NAME will be computed as the union of the
* explicit PREREQUISITES and the set of all other mongo initializers that name NAME in their
* list of DEPENDENTS.
*
* Usage:
* MONGO_INITIALIZER_GENERAL(myInitializer,
* ("myPrereq1", "myPrereq2", ...),
* ("myDependent1", "myDependent2", ...))(
* ::mongo::InitializerContext* context) {
* }
*
* TODO: May want to be able to name the initializer separately from the function name.
* A form that takes an existing function or that lets the programmer supply the name
* of the function to declare would be options.
*/
#define MONGO_INITIALIZER_GENERAL(NAME, PREREQUISITES, DEPENDENTS) \
void MONGO_INITIALIZER_FUNCTION_NAME_(NAME)(::mongo::InitializerContext*); \
namespace { \
::mongo::GlobalInitializerRegisterer _mongoInitializerRegisterer_##NAME( \
std::string(#NAME), \
mongo::InitializerFunction(MONGO_INITIALIZER_FUNCTION_NAME_(NAME)), \
mongo::DeinitializerFunction(nullptr), \
std::vector<std::string>{MONGO_INITIALIZER_STRIP_PARENS_ PREREQUISITES}, \
std::vector<std::string>{MONGO_INITIALIZER_STRIP_PARENS_ DEPENDENTS}); \
} \
void MONGO_INITIALIZER_FUNCTION_NAME_(NAME)
/**
* Macro to define an initializer group.
*
* An initializer group is an initializer that performs no actions. It is useful for organizing
* initialization steps into phases, such as "all global parameter declarations completed", "all
* global parameters initialized".
*/
#define MONGO_INITIALIZER_GROUP(NAME, PREREQUISITES, DEPENDENTS) \
MONGO_INITIALIZER_GENERAL(NAME, PREREQUISITES, DEPENDENTS)(::mongo::InitializerContext*) {}
/**
* Macro to produce a name for a mongo initializer function for an initializer operation
* named "NAME".
*/
#define MONGO_INITIALIZER_FUNCTION_NAME_(NAME) _mongoInitializerFunction_##NAME
namespace mongo {
/**
* Type representing the registration of a global initialization function.
*
* Create a nonlocal static storage duration instance of this type to register a new initializer, to
* be run by a call to a variant of mongo::runGlobalInitializers().
*/
class GlobalInitializerRegisterer {
public:
/**
* Constructor parameters:
*
* - std::string name
*
* - InitializerFunction initFn
* Must be nonnull.
* Example expression:
*
* [](InitializerContext* context) {
* // initialization code
* }
*
* - DeinitializerFunction deinitFn
* A deinitialization that will execute in reverse order from initialization and
* support re-initialization. If not specified, defaults to `nullptr`.
* Example expression:
*
* [](DeinitializerContext* context) {
* // deinitialization code
* }
*
* - std::vector<std::string> prerequisites
* If not specified, defaults to {"default"}.
*
* - std::vector<std::string> dependents
* If not specified, defaults to {} (no dependents).
*
*
* At run time, the full set of prerequisites for `name` will be computed as the union of the
* `prerequisites` (which can be defaulted) and all other mongo initializers that list `name` in
* their `dependents`.
*
* A non-null `deinitFn` will tag the initializer as supporting re-initialization.
*/
GlobalInitializerRegisterer(std::string name,
InitializerFunction initFn,
DeinitializerFunction deinitFn = nullptr,
std::vector<std::string> prerequisites = {"default"},
std::vector<std::string> dependents = {});
GlobalInitializerRegisterer(const GlobalInitializerRegisterer&) = delete;
GlobalInitializerRegisterer& operator=(const GlobalInitializerRegisterer&) = delete;
};
} // namespace mongo
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