eve::SnapshotMigrationChain类 参考

One directed payload migration step. 更多...

#include <Snapshot.h>

Public 类型
using	Migration = std::function< Result< Value >(const Value &payload)>

Public 成员函数
Result< void >	add (LogicalId schema, SchemaVersion from, SchemaVersion to, Migration migration)
	Register one schema-local migration edge.
Result< SnapshotEnvelope >	migrate (SnapshotEnvelope snapshot, SchemaVersion targetVersion, const SnapshotHashProvider &hashProvider) const
	Migrate and reseal an envelope to an exact target version.

详细描述

One directed payload migration step.

Steps must move forward to a larger version. The chain never guesses a missing step and never accepts an envelope newer than the requested target.

在文件 Snapshot.h 第 145 行定义.

成员类型定义说明

Migration

using eve::SnapshotMigrationChain::Migration = std::function<Result<Value>(const Value& payload)>

在文件 Snapshot.h 第 147 行定义.

成员函数说明

add()

Result< void > eve::SnapshotMigrationChain::add	(	LogicalId	schema,
		SchemaVersion	from,
		SchemaVersion	to,
		Migration	migration
	)

Register one schema-local migration edge.

参数

schema	Schema whose payload is transformed.
from	Version accepted by migration.
to	Version produced by migration; must be greater than from.
migration	Pure function that returns a new owning payload.

返回

Success, or Conflict/InvalidArgument when the edge is invalid or duplicated.

在文件 Snapshot.cpp 第 196 行定义.

引用了 eve::Conflict, eve::Diagnostic::error(), eve::Result< T >::failure(), eve::LogicalId::format(), from, eve::InvalidArgument, eve::LogicalId::isValid(), key, eve::Result< T >::success() , 以及 to.

migrate()

Result< SnapshotEnvelope > eve::SnapshotMigrationChain::migrate	(	SnapshotEnvelope	snapshot,
		SchemaVersion	targetVersion,
		const SnapshotHashProvider &	hashProvider
	)		const

Migrate and reseal an envelope to an exact target version.

参数

snapshot	Verified source envelope; it is consumed on success.
targetVersion	Required current version.
hashProvider	Provider used to verify source and seal migrated output.

返回

Migrated envelope, or UnknownVersion/Unsupported/failure.

备注

If source is newer than target, it is rejected as an unknown new version.

在文件 Snapshot.cpp 第 208 行定义.

引用了 eve::Diagnostic::error(), eve::Result< T >::failure(), eve::LogicalId::format(), eve::SnapshotEnvelope::instanceId, key, eve::makeSnapshotEnvelope(), eve::SnapshotEnvelope::payload, payload, eve::SnapshotEnvelope::revision, eve::SnapshotEnvelope::schema, eve::SnapshotEnvelope::schemaVersion, step, eve::Result< T >::success(), eve::SnapshotEnvelope::tick, eve::SnapshotEnvelope::type, eve::UnknownVersion, eve::Unsupported, eve::detail::StrongUint64< Tag >::value() , 以及 eve::verifySnapshotEnvelope().

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该类的文档由以下文件生成:

• src/engine/common/Snapshot.h
• src/engine/common/Snapshot.cpp