gitlab-org--gitlab-foss/app/models/pool_repository.rb

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2018-10-18 23:44:41 -04:00
# frozen_string_literal: true
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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# The PoolRepository model is the database equivalent of an ObjectPool for Gitaly
# That is; PoolRepository is the record in the database, ObjectPool is the
# repository on disk
class PoolRepository < ApplicationRecord
include Shardable
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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include AfterCommitQueue
belongs_to :source_project, class_name: 'Project'
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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validates :source_project, presence: true
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has_many :member_projects, class_name: 'Project'
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after_create :correct_disk_path
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Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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state_machine :state, initial: :none do
state :scheduled
state :ready
state :failed
state :obsolete
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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event :schedule do
transition none: :scheduled
end
event :mark_ready do
transition [:scheduled, :failed] => :ready
end
event :mark_failed do
transition all => :failed
end
event :mark_obsolete do
transition all => :obsolete
end
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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state all - [:ready] do
def joinable?
false
end
end
state :ready do
def joinable?
true
end
end
after_transition none: :scheduled do |pool, _|
pool.run_after_commit do
::ObjectPool::CreateWorker.perform_async(pool.id)
end
end
after_transition scheduled: :ready do |pool, _|
pool.run_after_commit do
::ObjectPool::ScheduleJoinWorker.perform_async(pool.id)
end
end
after_transition any => :obsolete do |pool, _|
pool.run_after_commit do
::ObjectPool::DestroyWorker.perform_async(pool.id)
end
end
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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end
def create_object_pool
object_pool.create
end
# The members of the pool should have fetched the missing objects to their own
# objects directory. If the caller fails to do so, data loss might occur
def delete_object_pool
object_pool.delete
end
def link_repository(repository)
object_pool.link(repository.raw)
end
def mark_obsolete_if_last(repository)
if member_projects.where.not(id: repository.project.id).exists?
true
else
mark_obsolete
end
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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end
def object_pool
@object_pool ||= Gitlab::Git::ObjectPool.new(
shard.name,
disk_path + '.git',
source_project.repository.raw,
source_project.full_path
)
Allow public forks to be deduplicated When a project is forked, the new repository used to be a deep copy of everything stored on disk by leveraging `git clone`. This works well, and makes isolation between repository easy. However, the clone is at the start 100% the same as the origin repository. And in the case of the objects in the object directory, this is almost always going to be a lot of duplication. Object Pools are a way to create a third repository that essentially only exists for its 'objects' subdirectory. This third repository's object directory will be set as alternate location for objects. This means that in the case an object is missing in the local repository, git will look in another location. This other location is the object pool repository. When Git performs garbage collection, it's smart enough to check the alternate location. When objects are duplicated, it will allow git to throw one copy away. This copy is on the local repository, where to pool remains as is. These pools have an origin location, which for now will always be a repository that itself is not a fork. When the root of a fork network is forked by a user, the fork still clones the full repository. Async, the pool repository will be created. Either one of these processes can be done earlier than the other. To handle this race condition, the Join ObjectPool operation is idempotent. Given its idempotent, we can schedule it twice, with the same effect. To accommodate the holding of state two migrations have been added. 1. Added a state column to the pool_repositories column. This column is managed by the state machine, allowing for hooks on transitions. 2. pool_repositories now has a source_project_id. This column in convenient to have for multiple reasons: it has a unique index allowing the database to handle race conditions when creating a new record. Also, it's nice to know who the host is. As that's a short link to the fork networks root. Object pools are only available for public project, which use hashed storage and when forking from the root of the fork network. (That is, the project being forked from itself isn't a fork) In this commit message I use both ObjectPool and Pool repositories, which are alike, but different from each other. ObjectPool refers to whatever is on the disk stored and managed by Gitaly. PoolRepository is the record in the database.
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end
def inspect
source = source_project ? source_project.full_path : 'nil'
"#<#{self.class.name} id:#{id} state:#{state} disk_path:#{disk_path} source_project: #{source}>"
end
private
def correct_disk_path
update!(disk_path: storage.disk_path)
end
def storage
Storage::Hashed
.new(self, prefix: Storage::Hashed::POOL_PATH_PREFIX)
end
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end
PoolRepository.prepend_mod_with('PoolRepository')