Class: Mistri::Workspace::ActiveRecord

Inherits:
Object
  • Object
show all
Defined in:
lib/mistri/workspace/active_record.rb

Overview

Documents in the host's own database, through a model class the host supplies, optionally scoped (per session, per tenant). Not auto-required; load it with require "mistri/workspace/active_record".

The model needs a non-null primary key plus non-null path, content, and scope columns, with a unique index whose columns are exactly the scope plus path. Atomic edits use that index plus a short row-locking transaction; no lock_version column is required. A migration to copy:

create_table :mistri_documents do |t|
t.string :session_id, null: false
t.string :path, null: false, limit: 512
t.text :content, size: :medium, null: false
t.timestamps
end
add_index :mistri_documents, [:session_id, :path], unique: true

Reads run uncached: other processes write documents by design, and a cached read inside a job would serve the job's first snapshot forever. Uncached only defeats Rails' cache; an open REPEATABLE READ transaction still pins what reads see, so do not read from inside one.

Instance Method Summary collapse

Constructor Details

#initialize(model, scope: {}) ⇒ ActiveRecord

Returns a new instance of ActiveRecord.

Raises:

  • (ArgumentError) 


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# File 'lib/mistri/workspace/active_record.rb', line 32

def initialize(model, scope: {})
  raise ArgumentError, "scope must be a Hash" unless scope.is_a?(Hash)

  names = scope.keys.map(&:to_s)
  if names.uniq.length != names.length
    raise ArgumentError, "scope keys must name distinct columns"
  end

  reserved = names & %w[path content]
  unless reserved.empty?
    raise ArgumentError, "scope cannot contain #{reserved.map(&:inspect).join(" or ")}"
  end

  @model = model
  @scope = own_scope(scope)
end

Instance Method Details

#atomic_writes? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mistri/workspace/active_record.rb', line 60

def atomic_writes?
  return @atomic_writes if defined?(@atomic_writes)

  @atomic_writes = atomic_storage?
end

#compare_and_write(path, content, expected_revision:) ⇒ Object 



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# File 'lib/mistri/workspace/active_record.rb', line 72

def compare_and_write(path, content, expected_revision:)
  verify_atomic_context!
  key = path.to_s
  return create_if_absent(key, content) if expected_revision.nil?

  @model.transaction do
    record = @model.lock.find_by(**@scope, path: key)
    actual = record && Snapshot.for(record.content.to_s).revision
    unless actual == expected_revision
      raise WorkspaceConflictError.new(
        key, expected_revision:, actual_revision: actual
      )
    end

    record.content = content.to_s
    record.save!
    committed_snapshot(record, key)
  end
end

#delete(path) ⇒ Object 



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# File 'lib/mistri/workspace/active_record.rb', line 92

def delete(path)
  @model.where(**@scope, path: path.to_s).delete_all
  nil
end

#list(prefix = nil) ⇒ Object 



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# File 'lib/mistri/workspace/active_record.rb', line 97

def list(prefix = nil)
  paths = @model.uncached { @model.where(**@scope).pluck(:path) }.sort
  prefix ? paths.select { |p| p.start_with?(prefix.to_s) } : paths
end

#read(path) ⇒ Object 



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# File 'lib/mistri/workspace/active_record.rb', line 49

def read(path)
  @model.uncached { @model.where(**@scope, path: path.to_s).pick(:content) }
end

#snapshot(path) ⇒ Object 



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# File 'lib/mistri/workspace/active_record.rb', line 66

def snapshot(path)
  verify_atomic_context!
  content = @model.uncached { relation(path).pick(:content) }
  content.nil? ? nil : Snapshot.for(content.to_s)
end

#write(path, content) ⇒ Object 



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# File 'lib/mistri/workspace/active_record.rb', line 53

def write(path, content)
  record = @model.find_or_initialize_by(**@scope, path: path.to_s)
  record.content = content.to_s
  record.save!
  nil
end