Class: Puppet::Context Private

Inherits:
Object show all
Defined in:
lib/puppet/context.rb

Overview

This class is part of a private API. You should avoid using this class if possible, as it may be removed or be changed in the future.

Puppet::Context is a system for tracking services and contextual information that puppet needs to be able to run. Values are “bound” in a context when it is created and cannot be changed; however a child context can be created, using #override, that provides a different value.

When binding a Proc, the proc is called when the value is looked up, and the result is memoized for subsequent lookups. This provides a lazy mechanism that can be used to delay expensive production of values until they are needed.

Defined Under Namespace

Classes: DuplicateRollbackMarkError, EmptyStack, Stack, StackUnderflow, TrustedInformation, UndefinedBindingError, UnknownRollbackMarkError

Instance Method Summary collapse

Constructor Details

#initialize(initial_bindings) ⇒ Context

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns a new instance of Context.

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# File 'lib/puppet/context.rb', line 25 def initialize(initial_bindings) @stack = Puppet::ThreadLocal.new(EmptyStack.new.push(initial_bindings)) # By initializing @rollbacks to nil and creating a hash lazily when #mark or  # #rollback are called we ensure that the hashes are never shared between  # threads and it's safe to mutate them  @rollbacks = Puppet::ThreadLocal.new(nil) end

Instance Method Details

#lookup(name, &block) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 

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# File 'lib/puppet/context.rb', line 55 def lookup(name, &block) @stack.value.lookup(name, &block) end

#mark(name) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Mark a place on the context stack to later return to with #rollback.

Parameters:

  • name (Object) —

    The identifier for the mark

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# File 'lib/puppet/context.rb', line 74 def mark(name) @rollbacks.value ||= {} if @rollbacks.value[name].nil? @rollbacks.value[name] = @stack.value else raise DuplicateRollbackMarkError, _("Mark for '%{name}' already exists") % { name: name } end end

#override(bindings, description = '', &block) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 

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# File 'lib/puppet/context.rb', line 60 def override(bindings, description = '', &block) saved_point = @stack.value push(bindings, description) yield ensure @stack.value = saved_point end

#pop ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 

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# File 'lib/puppet/context.rb', line 50 def pop @stack.value = @stack.value.pop end

#push(overrides, description = '') ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 

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# File 'lib/puppet/context.rb', line 35 def push(overrides, description = '') @stack.value = @stack.value.push(overrides, description) end

#rollback(name) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Roll back to a mark set by #mark.

Rollbacks can only reach a mark accessible via #pop. If the mark is not on the current context stack the behavior of rollback is undefined.

Parameters:

  • name (Object) —

    The identifier for the mark

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# File 'lib/puppet/context.rb', line 91 def rollback(name) @rollbacks.value ||= {} if @rollbacks.value[name].nil? raise UnknownRollbackMarkError, _("Unknown mark '%{name}'") % { name: name } end @stack.value = @rollbacks.value.delete(name) end

#unsafe_push_global(overrides, description = '') ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Push a context and make this global across threads Do not use in a context where multiple threads may already exist

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# File 'lib/puppet/context.rb', line 43 def unsafe_push_global(overrides, description = '') @stack = Puppet::ThreadLocal.new( @stack.value.push(overrides, description) ) end