Module: ScoutApm::Instruments::ActiveRecordQueryingInstruments
- Defined in:
- lib/scout_apm/instruments/active_record.rb
Overview
Entry-point of instruments.
Instrumentation starts in ActiveRecord::Relation#exec_queries (Rails >= 3.2.0) or ActiveRecord::FinderMethods#find_with_assocations (previous Rails versions).
ActiveRecord::Querying#find_by_sql is instrumented in all Rails versions even though it is also invoked by #exec_queries/#find_by_associations because it can be invoked directly from user code (e.g., Post.find_by_sql(“SELECT * FROM posts”)). The layer started by #exec_queries/#find_by_assocations is marked to ignore children, so it will not cause duplicate layers in the former case.
These methods are early in the chain of calls invoked when executing an ActiveRecord query, before the cache is consulted. If the query is later determined to be a cache miss, ‘#log` will be invoked, which we also instrument, and more details will be filled in (name, sql).
Caveats:
* We don't have a name for the query yet.
* The query hasn't hit the cache yet. In the case of a cache hit, we
won't hit #log, so won't get a name, leaving the misleading default.
* One call here can result in several calls to #log, especially in the
case where Rails needs to load the schema details for the table being
queried.
Class Method Summary collapse
Instance Method Summary collapse
Class Method Details
.included(instrumented_class) ⇒ Object
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# File 'lib/scout_apm/instruments/active_record.rb', line 257 def self.included(instrumented_class) ScoutApm::Agent.instance.context.logger.info "Instrumenting ActiveRecord::Querying - #{instrumented_class.inspect}" instrumented_class.class_eval do unless instrumented_class.method_defined?(:find_by_sql_without_scout_instruments) alias_method :find_by_sql_without_scout_instruments, :find_by_sql alias_method :find_by_sql, :find_by_sql_with_scout_instruments end end end |
Instance Method Details
#find_by_sql_with_scout_instruments(*args, &block) ⇒ Object
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# File 'lib/scout_apm/instruments/active_record.rb', line 267 def find_by_sql_with_scout_instruments(*args, &block) req = ScoutApm::RequestManager.lookup layer = ScoutApm::Layer.new("ActiveRecord", Utils::ActiveRecordMetricName::DEFAULT_METRIC) layer.annotate_layer(:ignorable => true) req.start_layer(layer) req.ignore_children! begin find_by_sql_without_scout_instruments(*args, &block) ensure req.acknowledge_children! req.stop_layer end end |