class OneApm::Collector::SqlSampler
This class contains the logic of recording slow SQL traces, which may represent multiple aggregated SQL queries.
A slow SQL trace consists of a collection of SQL instrumented SQL queries that all normalize to the same text. For example, the following two queries would be aggregated together into a single slow SQL trace:
SELECT * FROM table WHERE id=42 SELECT * FROM table WHERE id=1234
Each slow SQL trace keeps track of the number of times the same normalized query was seen, the min, max, and total time spent executing those queries, and an example backtrace from one of the aggregated queries.
@api public
Constants
- OA_MAX_SAMPLES
Attributes
this is for unit tests only
Public Class Methods
# File lib/one_apm/collector/containers/sql_sampler.rb, line 39 def initialize @sql_traces = {} # This lock is used to synchronize access to @sql_traces # and related variables. It can become necessary on JRuby or # any 'honest-to-god'-multithreaded system @samples_lock = Mutex.new end
Public Instance Methods
# File lib/one_apm/collector/containers/sql_sampler.rb, line 48 def enabled? OneApm::Manager.config[:'slow_sql.enabled'] && OneApm::Manager.config[:'transaction_tracer.enabled'] && OneApm::Agent::Database.should_record_sql?(:slow_sql) end
# File lib/one_apm/collector/containers/sql_sampler.rb, line 176 def harvest! return [] unless enabled? slowest = [] @samples_lock.synchronize do slowest = @sql_traces.values @sql_traces = {} end slowest.each {|trace| trace.prepare_to_send } slowest end
this should always be called under the @samples_lock
# File lib/one_apm/collector/containers/sql_sampler.rb, line 121 def has_room? @sql_traces.size < OA_MAX_SAMPLES end
# File lib/one_apm/collector/containers/sql_sampler.rb, line 163 def merge!(sql_traces) @samples_lock.synchronize do sql_traces.each do |trace| existing_trace = @sql_traces[trace.sql] if existing_trace existing_trace.aggregate_trace(trace) else @sql_traces[trace.sql] = trace end end end end
Records an SQL query, potentially creating a new slow SQL trace, or aggregating the query into an existing slow SQL trace.
This method should be used only by gem authors wishing to extend the Ruby agent to instrument new database interfaces - it should generally not be called directly from application code.
@param sql [String] the SQL query being recorded @param metric_name [String] is the metric name under which this query will be recorded @param config [Object] is the driver configuration for the connection @param duration [Float] number of seconds the query took to execute @param explainer [Proc] for internal use only - 3rd-party clients must
not pass this parameter.
@api public
# File lib/one_apm/collector/containers/sql_sampler.rb, line 147 def notice_sql(sql, metric_name, config, duration, state=nil, &explainer) state ||= OneApm::TransactionState.tl_get data = state.sql_sampler_transaction_data return unless data if state.is_sql_recorded? if duration > OneApm::Manager.config[:'slow_sql.explain_threshold'] backtrace = caller backtrace.reject! { |t| t.include?('one_apm') } data.sql_data << SlowSql.new(OneApm::Agent::Database.capture_query(sql), metric_name, config, duration, backtrace, &explainer) end end end
This is called when we are done with the transaction.
# File lib/one_apm/collector/containers/sql_sampler.rb, line 73 def on_finishing_transaction(state, name, time=Time.now) return unless enabled? data = state.sql_sampler_transaction_data return unless data data.set_transaction_name(name) if data.sql_data.size > 0 @samples_lock.synchronize do OneApm::Manager.logger.debug "Examining #{data.sql_data.size} slow transaction sql statement(s)" save_slow_sql data end end end
# File lib/one_apm/collector/containers/sql_sampler.rb, line 54 def on_start_transaction(state, start_time, uri=nil) return unless enabled? state.sql_sampler_transaction_data = TransactionSqlData.new if state.transaction_sample_builder guid = state.transaction_sample_builder.sample.guid end if OneApm::Manager.config[:'slow_sql.enabled'] && state.sql_sampler_transaction_data state.sql_sampler_transaction_data.set_transaction_info(uri, guid) end end
this should always be called under the @samples_lock
# File lib/one_apm/collector/containers/sql_sampler.rb, line 126 def remove_shortest_trace shortest_key, _ = @sql_traces.min_by { |(_, trace)| trace.max_call_time } @sql_traces.delete(shortest_key) end
# File lib/one_apm/collector/containers/sql_sampler.rb, line 188 def reset! @samples_lock.synchronize do @sql_traces = {} end end
this should always be called under the @samples_lock
# File lib/one_apm/collector/containers/sql_sampler.rb, line 89 def save_slow_sql(transaction_sql_data) path = transaction_sql_data.path uri = transaction_sql_data.uri transaction_sql_data.sql_data.each do |sql_item| normalized_sql = sql_item.normalize sql_trace = @sql_traces[normalized_sql] if sql_trace sql_trace.aggregate(sql_item, path, uri) else if has_room? sql_trace = SqlTrace.new(normalized_sql, sql_item, path, uri) elsif should_add_trace?(sql_item) remove_shortest_trace sql_trace = SqlTrace.new(normalized_sql, sql_item, path, uri) end if sql_trace @sql_traces[normalized_sql] = sql_trace end end end end
this should always be called under the @samples_lock
# File lib/one_apm/collector/containers/sql_sampler.rb, line 114 def should_add_trace?(sql_item) @sql_traces.any? do |(_, existing_trace)| existing_trace.max_call_time < sql_item.duration end end
# File lib/one_apm/collector/containers/sql_sampler.rb, line 68 def tl_transaction_data # only used for testing OneApm::TransactionState.tl_get.sql_sampler_transaction_data end