Class: OneApm::Collector::SqlSampler

Inherits:
Object
  • Object
show all
Defined in:
lib/one_apm/collector/containers/sql_sampler.rb

Overview

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.

Defined Under Namespace

Modules: Shim

Constant Summary collapse

OA_MAX_SAMPLES = 
10

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SqlSampler

Returns a new instance of SqlSampler.



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# 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

Instance Attribute Details

#disabled ⇒ Object (readonly) 



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# File 'lib/one_apm/collector/containers/sql_sampler.rb', line 32

def disabled
  @disabled
end

#sql_traces ⇒ Object (readonly)

this is for unit tests only



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# File 'lib/one_apm/collector/containers/sql_sampler.rb', line 35

def sql_traces
  @sql_traces
end

Instance Method Details

#enabled? ⇒ Boolean

Returns:

  • (Boolean) 


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# 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

#harvest! ⇒ Object 



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# 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

#has_room? ⇒ Boolean

this should always be called under the @samples_lock

Returns:

  • (Boolean) 


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# File 'lib/one_apm/collector/containers/sql_sampler.rb', line 121

def has_room?
  @sql_traces.size < OA_MAX_SAMPLES
end

#merge!(sql_traces) ⇒ Object 



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# 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

#notice_sql(sql, metric_name, config, duration, state = nil, &explainer) ⇒ Object

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.

Parameters:

  • sql (String) —

    the SQL query being recorded

  • metric_name (String) —

    is the metric name under which this query will be recorded

  • config (Object) —

    is the driver configuration for the connection

  • duration (Float) —

    number of seconds the query took to execute

  • explainer (Proc) —

    for internal use only - 3rd-party clients must not pass this parameter.



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# 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

#on_finishing_transaction(state, name, time = Time.now) ⇒ Object

This is called when we are done with the transaction.



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# 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

#on_start_transaction(state, start_time, uri = nil) ⇒ Object 



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# 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

#remove_shortest_trace ⇒ Object

this should always be called under the @samples_lock



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# 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

#reset! ⇒ Object 



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# File 'lib/one_apm/collector/containers/sql_sampler.rb', line 188

def reset!
  @samples_lock.synchronize do
    @sql_traces = {}
  end
end

#save_slow_sql(transaction_sql_data) ⇒ Object

this should always be called under the @samples_lock



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# 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

#should_add_trace?(sql_item) ⇒ Boolean

this should always be called under the @samples_lock

Returns:

  • (Boolean) 


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# 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

#tl_transaction_data ⇒ Object

only used for testing



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# 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