Class: NewRelic::Agent::SqlSampler

Inherits:
Object
  • Object
show all
Defined in:
lib/new_relic/agent/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.

Constant Summary collapse

MAX_SAMPLES = 
10
PRIORITY = 
'priority'.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SqlSampler

Returns a new instance of SqlSampler.



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# File 'lib/new_relic/agent/sql_sampler.rb', line 32

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/new_relic/agent/sql_sampler.rb', line 25

def disabled
  @disabled
end

#sql_traces ⇒ Object (readonly)

this is for unit tests only



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# File 'lib/new_relic/agent/sql_sampler.rb', line 28

def sql_traces
  @sql_traces
end

Instance Method Details

#distributed_trace_attributes(state) ⇒ Object 



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# File 'lib/new_relic/agent/sql_sampler.rb', line 126

def distributed_trace_attributes(state)
  transaction = state.current_transaction
  params = nil
  if transaction&.distributed_tracer&.distributed_trace_payload
    params = {}
    payload = transaction.distributed_tracer.distributed_trace_payload
    DistributedTraceAttributes.copy_from_transaction(transaction, payload, params)
    params[PRIORITY] = transaction.priority
  end
  params
end

#enabled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/new_relic/agent/sql_sampler.rb', line 41

def enabled?
  Agent.config[:'slow_sql.enabled'] &&
    Agent.config[:'transaction_tracer.enabled'] &&
    NewRelic::Agent::Database.should_record_sql?(:slow_sql)
end

#harvest! ⇒ Object 



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# File 'lib/new_relic/agent/sql_sampler.rb', line 165

def harvest!
  return NewRelic::EMPTY_ARRAY 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/new_relic/agent/sql_sampler.rb', line 114

def has_room?
  @sql_traces.size < MAX_SAMPLES
end

#merge!(sql_traces) ⇒ Object 



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# File 'lib/new_relic/agent/sql_sampler.rb', line 152

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_statement(statement, metric_name, duration) ⇒ Object 



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# File 'lib/new_relic/agent/sql_sampler.rb', line 138

def notice_sql_statement(statement, metric_name, duration)
  state ||= Tracer.state
  data = state.sql_sampler_transaction_data
  return unless data

  if state.is_sql_recorded?
    if duration > Agent.config[:'slow_sql.explain_threshold']
      backtrace = caller.join("\n")
      params = distributed_trace_attributes(state)
      data.sql_data << SlowSql.new(statement, metric_name, duration, backtrace, params)
    end
  end
end

#on_finishing_transaction(state, name) ⇒ Object

This is called when we are done with the transaction.



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# File 'lib/new_relic/agent/sql_sampler.rb', line 66

def on_finishing_transaction(state, name)
  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
      ::NewRelic::Agent.logger.debug("Examining #{data.sql_data.size} slow transaction sql statement(s)")
      save_slow_sql(data)
    end
  end
end

#on_start_transaction(state, uri = nil) ⇒ Object 



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# File 'lib/new_relic/agent/sql_sampler.rb', line 47

def on_start_transaction(state, uri = nil)
  return unless enabled?

  state.sql_sampler_transaction_data = TransactionSqlData.new

  if state.current_transaction
    guid = state.current_transaction.guid
  end

  if Agent.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/new_relic/agent/sql_sampler.rb', line 119

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/new_relic/agent/sql_sampler.rb', line 177

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/new_relic/agent/sql_sampler.rb', line 82

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/new_relic/agent/sql_sampler.rb', line 107

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/new_relic/agent/sql_sampler.rb', line 61

def tl_transaction_data # only used for testing
  Tracer.state.sql_sampler_transaction_data
end