fix: do not consume a lot of time to collect debug data if no one is listening

--HG--
branch : 3.29

cubicweb/cwvreg.py

@@ -33,7 +33,7 @@ from rql import RQLHelper
 from yams.constraints import BASE_CONVERTERS
 
 from cubicweb import _
-from cubicweb.debug import emit_to_debug_channel
+from cubicweb.debug import debug_channel_has_subscribers, emit_to_debug_channel
 from cubicweb import (CW_SOFTWARE_ROOT, ETYPE_NAME_MAP, CW_EVENT_MANAGER,
                       onevent, Binary, UnknownProperty, UnknownEid)
 from cubicweb.predicates import appobject_selectable, _reset_is_instance_cache
@@ -72,7 +72,8 @@ class CWRegistry(Registry):
         """
         super(CWRegistry, self).__init__(True)
         self.vreg = vreg
-        self.add_select_best_listener(self._emit_registry_debug_information)
+        if debug_channel_has_subscribers("registry_decisions"):
+            self.add_select_best_listener(self._emit_registry_debug_information)
 
     def _emit_registry_debug_information(self, debug_registry_select_best):
         emit_to_debug_channel("registry_decisions", debug_registry_select_best)

cubicweb/debug.py

@@ -30,6 +30,10 @@ SUBSCRIBERS = {
 }
 
 
+def debug_channel_has_subscribers(channel):
+    return len(SUBSCRIBERS.get(channel, [])) > 0
+
+
 def subscribe_to_debug_channel(channel, subscriber):
     """
     Allow to subscribe a callable to one of the debug channels.

cubicweb/server/querier.py

@@ -33,7 +33,7 @@ from cubicweb import ValidationError, Unauthorized, UnknownEid, QueryError
 from cubicweb.rqlrewrite import RQLRelationRewriter
 from cubicweb import Binary, server
 from cubicweb.rset import ResultSet
-from cubicweb.debug import emit_to_debug_channel
+from cubicweb.debug import debug_channel_has_subscribers, emit_to_debug_channel
 
 from cubicweb.utils import QueryCache, RepeatList
 from cubicweb.misc.source_highlight import highlight_terminal
@@ -511,6 +511,8 @@ class QuerierHelper(object):
         always use substitute arguments in queries (i.e. avoid query such as
         'Any X WHERE X eid 123'!)
         """
+        use_debug_channel = debug_channel_has_subscribers("rql")
+
         if server.DEBUG & (server.DBG_RQL | server.DBG_SQL):
             if server.DEBUG & (server.DBG_MORE | server.DBG_SQL):
                 print('*'*80)
@@ -549,14 +551,15 @@ class QuerierHelper(object):
         plan.rql_query_tracing_token = str(uuid.uuid4())
         prepare_plan(plan, self.schema, self._repo.vreg.rqlhelper)
 
-        query_debug_informations = {
-            "rql": rql,
-            "rql_query_tracing_token": plan.rql_query_tracing_token,
-            "args": args,
-            # remove the last part of the stack which is: this line
-            "callstack": "".join(traceback.format_stack()[:-1]),
-            "description": "",
-        }
+        if use_debug_channel:
+            query_debug_informations = {
+                "rql": rql,
+                "rql_query_tracing_token": plan.rql_query_tracing_token,
+                "args": args,
+                # remove the last part of the stack which is: this line
+                "callstack": "".join(traceback.format_stack()[:-1]),
+                "description": "",
+            }
 
         start = time.time()
         # execute the plan
@@ -575,8 +578,9 @@ class QuerierHelper(object):
                 cnx.commit_state = 'uncommitable'
             raise
 
-        query_debug_informations["time"] = ((time.time() - start) * 1000)
-        query_debug_informations["result"] = results
+        if use_debug_channel:
+            query_debug_informations["time"] = (time.time() - start) * 1000
+            query_debug_informations["result"] = results
 
         # build a description for the results if necessary
         descr = ()
@@ -604,9 +608,11 @@ class QuerierHelper(object):
                 descr = _build_descr(cnx, results, basedescr, todetermine)
             # FIXME: get number of affected entities / relations on non
             # selection queries ?
-            query_debug_informations["description"] = descr
+            if use_debug_channel:
+                query_debug_informations["description"] = descr
 
-        emit_to_debug_channel("rql", query_debug_informations)
+        if use_debug_channel:
+            emit_to_debug_channel("rql", query_debug_informations)
 
         # return a result set object
         return ResultSet(results, rql, args, descr, variables)

cubicweb/server/sources/native.py

@@ -41,7 +41,7 @@ from cubicweb import (UnknownEid, AuthenticationError, ValidationError, Binary,
                       UniqueTogetherError, UndoTransactionException, ViolatedConstraint)
 from cubicweb import transaction as tx, server, neg_role, _
 from cubicweb.utils import QueryCache
-from cubicweb.debug import emit_to_debug_channel
+from cubicweb.debug import debug_channel_has_subscribers, emit_to_debug_channel
 from cubicweb.schema import VIRTUAL_RTYPES
 from cubicweb.cwconfig import CubicWebNoAppConfiguration
 from cubicweb.server import hook
@@ -687,14 +687,15 @@ class NativeSQLSource(SQLAdapterMixIn, AbstractSource):
         """Execute a query.
         it's a function just so that it shows up in profiling
         """
-
-        query_debug_informations = {
-            "sql": query,
-            "args": args,
-            "rollback": False,
-            "callstack": "".join(traceback.format_stack()[:-1]),
-            "rql_query_tracing_token": rql_query_tracing_token,
-        }
+        use_debug_channel = debug_channel_has_subscribers("sql")
+        if use_debug_channel:
+            query_debug_informations = {
+                "sql": query,
+                "args": args,
+                "rollback": False,
+                "callstack": "".join(traceback.format_stack()[:-1]),
+                "rql_query_tracing_token": rql_query_tracing_token,
+            }
 
         start = time.time()
 
@@ -713,7 +714,8 @@ class NativeSQLSource(SQLAdapterMixIn, AbstractSource):
             if rollback:
                 try:
                     cnx.cnxset.rollback()
-                    query_debug_informations["rollback"] = True
+                    if use_debug_channel:
+                        query_debug_informations["rollback"] = True
                     if self.repo.config.mode != 'test':
                         self.debug('transaction has been rolled back')
                 except Exception as rollback_exc:
@@ -758,8 +760,9 @@ class NativeSQLSource(SQLAdapterMixIn, AbstractSource):
                                                  query=query)
             raise
         finally:
-            query_debug_informations["time"] = (time.time() - start) * 1000
-            emit_to_debug_channel("sql", query_debug_informations)
+            if use_debug_channel:
+                query_debug_informations["time"] = (time.time() - start) * 1000
+                emit_to_debug_channel("sql", query_debug_informations)
         return cursor
 
     @statsd_timeit