user configurable event buffer size

core/dbt/events/functions.py

@@ -25,9 +25,8 @@
 
 # create the global event history buffer with a max size of 100k records
 # python 3.7 doesn't support type hints on globals, but mypy requires them. hence the ignore.
-# TODO: make the maxlen something configurable from the command line via args(?)
 global EVENT_HISTORY
-EVENT_HISTORY = deque(maxlen=100000)  # type: ignore
+EVENT_HISTORY = deque(maxlen=flags.EVENT_BUFFER_SIZE)  # type: ignore
 
 # create the global file logger with no configuration
 global FILE_LOG
@@ -310,13 +309,15 @@ def fire_event(e: Event) -> None:
     # skip logs when `--log-cache-events` is not passed
     if isinstance(e, Cache) and not flags.LOG_CACHE_EVENTS:
         return
+
     # if and only if the event history deque will be completely filled by this event
     # fire warning that old events are now being dropped
     global EVENT_HISTORY
-    if len(EVENT_HISTORY) == ((EVENT_HISTORY.maxlen or 100000) - 1):
+    if len(EVENT_HISTORY) == (flags.EVENT_BUFFER_SIZE - 1):
+        EVENT_HISTORY.append(e)
         fire_event(EventBufferFull())
-
-    EVENT_HISTORY.append(e)
+    else:
+        EVENT_HISTORY.append(e)
 
     # backwards compatibility for plugins that require old logger (dbt-rpc)
     if flags.ENABLE_LEGACY_LOGGER:

core/dbt/flags.py

@@ -34,6 +34,7 @@
 WHICH = None
 INDIRECT_SELECTION = None
 LOG_CACHE_EVENTS = None
+EVENT_BUFFER_SIZE = 100000
 
 # Global CLI defaults. These flags are set from three places:
 # CLI args, environment variables, and user_config (profiles.yml).
@@ -53,7 +54,8 @@
     "SEND_ANONYMOUS_USAGE_STATS": True,
     "PRINTER_WIDTH": 80,
     "INDIRECT_SELECTION": 'eager',
-    "LOG_CACHE_EVENTS": False
+    "LOG_CACHE_EVENTS": False,
+    "EVENT_BUFFER_SIZE": 100000
 }
 
 
@@ -101,7 +103,7 @@ def set_from_args(args, user_config):
         USE_EXPERIMENTAL_PARSER, STATIC_PARSER, WRITE_JSON, PARTIAL_PARSE, \
         USE_COLORS, STORE_FAILURES, PROFILES_DIR, DEBUG, LOG_FORMAT, INDIRECT_SELECTION, \
         VERSION_CHECK, FAIL_FAST, SEND_ANONYMOUS_USAGE_STATS, PRINTER_WIDTH, \
-        WHICH, LOG_CACHE_EVENTS
+        WHICH, LOG_CACHE_EVENTS, EVENT_BUFFER_SIZE
 
     STRICT_MODE = False  # backwards compatibility
     # cli args without user_config or env var option
@@ -125,6 +127,7 @@ def set_from_args(args, user_config):
     PRINTER_WIDTH = get_flag_value('PRINTER_WIDTH', args, user_config)
     INDIRECT_SELECTION = get_flag_value('INDIRECT_SELECTION', args, user_config)
     LOG_CACHE_EVENTS = get_flag_value('LOG_CACHE_EVENTS', args, user_config)
+    EVENT_BUFFER_SIZE = get_flag_value('EVENT_BUFFER_SIZE', args, user_config)
 
 
 def get_flag_value(flag, args, user_config):
@@ -137,15 +140,21 @@ def get_flag_value(flag, args, user_config):
         if env_value is not None and env_value != '':
             env_value = env_value.lower()
             # non Boolean values
-            if flag in ['LOG_FORMAT', 'PRINTER_WIDTH', 'PROFILES_DIR', 'INDIRECT_SELECTION']:
+            if flag in [
+                'LOG_FORMAT',
+                'PRINTER_WIDTH',
+                'PROFILES_DIR',
+                'INDIRECT_SELECTION',
+                'EVENT_BUFFER_SIZE'
+            ]:
                 flag_value = env_value
             else:
                 flag_value = env_set_bool(env_value)
         elif user_config is not None and getattr(user_config, lc_flag, None) is not None:
             flag_value = getattr(user_config, lc_flag)
         else:
             flag_value = flag_defaults[flag]
-    if flag == 'PRINTER_WIDTH':  # printer_width must be an int or it hangs
+    if flag in ['PRINTER_WIDTH', 'EVENT_BUFFER_SIZE']:  # must be ints
         flag_value = int(flag_value)
     if flag == 'PROFILES_DIR':
         flag_value = os.path.abspath(flag_value)
@@ -169,5 +178,6 @@ def get_flag_dict():
         "send_anonymous_usage_stats": SEND_ANONYMOUS_USAGE_STATS,
         "printer_width": PRINTER_WIDTH,
         "indirect_selection": INDIRECT_SELECTION,
-        "log_cache_events": LOG_CACHE_EVENTS
+        "log_cache_events": LOG_CACHE_EVENTS,
+        "event_buffer_size": EVENT_BUFFER_SIZE
     }

test/unit/test_events.py

@@ -1,19 +1,20 @@
-from dbt import events
-from dbt.events.functions import EVENT_HISTORY, fire_event
+
 from dbt.events.test_types import UnitTestInfo
 from argparse import Namespace
 from dbt.events import AdapterLogger
 from dbt.events.functions import event_to_serializable_dict
 from dbt.events.types import *
 from dbt.events.test_types import *
-from dbt.events.base_types import Event, Node
+from dbt.events.base_types import Event
 from dbt.events.stubs import _CachedRelation, BaseRelation, _ReferenceKey, ParsedModelNode
+from importlib import reload
+import dbt.events.functions as event_funcs
+import dbt.flags as flags
 import inspect
 import json
-import datetime
 from unittest import TestCase
 from dbt.contracts.graph.parsed import (
-    ParsedModelNode, NodeConfig, DependsOn, ParsedMacro
+    ParsedModelNode, NodeConfig, DependsOn
 )
 from dbt.contracts.files import FileHash
 
@@ -88,25 +89,29 @@ def test_event_codes(self):
 
 class TestEventBuffer(TestCase):
 
+    def setUp(self) -> None:
+        flags.EVENT_BUFFER_SIZE = 10
+        reload(event_funcs)
+
     # ensure events are populated to the buffer exactly once
     def test_buffer_populates(self):
-        fire_event(UnitTestInfo(msg="Test Event 1"))
-        fire_event(UnitTestInfo(msg="Test Event 2"))
+        event_funcs.fire_event(UnitTestInfo(msg="Test Event 1"))
+        event_funcs.fire_event(UnitTestInfo(msg="Test Event 2"))
         self.assertTrue(
-            EVENT_HISTORY.count(UnitTestInfo(msg='Test Event 1', code='T006')) == 1
+            event_funcs.EVENT_HISTORY.count(UnitTestInfo(msg='Test Event 1', code='T006')) == 1
         )
 
     # ensure events drop from the front of the buffer when buffer maxsize is reached
-    # TODO commenting out till we can make this not spit out 100k log lines.
-    # def test_buffer_FIFOs(self):
-    #     for n in range(0,100001):
-    #         fire_event(UnitTestInfo(msg=f"Test Event {n}"))
-    #     self.assertTrue(
-    #         EVENT_HISTORY.count(EventBufferFull(code='Z048')) == 1
-    #     )
-    #     self.assertTrue(
-    #         EVENT_HISTORY.count(UnitTestInfo(msg='Test Event 1', code='T006')) == 0
-    #     )
+    def test_buffer_FIFOs(self):
+        for n in range(0,(flags.EVENT_BUFFER_SIZE + 1)):
+            event_funcs.fire_event(UnitTestInfo(msg=f"Test Event {n}"))
+
+        self.assertTrue(
+            event_funcs.EVENT_HISTORY.count(EventBufferFull(code='Z048')) == 1
+        )
+        self.assertTrue(
+             event_funcs.EVENT_HISTORY.count(UnitTestInfo(msg='Test Event 1', code='T006')) == 0
+         )
 
 def MockNode():
     return ParsedModelNode(