* a :class:`~google.cloud.spanner_v1.instance.Instance` owns a

:class:`~google.cloud.spanner_v1.database.Database`

"""

import grpc

import os

import logging

import warnings

import threading

from google.api_core.gapic_v1 import client_info

from google.auth.credentials import AnonymousCredentials

log = logging.getLogger(__name__)

_metrics_monitor_initialized = False

_metrics_monitor_lock = threading.Lock()

def _get_spanner_enable_builtin_metrics_env():

return os.getenv(SPANNER_DISABLE_BUILTIN_METRICS_ENV_VAR) != "true"

def _initialize_metrics(project, credentials):

"""

Initializes the Spanner built-in metrics.

This function sets up the OpenTelemetry MeterProvider and the SpannerMetricsTracerFactory.

It uses a lock to ensure that initialization happens only once.

"""

global _metrics_monitor_initialized

if not _metrics_monitor_initialized:

with _metrics_monitor_lock:

if not _metrics_monitor_initialized:

meter_provider = metrics.NoOpMeterProvider()

try:

if not _get_spanner_emulator_host():

meter_provider = MeterProvider(

metric_readers=[

PeriodicExportingMetricReader(

CloudMonitoringMetricsExporter(

project_id=project,

credentials=credentials,

),

export_interval_millis=METRIC_EXPORT_INTERVAL_MS,

),

]

)

metrics.set_meter_provider(meter_provider)

SpannerMetricsTracerFactory()

_metrics_monitor_initialized = True

except Exception as e:

# log is already defined at module level

log.warning(

"Failed to initialize Spanner built-in metrics. Error: %s",

e,

)

class Client(ClientWithProject):

"""Client for interacting with Cloud Spanner API.

"http://" in self._emulator_host or "https://" in self._emulator_host

):

warnings.warn(_EMULATOR_HOST_HTTP_SCHEME)

# Check flag to enable Spanner builtin metrics

if (

_get_spanner_enable_builtin_metrics_env()

and not disable_builtin_metrics

and HAS_GOOGLE_CLOUD_MONITORING_INSTALLED

):

meter_provider = metrics.NoOpMeterProvider()

try:

if not _get_spanner_emulator_host():

meter_provider = MeterProvider(

metric_readers=[

PeriodicExportingMetricReader(

CloudMonitoringMetricsExporter(

project_id=project, credentials=credentials

),

export_interval_millis=METRIC_EXPORT_INTERVAL_MS,

),

]

)

metrics.set_meter_provider(meter_provider)

SpannerMetricsTracerFactory()

except Exception as e:

log.warning(

"Failed to initialize Spanner built-in metrics. Error: %s", e

)

_initialize_metrics(project, credentials)

else:

SpannerMetricsTracerFactory(enabled=False)