feat: enable multiplex session for all operations unless explicitly set to false

Author: rahul2393

…t-emulator-with-multiplexed-session.yaml …ainst-emulator-with-regular-session.yaml.github/workflows/integration-tests-against-emulator-with-multiplexed-session.yaml renamed to .github/workflows/integration-tests-against-emulator-with-regular-session.yaml .github/workflows/integration-tests-against-emulator-with-multiplexed-session.yaml renamed to .github/workflows/integration-tests-against-emulator-with-regular-session.yaml

@@ -30,5 +30,6 @@ jobs:
           SPANNER_EMULATOR_HOST: localhost:9010
           GOOGLE_CLOUD_PROJECT: emulator-test-project
           GOOGLE_CLOUD_TESTS_CREATE_SPANNER_INSTANCE: true
-          GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS: true
-          GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS_PARTITIONED_OPS: true
+          GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS: false
+          GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS_PARTITIONED_OPS: false
+          GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS_FOR_RW: false

…gration-multiplexed-sessions-enabled.cfg …integration-regular-sessions-enabled.cfg.kokoro/presubmit/integration-multiplexed-sessions-enabled.cfg renamed to .kokoro/presubmit/integration-regular-sessions-enabled.cfg .kokoro/presubmit/integration-multiplexed-sessions-enabled.cfg renamed to .kokoro/presubmit/integration-regular-sessions-enabled.cfg

@@ -8,10 +8,15 @@ env_vars: {
 
 env_vars: {
     key: "GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS"
-    value: "true"
+    value: "false"
 }
 
 env_vars: {
     key: "GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS_PARTITIONED_OPS"
-    value: "true"
+    value: "false"
+}
+
+env_vars: {
+    key: "GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS_FOR_RW"
+    value: "false"
 }

google/cloud/spanner_v1/database_sessions_manager.py

@@ -230,15 +230,13 @@ def _use_multiplexed(cls, transaction_type: TransactionType) -> bool:
         """Returns whether to use multiplexed sessions for the given transaction type.
 
         Multiplexed sessions are enabled for read-only transactions if:
-            * _ENV_VAR_MULTIPLEXED is set to true.
+            * _ENV_VAR_MULTIPLEXED != 'false'.
 
         Multiplexed sessions are enabled for partitioned transactions if:
-            * _ENV_VAR_MULTIPLEXED is set to true; and
-            * _ENV_VAR_MULTIPLEXED_PARTITIONED is set to true.
+            * _ENV_VAR_MULTIPLEXED_PARTITIONED != 'false'.
 
         Multiplexed sessions are enabled for read/write transactions if:
-            * _ENV_VAR_MULTIPLEXED is set to true; and
-            * _ENV_VAR_MULTIPLEXED_READ_WRITE is set to true.
+            * _ENV_VAR_MULTIPLEXED_READ_WRITE != 'false'.
 
         :type transaction_type: :class:`TransactionType`
         :param transaction_type: the type of transaction
@@ -254,30 +252,26 @@ def _use_multiplexed(cls, transaction_type: TransactionType) -> bool:
             return cls._getenv(cls._ENV_VAR_MULTIPLEXED)
 
         elif transaction_type is TransactionType.PARTITIONED:
-            return cls._getenv(cls._ENV_VAR_MULTIPLEXED) and cls._getenv(
-                cls._ENV_VAR_MULTIPLEXED_PARTITIONED
-            )
+            return cls._getenv(cls._ENV_VAR_MULTIPLEXED_PARTITIONED)
 
         elif transaction_type is TransactionType.READ_WRITE:
-            return cls._getenv(cls._ENV_VAR_MULTIPLEXED) and cls._getenv(
-                cls._ENV_VAR_MULTIPLEXED_READ_WRITE
-            )
+            return cls._getenv(cls._ENV_VAR_MULTIPLEXED_READ_WRITE)
 
         raise ValueError(f"Transaction type {transaction_type} is not supported.")
 
     @classmethod
     def _getenv(cls, env_var_name: str) -> bool:
         """Returns the value of the given environment variable as a boolean.
 
-        True values are '1' and 'true' (case-insensitive).
-        All other values are considered false.
+        True unless explicitly 'false' (case-insensitive).
+        All other values (including unset) are considered true.
 
         :type env_var_name: str
         :param env_var_name: the name of the boolean environment variable
 
         :rtype: bool
-        :returns: True if the environment variable is set to a true value, False otherwise.
+        :returns: True unless the environment variable is set to 'false', False otherwise.
         """
 
-        env_var_value = getenv(env_var_name, "").lower().strip()
-        return env_var_value in ["1", "true"]
+        env_var_value = getenv(env_var_name, "true").lower().strip()
+        return env_var_value != "false"