Remove IsolationLevel

At the moment, isolation level of a transaction can only be
SERIALIZABLE. It can be specified when opening a connection, but
if it is not, it will default to SERIALIZABLE.

There is also no plans to support other level soon.

IsolationLevel thus serves no purpse and also cannot be set outside
of this crate, since it is not public.

So there is no harm in removing it. When/if we implement other
levels, we can revert this commit.

edgedb-tokio/src/lib.rs

@@ -142,7 +142,7 @@ pub use builder::{Builder, Config, InstanceName, ClientSecurity};
 pub use credentials::TlsSecurity;
 pub use client::Client;
 pub use errors::Error;
-pub use options::{TransactionOptions, RetryOptions, RetryCondition, IsolationLevel};
+pub use options::{TransactionOptions, RetryOptions, RetryCondition};
 pub use state::{GlobalsDelta, ConfigDelta};
 pub use transaction::Transaction;
 

edgedb-tokio/src/options.rs

@@ -18,15 +18,6 @@ static IDLE_TIMEOUT_RULE: Lazy<RetryRule> = Lazy::new(|| RetryRule {
 });
 
 
-/// Transaction isolation level
-///
-/// Only single isolation level is supported for now
-#[derive(Debug, Clone)]
-pub enum IsolationLevel {
-    /// Serializable isolation level
-    Serializable,
-}
-
 /// Specific condition for retrying queries
 ///
 /// This is used for fine-grained control for retrying queries and transactions
@@ -45,7 +36,6 @@ pub enum RetryCondition {
 /// [`with_transaction_options`](crate::Client::with_transaction_options).
 #[derive(Debug, Clone)]
 pub struct TransactionOptions {
-    isolation: IsolationLevel,
     read_only: bool,
     deferrable: bool,
 }
@@ -72,19 +62,13 @@ pub(crate) struct RetryRule {
 impl Default for TransactionOptions {
     fn default() -> TransactionOptions {
         TransactionOptions {
-            isolation: IsolationLevel::Serializable,
             read_only: false,
             deferrable: false,
         }
     }
 }
 
 impl TransactionOptions {
-    /// Set isolation level for the transaction
-    pub fn isolation(mut self, isolation: IsolationLevel) -> Self {
-        self.isolation = isolation;
-        self
-    }
     /// Set whether transaction is read-only
     pub fn read_only(mut self, read_only: bool) -> Self {
         self.read_only = read_only;