statement: implement Debug for PreparedStatement

For debugging purposes.

Author: psarna

examples/parallel-prepared.rs

@@ -28,6 +28,7 @@ async fn main() -> Result<()> {
             .prepare("INSERT INTO ks.t2 (a, b, c) VALUES (?, ?, 'abc')")
             .await?,
     );
+    println!("Prepared statement: {:#?}", prepared);
 
     let parallelism = 256;
     let sem = Arc::new(Semaphore::new(parallelism));

scylla/src/statement/mod.rs

@@ -9,6 +9,7 @@ pub mod query;
 
 pub use crate::frame::types::{Consistency, SerialConsistency};
 
+#[derive(Debug)]
 pub struct StatementConfig {
     pub consistency: Option<Consistency>,
     pub serial_consistency: Option<SerialConsistency>,

scylla/src/statement/prepared_statement.rs

@@ -12,6 +12,7 @@ use crate::transport::partitioner::PartitionerName;
 use crate::transport::retry_policy::RetryPolicy;
 
 /// Represents a statement prepared on the server.
+#[derive(Debug)]
 pub struct PreparedStatement {
     pub(crate) config: StatementConfig,
     pub prepare_tracing_ids: Vec<Uuid>,

scylla/src/transport/retry_policy.rs

@@ -25,7 +25,7 @@ pub enum RetryDecision {
 }
 
 /// Specifies a policy used to decide when to retry a query
-pub trait RetryPolicy: Send + Sync {
+pub trait RetryPolicy: std::fmt::Debug + Send + Sync {
     /// Called for each new query, starts a session of deciding about retries
     fn new_session(&self) -> Box<dyn RetrySession>;
 
@@ -50,6 +50,7 @@ pub trait RetrySession: Send + Sync {
 }
 
 /// Forwards all errors directly to the user, never retries
+#[derive(Debug)]
 pub struct FallthroughRetryPolicy;
 pub struct FallthroughRetrySession;
 
@@ -85,6 +86,7 @@ impl RetrySession for FallthroughRetrySession {
 
 /// Default retry policy - retries when there is a high chance that a retry might help.\
 /// Behaviour based on [DataStax Java Driver](https://docs.datastax.com/en/developer/java-driver/4.10/manual/core/retries/)
+#[derive(Debug)]
 pub struct DefaultRetryPolicy;
 
 impl DefaultRetryPolicy {

scylla/src/transport/speculative_execution.rs

@@ -14,7 +14,7 @@ pub struct Context {
 
 /// The policy that decides if the driver will send speculative queries to the
 /// next hosts when the current host takes too long to respond.
-pub trait SpeculativeExecutionPolicy: Send + Sync {
+pub trait SpeculativeExecutionPolicy: std::fmt::Debug + Send + Sync {
     /// The maximum number of speculative executions that will be triggered
     /// for a given request (does not include the initial request)
     fn max_retry_count(&self, context: &Context) -> usize;