libsql: Add max_write_replication_index field to Database

This field will store replication index of the latest write performed
using any connection created with this Database object.

This will allow a client to know what is a minimal replication index
they have to use to see all the writes they performed so far.

Signed-off-by: Piotr Jastrzebski <piotr@chiselstrike.com>

Author: haaawk

libsql/src/database.rs

@@ -7,9 +7,10 @@ pub use builder::Builder;
 #[cfg(feature = "core")]
 pub use libsql_sys::{Cipher, EncryptionConfig};
 
-use std::fmt;
-
 use crate::{Connection, Result};
+use std::fmt;
+use std::sync::atomic::AtomicU64;
+use std::sync::Arc;
 
 cfg_core! {
     bitflags::bitflags! {
@@ -76,6 +77,9 @@ impl fmt::Debug for DbType {
 /// not do much work until the [`Database::connect`] fn is called.
 pub struct Database {
     db_type: DbType,
+    /// The maximum replication index returned from a write performed using any connection created using this Database object.
+    #[allow(dead_code)]
+    max_write_replication_index: Arc<AtomicU64>,
 }
 
 cfg_core! {
@@ -87,6 +91,7 @@ cfg_core! {
 
             Ok(Database {
                 db_type: DbType::Memory { db },
+                max_write_replication_index: Default::default(),
             })
         }
 
@@ -105,6 +110,7 @@ cfg_core! {
                     flags,
                     encryption_config: None,
                 },
+                max_write_replication_index: Default::default(),
             })
         }
     }
@@ -130,6 +136,7 @@ cfg_replication! {
 
             Ok(Database {
                 db_type: DbType::Sync { db, encryption_config },
+                max_write_replication_index: Default::default(),
             })
         }
 
@@ -191,6 +198,7 @@ cfg_replication! {
 
             Ok(Database {
                 db_type: DbType::Sync { db, encryption_config },
+                max_write_replication_index: Default::default(),
             })
         }
 
@@ -317,6 +325,7 @@ cfg_replication! {
 
             Ok(Database {
                 db_type: DbType::Sync { db, encryption_config },
+                max_write_replication_index: Default::default(),
             })
         }
 
@@ -372,7 +381,8 @@ cfg_replication! {
                DbType::Sync { db, .. } => {
                    let path = db.path().to_string();
                    Ok(Database {
-                       db_type: DbType::File { path, flags: OpenFlags::default(), encryption_config: None}
+                       db_type: DbType::File { path, flags: OpenFlags::default(), encryption_config: None},
+                       max_write_replication_index: Default::default(),
                    })
                }
                t => Err(Error::FreezeNotSupported(format!("{:?}", t)))
@@ -445,6 +455,7 @@ cfg_remote! {
                     connector: crate::util::ConnectorService::new(svc),
                     version,
                 },
+                max_write_replication_index: Default::default(),
             })
         }
     }

libsql/src/database/builder.rs

@@ -135,6 +135,7 @@ cfg_core! {
                 let db = crate::local::Database::open(":memory:", crate::OpenFlags::default())?;
                 Database {
                     db_type: DbType::Memory { db } ,
+                    max_write_replication_index: Default::default(),
                 }
             } else {
                 let path = self
@@ -150,6 +151,7 @@ cfg_core! {
                         flags: self.inner.flags,
                         encryption_config: self.inner.encryption_config,
                     },
+                    max_write_replication_index: Default::default(),
                 }
             };
 
@@ -291,6 +293,7 @@ cfg_replication! {
 
             Ok(Database {
                 db_type: DbType::Sync { db, encryption_config },
+                max_write_replication_index: Default::default(),
             })
         }
     }
@@ -360,6 +363,7 @@ cfg_replication! {
 
             Ok(Database {
                 db_type: DbType::Sync { db, encryption_config },
+                max_write_replication_index: Default::default(),
             })
         }
     }
@@ -414,6 +418,7 @@ cfg_remote! {
                     connector,
                     version,
                 },
+                max_write_replication_index: Default::default(),
             })
         }
     }