feat: databend-meta transaction support generic bool-expression and e…

…lse-if chain

Since this commit, application is allowed to specify a complex bool
expressions as the transaction predicate.

For example, the transaction will execute as if running the following
pseudo codes:
```
if (a == 1 || b == 2) && (x == 3 || y == 4) { ops1 }
else if (x == 2 || y == 1) { ops2 }
else if (y == 3 && z == 4) { ops3 }
else { ops4 }
```

```rust
let eq = |key: &str, val: &str| TxnCondition::eq_value(sample(key), b(val));

TxnRequest{
    operations: vec![
                BoolExpression::new(
                    Some(eq("a", 1).or(eq("b", 2))
                         .and(eq("x", 3).or(eq("y", 4)))),
                    ops1),
                BoolExpression::new(
                    Some(eq("x", 2).or(eq("y", 1))),
                    ops2),
            ],

    condition: vec![eq("y", 3), eq("z", 4)],
    if_then: ops3,
    else_then: ops4,
}
```

For backward compatibility, both already existing `condition` and the new
`operations` will be evaluated: transaction handler evaluate the
`operations` first. If there is a met condition, execute and return.
Otherwise, it evaluate `condition` and then execute `if_then` branch or
`else_then` branch.

TxnReply changes:

Add field `execution_path` to indicate the executed branch, which is one
of:
- `"operation:<index>"`, operation at `index` is executed.
- `"then"`: `if_then` is executed.
- `"else"`: `else_then` is executed.

`TxnReply.success` is set to `false` only when `else` is executed.

src/meta/api/src/schema_api_impl.rs

@@ -439,18 +439,17 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 }
                 db_meta.drop_on = None;
 
-                let txn_req = TxnRequest {
-                    condition: vec![
+                let txn_req = TxnRequest::new(
+                    vec![
                         txn_cond_seq(name_key, Eq, 0),
                         txn_cond_seq(&dbid_idlist, Eq, db_id_list_seq),
                         txn_cond_seq(&dbid, Eq, db_meta_seq),
                     ],
-                    if_then: vec![
+                    vec![
                         txn_op_put(name_key, serialize_u64(db_id)?), // (tenant, db_name) -> db_id
                         txn_op_put(&dbid, serialize_struct(&db_meta)?), // (db_id) -> db_meta
                     ],
-                    else_then: vec![],
-                };
+                );
 
                 let (succ, _responses) = send_txn(self, txn_req).await?;
 
@@ -594,11 +593,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 ), /* __fd_database_id_to_name/<db_id> -> (tenant,db_name) */
             ];
 
-            let txn_req = TxnRequest {
-                condition,
-                if_then,
-                else_then: vec![],
-            };
+            let txn_req = TxnRequest::new(condition, if_then);
 
             let (succ, _responses) = send_txn(self, txn_req).await?;
 
@@ -1203,19 +1198,19 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                     txn_cond_seq(&save_key_table_id_list, Eq, tb_id_list_seq),
                 ]);
 
-                txn.if_then.extend( vec![
-                        // Changing a table in a db has to update the seq of db_meta,
-                        // to block the batch-delete-tables when deleting a db.
-                        txn_op_put(&key_dbid, serialize_struct(&db_meta.data)?), /* (db_id) -> db_meta */
-                        txn_op_put(
-                            key_table_id,
-                            serialize_struct(&req.table_meta)?,
-                        ), /* (tenant, db_id, tb_id) -> tb_meta */
-                        txn_op_put(&save_key_table_id_list, serialize_struct(&tb_id_list)?), /* _fd_table_id_list/db_id/table_name -> tb_id_list */
-                        // This record does not need to assert `table_id_to_name_key == 0`,
-                        // Because this is a reverse index for db_id/table_name -> table_id, and it is unique.
-                        txn_op_put(&key_table_id_to_name, serialize_struct(&key_dbid_tbname)?), /* __fd_table_id_to_name/db_id/table_name -> DBIdTableName */
-                    ]);
+                txn.if_then.extend(vec![
+                    // Changing a table in a db has to update the seq of db_meta,
+                    // to block the batch-delete-tables when deleting a db.
+                    txn_op_put(&key_dbid, serialize_struct(&db_meta.data)?), /* (db_id) -> db_meta */
+                    txn_op_put(
+                        key_table_id,
+                        serialize_struct(&req.table_meta)?,
+                    ), /* (tenant, db_id, tb_id) -> tb_meta */
+                    txn_op_put(&save_key_table_id_list, serialize_struct(&tb_id_list)?), /* _fd_table_id_list/db_id/table_name -> tb_id_list */
+                    // This record does not need to assert `table_id_to_name_key == 0`,
+                    // Because this is a reverse index for db_id/table_name -> table_id, and it is unique.
+                    txn_op_put(&key_table_id_to_name, serialize_struct(&key_dbid_tbname)?), /* __fd_table_id_to_name/db_id/table_name -> DBIdTableName */
+                ]);
 
                 if req.as_dropped {
                     // To create the table in a "dropped" state,
@@ -1401,8 +1396,8 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 tb_id_list.pop();
                 new_tb_id_list.append(table_id);
 
-                let mut txn = TxnRequest {
-                    condition: vec![
+                let mut txn = TxnRequest::new(
+                    vec![
                         // db has not to change, i.e., no new table is created.
                         // Renaming db is OK and does not affect the seq of db_meta.
                         txn_cond_seq(&seq_db_id.data, Eq, db_meta.seq),
@@ -1416,7 +1411,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                         txn_cond_seq(&new_dbid_tbname_idlist, Eq, new_tb_id_list_seq),
                         txn_cond_seq(&table_id_to_name_key, Eq, table_id_to_name_seq),
                     ],
-                    if_then: vec![
+                    vec![
                         txn_op_del(&dbid_tbname), // (db_id, tb_name) -> tb_id
                         txn_op_put(&newdbid_newtbname, serialize_u64(table_id)?), /* (db_id, new_tb_name) -> tb_id */
                         // Changing a table in a db has to update the seq of db_meta,
@@ -1426,8 +1421,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                         txn_op_put(&new_dbid_tbname_idlist, serialize_struct(&new_tb_id_list)?), /* _fd_table_id_list/db_id/new_table_name -> tb_id_list */
                         txn_op_put(&table_id_to_name_key, serialize_struct(&db_id_table_name)?), /* __fd_table_id_to_name/db_id/table_name -> DBIdTableName */
                     ],
-                    else_then: vec![],
-                };
+                );
 
                 if *seq_db_id.data != *new_seq_db_id.data {
                     txn.if_then.push(
@@ -1909,8 +1903,8 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 }
                 tb_meta.drop_on = None;
 
-                let txn_req = TxnRequest {
-                    condition: vec![
+                let txn_req = TxnRequest::new(
+                    vec![
                         // db has not to change, i.e., no new table is created.
                         // Renaming db is OK and does not affect the seq of db_meta.
                         txn_cond_seq(&DatabaseId { db_id }, Eq, db_meta_seq),
@@ -1921,7 +1915,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                         txn_cond_seq(&orphan_dbid_tbname_idlist, Eq, orphan_tb_id_list.seq),
                         txn_cond_seq(&dbid_tbname_idlist, Eq, tb_id_list.seq),
                     ],
-                    if_then: vec![
+                    vec![
                         // Changing a table in a db has to update the seq of db_meta,
                         // to block the batch-delete-tables when deleting a db.
                         txn_op_put(&DatabaseId { db_id }, serialize_struct(&db_meta)?), /* (db_id) -> db_meta */
@@ -1931,8 +1925,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                         txn_op_del(&orphan_dbid_tbname_idlist),         // del orphan table idlist
                         txn_op_put(&dbid_tbname_idlist, serialize_struct(&tb_id_list.data)?), /* _fd_table_id_list/db_id/table_name -> tb_id_list */
                     ],
-                    else_then: vec![],
-                };
+                );
 
                 let (succ, _responses) = send_txn(self, txn_req).await?;
 
@@ -2061,16 +2054,15 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
         //   non-changed ones.
 
         for chunk in copied_files.chunks(chunk_size as usize) {
-            let txn = TxnRequest {
-                condition: vec![],
-                if_then: chunk
+            let txn = TxnRequest::new(
+                vec![],
+                chunk
                     .iter()
                     .map(|(name, seq_file)| {
                         TxnOp::delete_exact(name.to_string_key(), Some(seq_file.seq()))
                     })
                     .collect(),
-                else_then: vec![],
-            };
+            );
 
             let (_succ, _responses) = send_txn(self, txn).await?;
         }
@@ -2377,16 +2369,15 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 }
             }
 
-            let mut txn_req = TxnRequest {
-                condition: vec![
+            let mut txn_req = TxnRequest::new(
+                vec![
                     // table is not changed
                     txn_cond_seq(&tbid, Eq, seq_meta.seq),
                 ],
-                if_then: vec![
+                vec![
                     txn_op_put(&tbid, serialize_struct(&new_table_meta)?), // tb_id -> tb_meta
                 ],
-                else_then: vec![],
-            };
+            );
 
             let _ = update_mask_policy(self, &req.action, &mut txn_req, &req.tenant, req.table_id)
                 .await;
@@ -2485,13 +2476,13 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
             };
             indexes.insert(req.name.clone(), index);
 
-            let txn_req = TxnRequest {
-                condition: vec![txn_cond_eq_seq(&tbid, tb_meta_seq)],
-                if_then: vec![
+            let txn_req = TxnRequest::new(
+                //
+                vec![txn_cond_eq_seq(&tbid, tb_meta_seq)],
+                vec![
                     txn_op_put_pb(&tbid, &table_meta, None)?, // tb_id -> tb_meta
                 ],
-                else_then: vec![],
-            };
+            );
 
             let (succ, _responses) = send_txn(self, txn_req).await?;
 
@@ -2540,16 +2531,15 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
             }
             indexes.remove(&req.name);
 
-            let txn_req = TxnRequest {
-                condition: vec![
+            let txn_req = TxnRequest::new(
+                vec![
                     // table is not changed
                     txn_cond_seq(&tbid, Eq, seq_meta.seq),
                 ],
-                if_then: vec![
+                vec![
                     txn_op_put(&tbid, serialize_struct(&table_meta)?), // tb_id -> tb_meta
                 ],
-                else_then: vec![],
-            };
+            );
 
             let (succ, _responses) = send_txn(self, txn_req).await?;
             debug!(id :? =(&tbid),succ = succ;"drop_table_index");
@@ -2742,11 +2732,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 txn_op_put(&id_generator, b"".to_vec()),
                 txn_op_put_pb(&key, &lock_meta, Some(req.ttl))?,
             ];
-            let txn_req = TxnRequest {
-                condition,
-                if_then,
-                else_then: vec![],
-            };
+            let txn_req = TxnRequest::new(condition, if_then);
             let (succ, _responses) = send_txn(self, txn_req).await?;
 
             if succ {
@@ -3053,11 +3039,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SchemaApi for KV {
                 txn_op_put_pb(&new_name_ident, &dict_id.data, None)?, // put new dict name
             ];
 
-            let txn_req = TxnRequest {
-                condition,
-                if_then,
-                else_then: vec![],
-            };
+            let txn_req = TxnRequest::new(condition, if_then);
 
             let (succ, _responses) = send_txn(self, txn_req).await?;
 
@@ -4042,8 +4024,8 @@ async fn handle_undrop_table(
             // reset drop on time
             seq_table_meta.drop_on = None;
 
-            let txn = TxnRequest {
-                condition: vec![
+            let txn = TxnRequest::new(
+                vec![
                     // db has not to change, i.e., no new table is created.
                     // Renaming db is OK and does not affect the seq of db_meta.
                     txn_cond_eq_seq(&DatabaseId { db_id }, seq_db_meta.seq),
@@ -4052,15 +4034,14 @@ async fn handle_undrop_table(
                     // table is not changed
                     txn_cond_eq_seq(&tbid, seq_table_meta.seq),
                 ],
-                if_then: vec![
+                vec![
                     // Changing a table in a db has to update the seq of db_meta,
                     // to block the batch-delete-tables when deleting a db.
                     txn_op_put_pb(&DatabaseId { db_id }, &seq_db_meta.data, None)?, /* (db_id) -> db_meta */
                     txn_op_put(&dbid_tbname, serialize_u64(table_id)?), /* (tenant, db_id, tb_name) -> tb_id */
                     txn_op_put_pb(&tbid, &seq_table_meta.data, None)?, /* (tenant, db_id, tb_id) -> tb_meta */
                 ],
-                else_then: vec![],
-            };
+            );
 
             let (succ, _responses) = send_txn(kv_api, txn).await?;
 

src/meta/api/src/sequence_api_impl.rs

@@ -142,11 +142,7 @@ impl<KV: kvapi::KVApi<Error = MetaError> + ?Sized> SequenceApi for KV {
                 txn_op_put_pb(&ident, &sequence_meta, None)?, // name -> meta
             ];
 
-            let txn_req = TxnRequest {
-                condition,
-                if_then,
-                else_then: vec![],
-            };
+            let txn_req = TxnRequest::new(condition, if_then);
 
             let (succ, _responses) = send_txn(self, txn_req).await?;
 

src/meta/binaries/metabench/main.rs

@@ -298,11 +298,7 @@ async fn benchmark_table_copy_file(
         serde_json::from_str(param).unwrap()
     };
 
-    let mut txn = TxnRequest {
-        condition: vec![],
-        if_then: vec![],
-        else_then: vec![],
-    };
+    let mut txn = TxnRequest::default();
 
     for file_index in 0..param.file_cnt {
         let copied_file_ident = TableCopiedFileNameIdent {

src/meta/client/src/lib.rs

@@ -117,6 +117,10 @@ pub static METACLI_COMMIT_SEMVER: LazyLock<Version> = LazyLock::new(|| {
 ///   🖥 server: add `txn_condition::Target::KeysWithPrefix`,
 ///              to support matching the key count by a prefix.
 ///
+/// - 2024-12-1*: since 1.2.*
+///   🖥 server: add `TxnRequest::condition_tree`,
+///              to specify a complex bool expression.
+///
 ///
 /// Server feature set:
 /// ```yaml

src/meta/kvapi/Cargo.toml

@@ -15,6 +15,7 @@ test = true
 [dependencies]
 anyhow = { workspace = true }
 async-trait = { workspace = true }
+databend-common-base = { workspace = true }
 databend-common-meta-types = { workspace = true }
 fastrace = { workspace = true }
 futures-util = { workspace = true }