Derive Macro DBMapUtils

#[derive(DBMapUtils)]
{
    // Attributes available to this derive:
    #[default_options_override_fn]
    #[rename]
    #[tidehunter]
}

A helper macro to simplify common operations for opening and debugging TypedStore (currently internally structs of DBMaps) It operates on a struct where all the members are DBMap<K, V> The main features are:

1. Flexible configuration of each table (column family) via defaults and overrides

2. Auto-generated open routine

3. Auto-generated read_only_mode handle

4. Auto-generated memory stats method

5. Other convenience features

6. Flexible configuration: a. Static options specified at struct definition

The definer of the struct can specify the default options for each table using annotations We can also supply column family options on the default ones A user defined function of signature () -> Options can be provided for each table If an override function is not specified, the default in typed_store::rocks::default_db_options is used

use typed_store::rocks::DBOptions;
use typed_store::rocks::DBMap;
use typed_store::rocks::MetricConf;
use typed_store::DBMapUtils;
use core::fmt::Error;
/// Define a struct with all members having type DBMap<K, V>

fn custom_fn_name1() -> DBOptions {DBOptions::default()}
fn custom_fn_name2() -> DBOptions {
    let mut op = custom_fn_name1();
    op.options.set_write_buffer_size(123456);
    op
}
#[derive(DBMapUtils)]
struct Tables {
    /// Specify custom options function `custom_fn_name1`
    #[default_options_override_fn = "custom_fn_name1"]
    table1: DBMap<String, String>,
    #[default_options_override_fn = "custom_fn_name2"]
    table2: DBMap<i32, String>,
    // Nothing specified so `typed_store::rocks::default_db_options` is used
    table3: DBMap<i32, String>,
    #[default_options_override_fn = "custom_fn_name1"]
    table4: DBMap<i32, String>,
}

2. Auto-generated open routine The function open_tables_read_write is generated which allows for specifying DB wide options and custom table configs as mentioned above

3. Auto-generated read_only_mode handle This mode provides handle struct which opens the DB in read only mode and has certain features like dumping and counting the keys in the tables

Use the function Tables::get_read_only_handle which returns a handle that only allows read only features

 use typed_store::rocks::DBOptions;
 use typed_store::rocks::DBMap;
 use typed_store::DBMapUtils;
 use core::fmt::Error;
 /// Define a struct with all members having type DBMap<K, V>

 fn custom_fn_name1() -> DBOptions {DBOptions::default()}
 fn custom_fn_name2() -> DBOptions {
     let mut op = custom_fn_name1();
     op.options.set_write_buffer_size(123456);
     op
 }
 #[derive(DBMapUtils)]
 struct Tables {
     /// Specify custom options function `custom_fn_name1`
     #[default_options_override_fn = "custom_fn_name1"]
     table1: DBMap<String, String>,
     #[default_options_override_fn = "custom_fn_name2"]
     table2: DBMap<i32, String>,
     // Nothing specified so `typed_store::rocks::default_db_options` is used
     table3: DBMap<i32, String>,
     #[default_options_override_fn = "custom_fn_name1"]
     table4: DBMap<i32, String>,
 }
 #[tokio::main]
 async fn main() -> Result<(), Error> {

 use typed_store::rocks::MetricConf;let primary_path = tempfile::tempdir().expect("Failed to open temporary directory").keep();
 let _ = Tables::open_tables_read_write(primary_path.clone(), typed_store::rocks::MetricConf::default(), None, None);

 // Get the read only handle
 let read_only_handle = Tables::get_read_only_handle(primary_path, None, None, MetricConf::default());
 // Use this handle for dumping
 let ret = read_only_handle.dump("table2", 100, 0).unwrap();
 Ok(())
 }

4. Auto-generated memory stats method self.get_memory_usage is derived to provide memory and cache usage

5. Other convenience features Tables::describe_tables is used to get a list of the table names and key-value types as string in a BTreeMap

// Bad usage example // Structs fields most only be of type Store<K, V> or DMBap<K, V> // This will fail to compile with error All struct members must be of type Store<K, V> or DMBap<K, V> // #[derive(DBMapUtils)] // struct BadTables { // table1: Store<String, String>, // bad_field: u32, // #}