feat: first implementation of KeyValue data export

src/database/abstraction.rs

@@ -41,6 +41,17 @@ pub trait KeyValueDatabaseEngine: Send + Sync {
     fn memory_usage(&self) -> Result<String> {
         Ok("Current database engine does not support memory usage reporting.".to_owned())
     }
+    fn clear_caches(&self) {}
+
+    fn export(&self, _exporter: &mut Box<dyn KvExport>) -> Result<()> {
+        unimplemented!()
+    }
+}
+
+pub trait KvExport {
+    fn start_index(&mut self, name: &str) -> Result<()>;
+    fn key_value(&mut self, key: &[u8], value: &[u8]) -> Result<()>;
+    fn end_index(&mut self, name: &str) -> Result<()>;
 }
 
 pub trait KvTree: Send + Sync {

src/database/abstraction/persy.rs

@@ -1,6 +1,6 @@
 use crate::{
     database::{
-        abstraction::{watchers::Watchers, KeyValueDatabaseEngine, KvTree},
+        abstraction::{watchers::Watchers, KeyValueDatabaseEngine, KvExport, KvTree},
         Config,
     },
     Result,
@@ -45,6 +45,22 @@ impl KeyValueDatabaseEngine for Arc<Engine> {
     fn flush(&self) -> Result<()> {
         Ok(())
     }
+
+    fn export(&self, exporter: &mut Box<dyn KvExport>) -> Result<()> {
+        let snapshot = self.persy.snapshot()?;
+        let indexes = snapshot.list_indexes()?;
+        for (index, _) in indexes {
+            exporter.start_index(&index)?;
+            let data = snapshot.range::<ByteVec, ByteVec, _>(&index, ..)?;
+            for (key, values) in data {
+                for value in values {
+                    exporter.key_value(&key, &value)?;
+                }
+            }
+            exporter.end_index(&index)?;
+        }
+        Ok(())
+    }
 }
 
 pub struct PersyTree {

src/database/abstraction/rocksdb.rs

@@ -1,4 +1,4 @@
-use super::{super::Config, watchers::Watchers, KeyValueDatabaseEngine, KvTree};
+use super::{super::Config, watchers::Watchers, KeyValueDatabaseEngine, KvExport, KvTree};
 use crate::{utils, Result};
 use std::{
     future::Future,
@@ -11,6 +11,7 @@ pub struct Engine {
     max_open_files: i32,
     cache: rocksdb::Cache,
     old_cfs: Vec<String>,
+    database_path: String,
 }
 
 pub struct RocksDbEngineTree<'a> {
@@ -85,6 +86,7 @@ impl KeyValueDatabaseEngine for Arc<Engine> {
             max_open_files: config.rocksdb_max_open_files,
             cache: rocksdb_cache,
             old_cfs: cfs,
+            database_path: config.database_path.clone(),
         }))
     }
 
@@ -126,6 +128,30 @@ impl KeyValueDatabaseEngine for Arc<Engine> {
             self.cache.get_pinned_usage() as f64 / 1024.0 / 1024.0,
         ))
     }
+
+    fn export(&self, exporter: &mut Box<dyn KvExport>) -> Result<()> {
+        let snapshot = self.rocks.snapshot();
+        let indexes = rocksdb::DBWithThreadMode::<rocksdb::MultiThreaded>::list_cf(
+            &rocksdb::Options::default(),
+            &self.database_path,
+        )
+        .unwrap();
+        for index in indexes {
+            if let Some(handle) = self.rocks.cf_handle(&index) {
+                exporter.start_index(&index)?;
+                let data = snapshot.iterator_cf(&handle, rocksdb::IteratorMode::Start);
+                for ele in data {
+                    if let Ok((key, value)) = ele {
+                        exporter.key_value(&key, &value)?;
+                    }
+                }
+                exporter.end_index(&index)?;
+            }
+        }
+        Ok(())
+    }
+
+    fn clear_caches(&self) {}
 }
 
 impl RocksDbEngineTree<'_> {