Add basic `Snapshot` object

Cargo.lock

@@ -35,6 +35,12 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
 [[package]]
 name = "bincode"
 version = "1.3.1"
@@ -75,6 +81,19 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "chrono"
+version = "0.4.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "670ad68c9088c2a963aaa298cb369688cf3f9465ce5e2d4ca10e6e0098a1ce73"
+dependencies = [
+ "libc",
+ "num-integer",
+ "num-traits",
+ "time",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "clap"
 version = "2.33.3"
@@ -161,7 +180,7 @@ checksum = "fc587bc0ec293155d5bfa6b9891ec18a1e330c234f896ea47fbada4cadbe47e6"
 dependencies = [
  "cfg-if",
  "libc",
- "wasi",
+ "wasi 0.9.0+wasi-snapshot-preview1",
 ]
 
 [[package]]
@@ -348,6 +367,25 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "num-integer"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d59457e662d541ba17869cf51cf177c0b5f0cbf476c66bdc90bf1edac4f875b"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac267bcc07f48ee5f8935ab0d24f316fb722d7a1292e2913f0cc196b29ffd611"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "num_cpus"
 version = "1.13.0"
@@ -568,6 +606,7 @@ version = "0.4.3"
 dependencies = [
  "bincode",
  "bytes",
+ "chrono",
  "clap",
  "env_logger",
  "jemallocator",
@@ -632,6 +671,17 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "time"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6db9e6914ab8b1ae1c260a4ae7a49b6c5611b40328a735b21862567685e73255"
+dependencies = [
+ "libc",
+ "wasi 0.10.0+wasi-snapshot-preview1",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "tokio"
 version = "0.2.22"
@@ -711,6 +761,12 @@ version = "0.9.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
 
+[[package]]
+name = "wasi"
+version = "0.10.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a143597ca7c7793eff794def352d41792a93c481eb1042423ff7ff72ba2c31f"
+
 [[package]]
 name = "winapi"
 version = "0.2.8"

server/Cargo.toml

@@ -19,6 +19,7 @@ toml = "0.5.6"
 clap = {version = "2.33.3", features=["yaml"]}
 env_logger = "0.7.1"
 log = "0.4.11"
+chrono = "0.4.19"
 
 [target.'cfg(not(target_env = "msvc"))'.dependencies]
 jemallocator = "0.3.2"

server/src/coredb/mod.rs

@@ -27,6 +27,7 @@ use crate::protocol::Connection;
 use crate::protocol::Query;
 use crate::queryengine;
 use bytes::Bytes;
+use diskstore::PERSIST_FILE;
 use libtdb::TResult;
 use parking_lot::RwLock;
 use parking_lot::RwLockReadGuard;
@@ -67,7 +68,7 @@ impl Shared {
             return None;
         }
         // Kick in BGSAVE
-        match diskstore::flush_data(&self.table.read().get_ref()) {
+        match diskstore::flush_data(PERSIST_FILE, &self.table.read().get_ref()) {
             Ok(_) => log::info!("BGSAVE completed successfully"),
             Err(e) => log::error!("BGSAVE failed with error: '{}'", e),
         }
@@ -189,7 +190,7 @@ impl CoreDB {
     /// Flush the contents of the in-memory table onto disk
     pub fn flush_db(&self) -> TResult<()> {
         let data = &self.acquire_write();
-        diskstore::flush_data(&data.coremap)?;
+        diskstore::flush_data(PERSIST_FILE, &data.coremap)?;
         Ok(())
     }
 

server/src/diskstore/mod.rs

@@ -33,8 +33,10 @@ use std::iter::FromIterator;
 use std::time::Duration;
 use tokio::time;
 mod cyansfw;
+mod snapshot;
 
 type DiskStore = (Vec<String>, Vec<Vec<u8>>);
+pub const PERSIST_FILE: &'static str = "./data.bin";
 
 /// Try to get the saved data from disk. This returns `None`, if the `data.bin` wasn't found
 /// otherwise the `data.bin` file is deserialized and parsed into a `HashMap`
@@ -64,13 +66,13 @@ pub fn get_saved() -> TResult<Option<HashMap<String, Data>>> {
 ///
 /// This functions takes the entire in-memory table and writes it to the disk,
 /// more specifically, the `data.bin` file
-pub fn flush_data(data: &HashMap<String, Data>) -> TResult<()> {
+pub fn flush_data(filename: &str, data: &HashMap<String, Data>) -> TResult<()> {
     let ds: DiskStore = (
         data.keys().into_iter().map(|val| val.to_string()).collect(),
         data.values().map(|val| val.get_blob().to_vec()).collect(),
     );
     let encoded = bincode::serialize(&ds)?;
-    let mut file = fs::File::create("./data.bin")?;
+    let mut file = fs::File::create(filename)?;
     file.write_all(&encoded)?;
     Ok(())
 }

server/src/diskstore/snapshot.rs

@@ -0,0 +1,60 @@
+/*
+ * Created on Thu Oct 01 2020
+ *
+ * This file is a part of TerrabaseDB
+ * Copyright (c) 2020, Sayan Nandan <ohsayan at outlook dot com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+*/
+
+//! Tools for creating snapshots
+
+use crate::coredb::CoreDB;
+use chrono::prelude::*;
+use libtdb::TResult;
+
+/// # Snapshot
+///
+/// This object provides methods to create and delete snapshots. There should be a
+/// `snapshot_scheduler` which should hold an instance of this object, on startup.
+/// Whenever the duration expires, the caller should call `mksnap()`
+pub struct Snapshot {
+    /// File names of the snapshots (relative paths)
+    snaps: Vec<String>,
+    /// The maximum number of snapshots to be kept
+    maxtop: usize,
+    /// An atomic reference to the coretable
+    dbref: CoreDB,
+}
+
+impl Snapshot {
+    /// Create a new `Snapshot` instance
+    pub fn new(maxtop: usize, dbref: CoreDB) -> Self {
+        Snapshot {
+            snaps: Vec::with_capacity(maxtop),
+            maxtop,
+            dbref,
+        }
+    }
+    /// Generate the snapshot name
+    fn get_snapname(&self) -> String {
+        Utc::now()
+            .format("./snapshots/%Y%m%d-%H%M%S.snapshot")
+            .to_string()
+    }
+    pub fn mksnap(&mut self) -> TResult<()> {
+        todo!("Snapshotting hasn't been implemented yet!")
+    }
+}