Make MKSNAP return code 3 for `howmany != 0`

To streamline the actions we'll make sure that mksnap returns code 3
if an incorrect number of arguments are provided
The actiondoc for the `mksnap` action was added and the contributing
guide was also updated

Signed-off-by: Sayan Nandan <nandansayan@outlook.com>

CONTRIBUTING.md

@@ -32,15 +32,23 @@ In other cases, use the C style.
 
 ### Parts of the project
 
-The project root has three main directories:
+* `ci` , `.github` : CI scripts (which, under normal circumstances, don't need to be modified)
+* `cli` : Source for `tsh` which is the command-line client for TDB
+* `examples` : Example configuration files
+* `libtdb` : This contains functions, structs, ... used by both the `cli` and the 
+* `server` : Source for the main database server `tdb`
+* `tdb-bench` : The source for the benchmarking tool resides here
+* `tdb-macros` : The source for custom compiler macros used by TerrabaseDB
 
-* `cli` : This contains code for `tsh` which is the command-line client for TDB
-* `libtdb` : This contains function, structs, ... used by both the `cli` and the `server`
-* `server` : This contains code for the main database server
+### Jargon
+
+Each project has its own jargon — and so do we!
+
+* _actiondoc_ and _actions docs_ : This refers to the `actions.jsonc` file, which is used by the TerrabaseDB documentation website for automatically building documentation for the actions
 
 ### Branches
 
-The `next` branch is the _kind of_ stable branch which contains the latest changes. However, for most purposes, you should always download the sources from the tags. Usually, when a feature is worked on, the work will be done on a separate branch, and then it will be merged into next.
+The `next` branch is the _kind of_ stable branch which contains the latest changes. However, for most purposes, you should always download sources from the tags. Usually, when a feature is worked on, the work will be done on a separate branch, and then it will be merged into next.
 
 ## Steps
 

actions.jsonc

@@ -143,5 +143,13 @@
         "args": "KEYLEN <key>",
         "desc": "Returns the length of the UTF-8 string",
         "return": "Length of the key as an unsigned int",
+    },
+    {
+        "name": "MKSNAP",
+        "since": "0.4.5",
+        "complexity": "O(n)",
+        "args": "MKSNAP",
+        "desc": "Create a snapshot",
+        "return": "Okay if succeeded, otherwise it returns `err-snapshot-disabled` if snapshotting is disabled or `err-snapshot-busy` if a snapshotting operation is already in progress"
     }
-]
+]

server/src/diskstore/snapshot.rs

@@ -23,6 +23,7 @@
 
 use crate::config::SnapshotConfig;
 use crate::coredb::CoreDB;
+#[cfg(test)]
 use crate::coredb::SnapshotStatus;
 use crate::diskstore;
 use chrono::prelude::*;

server/src/kvengine/mksnap.rs

@@ -30,16 +30,15 @@ use std::hint::unreachable_unchecked;
 /// Create a snapshot
 ///
 pub async fn mksnap(handle: &CoreDB, con: &mut Connection, act: ActionGroup) -> TResult<()> {
-    if !handle.is_snapshot_enabled() {
-        // Since snapshotting is disabled, we can't create a snapshot!
-        // We'll just return an error returning the same
-        let error = "Snapshotting is disabled";
-        con.write_response(GroupBegin(1)).await?;
-        let error = RespCodes::OtherError(Some(error.to_string()));
-        return con.write_response(error).await;
-    }
-    let howmany = act.howmany();
-    if howmany == 0 {
+    if act.howmany() == 0 {
+        if !handle.is_snapshot_enabled() {
+            // Since snapshotting is disabled, we can't create a snapshot!
+            // We'll just return an error returning the same
+            let error = "err-snapshot-disabled";
+            con.write_response(GroupBegin(1)).await?;
+            let error = RespCodes::OtherError(Some(error.to_string()));
+            return con.write_response(error).await;
+        }
         // We will just follow the standard convention of creating snapshots
         let mut was_engine_error = false;
         let mut outerror = None;
@@ -70,7 +69,7 @@ pub async fn mksnap(handle: &CoreDB, con: &mut Connection, act: ActionGroup) ->
         }
         if engine_was_busy {
             con.write_response(GroupBegin(1)).await?;
-            let error = RespCodes::OtherError(Some("Snapshotting already in progress".to_owned()));
+            let error = RespCodes::OtherError(Some("err-snapshot-busy".to_owned()));
             return con.write_response(error).await;
         }
         if let Some(val) = outerror {
@@ -90,7 +89,7 @@ pub async fn mksnap(handle: &CoreDB, con: &mut Connection, act: ActionGroup) ->
             // We shouldn't ever reach here if all our logic is correct
             // but if we do, something is wrong with the runtime
             con.write_response(GroupBegin(1)).await?;
-            let error = RespCodes::OtherError(Some("access-after-termsig".to_owned()));
+            let error = RespCodes::OtherError(Some("err-access-after-termsig".to_owned()));
             return con.write_response(error).await;
         }
     } else {