Introduce namespace reload on runtime (related to #38)

Introduce new 'RELOAD <namespace>' admin command.
This command clean the namespace and reload it from disk, like a fresh
boot. During the reload time, the daemon won't take any new commands.

Author: maxux

src/commands.c

@@ -90,6 +90,7 @@ static command_t commands_handlers[] = {
     {.command = "NSSET",  .handler = command_nsset},   // custom command to edit namespace settings
     {.command = "NSINFO", .handler = command_nsinfo},  // custom command to get namespace information
     {.command = "SELECT", .handler = command_select},  // default SELECT (with pwd) namespace switch
+    {.command = "RELOAD", .handler = command_reload},  // custom command to reload a namespace
 };
 
 int redis_dispatcher(redis_client_t *client) {

src/commands_namespace.c

@@ -362,3 +362,38 @@ int command_dbsize(redis_client_t *client) {
     return 0;
 }
 
+int command_reload(redis_client_t *client) {
+    char target[COMMAND_MAXLEN];
+    namespace_t *namespace = NULL;
+    resp_request_t *request = client->request;
+
+    // command restricted to admin only
+    if(!command_admin_authorized(client))
+        return 1;
+
+    if(!command_args_validate(client, 2))
+        return 1;
+
+    if(request->argv[1]->length > 128) {
+        redis_hardsend(client, "-Namespace too long");
+        return 1;
+    }
+
+    // get name as usable string
+    sprintf(target, "%.*s", request->argv[1]->length, (char *) request->argv[1]->buffer);
+
+    // checking for existing namespace
+    if(!(namespace = namespace_get(target))) {
+        debug("[-] command: nsset: namespace not found\n");
+        redis_hardsend(client, "-Namespace not found");
+        return 1;
+    }
+
+    // reload that namespace
+    namespace_reload(client->ns);
+
+    redis_hardsend(client, "+OK");
+
+    return 0;
+}
+

src/commands_namespace.h

@@ -8,4 +8,5 @@
     int command_nsinfo(redis_client_t *client);
     int command_nsset(redis_client_t *client);
     int command_dbsize(redis_client_t *client);
+    int command_reload(redis_client_t *client);
 #endif

src/namespace.c

@@ -190,6 +190,19 @@ namespace_t *namespace_ensure(namespace_t *namespace) {
     return namespace;
 }
 
+// lazy load a namespace
+// this just populate data and index from disk
+// based on an existing namespace object
+// this can be used to load and reload a namespace
+static int namespace_load_lazy(ns_root_t *nsroot, namespace_t *namespace) {
+    // now, we are sure the namespace exists, but it's maybe empty
+    // let's call index and data initializer, they will take care about that
+    namespace->index = index_init(nsroot->settings, namespace->indexpath, namespace, nsroot->branches);
+    namespace->data = data_init(nsroot->settings, namespace->datapath, namespace->index->indexid);
+
+    return 0;
+}
+
 // load (or create if it doesn't exists) a namespace
 static namespace_t *namespace_load(ns_root_t *nsroot, char *name) {
     namespace_t *namespace;
@@ -212,12 +225,9 @@ static namespace_t *namespace_load(ns_root_t *nsroot, char *name) {
     if(!namespace_ensure(namespace))
         return NULL;
 
+    // load data from disk
     namespace_descriptor_load(namespace);
-
-    // now, we are sure the namespace exists, but it's maybe empty
-    // let's call index and data initializer, they will take care about that
-    namespace->index = index_init(nsroot->settings, namespace->indexpath, namespace, nsroot->branches);
-    namespace->data = data_init(nsroot->settings, namespace->datapath, namespace->index->indexid);
+    namespace_load_lazy(nsroot, namespace);
 
     return namespace;
 }
@@ -448,6 +458,22 @@ static void namespace_kick_slot(namespace_t *namespace) {
     }
 }
 
+int namespace_reload(namespace_t *namespace) {
+    debug("[+] namespace: reloading: %s\n", namespace->name);
+
+    debug("[+] namespace: reload: cleaning index\n");
+    index_clean_namespace(namespace->index, namespace);
+
+    debug("[+] namespace: reload: destroying objects\n")
+    index_destroy(namespace->index);
+    data_destroy(namespace->data);
+
+    debug("[+] namespace: reload: reloading data\n");
+    namespace_load_lazy(nsroot, namespace);
+
+    return 0;
+}
+
 //
 // delete (clean and remove files) a namespace
 //

src/namespace.h

@@ -57,6 +57,7 @@
     int namespace_create(char *name);
     int namespace_delete(namespace_t *namespace);
     namespace_t *namespace_get(char *name);
+    int namespace_reload(namespace_t *namespace);
 
     void namespace_commit(namespace_t *namespace);