From 8068e1a2ae9a42c3dd4f1d901cdc765d9d855390 Mon Sep 17 00:00:00 2001
From: Roman Gershman <roman@dragonflydb.io>
Date: Wed, 15 Feb 2023 06:19:12 +0200
Subject: [PATCH] feat(server): save dragonfly snapshot in a new format by
 default (#802)

Introduce a new flag `df_snapshot_format` that controls the default behavior.
The flag itself is defaulted to save snapshots in a new Dragonfly
specific format.

BREAKING CHANGE: before that Dragonfly saved snapshots in rdb format by default.
Now the flag controls which format is chosen when issuing SAVE/BGSAVE commands.
In addition, "SAVE DF", "SAVE RDB" can be used to save using dragonfly/redis formats
accordingly.

Signed-off-by: Roman Gershman <roman@dragonflydb.io>
---
 src/server/debugcmd.cc      | 3 ++-
 src/server/server_family.cc | 8 ++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/server/debugcmd.cc b/src/server/debugcmd.cc
index edc6763fa..6b6d18bcd 100644
--- a/src/server/debugcmd.cc
+++ b/src/server/debugcmd.cc
@@ -27,6 +27,7 @@ using namespace std;
 
 ABSL_DECLARE_FLAG(string, dir);
 ABSL_DECLARE_FLAG(string, dbfilename);
+ABSL_DECLARE_FLAG(bool, df_snapshot_format);
 
 namespace dfly {
 
@@ -174,7 +175,7 @@ void DebugCmd::Reload(CmdArgList args) {
     trans->InitByArgs(0, {});
     VLOG(1) << "Performing save";
 
-    GenericError ec = sf_.DoSave(false, trans.get());
+    GenericError ec = sf_.DoSave(absl::GetFlag(FLAGS_df_snapshot_format), trans.get());
     if (ec) {
       return (*cntx_)->SendError(ec.Format());
     }
diff --git a/src/server/server_family.cc b/src/server/server_family.cc
index ec00e1546..dcded575b 100644
--- a/src/server/server_family.cc
+++ b/src/server/server_family.cc
@@ -56,6 +56,8 @@ ABSL_FLAG(string, requirepass, "",
           "If empty can also be set with DFLY_PASSWORD environment variable.");
 ABSL_FLAG(string, save_schedule, "",
           "glob spec for the UTC time to save a snapshot which matches HH:MM 24h time");
+ABSL_FLAG(bool, df_snapshot_format, true,
+          "if true, save in dragonfly-specific snapshotting format");
 
 ABSL_DECLARE_FLAG(uint32_t, port);
 ABSL_DECLARE_FLAG(bool, cache_mode);
@@ -567,7 +569,7 @@ void ServerFamily::SnapshotScheduling(const SnapshotSpec& spec) {
     boost::intrusive_ptr<Transaction> trans(new Transaction{cid});
     trans->InitByArgs(0, {});
 
-    GenericError ec = DoSave(false, trans.get());
+    GenericError ec = DoSave(absl::GetFlag(FLAGS_df_snapshot_format), trans.get());
     if (ec) {
       LOG(WARNING) << "Failed to perform snapshot " << ec.Format();
     }
@@ -1185,7 +1187,7 @@ void ServerFamily::Memory(CmdArgList args, ConnectionContext* cntx) {
 
 void ServerFamily::Save(CmdArgList args, ConnectionContext* cntx) {
   string err_detail;
-  bool new_version = false;
+  bool new_version = absl::GetFlag(FLAGS_df_snapshot_format);
   if (args.size() > 2) {
     return (*cntx)->SendError(kSyntaxErr);
   }
@@ -1195,6 +1197,8 @@ void ServerFamily::Save(CmdArgList args, ConnectionContext* cntx) {
     string_view sub_cmd = ArgS(args, 1);
     if (sub_cmd == "DF") {
       new_version = true;
+    } else if (sub_cmd == "RDB") {
+      new_version = false;
     } else {
       return (*cntx)->SendError(UnknownSubCmd(sub_cmd, "SAVE"), kSyntaxErrType);
     }