From b13454d54b32b555a8972d723721421814bd8084 Mon Sep 17 00:00:00 2001
From: Andrey Chursin <achursin@fb.com>
Date: Wed, 23 Jun 2021 14:50:31 -0700
Subject: [PATCH] segmented_changelog: introduce
 SegmentedChangelog::pull_fast_forward_master

Summary: The naming is used in other parts of dag crate - this introduce mononoke side binding for corresponding functions on dag side

Reviewed By: quark-zju

Differential Revision: D29318722

fbshipit-source-id: e9eea5536b041b6ab2ce578914817bca43a10d48
---
 eden/mononoke/segmented_changelog/src/lib.rs  | 21 +++++++++++++++++++
 .../segmented_changelog/src/on_demand.rs      | 14 +++++++++++++
 .../segmented_changelog/src/read_only.rs      |  9 ++++++++
 .../mononoke/segmented_changelog/types/lib.rs |  8 +++++++
 4 files changed, 52 insertions(+)

diff --git a/eden/mononoke/segmented_changelog/src/lib.rs b/eden/mononoke/segmented_changelog/src/lib.rs
index e315cc404e..f458c84a1b 100644
--- a/eden/mononoke/segmented_changelog/src/lib.rs
+++ b/eden/mononoke/segmented_changelog/src/lib.rs
@@ -80,6 +80,17 @@ impl SegmentedChangelog for DisabledSegmentedChangelog {
         ))
     }
 
+    async fn pull_fast_forward_master(
+        &self,
+        _ctx: &CoreContext,
+        _old_master: ChangesetId,
+        _new_master: ChangesetId,
+    ) -> Result<CloneData<ChangesetId>> {
+        Err(format_err!(
+            "Segmented Changelog is not enabled for this repo",
+        ))
+    }
+
     async fn full_idmap_clone_data(
         &self,
         _ctx: &CoreContext,
@@ -127,6 +138,16 @@ macro_rules! segmented_changelog_delegate {
                 delegate.clone_data($ctx).await
             }
 
+            async fn pull_fast_forward_master(
+                &$self,
+                $ctx: &CoreContext,
+                old_master: ChangesetId,
+                new_master: ChangesetId,
+            ) -> Result<CloneData<ChangesetId>> {
+                let delegate = $delegate;
+                delegate.pull_fast_forward_master($ctx, old_master, new_master).await
+            }
+
             async fn full_idmap_clone_data(
                 &$self,
                 $ctx: &CoreContext,
diff --git a/eden/mononoke/segmented_changelog/src/on_demand.rs b/eden/mononoke/segmented_changelog/src/on_demand.rs
index cf47414e27..b2f3d50918 100644
--- a/eden/mononoke/segmented_changelog/src/on_demand.rs
+++ b/eden/mononoke/segmented_changelog/src/on_demand.rs
@@ -390,6 +390,20 @@ impl SegmentedChangelog for OnDemandUpdateSegmentedChangelog {
         read_dag.clone_data(ctx).await
     }
 
+    async fn pull_fast_forward_master(
+        &self,
+        ctx: &CoreContext,
+        old_master: ChangesetId,
+        new_master: ChangesetId,
+    ) -> Result<CloneData<ChangesetId>> {
+        // Might need to wait here for segmented changelog to catch up
+        let iddag = self.iddag.read().await;
+        let read_dag = ReadOnlySegmentedChangelog::new(&iddag, self.idmap.clone());
+        read_dag
+            .pull_fast_forward_master(ctx, old_master, new_master)
+            .await
+    }
+
     async fn full_idmap_clone_data(
         &self,
         ctx: &CoreContext,
diff --git a/eden/mononoke/segmented_changelog/src/read_only.rs b/eden/mononoke/segmented_changelog/src/read_only.rs
index c66f88893e..8ab8d42121 100644
--- a/eden/mononoke/segmented_changelog/src/read_only.rs
+++ b/eden/mononoke/segmented_changelog/src/read_only.rs
@@ -138,6 +138,15 @@ impl<'a> SegmentedChangelog for ReadOnlySegmentedChangelog<'a> {
         Ok(clone_data)
     }
 
+    async fn pull_fast_forward_master(
+        &self,
+        _ctx: &CoreContext,
+        _old_master: ChangesetId,
+        _new_master: ChangesetId,
+    ) -> Result<CloneData<ChangesetId>> {
+        unimplemented!()
+    }
+
     async fn full_idmap_clone_data(
         &self,
         ctx: &CoreContext,
diff --git a/eden/mononoke/segmented_changelog/types/lib.rs b/eden/mononoke/segmented_changelog/types/lib.rs
index eb13705494..a09e09f536 100644
--- a/eden/mononoke/segmented_changelog/types/lib.rs
+++ b/eden/mononoke/segmented_changelog/types/lib.rs
@@ -104,6 +104,14 @@ pub trait SegmentedChangelog: Send + Sync {
     /// only needs one head.
     async fn clone_data(&self, ctx: &CoreContext) -> Result<CloneData<ChangesetId>>;
 
+    /// Uses segmented changelog fast forward master pull fastpath.
+    async fn pull_fast_forward_master(
+        &self,
+        ctx: &CoreContext,
+        old_master: ChangesetId,
+        new_master: ChangesetId,
+    ) -> Result<CloneData<ChangesetId>>;
+
     /// An intermediate step in the quest for Segmented Changelog clones requires the server to
     /// send over the full idmap. For every commit (in master) we send the id that it corresponds
     /// to in the iddag.