From f8200a638692b8833bceba5cdbbc2f110cc4f3f7 Mon Sep 17 00:00:00 2001
From: Christian Schwarz <me@cschwarz.com>
Date: Thu, 2 Jan 2020 14:29:02 +0100
Subject: [PATCH] replication/driver: regulate per-filesystem step planning
 through stepQueue

before this patch, we'd have unbounded parallelism for ListFilesystemVersions RPCs
---
 replication/driver/replication_driver.go | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/replication/driver/replication_driver.go b/replication/driver/replication_driver.go
index 0c1cd8f..a9c2ce7 100644
--- a/replication/driver/replication_driver.go
+++ b/replication/driver/replication_driver.go
@@ -371,9 +371,21 @@ func (a *attempt) do(ctx context.Context, prev *attempt) {
 }
 
 func (fs *fs) do(ctx context.Context, pq *stepQueue, prev *fs) {
-	psteps, err := fs.fs.PlanFS(ctx)
-	errTime := time.Now()
+
 	defer fs.l.Lock().Unlock()
+
+	// get planned steps from replication logic
+	var psteps []Step
+	var errTime time.Time
+	var err error
+	fs.l.DropWhile(func() {
+		// TODO hacky
+		// choose target time that is earlier than any snapshot, so fs planning is always prioritized
+		targetDate := time.Unix(0, 0)
+		defer pq.WaitReady(fs, targetDate)()
+		psteps, err = fs.fs.PlanFS(ctx) // no shadow
+		errTime = time.Now()            // no shadow
+	})
 	debug := debugPrefix("fs=%s", fs.fs.ReportInfo().Name)
 	fs.planning.done = true
 	if err != nil {