X-Git-Url: https://git.giacomolli.uk/onechat/blobdiff_plain/baf7a940be8927278e3b4b87e7366cebfc16532f..0018014ab36f3de61a4b8a5515009dab803d6c38:/memory.go?ds=inline

diff --git a/memory.go b/memory.go
index 9846c98..0fd7d83 100644
--- a/memory.go
+++ b/memory.go
@@ -12,8 +12,14 @@ import (
 	"time"
 )
 
-// errMemoryNoView tells that a chat has messages but no saved view.
-var errMemoryNoView = errors.New("the chat has messages but no saved view")
+var (
+	// errMemoryNoView tells that a chat has messages but no saved view.
+	errMemoryNoView = errors.New("the chat has messages but no saved view")
+
+	// errMemoryUnsettled tells that a line of the view stays pending,
+	// because its build failed.
+	errMemoryUnsettled = errors.New("a summary of the view failed, and it is tried again at the next message")
+)
 
 // openMemory opens the chat in root and starts the builds that are ready. The
 // clock gives the dates of new messages and the days of new nodes. The builds
@@ -195,6 +201,34 @@ func (m *Memory) Wait(ctx context.Context) error {
 	}
 }
 
+// Settle returns when the chat view has no pending line, so that every message
+// so far is summarized. A pending line with no build that runs belongs to a
+// failed build, which waits for the next message, so Settle returns
+// errMemoryUnsettled in place of a wait that never ends.
+func (m *Memory) Settle(ctx context.Context) error {
+	for {
+		m.mutex.Lock()
+		pending := m.chat.Pending()
+		running := m.queue.Running()
+		changed := m.changed
+		m.mutex.Unlock()
+
+		if !pending {
+			return nil
+		}
+
+		if running == 0 {
+			return errMemoryUnsettled
+		}
+
+		select {
+		case <-changed:
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+}
+
 // Flush returns when every write before the call is durable.
 func (m *Memory) Flush(ctx context.Context) error {
 	return m.syncer.Flush(ctx)