Keep the README for the user

[onechat] / memory.go

diff --git a/memory.go b/memory.go
index 20f46d62ba6d50397cf6a0b7f892f8a59c2cf688..a240b6c16d1d898e3051f3e0a0c7a19434061b3e 100644 (file)
--- a/memory.go
+++ b/memory.go
@@ -149,6 +149,11 @@ func (m *Memory) AppendDated(kind, text, date string) (Message, error) {
        m.mutex.Lock()
        defer m.mutex.Unlock()
 
        m.mutex.Lock()
        defer m.mutex.Unlock()
 

+       return m.appendDated(kind, text, date)
+}
+
+// appendDated appends under the memory lock and updates the views and builds.
+func (m *Memory) appendDated(kind, text, date string) (Message, error) {

        message, err := m.log.AppendDated(kind, text, date)
        if err != nil {
                return Message{}, fmt.Errorf("append dated log message: %w", err)
        message, err := m.log.AppendDated(kind, text, date)
        if err != nil {
                return Message{}, fmt.Errorf("append dated log message: %w", err)


@@ -172,6 +177,44 @@ func (m *Memory) AppendDated(kind, text, date string) (Message, error) {
        return message, nil
 }
 
        return message, nil
 }
 

+// AppendOnce appends a queued message. prepare saves its log ID before the
+// append, under the memory lock. A saved ID permits recovery after a stop
+// between that save and the append, without a second log entry. prepare must
+// not call Memory. The caller stops delivery after a failed append.
+func (m *Memory) AppendOnce(kind, text string, id *int, prepare func(int) error) (Message, error) {
+       m.mutex.Lock()
+       defer m.mutex.Unlock()
+
+       if id != nil && *id < m.log.Len() {
+               message, err := m.log.Message(*id)
+               if err != nil {
+                       return Message{}, fmt.Errorf("read queued message: %w", err)
+               }
+
+               if message.Kind != kind || message.Text != text {
+                       return Message{}, errors.New("queued message does not match its log entry")
+               }
+
+               return message, nil
+       }
+
+       if id != nil && *id != m.log.Len() {
+               return Message{}, errors.New("queued message is beyond the log")
+       }
+
+       err := prepare(m.log.Len())
+       if err != nil {
+               return Message{}, fmt.Errorf("prepare queued message: %w", err)
+       }
+
+       message, err := m.appendDated(kind, text, "")
+       if err != nil {
+               return Message{}, fmt.Errorf("append queued message: %w", err)
+       }
+
+       return message, nil
+}
+

 // children reads the two children of the node key.
 func (m *Memory) children(key NodeKey) (Node, Node, error) {
        var children [2]Node
 // children reads the two children of the node key.
 func (m *Memory) children(key NodeKey) (Node, Node, error) {
        var children [2]Node


@@ -247,6 +290,26 @@ func (m *Memory) Flush(ctx context.Context) error {
        return m.syncer.Flush(ctx)
 }
 
        return m.syncer.Flush(ctx)
 }
 

+// Snapshot flushes all memory writes and runs snapshot while no append or
+// summary write can change the log, indexes, tree, or views. snapshot must not
+// call Memory.
+func (m *Memory) Snapshot(ctx context.Context, snapshot func() error) error {
+       m.mutex.Lock()
+       defer m.mutex.Unlock()
+
+       err := m.Flush(ctx)
+       if err != nil {
+               return fmt.Errorf("flush memory snapshot: %w", err)
+       }
+
+       err = snapshot()
+       if err != nil {
+               return fmt.Errorf("copy memory snapshot: %w", err)
+       }
+
+       return nil
+}
+

 // ViewLines returns the lines of the chat view, each with its newline, without
 // the leaf lines of the messages in skip.
 func (m *Memory) ViewLines(skip map[int]bool) []string {
 // ViewLines returns the lines of the chat view, each with its newline, without
 // the leaf lines of the messages in skip.
 func (m *Memory) ViewLines(skip map[int]bool) []string {