[geary/mjog/invert-folder-class-hierarchy: 63/72] Geary.Imap.ClientConnection: Coalesce received_bytes signal emmission

[Michael Gratton <mjog src gnome org>]

commit 0ee85dee12785c397cbdaa5fe4218c8a780e6906
Author: Michael Gratton <mike vee net>
Date:   Sun Feb 28 20:04:36 2021 +1100

    Geary.Imap.ClientConnection: Coalesce received_bytes signal emmission
    
    Since `received_bytes` is emitted whenever a complete line is received
    from the server, it can be emitted a *lot*. To reduce the CPU overhead
    of this, and since it's only used for timekeeping at higher levels,
    coalesce emission to only occur at most once a second.

 src/engine/imap/transport/imap-client-connection.vala | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)
---
diff --git a/src/engine/imap/transport/imap-client-connection.vala 
b/src/engine/imap/transport/imap-client-connection.vala
index 390984e94..25156ec3a 100644
--- a/src/engine/imap/transport/imap-client-connection.vala
+++ b/src/engine/imap/transport/imap-client-connection.vala
@@ -73,6 +73,10 @@ public class Geary.Imap.ClientConnection : BaseObject, Logging.Source {
     private int tag_counter = 0;
     private char tag_prefix = 'a';
 
+    private int64 last_seen = 0;
+
+    private size_t bytes_accumulator = 0;
+
     private Geary.Nonblocking.Queue<Command> pending_queue =
         new Geary.Nonblocking.Queue<Command>.fifo();
     private Gee.Queue<Command> sent_queue = new Gee.LinkedList<Command>();
@@ -555,7 +559,17 @@ public class Geary.Imap.ClientConnection : BaseObject, Logging.Source {
     }
 
     private void on_bytes_received(size_t bytes) {
-        received_bytes(bytes);
+        // the deser's bytes_received signal can be called 10's of
+        // times per second, so avoid some CPU overhead by turning
+        // down the number of times per second it is emitted to higher
+        // levels.
+        this.bytes_accumulator += bytes;
+        var now = GLib.get_real_time();
+        if (this.last_seen + 1000000 <= now) {
+            received_bytes(this.bytes_accumulator);
+            this.bytes_accumulator = 0;
+            this.last_seen = now;
+        }
     }
 
     private void on_eos() {