[geary] Increase window size during background prefetch

[Jim Nelson <jnelson src gnome org>]

commit 1b62b3b6ec8bd2882611038ca4cef1abb84d8d80
Author: Jim Nelson <jim yorba org>
Date:   Tue Apr 15 12:10:41 2014 -0700

    Increase window size during background prefetch
    
    This will speed up the process of synchronizing with the server at
    the cost of increasing delays when the user requests immediate
    information, but experience shows this is worth it.
    
    This also fixes a minor bug where closing the folder is not detected
    during prefetch.

 .../imap-engine/imap-engine-email-prefetcher.vala  |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)
---
diff --git a/src/engine/imap-engine/imap-engine-email-prefetcher.vala 
b/src/engine/imap-engine/imap-engine-email-prefetcher.vala
index 13a2c44..4fd3a47 100644
--- a/src/engine/imap-engine/imap-engine-email-prefetcher.vala
+++ b/src/engine/imap-engine/imap-engine-email-prefetcher.vala
@@ -14,11 +14,9 @@
 private class Geary.ImapEngine.EmailPrefetcher : Object {
     public const int PREFETCH_DELAY_SEC = 1;
     
-    // Don't fetch FLAGS; those are fetched by the FlagWatcher and during normalization when a
-    // standard open_async() is invoked on the Folder
     private const Geary.Email.Field PREFETCH_FIELDS = Geary.Email.Field.ALL;
     private const int PREFETCH_IDS_CHUNKS = 500;
-    private const int PREFETCH_CHUNK_BYTES = 8 * 1024;
+    private const int PREFETCH_CHUNK_BYTES = 32 * 1024;
     
     public Nonblocking.CountingSemaphore active_sem { get; private set;
         default = new Nonblocking.CountingSemaphore(null); }
@@ -227,7 +225,7 @@ private class Geary.ImapEngine.EmailPrefetcher : Object {
         debug("finished do_prefetch_batch_async %s end_total=%d", folder.to_string(), count);
     }
     
-    // Return true to continue, false to stop prefetching (cancelled)
+    // Return true to continue, false to stop prefetching (cancelled or not open)
     private async bool do_prefetch_email_async(Gee.Collection<Geary.EmailIdentifier> ids, int64 chunk_bytes) 
{
         debug("do_prefetch_email_async: %s prefetching %d emails (%sb)", folder.to_string(),
             ids.size, chunk_bytes.to_string());
@@ -236,11 +234,11 @@ private class Geary.ImapEngine.EmailPrefetcher : Object {
             yield folder.list_email_by_sparse_id_async(ids, PREFETCH_FIELDS, Folder.ListFlags.NONE,
                 cancellable);
         } catch (Error err) {
-            if (!(err is IOError.CANCELLED)) {
+            if (!(err is IOError.CANCELLED) && !(err is EngineError.OPEN_REQUIRED)) {
                 debug("Error prefetching %d emails for %s: %s", ids.size, folder.to_string(),
                     err.message);
             } else {
-                // only exit if cancelled; fetch_email_async() can error out on lots of things,
+                // only exit if cancelled or not open; fetch_email_async() can error out on lots of things,
                 // including mail that's been deleted, and that shouldn't stop the prefetcher
                 return false;
             }