From 3506c78afcfcf63d74d1b57b53518ea27dae2f8c Mon Sep 17 00:00:00 2001
From: Christian Mollekopf <chrigi_1@fastmail.fm>
Date: Tue, 7 Mar 2017 14:56:03 +0100
Subject: Merge synchronization requests for individual mails of the same
 folder.

We use this frequently when loading conversations, so this results in a
significant preformance improvement.
---
 common/synchronizer.cpp                | 14 +++++++++----
 common/synchronizer.h                  |  5 +++++
 examples/imapresource/imapresource.cpp | 38 ++++++++++++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/common/synchronizer.cpp b/common/synchronizer.cpp
index b147615..fcdb5b8 100644
--- a/common/synchronizer.cpp
+++ b/common/synchronizer.cpp
@@ -252,15 +252,21 @@ void Synchronizer::modify(const DomainType &entity, const QByteArray &newResourc
 
 QList<Synchronizer::SyncRequest> Synchronizer::getSyncRequests(const Sink::QueryBase &query)
 {
-    QList<Synchronizer::SyncRequest> list;
-    list << Synchronizer::SyncRequest{query, "sync"};
-    return list;
+    return QList<Synchronizer::SyncRequest>() << Synchronizer::SyncRequest{query, "sync"};
+}
+
+void Synchronizer::mergeIntoQueue(const Synchronizer::SyncRequest &request, QList<Synchronizer::SyncRequest> &queue)
+{
+    mSyncRequestQueue << request;
 }
 
 void Synchronizer::synchronize(const Sink::QueryBase &query)
 {
     SinkTraceCtx(mLogCtx) << "Synchronizing";
-    mSyncRequestQueue << getSyncRequests(query);
+    auto newRequests = getSyncRequests(query);
+    for (const auto &request: newRequests) {
+        mergeIntoQueue(request, mSyncRequestQueue);
+    }
     processSyncQueue().exec();
 }
 
diff --git a/common/synchronizer.h b/common/synchronizer.h
index 120a8a5..af042cb 100644
--- a/common/synchronizer.h
+++ b/common/synchronizer.h
@@ -175,6 +175,11 @@ protected:
      */
     virtual QList<Synchronizer::SyncRequest> getSyncRequests(const Sink::QueryBase &query);
 
+    /**
+     * This allows the synchronizer to merge new requests with existing requests in the queue.
+     */
+    virtual void mergeIntoQueue(const Synchronizer::SyncRequest &request, QList<Synchronizer::SyncRequest> &queue);
+
 protected:
     Sink::Log::Context mLogCtx;
 private:
diff --git a/examples/imapresource/imapresource.cpp b/examples/imapresource/imapresource.cpp
index 09f57d5..fff4dc7 100644
--- a/examples/imapresource/imapresource.cpp
+++ b/examples/imapresource/imapresource.cpp
@@ -393,6 +393,44 @@ public:
         return list;
     }
 
+    QByteArray getFolderFromLocalId(const QByteArray &id)
+    {
+        auto mailRemoteId = syncStore().resolveLocalId(ApplicationDomain::getTypeName<ApplicationDomain::Mail>(), id);
+        return folderIdFromMailRid(mailRemoteId);
+    }
+
+    void mergeIntoQueue(const Synchronizer::SyncRequest &request, QList<Synchronizer::SyncRequest> &queue)  Q_DECL_OVERRIDE
+    {
+        auto isIndividualMailSync = [](const Synchronizer::SyncRequest &request) {
+            if (request.requestType == SyncRequest::Synchronization) {
+                const auto query = request.query;
+                if (query.type() == ApplicationDomain::getTypeName<ApplicationDomain::Mail>()) {
+                    return !query.ids().isEmpty();
+                }
+            }
+            return false;
+
+        };
+
+        if (isIndividualMailSync(request)) {
+            auto newId = request.query.ids().first();
+            auto requestFolder = getFolderFromLocalId(newId);
+            for (auto &r : queue) {
+                if (isIndividualMailSync(r)) {
+                    auto queueFolder = getFolderFromLocalId(r.query.ids().first());
+                    if (requestFolder == queueFolder) {
+                        //Merge
+                        r.query.filter(newId);
+                        SinkTrace() << "Merging request " << request.query;
+                        SinkTrace() << " to " << r.query;
+                        return;
+                    }
+                }
+            }
+        }
+        queue << request;
+    }
+
     KAsync::Job<void> login(QSharedPointer<ImapServerProxy> imap)
     {
         SinkTrace() << "Connecting to:" << mServer << mPort;
-- 
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