Move SendPreloadRequest out of HistoryWidget.

Telegram/CMakeLists.txt

@@ -1097,6 +1097,8 @@ PRIVATE
     support/support_common.h
     support/support_helper.cpp
     support/support_helper.h
+    support/support_preload.cpp
+    support/support_preload.h
     support/support_templates.cpp
     support/support_templates.h
     ui/chat/attach/attach_item_single_file_preview.cpp

Telegram/SourceFiles/history/history_widget.cpp

@@ -143,6 +143,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "core/shortcuts.h"
 #include "support/support_common.h"
 #include "support/support_autocomplete.h"
+#include "support/support_preload.h"
 #include "dialogs/dialogs_key.h"
 #include "calls/calls_instance.h"
 #include "facades.h"
@@ -3387,59 +3388,10 @@ void HistoryWidget::checkSupportPreload(bool force) {
 	}
 	clearSupportPreloadRequest();
 	_supportPreloadHistory = history;
-	auto offsetId = MsgId();
+	_supportPreloadRequest = Support::SendPreloadRequest(history, [=] {
-	auto offset = 0;
+		_supportPreloadRequest = 0;
-	auto loadCount = kMessagesPerPage;
+		_supportPreloadHistory = nullptr;
-	if (const auto around = history->loadAroundId()) {
+		crl::on_main(this, [=] { checkSupportPreload(); });
-		history->getReadyFor(ShowAtUnreadMsgId);
-		offset = -loadCount / 2;
-		offsetId = around;
-	}
-	const auto offsetDate = 0;
-	const auto maxId = 0;
-	const auto minId = 0;
-	const auto historyHash = uint64(0);
-	const auto type = Data::Histories::RequestType::History;
-	auto &histories = history->owner().histories();
-	_supportPreloadRequest = histories.sendRequest(history, type, [=](Fn<void()> finish) {
-		return history->session().api().request(MTPmessages_GetHistory(
-			history->peer->input,
-			MTP_int(offsetId),
-			MTP_int(offsetDate),
-			MTP_int(offset),
-			MTP_int(loadCount),
-			MTP_int(maxId),
-			MTP_int(minId),
-			MTP_long(historyHash)
-		)).done([=](const MTPmessages_Messages &result) {
-			if (const auto around = history->loadAroundId()) {
-				if (around != offsetId) {
-					_supportPreloadRequest = 0;
-					_supportPreloadHistory = nullptr;
-					crl::on_main(this, [=] { checkSupportPreload(); });
-					return;
-				}
-				history->clear(History::ClearType::Unload);
-				history->getReadyFor(ShowAtUnreadMsgId);
-			} else if (offsetId) {
-				_supportPreloadRequest = 0;
-				_supportPreloadHistory = nullptr;
-				crl::on_main(this, [=] { checkSupportPreload(); });
-				return;
-			} else {
-				history->clear(History::ClearType::Unload);
-				history->getReadyFor(ShowAtTheEndMsgId);
-			}
-			result.match([](const MTPDmessages_messagesNotModified&) {
-			}, [&](const auto &data) {
-				history->owner().processUsers(data.vusers());
-				history->owner().processChats(data.vchats());
-				history->addOlderSlice(data.vmessages().v);
-			});
-			finish();
-		}).fail([=](const MTP::Error &error) {
-			finish();
-		}).send();
 	});
 }
 

Telegram/SourceFiles/support/support_preload.cpp

@@ -0,0 +1,77 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "support/support_preload.h"
+
+#include "history/history.h"
+#include "data/data_peer.h"
+#include "data/data_session.h"
+#include "data/data_histories.h"
+#include "main/main_session.h"
+#include "apiwrap.h"
+
+namespace Support {
+namespace {
+
+constexpr auto kPreloadMessagesCount = 50;
+
+} // namespace
+
+int SendPreloadRequest(not_null<History*> history, Fn<void()> retry) {
+	auto offsetId = MsgId();
+	auto offset = 0;
+	auto loadCount = kPreloadMessagesCount;
+	if (const auto around = history->loadAroundId()) {
+		history->getReadyFor(ShowAtUnreadMsgId);
+		offset = -loadCount / 2;
+		offsetId = around;
+	}
+	const auto offsetDate = 0;
+	const auto maxId = 0;
+	const auto minId = 0;
+	const auto historyHash = uint64(0);
+	const auto type = Data::Histories::RequestType::History;
+	auto &histories = history->owner().histories();
+	return histories.sendRequest(history, type, [=](Fn<void()> finish) {
+		return history->session().api().request(MTPmessages_GetHistory(
+			history->peer->input,
+			MTP_int(offsetId),
+			MTP_int(offsetDate),
+			MTP_int(offset),
+			MTP_int(loadCount),
+			MTP_int(maxId),
+			MTP_int(minId),
+			MTP_long(historyHash)
+		)).done([=](const MTPmessages_Messages &result) {
+			if (const auto around = history->loadAroundId()) {
+				if (around != offsetId) {
+					retry();
+					return;
+				}
+				history->clear(History::ClearType::Unload);
+				history->getReadyFor(ShowAtUnreadMsgId);
+			} else if (offsetId) {
+				retry();
+				return;
+			} else {
+				history->clear(History::ClearType::Unload);
+				history->getReadyFor(ShowAtTheEndMsgId);
+			}
+			result.match([](const MTPDmessages_messagesNotModified&) {
+			}, [&](const auto &data) {
+				history->owner().processUsers(data.vusers());
+				history->owner().processChats(data.vchats());
+				history->addOlderSlice(data.vmessages().v);
+			});
+			finish();
+		}).fail([=](const MTP::Error &error) {
+			finish();
+		}).send();
+	});
+}
+
+} // namespace Support

Telegram/SourceFiles/support/support_preload.h

@@ -0,0 +1,19 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+class History;
+
+namespace Support {
+
+// Returns histories().request, not api().request.
+[[nodiscard]] int SendPreloadRequest(
+	not_null<History*> history,
+	Fn<void()> retry);
+
+} // namespace Support