From 2860650859f611edbfbc9f1de73b848d1a1ba729 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20Gro=C3=9F?= <julian.g@posteo.de>
Date: Sun, 9 Jul 2023 21:01:23 +0200
Subject: [PATCH] Truncate logs read by FileLogger

---
 interface/src/ui/LogDialog.cpp                    |  3 ++-
 .../shared/src/shared/AbstractLoggerInterface.h   |  2 +-
 libraries/shared/src/shared/FileLogger.cpp        | 15 +++++++++++++--
 libraries/shared/src/shared/FileLogger.h          |  2 +-
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/interface/src/ui/LogDialog.cpp b/interface/src/ui/LogDialog.cpp
index f21b7ab43a..747183b0ec 100644
--- a/interface/src/ui/LogDialog.cpp
+++ b/interface/src/ui/LogDialog.cpp
@@ -321,7 +321,8 @@ void LogDialog::handleFilterDropdownChanged(int selection) {
 }
 
 QString LogDialog::getCurrentLog() {
-    return _logger->getLogData();
+    // We start 512 KiB from the end of the file.
+    return _logger->getLogData(524288);
 }
 
 void LogDialog::appendLogLine(QString logLine) {
diff --git a/libraries/shared/src/shared/AbstractLoggerInterface.h b/libraries/shared/src/shared/AbstractLoggerInterface.h
index f222442df9..d2314cf560 100644
--- a/libraries/shared/src/shared/AbstractLoggerInterface.h
+++ b/libraries/shared/src/shared/AbstractLoggerInterface.h
@@ -43,7 +43,7 @@ public:
     inline void setUnknownPrint(bool unknownPrint) { _unknownPrint = unknownPrint; }
 
     virtual void addMessage(const QString&) = 0;
-    virtual QString getLogData() = 0;
+    virtual QString getLogData(const qint64 maxSize = 0) = 0;
     virtual void locateLog() = 0;
     virtual void sync() {}
 
diff --git a/libraries/shared/src/shared/FileLogger.cpp b/libraries/shared/src/shared/FileLogger.cpp
index ae206e21b7..d467aed0f8 100644
--- a/libraries/shared/src/shared/FileLogger.cpp
+++ b/libraries/shared/src/shared/FileLogger.cpp
@@ -157,11 +157,22 @@ void FileLogger::locateLog() {
     FileUtils::locateFile(_fileName);
 }
 
-QString FileLogger::getLogData() {
+QString FileLogger::getLogData(const qint64 maxSize) {
     QString result;
     QFile f(_fileName);
     if (f.open(QFile::ReadOnly | QFile::Text)) {
-        result = QTextStream(&f).readAll();
+        if (maxSize != 0) {
+            f.seek(f.size() - maxSize);
+        }
+        QTextStream stream(&f);
+        if (maxSize != 0) {
+            // Continue one line, in case we are in the middle of a line.
+            stream.readLine();
+            result = "Log has been truncated to " + QString::number(maxSize) + " bytes.\n" + stream.readAll();
+        }
+        else {
+            result = stream.readAll();
+        }
     }
     return result;
 }
diff --git a/libraries/shared/src/shared/FileLogger.h b/libraries/shared/src/shared/FileLogger.h
index d9d7651147..72ab4bbb37 100644
--- a/libraries/shared/src/shared/FileLogger.h
+++ b/libraries/shared/src/shared/FileLogger.h
@@ -27,7 +27,7 @@ public:
     QString getFilename() const { return _fileName; }
     virtual void addMessage(const QString&) override;
     virtual void setSessionID(const QUuid&);
-    virtual QString getLogData() override;
+    virtual QString getLogData(const qint64 maxSize = 0) override;
     virtual void locateLog() override;
     virtual void sync() override;