Do not override previous attributes

The attributes available in the features struct contains more
information. We used to overwrite that by the less-interesting
data available in the attributes list.

Instead of doing this, check whether a given attribute was
encountered already. If so, don't report it a second time.

Change-Id: I308c3cf7ceeb8e6f0ca33de52ecfc1a63f62477d
Reviewed-by: Milian Wolff <milian.wolff@kdab.com>

1 files changed, 22 insertions, 9 deletions

diff --git a/app/perfunwind.cpp b/app/perfunwind.cpp
index 393e515..baeea39 100644
--- a/app/perfunwind.cpp
+++ b/app/perfunwind.cpp
@@ -236,18 +236,21 @@ void PerfUnwind::attr(const PerfRecordAttr &attr)
 void PerfUnwind::addAttributes(const PerfEventAttributes &attributes, const QByteArray &name,
                               const QList<quint64> &ids)
 {
-    const qint32 internalId = m_attributes.size();
-    m_attributes.append(attributes);
-    sendAttributes(internalId, attributes, name);
-
-    if (ids.isEmpty()) {
+    auto filteredIds = ids;
+    if (filteredIds.isEmpty()) {
         // If we only get one attribute, it doesn't have an ID.
         // The default ID for samples is 0, so we assign that here,
         // in order to look it up in analyze().
-        m_attributeIds[0] = internalId;
-    } else {
-        foreach (quint64 id, ids)
-            m_attributeIds[id] = internalId;
+        filteredIds = {0};
+    }
+
+    {
+        // remove attributes that are known already
+        auto it = std::remove_if(filteredIds.begin(), filteredIds.end(),
+                                 [this] (quint64 id) {
+                                     return m_attributeIds.contains(id);
+                                });
+        filteredIds.erase(it, filteredIds.end());
     }
 
     // Switch to dynamic buffering if it's a trace point
@@ -255,6 +258,16 @@ void PerfUnwind::addAttributes(const PerfEventAttributes &attributes, const QByt
         qDebug() << "Trace point attributes detected. Switching to dynamic buffering";
         revertTargetEventBufferSize();
     }
+
+    if (filteredIds.isEmpty())
+        return;
+
+    const qint32 internalId = m_attributes.size();
+    m_attributes.append(attributes);
+    sendAttributes(internalId, attributes, name);
+
+    foreach (quint64 id, filteredIds)
+        m_attributeIds[id] = internalId;
 }
 
 void PerfUnwind::sendAttributes(qint32 id, const PerfEventAttributes &attributes, const QByteArray &name)